SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 PM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...TX... HERMINE IS EXPECTED TO MOVE ONSHORE LATE DAY1 NEAR BRO THEN TRACK INTO CNTRL TX BEFORE CURVING INTO THE SRN PLAINS LATE. GIVEN THE INTENSITY OF THIS TROPICAL SYSTEM...LOW-MID LEVEL SHEAR WILL BECOME FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS ACROSS THE MIDDLE TX COAST INTO THE HILL COUNTRY OF CNTRL TX...PRIMARILY THE ERN PERIPHERY OF THE CYCLONE. FORECAST SOUNDINGS SUGGEST SUPERCELL STRUCTURES ARE POSSIBLE THUS WILL MAINTAIN A 5% PROBABILITY FOR ISOLATED TORNADOES WITH THIS SYSTEM. WILL ADJUST THE 5% RISK INLAND TO REFLECT EXPECTED STORM TRACK. ...OH VALLEY... FAST MOVING SHORTWAVE TROUGH WILL EJECT ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES DURING THE DAY WITH MEANINGFUL HEIGHT FALLS EXPECTED TO OVERSPREAD THE REGION PRIMARILY NORTH OF I-70. FRONTAL CONVERGENCE AND STRONG BOUNDARY LAYER HEATING SHOULD PROVE ADEQUATE FOR AT LEAST ISOLATED THUNDERSTORMS WITHIN DEEP WSWLY FLOW. WHILE MARGINAL LOW LEVEL MOISTURE AND WEAK MID LEVEL LAPSE RATES WILL LIMIT INSTABILITY ACROSS THIS REGION A STORMS MAY PRODUCE GUSTY WINDS WITHIN AN OTHERWISE MODESTLY SHEARED ENVIRONMENT WHERE SFC TEMPERATURES ARE EXPECTED TO WARM TO NEAR 90F. ..DARROW.. 09/06/2010 Read more

SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 PM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...TX... HERMINE IS EXPECTED TO MOVE ONSHORE LATE DAY1 NEAR BRO THEN TRACK INTO CNTRL TX BEFORE CURVING INTO THE SRN PLAINS LATE. GIVEN THE INTENSITY OF THIS TROPICAL SYSTEM...LOW-MID LEVEL SHEAR WILL BECOME FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS ACROSS THE MIDDLE TX COAST INTO THE HILL COUNTRY OF CNTRL TX...PRIMARILY THE ERN PERIPHERY OF THE CYCLONE. FORECAST SOUNDINGS SUGGEST SUPERCELL STRUCTURES ARE POSSIBLE THUS WILL MAINTAIN A 5% PROBABILITY FOR ISOLATED TORNADOES WITH THIS SYSTEM. WILL ADJUST THE 5% RISK INLAND TO REFLECT EXPECTED STORM TRACK. ...OH VALLEY... FAST MOVING SHORTWAVE TROUGH WILL EJECT ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES DURING THE DAY WITH MEANINGFUL HEIGHT FALLS EXPECTED TO OVERSPREAD THE REGION PRIMARILY NORTH OF I-70. FRONTAL CONVERGENCE AND STRONG BOUNDARY LAYER HEATING SHOULD PROVE ADEQUATE FOR AT LEAST ISOLATED THUNDERSTORMS WITHIN DEEP WSWLY FLOW. WHILE MARGINAL LOW LEVEL MOISTURE AND WEAK MID LEVEL LAPSE RATES WILL LIMIT INSTABILITY ACROSS THIS REGION A STORMS MAY PRODUCE GUSTY WINDS WITHIN AN OTHERWISE MODESTLY SHEARED ENVIRONMENT WHERE SFC TEMPERATURES ARE EXPECTED TO WARM TO NEAR 90F. ..DARROW.. 09/06/2010 Read more

SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 PM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO SVR TSTM AREAS FORECAST... ...TX... HERMINE IS EXPECTED TO MOVE ONSHORE LATE DAY1 NEAR BRO THEN TRACK INTO CNTRL TX BEFORE CURVING INTO THE SRN PLAINS LATE. GIVEN THE INTENSITY OF THIS TROPICAL SYSTEM...LOW-MID LEVEL SHEAR WILL BECOME FAVORABLE FOR SUSTAINED ROTATING UPDRAFTS ACROSS THE MIDDLE TX COAST INTO THE HILL COUNTRY OF CNTRL TX...PRIMARILY THE ERN PERIPHERY OF THE CYCLONE. FORECAST SOUNDINGS SUGGEST SUPERCELL STRUCTURES ARE POSSIBLE THUS WILL MAINTAIN A 5% PROBABILITY FOR ISOLATED TORNADOES WITH THIS SYSTEM. WILL ADJUST THE 5% RISK INLAND TO REFLECT EXPECTED STORM TRACK. ...OH VALLEY... FAST MOVING SHORTWAVE TROUGH WILL EJECT ACROSS THE UPPER MS VALLEY INTO THE GREAT LAKES DURING THE DAY WITH MEANINGFUL HEIGHT FALLS EXPECTED TO OVERSPREAD THE REGION PRIMARILY NORTH OF I-70. FRONTAL CONVERGENCE AND STRONG BOUNDARY LAYER HEATING SHOULD PROVE ADEQUATE FOR AT LEAST ISOLATED THUNDERSTORMS WITHIN DEEP WSWLY FLOW. WHILE MARGINAL LOW LEVEL MOISTURE AND WEAK MID LEVEL LAPSE RATES WILL LIMIT INSTABILITY ACROSS THIS REGION A STORMS MAY PRODUCE GUSTY WINDS WITHIN AN OTHERWISE MODESTLY SHEARED ENVIRONMENT WHERE SFC TEMPERATURES ARE EXPECTED TO WARM TO NEAR 90F. ..DARROW.. 09/06/2010 Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1139 AM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO CRITICAL AREAS... ...PORTIONS OF CNTRL/ERN NV... MODEL DIFFERENCES DISCUSSED IN PREVIOUS D2 FORECAST CONTINUE TO BE OBSERVED. THEREFORE...NO CHANGES WILL BE MADE ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... NO CHANGES MADE TO THE PREVIOUS FORECAST. ...SRN LOWER MI... NO CHANGES MADE TO THE PREVIOUS FORECAST. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... NO CHANGES MADE TO THE PREVIOUS FORECAST. ..GARNER.. 09/06/2010 .PREV DISCUSSION... /ISSUED 0456 AM CDT MON SEP 06 2010/ ...SYNOPSIS... POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE UPPER MS VALLEY WILL TRANSLATE EWD ACROSS THE GREAT LAKES/SRN ONTARIO THROUGH EARLY WED. ATTENDANT SURFACE COLD FRONT WILL MARCH EWD ACROSS THE UPPER GREAT LAKES AND MIDWEST BY TUE AFTERNOON. IN THE WEST...A LARGE-SCALE UPPER-LEVEL TROUGH WILL BECOME ANCHORED ACROSS THE PACIFIC NW INTO NRN CA. ...PORTIONS OF CNTRL/ERN NV... LATEST MODEL FORECASTS ARE FAIRLY CONSISTENT WITH THE DEPICTION OF A WEAK MID-LEVEL IMPULSE EJECTING OUT AHEAD OF A LARGE-SCALE TROUGH AMPLIFYING OVER THE PACIFIC NW. ASSOCIATED SPEED MAX WILL AID IN STRENGTHENING BOUNDARY LAYER FLOW TUE AFTERNOON. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING. 06Z NAM AND ASSOCIATED WRF MEMBERS IN THE 03Z SREF APPEAR STRONGER THAN 00Z GFS/ECMWF GUIDANCE. IN ADDITION...BOTH THE GFS/ECMWF INDICATE MORE ROBUST SUB-TROPICAL MOISTURE EMANATING NWD FROM NWRN MEXICO/AZ...SUGGESTING THE JUXTAPOSITION OF STRONG WINDS/LOW RH WOULD BE NARROW BOTH SPATIALLY AND TEMPORALLY. AS SUCH...CONFIDENCE IS LOWER THAN AVERAGE FOR DELINEATING A CRITICAL AREA ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... LOW/MID-LEVEL SWLYS WILL STRENGTHEN WITH APPROACH OF AN UPPER-LEVEL TROUGH DIGGING ACROSS THE PACIFIC NW. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING DURING THE DIURNAL HEATING CYCLE...WITH THE NAM/WRF-BASED SREF MEMBERS STRONGER THAN THE GFS/ECMWF. CONSENSUS OF MODEL GUIDANCE SUGGESTS THE STRONGEST FLOW WILL DEVELOP DURING THE EARLY EVENING WHICH MAY MARGINALIZE THE DURATION OF POTENTIALLY STRONG WINDS OVERLAPPING WITH LOW RH. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY DELINEATE A CRITICAL AREA ATTM. ...SRN LOWER MI... A SHORT-DURATION PERIOD OF CRITICAL CONDITIONS MAY DEVELOP DURING MID AFTERNOON ON TUE. CONSENSUS OF MODEL GUIDANCE INDICATES SUBSTANTIAL LOWER-TROPOSPHERIC DRYING WILL OCCUR AS A MID-LEVEL DRY SLOT OVERSPREADS THE UPPER GREAT LAKES AND A SURFACE COLD FRONT PUSHES EWD TOWARDS THE LOWER GREAT LAKES. RH VALUES SHOULD BECOME MARGINALLY LOW FOR A FEW HOURS /FROM 25 TO 35 PERCENT/ UNTIL MORE PRONOUNCED COOLING OCCURS LATE IN THE DAY. WITH 40 TO 50 MPH LOW-LEVEL FLOW...SUSTAINED SURFACE WINDS OF 25 TO 30 MPH APPEAR LIKELY. RAINFALL DURING THE PAST WEEK AND THE SHORT DURATION OF MARGINALLY LOW RH SHOULD HELP MITIGATE THE OVERALL THREAT. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... MARGINAL FIRE WEATHER CONDITIONS SHOULD DEVELOP TUE AFTERNOON AS A RELATIVELY WARM/DRY AIR MASS REMAINS WITHIN A NARROW SW TO NE CORRIDOR DOWNSTREAM OF AN APPROACHING COLD FRONT. AS SWLY LOW-LEVEL FLOW INCREASES...SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/. ABOVE-NORMAL TEMPERATURES IN THE MIDDLE 80S TO LOWER 90S WILL SUPPORT RH VALUES BECOMING MARGINALLY LOW /AROUND 25 TO 30 PERCENT/. GIVEN BELOW-NORMAL RAINFALL ACROSS THE REGION DURING THE PAST FEW WEEKS...AN ENHANCED FIRE WEATHER THREAT APPEARS PROBABLE. ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1139 AM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO CRITICAL AREAS... ...PORTIONS OF CNTRL/ERN NV... MODEL DIFFERENCES DISCUSSED IN PREVIOUS D2 FORECAST CONTINUE TO BE OBSERVED. THEREFORE...NO CHANGES WILL BE MADE ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... NO CHANGES MADE TO THE PREVIOUS FORECAST. ...SRN LOWER MI... NO CHANGES MADE TO THE PREVIOUS FORECAST. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... NO CHANGES MADE TO THE PREVIOUS FORECAST. ..GARNER.. 09/06/2010 .PREV DISCUSSION... /ISSUED 0456 AM CDT MON SEP 06 2010/ ...SYNOPSIS... POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE UPPER MS VALLEY WILL TRANSLATE EWD ACROSS THE GREAT LAKES/SRN ONTARIO THROUGH EARLY WED. ATTENDANT SURFACE COLD FRONT WILL MARCH EWD ACROSS THE UPPER GREAT LAKES AND MIDWEST BY TUE AFTERNOON. IN THE WEST...A LARGE-SCALE UPPER-LEVEL TROUGH WILL BECOME ANCHORED ACROSS THE PACIFIC NW INTO NRN CA. ...PORTIONS OF CNTRL/ERN NV... LATEST MODEL FORECASTS ARE FAIRLY CONSISTENT WITH THE DEPICTION OF A WEAK MID-LEVEL IMPULSE EJECTING OUT AHEAD OF A LARGE-SCALE TROUGH AMPLIFYING OVER THE PACIFIC NW. ASSOCIATED SPEED MAX WILL AID IN STRENGTHENING BOUNDARY LAYER FLOW TUE AFTERNOON. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING. 06Z NAM AND ASSOCIATED WRF MEMBERS IN THE 03Z SREF APPEAR STRONGER THAN 00Z GFS/ECMWF GUIDANCE. IN ADDITION...BOTH THE GFS/ECMWF INDICATE MORE ROBUST SUB-TROPICAL MOISTURE EMANATING NWD FROM NWRN MEXICO/AZ...SUGGESTING THE JUXTAPOSITION OF STRONG WINDS/LOW RH WOULD BE NARROW BOTH SPATIALLY AND TEMPORALLY. AS SUCH...CONFIDENCE IS LOWER THAN AVERAGE FOR DELINEATING A CRITICAL AREA ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... LOW/MID-LEVEL SWLYS WILL STRENGTHEN WITH APPROACH OF AN UPPER-LEVEL TROUGH DIGGING ACROSS THE PACIFIC NW. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING DURING THE DIURNAL HEATING CYCLE...WITH THE NAM/WRF-BASED SREF MEMBERS STRONGER THAN THE GFS/ECMWF. CONSENSUS OF MODEL GUIDANCE SUGGESTS THE STRONGEST FLOW WILL DEVELOP DURING THE EARLY EVENING WHICH MAY MARGINALIZE THE DURATION OF POTENTIALLY STRONG WINDS OVERLAPPING WITH LOW RH. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY DELINEATE A CRITICAL AREA ATTM. ...SRN LOWER MI... A SHORT-DURATION PERIOD OF CRITICAL CONDITIONS MAY DEVELOP DURING MID AFTERNOON ON TUE. CONSENSUS OF MODEL GUIDANCE INDICATES SUBSTANTIAL LOWER-TROPOSPHERIC DRYING WILL OCCUR AS A MID-LEVEL DRY SLOT OVERSPREADS THE UPPER GREAT LAKES AND A SURFACE COLD FRONT PUSHES EWD TOWARDS THE LOWER GREAT LAKES. RH VALUES SHOULD BECOME MARGINALLY LOW FOR A FEW HOURS /FROM 25 TO 35 PERCENT/ UNTIL MORE PRONOUNCED COOLING OCCURS LATE IN THE DAY. WITH 40 TO 50 MPH LOW-LEVEL FLOW...SUSTAINED SURFACE WINDS OF 25 TO 30 MPH APPEAR LIKELY. RAINFALL DURING THE PAST WEEK AND THE SHORT DURATION OF MARGINALLY LOW RH SHOULD HELP MITIGATE THE OVERALL THREAT. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... MARGINAL FIRE WEATHER CONDITIONS SHOULD DEVELOP TUE AFTERNOON AS A RELATIVELY WARM/DRY AIR MASS REMAINS WITHIN A NARROW SW TO NE CORRIDOR DOWNSTREAM OF AN APPROACHING COLD FRONT. AS SWLY LOW-LEVEL FLOW INCREASES...SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/. ABOVE-NORMAL TEMPERATURES IN THE MIDDLE 80S TO LOWER 90S WILL SUPPORT RH VALUES BECOMING MARGINALLY LOW /AROUND 25 TO 30 PERCENT/. GIVEN BELOW-NORMAL RAINFALL ACROSS THE REGION DURING THE PAST FEW WEEKS...AN ENHANCED FIRE WEATHER THREAT APPEARS PROBABLE. ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1139 AM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO CRITICAL AREAS... ...PORTIONS OF CNTRL/ERN NV... MODEL DIFFERENCES DISCUSSED IN PREVIOUS D2 FORECAST CONTINUE TO BE OBSERVED. THEREFORE...NO CHANGES WILL BE MADE ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... NO CHANGES MADE TO THE PREVIOUS FORECAST. ...SRN LOWER MI... NO CHANGES MADE TO THE PREVIOUS FORECAST. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... NO CHANGES MADE TO THE PREVIOUS FORECAST. ..GARNER.. 09/06/2010 .PREV DISCUSSION... /ISSUED 0456 AM CDT MON SEP 06 2010/ ...SYNOPSIS... POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE UPPER MS VALLEY WILL TRANSLATE EWD ACROSS THE GREAT LAKES/SRN ONTARIO THROUGH EARLY WED. ATTENDANT SURFACE COLD FRONT WILL MARCH EWD ACROSS THE UPPER GREAT LAKES AND MIDWEST BY TUE AFTERNOON. IN THE WEST...A LARGE-SCALE UPPER-LEVEL TROUGH WILL BECOME ANCHORED ACROSS THE PACIFIC NW INTO NRN CA. ...PORTIONS OF CNTRL/ERN NV... LATEST MODEL FORECASTS ARE FAIRLY CONSISTENT WITH THE DEPICTION OF A WEAK MID-LEVEL IMPULSE EJECTING OUT AHEAD OF A LARGE-SCALE TROUGH AMPLIFYING OVER THE PACIFIC NW. ASSOCIATED SPEED MAX WILL AID IN STRENGTHENING BOUNDARY LAYER FLOW TUE AFTERNOON. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING. 06Z NAM AND ASSOCIATED WRF MEMBERS IN THE 03Z SREF APPEAR STRONGER THAN 00Z GFS/ECMWF GUIDANCE. IN ADDITION...BOTH THE GFS/ECMWF INDICATE MORE ROBUST SUB-TROPICAL MOISTURE EMANATING NWD FROM NWRN MEXICO/AZ...SUGGESTING THE JUXTAPOSITION OF STRONG WINDS/LOW RH WOULD BE NARROW BOTH SPATIALLY AND TEMPORALLY. AS SUCH...CONFIDENCE IS LOWER THAN AVERAGE FOR DELINEATING A CRITICAL AREA ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... LOW/MID-LEVEL SWLYS WILL STRENGTHEN WITH APPROACH OF AN UPPER-LEVEL TROUGH DIGGING ACROSS THE PACIFIC NW. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING DURING THE DIURNAL HEATING CYCLE...WITH THE NAM/WRF-BASED SREF MEMBERS STRONGER THAN THE GFS/ECMWF. CONSENSUS OF MODEL GUIDANCE SUGGESTS THE STRONGEST FLOW WILL DEVELOP DURING THE EARLY EVENING WHICH MAY MARGINALIZE THE DURATION OF POTENTIALLY STRONG WINDS OVERLAPPING WITH LOW RH. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY DELINEATE A CRITICAL AREA ATTM. ...SRN LOWER MI... A SHORT-DURATION PERIOD OF CRITICAL CONDITIONS MAY DEVELOP DURING MID AFTERNOON ON TUE. CONSENSUS OF MODEL GUIDANCE INDICATES SUBSTANTIAL LOWER-TROPOSPHERIC DRYING WILL OCCUR AS A MID-LEVEL DRY SLOT OVERSPREADS THE UPPER GREAT LAKES AND A SURFACE COLD FRONT PUSHES EWD TOWARDS THE LOWER GREAT LAKES. RH VALUES SHOULD BECOME MARGINALLY LOW FOR A FEW HOURS /FROM 25 TO 35 PERCENT/ UNTIL MORE PRONOUNCED COOLING OCCURS LATE IN THE DAY. WITH 40 TO 50 MPH LOW-LEVEL FLOW...SUSTAINED SURFACE WINDS OF 25 TO 30 MPH APPEAR LIKELY. RAINFALL DURING THE PAST WEEK AND THE SHORT DURATION OF MARGINALLY LOW RH SHOULD HELP MITIGATE THE OVERALL THREAT. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... MARGINAL FIRE WEATHER CONDITIONS SHOULD DEVELOP TUE AFTERNOON AS A RELATIVELY WARM/DRY AIR MASS REMAINS WITHIN A NARROW SW TO NE CORRIDOR DOWNSTREAM OF AN APPROACHING COLD FRONT. AS SWLY LOW-LEVEL FLOW INCREASES...SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/. ABOVE-NORMAL TEMPERATURES IN THE MIDDLE 80S TO LOWER 90S WILL SUPPORT RH VALUES BECOMING MARGINALLY LOW /AROUND 25 TO 30 PERCENT/. GIVEN BELOW-NORMAL RAINFALL ACROSS THE REGION DURING THE PAST FEW WEEKS...AN ENHANCED FIRE WEATHER THREAT APPEARS PROBABLE. ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1134 AM CDT MON SEP 06 2010 VALID 061700Z - 071200Z ...NO CRITICAL AREAS... ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... MID MORNING SURFACE OBSERVATIONS AND OBJECTIVE ANALYSIS GUIDANCE SHOW LOW PRESSURE MOVING NEWD ACROSS SRN NEB...WITH A COLD FRONT TRAILING SWWD INTO WRN KS AND ERN CO. WIND SPEEDS AOA 20 MPH ARE OBSERVED IN THE WAKE OF THE FRONT AT 15Z...AND ARE FORECAST BY LATEST MODEL GUIDANCE TO SUBSIDE DURING THE AFTERNOON AS POST FRONTAL PRESSURE GRADIENT BEGINS TO RELAX. AS THIS TAKES PLACE...A BRIEF PERIOD OF CRITICALLY LOW RH VALUES /15-20 PERCENT/ MAY OVERLAP THE STRONG SUSTAINED WINDS...LEADING TO AN HR OR TWO OF LOCALLY CRITICAL FIRE WEATHER CONDITIONS DURING THE LATE MORNING/EARLY AFTERNOON OVER N-CNTRL CO AND SERN WY. FARTHER E OVER WRN NEB/KS...MODEL GUIDANCE CONTINUES TO INDICATE A LONGER DURATION OF STRONG N/NWLY WINDS...BUT ALSO SHOWS SLIGHTLY MORE MARGINAL RH VALUES /GENERALLY AOA 20 PERCENT/. THEREFORE...NO CHANGES HAVE BEEN MADE TO THE PREVIOUS FORECAST. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... PREVIOUS FORECAST APPEARS TO BE ON TRACK. MORNING SURFACE AND UPPER AIR OBSERVATIONS...IN ADDITION TO LATEST MODEL GUIDANCE INDICATE NEAR TO LOCALLY CRITICAL FIRE WEATHER CONDITIONS ARE LIKELY ACROSS THE MID SOUTH REGION. THIS IS PARTICULARLY TRUE FOR SERN MO...SRN IL AND SRN IND...WHERE SUSTAINED WIND SPEEDS OF 15 MPH ARE EXPECTED TO OVERLAP CRITICALLY LOW RH VALUES /15 TO 25 PERCENT/ FOR A FEW HOURS. ...NRN SACRAMENTO VALLEY OF NRN CA... NO CHANGES MADE TO THE PREVIOUS FORECAST. ..GARNER.. 09/06/2010 .PREV DISCUSSION... /ISSUED 0236 AM CDT MON SEP 06 2010/ ...SYNOPSIS... A VIGOROUS UPPER-LEVEL SHORT WAVE TROUGH WILL PROGRESS EWD FROM THE NRN HIGH PLAINS/CNTRL ROCKIES TOWARDS THE UPPER MS VALLEY THROUGH EARLY TUE. ATTENDANT SURFACE CYCLONE OVER THE CNTRL HIGH PLAINS WILL TRACK NEWD TO MN...WHILE A COLD FRONT PUSHES SEWD ACROSS THE CNTRL HIGH PLAINS INTO THE OK/TX PANHANDLES BY EARLY EVENING. IN THE WEST...AN UPPER-LEVEL SHORT WAVE TROUGH WILL DIG ALONG THE BRITISH COLUMBIA COAST WITH A SURFACE RIDGE WEAKENING OVER THE PACIFIC NW. ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... AREAS OF SHORT-DURATION CRITICAL CONDITIONS TO LONGER-DURATION MARGINAL CONDITIONS APPEAR PROBABLE FROM LATER THIS MORNING INTO THE AFTERNOON. RELATIVELY LARGE SPREAD PERSISTS AMONGST LATEST NAM/GFS/SREF GUIDANCE WITH THE DEGREE OF DRYING OCCURRING IN THE WAKE OF A COLD FRONT PASSAGE THIS MORNING. 00Z NAM AND 03Z SREF MEAN INDICATE CRITICALLY LOW RH VALUES WILL BE RELEGATED TO ALONG THE LEE OF THE FRONT RANGE IN N-CNTRL CO...WHILE THE 00Z GFS SUGGESTS LOW RH WILL ALSO BE PREVALENT TO THE N/E ACROSS SERN WY INTO WRN NEB/KS. MODEL FORECASTS ARE MORE CONSISTENT WITH THE DEPICTION OF A SURGE IN LOW-LEVEL W/NWLYS ACCOMPANYING SHORT WAVE TROUGH PASSAGE LATER THIS MORNING. THIS SHOULD LEAD TO A FEW HOURS OF CRITICAL CONDITIONS AROUND NOON ALONG THE FRONT RANGE IN N-CNTRL CO...PRIOR TO WINDS DIMINISHING THROUGH THE AFTERNOON AS A SURFACE RIDGE QUICKLY BUILDS ACROSS THE HIGH PLAINS. FARTHER E INTO WRN NEB/KS...LONGER DURATIONS OF STRONG N/NWLY WINDS /FROM 20 TO 30 MPH/ APPEAR LIKELY. HOWEVER...BASED ON UPSTREAM OBSERVATIONS OF MUCH COOLER/HIGHER RH VALUES...AFTERNOON RH VALUES MAY ONLY BECOME MARGINALLY LOW /FROM 20 TO 30 PERCENT/. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... AN ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP THIS AFTERNOON AS SLY SURFACE WINDS INCREASE WITHIN AN ANTECEDENT WARM/DRY AIR MASS ACROSS THE LOWER MS/OH VALLEY...WHERE ABNORMAL DRYNESS AND MODERATE DROUGHT PERSIST. MODEL FORECASTS REMAIN HIGHLY CONSISTENT THAT TEMPERATURES WILL WARM INTO THE MIDDLE TO UPPER 80S...WITH RH VALUES DROPPING TO BETWEEN 18 AND 25 PERCENT. ALTHOUGH S/SWLY LOW-LEVEL WINDS WILL STRENGTHEN...THIS REGION OF LOW RH VALUES SHOULD REMAIN TO THE E/SE OF STRONGER LOW-LEVEL FLOW CENTERED OVER THE MID-MO VALLEY. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/...WITH GUSTS TO AROUND 25 MPH. ...NRN SACRAMENTO VALLEY OF NRN CA... RECENT MESONET OBSERVATIONS CONFIRM AREAS OF GUSTY NLY WINDS /AROUND 2O TO 30 MPH/ OCCURRING ACROSS THE NRN SACRAMENTO VALLEY AND SURROUNDING FOOTHILLS. THIS HAS SUPPORTED POOR OVERNIGHT RH RECOVERY...WITH 12 TO 20 PERCENT READINGS COMMON AS OF 07Z. AS THE TIGHT LOW-LEVEL PRESSURE GRADIENT RELAXES WITH THE RIDGE AXIS OVER THE PACIFIC NW WEAKENING...WINDS WILL GRADUALLY DIMINISH DURING THE LATE MORNING/EARLY AFTERNOON AND SHOULD REMAIN WEAK THROUGH THE REST OF THE PERIOD. NEVERTHELESS...LONG DURATIONS OF LOW RH APPEAR LIKELY WITH MIN VALUES NEAR 5 PERCENT AT PEAK HEATING. ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1134 AM CDT MON SEP 06 2010 VALID 061700Z - 071200Z ...NO CRITICAL AREAS... ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... MID MORNING SURFACE OBSERVATIONS AND OBJECTIVE ANALYSIS GUIDANCE SHOW LOW PRESSURE MOVING NEWD ACROSS SRN NEB...WITH A COLD FRONT TRAILING SWWD INTO WRN KS AND ERN CO. WIND SPEEDS AOA 20 MPH ARE OBSERVED IN THE WAKE OF THE FRONT AT 15Z...AND ARE FORECAST BY LATEST MODEL GUIDANCE TO SUBSIDE DURING THE AFTERNOON AS POST FRONTAL PRESSURE GRADIENT BEGINS TO RELAX. AS THIS TAKES PLACE...A BRIEF PERIOD OF CRITICALLY LOW RH VALUES /15-20 PERCENT/ MAY OVERLAP THE STRONG SUSTAINED WINDS...LEADING TO AN HR OR TWO OF LOCALLY CRITICAL FIRE WEATHER CONDITIONS DURING THE LATE MORNING/EARLY AFTERNOON OVER N-CNTRL CO AND SERN WY. FARTHER E OVER WRN NEB/KS...MODEL GUIDANCE CONTINUES TO INDICATE A LONGER DURATION OF STRONG N/NWLY WINDS...BUT ALSO SHOWS SLIGHTLY MORE MARGINAL RH VALUES /GENERALLY AOA 20 PERCENT/. THEREFORE...NO CHANGES HAVE BEEN MADE TO THE PREVIOUS FORECAST. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... PREVIOUS FORECAST APPEARS TO BE ON TRACK. MORNING SURFACE AND UPPER AIR OBSERVATIONS...IN ADDITION TO LATEST MODEL GUIDANCE INDICATE NEAR TO LOCALLY CRITICAL FIRE WEATHER CONDITIONS ARE LIKELY ACROSS THE MID SOUTH REGION. THIS IS PARTICULARLY TRUE FOR SERN MO...SRN IL AND SRN IND...WHERE SUSTAINED WIND SPEEDS OF 15 MPH ARE EXPECTED TO OVERLAP CRITICALLY LOW RH VALUES /15 TO 25 PERCENT/ FOR A FEW HOURS. ...NRN SACRAMENTO VALLEY OF NRN CA... NO CHANGES MADE TO THE PREVIOUS FORECAST. ..GARNER.. 09/06/2010 .PREV DISCUSSION... /ISSUED 0236 AM CDT MON SEP 06 2010/ ...SYNOPSIS... A VIGOROUS UPPER-LEVEL SHORT WAVE TROUGH WILL PROGRESS EWD FROM THE NRN HIGH PLAINS/CNTRL ROCKIES TOWARDS THE UPPER MS VALLEY THROUGH EARLY TUE. ATTENDANT SURFACE CYCLONE OVER THE CNTRL HIGH PLAINS WILL TRACK NEWD TO MN...WHILE A COLD FRONT PUSHES SEWD ACROSS THE CNTRL HIGH PLAINS INTO THE OK/TX PANHANDLES BY EARLY EVENING. IN THE WEST...AN UPPER-LEVEL SHORT WAVE TROUGH WILL DIG ALONG THE BRITISH COLUMBIA COAST WITH A SURFACE RIDGE WEAKENING OVER THE PACIFIC NW. ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... AREAS OF SHORT-DURATION CRITICAL CONDITIONS TO LONGER-DURATION MARGINAL CONDITIONS APPEAR PROBABLE FROM LATER THIS MORNING INTO THE AFTERNOON. RELATIVELY LARGE SPREAD PERSISTS AMONGST LATEST NAM/GFS/SREF GUIDANCE WITH THE DEGREE OF DRYING OCCURRING IN THE WAKE OF A COLD FRONT PASSAGE THIS MORNING. 00Z NAM AND 03Z SREF MEAN INDICATE CRITICALLY LOW RH VALUES WILL BE RELEGATED TO ALONG THE LEE OF THE FRONT RANGE IN N-CNTRL CO...WHILE THE 00Z GFS SUGGESTS LOW RH WILL ALSO BE PREVALENT TO THE N/E ACROSS SERN WY INTO WRN NEB/KS. MODEL FORECASTS ARE MORE CONSISTENT WITH THE DEPICTION OF A SURGE IN LOW-LEVEL W/NWLYS ACCOMPANYING SHORT WAVE TROUGH PASSAGE LATER THIS MORNING. THIS SHOULD LEAD TO A FEW HOURS OF CRITICAL CONDITIONS AROUND NOON ALONG THE FRONT RANGE IN N-CNTRL CO...PRIOR TO WINDS DIMINISHING THROUGH THE AFTERNOON AS A SURFACE RIDGE QUICKLY BUILDS ACROSS THE HIGH PLAINS. FARTHER E INTO WRN NEB/KS...LONGER DURATIONS OF STRONG N/NWLY WINDS /FROM 20 TO 30 MPH/ APPEAR LIKELY. HOWEVER...BASED ON UPSTREAM OBSERVATIONS OF MUCH COOLER/HIGHER RH VALUES...AFTERNOON RH VALUES MAY ONLY BECOME MARGINALLY LOW /FROM 20 TO 30 PERCENT/. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... AN ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP THIS AFTERNOON AS SLY SURFACE WINDS INCREASE WITHIN AN ANTECEDENT WARM/DRY AIR MASS ACROSS THE LOWER MS/OH VALLEY...WHERE ABNORMAL DRYNESS AND MODERATE DROUGHT PERSIST. MODEL FORECASTS REMAIN HIGHLY CONSISTENT THAT TEMPERATURES WILL WARM INTO THE MIDDLE TO UPPER 80S...WITH RH VALUES DROPPING TO BETWEEN 18 AND 25 PERCENT. ALTHOUGH S/SWLY LOW-LEVEL WINDS WILL STRENGTHEN...THIS REGION OF LOW RH VALUES SHOULD REMAIN TO THE E/SE OF STRONGER LOW-LEVEL FLOW CENTERED OVER THE MID-MO VALLEY. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/...WITH GUSTS TO AROUND 25 MPH. ...NRN SACRAMENTO VALLEY OF NRN CA... RECENT MESONET OBSERVATIONS CONFIRM AREAS OF GUSTY NLY WINDS /AROUND 2O TO 30 MPH/ OCCURRING ACROSS THE NRN SACRAMENTO VALLEY AND SURROUNDING FOOTHILLS. THIS HAS SUPPORTED POOR OVERNIGHT RH RECOVERY...WITH 12 TO 20 PERCENT READINGS COMMON AS OF 07Z. AS THE TIGHT LOW-LEVEL PRESSURE GRADIENT RELAXES WITH THE RIDGE AXIS OVER THE PACIFIC NW WEAKENING...WINDS WILL GRADUALLY DIMINISH DURING THE LATE MORNING/EARLY AFTERNOON AND SHOULD REMAIN WEAK THROUGH THE REST OF THE PERIOD. NEVERTHELESS...LONG DURATIONS OF LOW RH APPEAR LIKELY WITH MIN VALUES NEAR 5 PERCENT AT PEAK HEATING. ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1134 AM CDT MON SEP 06 2010 VALID 061700Z - 071200Z ...NO CRITICAL AREAS... ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... MID MORNING SURFACE OBSERVATIONS AND OBJECTIVE ANALYSIS GUIDANCE SHOW LOW PRESSURE MOVING NEWD ACROSS SRN NEB...WITH A COLD FRONT TRAILING SWWD INTO WRN KS AND ERN CO. WIND SPEEDS AOA 20 MPH ARE OBSERVED IN THE WAKE OF THE FRONT AT 15Z...AND ARE FORECAST BY LATEST MODEL GUIDANCE TO SUBSIDE DURING THE AFTERNOON AS POST FRONTAL PRESSURE GRADIENT BEGINS TO RELAX. AS THIS TAKES PLACE...A BRIEF PERIOD OF CRITICALLY LOW RH VALUES /15-20 PERCENT/ MAY OVERLAP THE STRONG SUSTAINED WINDS...LEADING TO AN HR OR TWO OF LOCALLY CRITICAL FIRE WEATHER CONDITIONS DURING THE LATE MORNING/EARLY AFTERNOON OVER N-CNTRL CO AND SERN WY. FARTHER E OVER WRN NEB/KS...MODEL GUIDANCE CONTINUES TO INDICATE A LONGER DURATION OF STRONG N/NWLY WINDS...BUT ALSO SHOWS SLIGHTLY MORE MARGINAL RH VALUES /GENERALLY AOA 20 PERCENT/. THEREFORE...NO CHANGES HAVE BEEN MADE TO THE PREVIOUS FORECAST. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... PREVIOUS FORECAST APPEARS TO BE ON TRACK. MORNING SURFACE AND UPPER AIR OBSERVATIONS...IN ADDITION TO LATEST MODEL GUIDANCE INDICATE NEAR TO LOCALLY CRITICAL FIRE WEATHER CONDITIONS ARE LIKELY ACROSS THE MID SOUTH REGION. THIS IS PARTICULARLY TRUE FOR SERN MO...SRN IL AND SRN IND...WHERE SUSTAINED WIND SPEEDS OF 15 MPH ARE EXPECTED TO OVERLAP CRITICALLY LOW RH VALUES /15 TO 25 PERCENT/ FOR A FEW HOURS. ...NRN SACRAMENTO VALLEY OF NRN CA... NO CHANGES MADE TO THE PREVIOUS FORECAST. ..GARNER.. 09/06/2010 .PREV DISCUSSION... /ISSUED 0236 AM CDT MON SEP 06 2010/ ...SYNOPSIS... A VIGOROUS UPPER-LEVEL SHORT WAVE TROUGH WILL PROGRESS EWD FROM THE NRN HIGH PLAINS/CNTRL ROCKIES TOWARDS THE UPPER MS VALLEY THROUGH EARLY TUE. ATTENDANT SURFACE CYCLONE OVER THE CNTRL HIGH PLAINS WILL TRACK NEWD TO MN...WHILE A COLD FRONT PUSHES SEWD ACROSS THE CNTRL HIGH PLAINS INTO THE OK/TX PANHANDLES BY EARLY EVENING. IN THE WEST...AN UPPER-LEVEL SHORT WAVE TROUGH WILL DIG ALONG THE BRITISH COLUMBIA COAST WITH A SURFACE RIDGE WEAKENING OVER THE PACIFIC NW. ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... AREAS OF SHORT-DURATION CRITICAL CONDITIONS TO LONGER-DURATION MARGINAL CONDITIONS APPEAR PROBABLE FROM LATER THIS MORNING INTO THE AFTERNOON. RELATIVELY LARGE SPREAD PERSISTS AMONGST LATEST NAM/GFS/SREF GUIDANCE WITH THE DEGREE OF DRYING OCCURRING IN THE WAKE OF A COLD FRONT PASSAGE THIS MORNING. 00Z NAM AND 03Z SREF MEAN INDICATE CRITICALLY LOW RH VALUES WILL BE RELEGATED TO ALONG THE LEE OF THE FRONT RANGE IN N-CNTRL CO...WHILE THE 00Z GFS SUGGESTS LOW RH WILL ALSO BE PREVALENT TO THE N/E ACROSS SERN WY INTO WRN NEB/KS. MODEL FORECASTS ARE MORE CONSISTENT WITH THE DEPICTION OF A SURGE IN LOW-LEVEL W/NWLYS ACCOMPANYING SHORT WAVE TROUGH PASSAGE LATER THIS MORNING. THIS SHOULD LEAD TO A FEW HOURS OF CRITICAL CONDITIONS AROUND NOON ALONG THE FRONT RANGE IN N-CNTRL CO...PRIOR TO WINDS DIMINISHING THROUGH THE AFTERNOON AS A SURFACE RIDGE QUICKLY BUILDS ACROSS THE HIGH PLAINS. FARTHER E INTO WRN NEB/KS...LONGER DURATIONS OF STRONG N/NWLY WINDS /FROM 20 TO 30 MPH/ APPEAR LIKELY. HOWEVER...BASED ON UPSTREAM OBSERVATIONS OF MUCH COOLER/HIGHER RH VALUES...AFTERNOON RH VALUES MAY ONLY BECOME MARGINALLY LOW /FROM 20 TO 30 PERCENT/. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... AN ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP THIS AFTERNOON AS SLY SURFACE WINDS INCREASE WITHIN AN ANTECEDENT WARM/DRY AIR MASS ACROSS THE LOWER MS/OH VALLEY...WHERE ABNORMAL DRYNESS AND MODERATE DROUGHT PERSIST. MODEL FORECASTS REMAIN HIGHLY CONSISTENT THAT TEMPERATURES WILL WARM INTO THE MIDDLE TO UPPER 80S...WITH RH VALUES DROPPING TO BETWEEN 18 AND 25 PERCENT. ALTHOUGH S/SWLY LOW-LEVEL WINDS WILL STRENGTHEN...THIS REGION OF LOW RH VALUES SHOULD REMAIN TO THE E/SE OF STRONGER LOW-LEVEL FLOW CENTERED OVER THE MID-MO VALLEY. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/...WITH GUSTS TO AROUND 25 MPH. ...NRN SACRAMENTO VALLEY OF NRN CA... RECENT MESONET OBSERVATIONS CONFIRM AREAS OF GUSTY NLY WINDS /AROUND 2O TO 30 MPH/ OCCURRING ACROSS THE NRN SACRAMENTO VALLEY AND SURROUNDING FOOTHILLS. THIS HAS SUPPORTED POOR OVERNIGHT RH RECOVERY...WITH 12 TO 20 PERCENT READINGS COMMON AS OF 07Z. AS THE TIGHT LOW-LEVEL PRESSURE GRADIENT RELAXES WITH THE RIDGE AXIS OVER THE PACIFIC NW WEAKENING...WINDS WILL GRADUALLY DIMINISH DURING THE LATE MORNING/EARLY AFTERNOON AND SHOULD REMAIN WEAK THROUGH THE REST OF THE PERIOD. NEVERTHELESS...LONG DURATIONS OF LOW RH APPEAR LIKELY WITH MIN VALUES NEAR 5 PERCENT AT PEAK HEATING. ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1127 AM CDT MON SEP 06 2010 VALID 061630Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR IA...SRN MN...AND WRN WI... ...THERE IS A SLGT RISK OF SVR TSTMS FOR TONIGHT FOR THE MIDDLE TX COAST... ...IA/SRN MN/WRN WI LATE THIS AFTERNOON INTO EARLY TONIGHT... A STRONG MIDLEVEL SHORTWAVE TROUGH WILL MOVE ENEWD FROM THE CENTRAL HIGH PLAINS TO THE UPPER MS VALLEY BY TONIGHT. A REMNANT LEE CYCLONE IN E CENTRAL NEB WILL DEVELOP NNEWD TO SW AND W CENTRAL MN BY TONIGHT AS THE CYCLONE OCCLUDES...WHILE A TRAILING COLD FRONT SWEEPS EWD ACROSS IA/WI AND SEWD ACROSS NW MO/KS/NRN OK BY THE END OF THE PERIOD. THE WARM SECTOR IN ADVANCE OF THE CYCLONE IS INITIALLY CAPPED BY A VERY WARM EML...ABOVE A MARGINALLY MOIST BOUNDARY LAYER WITH DEWPOINTS IN THE LOWER 60S. THE MARITIME TROPICAL AIR MASS STILL RESIDES S OF I-20 IN TX PER SURFACE OBS/GOES PW IMAGERY AND 12Z SOUNDINGS...AND THE RECENT RUC/NAM FORECASTS OF 68-70 F DEWPOINTS INTO IA THIS EVENING APPEAR TOO AGGRESSIVE. THUS...EXPECT AT BEST MID 60S DEWPOINTS WITH AFTERNOON EVAPOTRANSPIRATION AND SOME NEWD MOISTURE ADVECTION FROM OK. THE VERY WARM EML WILL REQUIRE STRONG ASCENT TO ELIMINATE CONVECTIVE INHIBITION BY LATE AFTERNOON IN A NARROW BAND ALONG THE COLD FRONT...WHERE MLCAPE COULD APPROACH 1500-2000 J/KG. FORECAST WIND PROFILES AHEAD OF THE FRONT AND E/SE OF THE SURFACE CYCLONE WILL BE FAVORABLE FOR SUPERCELLS WITH LARGE CLOCKWISE-TURNING HODOGRAPHS. DEEP-LAYER SHEAR VECTOR ORIENTATION WILL ALSO FAVOR SEMI-DISCRETE STORMS FROM IA NWD INTO SRN MN. IT APPEARS THAT THE MARGINAL LOW-LEVEL MOISTURE AND STRONG CAP WILL LIMIT THE SPATIAL WINDOW OF OPPORTUNITY FOR SUPERCELLS AND MAKE IT DIFFICULT FOR STORMS TO SURVIVE MORE THAN A FEW COUNTIES E OF THE FRONT. THUS...WILL MAINTAIN 5% TORNADO AND 15% HAIL/WIND PROBABILITIES IN AN ENVIRONMENT THAT COULD OTHERWISE SUPPORT A MORE ROBUST SEVERE STORM THREAT. A FEW STORMS MAY DEVELOP SWWD ALONG THE COLD FRONT THIS EVENING FROM NW MO ACROSS ERN KS INTO N CENTRAL OK. STORM INITIATION WILL DEPEND ON STRONG LOW-LEVEL ASCENT ALONG THE FRONT AND RELATIVELY DEEP MIXING FARTHER SW TOWARD NRN OK...AND STORM COVERAGE IS QUESTIONABLE. IF STORMS FORM...A FEW STRONG WIND GUSTS AND MARGINALLY SEVERE HAIL WILL BE POSSIBLE FOR A FEW HOURS THIS EVENING. ...MIDDLE TX COAST TONIGHT... TROPICAL STORM HERMINE IS FORECAST TO APPROACH HURRICANE STRENGTH JUST PRIOR TO LANDFALL ALONG THE LOWER TX COAST LATE TONIGHT /SEE LATEST NHC ADVISORIES FOR DETAILS/. DEEPENING OF THE CYCLONE WILL RESULT IN A CORRIDOR OF INCREASING LOW-LEVEL FLOW/SHEAR TO THE RIGHT OF THE CYCLONE CENTER...WHICH WILL OVERSPREAD THE MIDDLE TX COAST OVERNIGHT. THE CORRIDOR OF INCREASING LOW-LEVEL SHEAR WILL ALSO COINCIDE WITH MID-UPPER 70S BOUNDARY LAYER DEWPOINTS AND AT LEAST WEAK SURFACE-BASED INSTABILITY. GIVEN THESE ENVIRONMENTAL FACTORS...WILL INTRODUCE A SLIGHT RISK AND 5% TORNADO PROBABILITIES FOR OUTER BAND SUPERCELLS DURING THE OVERNIGHT PERIOD. ..THOMPSON/HURLBUT.. 09/06/2010 Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1127 AM CDT MON SEP 06 2010 VALID 061630Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR IA...SRN MN...AND WRN WI... ...THERE IS A SLGT RISK OF SVR TSTMS FOR TONIGHT FOR THE MIDDLE TX COAST... ...IA/SRN MN/WRN WI LATE THIS AFTERNOON INTO EARLY TONIGHT... A STRONG MIDLEVEL SHORTWAVE TROUGH WILL MOVE ENEWD FROM THE CENTRAL HIGH PLAINS TO THE UPPER MS VALLEY BY TONIGHT. A REMNANT LEE CYCLONE IN E CENTRAL NEB WILL DEVELOP NNEWD TO SW AND W CENTRAL MN BY TONIGHT AS THE CYCLONE OCCLUDES...WHILE A TRAILING COLD FRONT SWEEPS EWD ACROSS IA/WI AND SEWD ACROSS NW MO/KS/NRN OK BY THE END OF THE PERIOD. THE WARM SECTOR IN ADVANCE OF THE CYCLONE IS INITIALLY CAPPED BY A VERY WARM EML...ABOVE A MARGINALLY MOIST BOUNDARY LAYER WITH DEWPOINTS IN THE LOWER 60S. THE MARITIME TROPICAL AIR MASS STILL RESIDES S OF I-20 IN TX PER SURFACE OBS/GOES PW IMAGERY AND 12Z SOUNDINGS...AND THE RECENT RUC/NAM FORECASTS OF 68-70 F DEWPOINTS INTO IA THIS EVENING APPEAR TOO AGGRESSIVE. THUS...EXPECT AT BEST MID 60S DEWPOINTS WITH AFTERNOON EVAPOTRANSPIRATION AND SOME NEWD MOISTURE ADVECTION FROM OK. THE VERY WARM EML WILL REQUIRE STRONG ASCENT TO ELIMINATE CONVECTIVE INHIBITION BY LATE AFTERNOON IN A NARROW BAND ALONG THE COLD FRONT...WHERE MLCAPE COULD APPROACH 1500-2000 J/KG. FORECAST WIND PROFILES AHEAD OF THE FRONT AND E/SE OF THE SURFACE CYCLONE WILL BE FAVORABLE FOR SUPERCELLS WITH LARGE CLOCKWISE-TURNING HODOGRAPHS. DEEP-LAYER SHEAR VECTOR ORIENTATION WILL ALSO FAVOR SEMI-DISCRETE STORMS FROM IA NWD INTO SRN MN. IT APPEARS THAT THE MARGINAL LOW-LEVEL MOISTURE AND STRONG CAP WILL LIMIT THE SPATIAL WINDOW OF OPPORTUNITY FOR SUPERCELLS AND MAKE IT DIFFICULT FOR STORMS TO SURVIVE MORE THAN A FEW COUNTIES E OF THE FRONT. THUS...WILL MAINTAIN 5% TORNADO AND 15% HAIL/WIND PROBABILITIES IN AN ENVIRONMENT THAT COULD OTHERWISE SUPPORT A MORE ROBUST SEVERE STORM THREAT. A FEW STORMS MAY DEVELOP SWWD ALONG THE COLD FRONT THIS EVENING FROM NW MO ACROSS ERN KS INTO N CENTRAL OK. STORM INITIATION WILL DEPEND ON STRONG LOW-LEVEL ASCENT ALONG THE FRONT AND RELATIVELY DEEP MIXING FARTHER SW TOWARD NRN OK...AND STORM COVERAGE IS QUESTIONABLE. IF STORMS FORM...A FEW STRONG WIND GUSTS AND MARGINALLY SEVERE HAIL WILL BE POSSIBLE FOR A FEW HOURS THIS EVENING. ...MIDDLE TX COAST TONIGHT... TROPICAL STORM HERMINE IS FORECAST TO APPROACH HURRICANE STRENGTH JUST PRIOR TO LANDFALL ALONG THE LOWER TX COAST LATE TONIGHT /SEE LATEST NHC ADVISORIES FOR DETAILS/. DEEPENING OF THE CYCLONE WILL RESULT IN A CORRIDOR OF INCREASING LOW-LEVEL FLOW/SHEAR TO THE RIGHT OF THE CYCLONE CENTER...WHICH WILL OVERSPREAD THE MIDDLE TX COAST OVERNIGHT. THE CORRIDOR OF INCREASING LOW-LEVEL SHEAR WILL ALSO COINCIDE WITH MID-UPPER 70S BOUNDARY LAYER DEWPOINTS AND AT LEAST WEAK SURFACE-BASED INSTABILITY. GIVEN THESE ENVIRONMENTAL FACTORS...WILL INTRODUCE A SLIGHT RISK AND 5% TORNADO PROBABILITIES FOR OUTER BAND SUPERCELLS DURING THE OVERNIGHT PERIOD. ..THOMPSON/HURLBUT.. 09/06/2010 Read more

SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1127 AM CDT MON SEP 06 2010 VALID 061630Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT FOR IA...SRN MN...AND WRN WI... ...THERE IS A SLGT RISK OF SVR TSTMS FOR TONIGHT FOR THE MIDDLE TX COAST... ...IA/SRN MN/WRN WI LATE THIS AFTERNOON INTO EARLY TONIGHT... A STRONG MIDLEVEL SHORTWAVE TROUGH WILL MOVE ENEWD FROM THE CENTRAL HIGH PLAINS TO THE UPPER MS VALLEY BY TONIGHT. A REMNANT LEE CYCLONE IN E CENTRAL NEB WILL DEVELOP NNEWD TO SW AND W CENTRAL MN BY TONIGHT AS THE CYCLONE OCCLUDES...WHILE A TRAILING COLD FRONT SWEEPS EWD ACROSS IA/WI AND SEWD ACROSS NW MO/KS/NRN OK BY THE END OF THE PERIOD. THE WARM SECTOR IN ADVANCE OF THE CYCLONE IS INITIALLY CAPPED BY A VERY WARM EML...ABOVE A MARGINALLY MOIST BOUNDARY LAYER WITH DEWPOINTS IN THE LOWER 60S. THE MARITIME TROPICAL AIR MASS STILL RESIDES S OF I-20 IN TX PER SURFACE OBS/GOES PW IMAGERY AND 12Z SOUNDINGS...AND THE RECENT RUC/NAM FORECASTS OF 68-70 F DEWPOINTS INTO IA THIS EVENING APPEAR TOO AGGRESSIVE. THUS...EXPECT AT BEST MID 60S DEWPOINTS WITH AFTERNOON EVAPOTRANSPIRATION AND SOME NEWD MOISTURE ADVECTION FROM OK. THE VERY WARM EML WILL REQUIRE STRONG ASCENT TO ELIMINATE CONVECTIVE INHIBITION BY LATE AFTERNOON IN A NARROW BAND ALONG THE COLD FRONT...WHERE MLCAPE COULD APPROACH 1500-2000 J/KG. FORECAST WIND PROFILES AHEAD OF THE FRONT AND E/SE OF THE SURFACE CYCLONE WILL BE FAVORABLE FOR SUPERCELLS WITH LARGE CLOCKWISE-TURNING HODOGRAPHS. DEEP-LAYER SHEAR VECTOR ORIENTATION WILL ALSO FAVOR SEMI-DISCRETE STORMS FROM IA NWD INTO SRN MN. IT APPEARS THAT THE MARGINAL LOW-LEVEL MOISTURE AND STRONG CAP WILL LIMIT THE SPATIAL WINDOW OF OPPORTUNITY FOR SUPERCELLS AND MAKE IT DIFFICULT FOR STORMS TO SURVIVE MORE THAN A FEW COUNTIES E OF THE FRONT. THUS...WILL MAINTAIN 5% TORNADO AND 15% HAIL/WIND PROBABILITIES IN AN ENVIRONMENT THAT COULD OTHERWISE SUPPORT A MORE ROBUST SEVERE STORM THREAT. A FEW STORMS MAY DEVELOP SWWD ALONG THE COLD FRONT THIS EVENING FROM NW MO ACROSS ERN KS INTO N CENTRAL OK. STORM INITIATION WILL DEPEND ON STRONG LOW-LEVEL ASCENT ALONG THE FRONT AND RELATIVELY DEEP MIXING FARTHER SW TOWARD NRN OK...AND STORM COVERAGE IS QUESTIONABLE. IF STORMS FORM...A FEW STRONG WIND GUSTS AND MARGINALLY SEVERE HAIL WILL BE POSSIBLE FOR A FEW HOURS THIS EVENING. ...MIDDLE TX COAST TONIGHT... TROPICAL STORM HERMINE IS FORECAST TO APPROACH HURRICANE STRENGTH JUST PRIOR TO LANDFALL ALONG THE LOWER TX COAST LATE TONIGHT /SEE LATEST NHC ADVISORIES FOR DETAILS/. DEEPENING OF THE CYCLONE WILL RESULT IN A CORRIDOR OF INCREASING LOW-LEVEL FLOW/SHEAR TO THE RIGHT OF THE CYCLONE CENTER...WHICH WILL OVERSPREAD THE MIDDLE TX COAST OVERNIGHT. THE CORRIDOR OF INCREASING LOW-LEVEL SHEAR WILL ALSO COINCIDE WITH MID-UPPER 70S BOUNDARY LAYER DEWPOINTS AND AT LEAST WEAK SURFACE-BASED INSTABILITY. GIVEN THESE ENVIRONMENTAL FACTORS...WILL INTRODUCE A SLIGHT RISK AND 5% TORNADO PROBABILITIES FOR OUTER BAND SUPERCELLS DURING THE OVERNIGHT PERIOD. ..THOMPSON/HURLBUT.. 09/06/2010 Read more

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0746 AM CDT MON SEP 06 2010 VALID 061300Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER PARTS OF MN...IA AND WI... ...UPPER MIDWEST/UPPER MS VALLEY INTO THE LOWER MO VALLEY... A COMPACT BUT POTENT SHORT WAVE TROUGH CURRENTLY OVER WY WILL TRANSLATE RAPIDLY EWD TODAY FORMING A CLOSED MIDLEVEL CIRCULATION OVER ERN SD INTO MN BY TONIGHT. THIS SYSTEM WILL BE ACCOMPANIED BY A MIDLEVEL JET STREAK WHICH IS FORECAST TO STRENGTHEN TO 80-90 KT AND A CORRIDOR OF SIGNIFICANT HEIGHT FALLS --I.E. 100-150 M/12 H-- SPREADING EWD ACROSS SD/NEB TODAY AND MN/IA/WI TONIGHT. AT THE SURFACE...CYCLONE CURRENTLY ALONG THE NEB/KS BORDER E OF MCK WILL CONTINUE TO DEEPEN WHILE ACCELERATING NNEWD INTO W-CNTRL MN BY LATE AFTERNOON. THIS LOW WILL UNDERGO OCCLUSION TONIGHT WHILE DECELERATING OVER CNTRL MN. MEANWHILE...STRONG COLD FRONT CURRENTLY FROM THE WRN DAKOTAS SWD THROUGH WRN NEB INTO NWRN KS AND E-CNTRL CO WILL SURGE EWD THROUGH THE MID/LOWER MO VALLEY AND UPPER MIDWEST BY TUESDAY MORNING. THIS BOUNDARY WILL LIKELY SERVE AS THE FOCUS FOR STRONG TO SEVERE TSTM DEVELOPMENT LATER THIS AFTERNOON INTO TONIGHT. NW-SE ORIENTED BAND OF ELEVATED STRONG TO MARGINALLY SEVERE TSTMS IS ONGOING THIS MORNING OVER WI...DRIVEN BY WAA/ISENTROPIC ASCENT IN EXIT REGION OF 45-60 KT SWLY...NOCTURNAL LLJ AND DEEPER-LAYER FORCING ATTENDANT TO A LOW AMPLITUDE PERTURBATION PROGRESSING ESEWD THROUGH MN/WI. GIVEN THE PRESENCE OF MODEST INSTABILITY AND RELATIVELY STRONG CLOUD-BEARING SHEAR...THE MOST INTENSE STORMS WILL BE CAPABLE OF MARGINALLY SEVERE HAIL THIS MORNING. ACTIVITY SHOULD GRADUALLY WEAKEN WITH THE CESSATION OF THE NOCTURNAL LLJ. MEANWHILE...12Z UPSTREAM OBSERVED SOUNDINGS INDICATE THE PRESENCE OF A STRONG CAP ASSOCIATED WITH A WELL-DEFINED EML WHICH HAS BEEN ADVECTED EWD INTO THE PLAINS IN ADVANCE OF THE NRN/CNTRL ROCKIES UPPER TROUGH. BENEATH THE EML...THE 12Z SOUNDING DATA AND SATELLITE-DERIVED PW IMAGERY SHOW SIMILAR MOISTURE CONTENT EXTENDING SWWD INTO NRN TX. THIS WOULD SUGGEST THAT THE HORIZONTAL ADVECTION OF MOISTURE IN THE LOWER TROPOSPHERE WILL CONTRIBUTE LITTLE TO THE DESTABILIZATION PROCESS WITHIN THE WARM SECTOR TODAY. AS SUCH...IT APPEARS THAT THE CAP WILL REMAIN ROBUST AND LIKELY INHIBIT SURFACE-BASED STORM DEVELOPMENT THROUGH MUCH OF THE DIURNAL HEATING CYCLE. LATEST MESOSCALE AND CONVECTION-ALLOWING MODEL GUIDANCE INDICATES THAT TSTMS WILL BECOME INCREASINGLY LIKELY BY 07/00Z FROM VICINITY OF SURFACE LOW SEWD ALONG BENT BACK PORTION OF COLD FRONT OVER W-CNTRL INTO SRN MN AND NRN IA AS STRONG DYNAMIC FORCING FOR ASCENT ASSOCIATED WITH THE APPROACHING UPPER WAVE BEGINS TO RAPIDLY ERODE THE CAP. FARTHER SWD/SWWD ALONG THE FRONT --I.E. CNTRL/SRN IA INTO NERN KS/NRN AND WRN MO-- STORM INITIATION AND SUSTENANCE BECOME MORE UNCERTAIN DUE TO THE COMPACT NATURE OF THE UPPER TROUGH AND TENDENCY FOR LARGE-SCALE FORCING TO RAPIDLY DIMINISH ON THE ANTICYCLONIC SIDE OF THE ATTENDANT MIDLEVEL JET STREAK. AMBIENT WARM SECTOR ENVIRONMENT --PARTICULARLY OVER SRN MN INTO IA-- WILL BE QUITE SUPPORTIVE OF ORGANIZED STORMS WHERE MLCAPE OF 1000-1500 J/KG WILL COINCIDE WITH 150-300 M2/S2 0-1 KM SRH AND 50-70 KT OF DEEP-LAYER SHEAR. A LARGELY NORMAL ORIENTATION OF THE DEEP-LAYER SHEAR VECTOR TO THE SURFACE FRONT SUGGESTS THAT INITIAL STORM MODE WOULD BE SUPERCELLULAR WITH THE THREAT FOR HAIL...DAMAGING WINDS AND A FEW TORNADOES. SHOULD ACTIVITY GROW UPSCALE INTO A LINEAR CONVECTIVE SYSTEM...THEN A RISK FOR DAMAGING WIND GUSTS WILL CONTINUE AFTER DARK...MAINLY ALONG AND AHEAD OF THE MIDLEVEL JET STREAK. CURRENTLY...UNCERTAINTIES IN THE DAYTIME INITIATION OF STORMS WITHIN THE ZONE OF MOST FAVORABLE PARAMETERS PRECLUDES AN INCREASE IN SEVERE WEATHER PROBABILITIES. HOWEVER...AN UPGRADE MAY BE NECESSARY IN SUBSEQUENT OUTLOOKS. ...TX... RECENTLY NAMED TS HERMINE IS FORECAST TO MOVE NWWD THROUGH THE WRN GULF OF MEXICO TODAY AND INTO DEEP S TX TONIGHT. AN ASSOCIATED INCREASE IN LOWER-TROPOSPHERIC SHEAR AND MOISTURE WILL ACCOMPANY THIS SYSTEM INLAND...AND AT LEAST A MARGINAL RISK FOR A BRIEF TORNADO OR TWO WILL EXIST ALONG THE LOWER TO MIDDLE COASTAL PLAIN DURING THE LATTER HALF OF THE FORECAST PERIOD. ..MEAD/GRAMS.. 09/06/2010 Read more

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0746 AM CDT MON SEP 06 2010 VALID 061300Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT OVER PARTS OF MN...IA AND WI... ...UPPER MIDWEST/UPPER MS VALLEY INTO THE LOWER MO VALLEY... A COMPACT BUT POTENT SHORT WAVE TROUGH CURRENTLY OVER WY WILL TRANSLATE RAPIDLY EWD TODAY FORMING A CLOSED MIDLEVEL CIRCULATION OVER ERN SD INTO MN BY TONIGHT. THIS SYSTEM WILL BE ACCOMPANIED BY A MIDLEVEL JET STREAK WHICH IS FORECAST TO STRENGTHEN TO 80-90 KT AND A CORRIDOR OF SIGNIFICANT HEIGHT FALLS --I.E. 100-150 M/12 H-- SPREADING EWD ACROSS SD/NEB TODAY AND MN/IA/WI TONIGHT. AT THE SURFACE...CYCLONE CURRENTLY ALONG THE NEB/KS BORDER E OF MCK WILL CONTINUE TO DEEPEN WHILE ACCELERATING NNEWD INTO W-CNTRL MN BY LATE AFTERNOON. THIS LOW WILL UNDERGO OCCLUSION TONIGHT WHILE DECELERATING OVER CNTRL MN. MEANWHILE...STRONG COLD FRONT CURRENTLY FROM THE WRN DAKOTAS SWD THROUGH WRN NEB INTO NWRN KS AND E-CNTRL CO WILL SURGE EWD THROUGH THE MID/LOWER MO VALLEY AND UPPER MIDWEST BY TUESDAY MORNING. THIS BOUNDARY WILL LIKELY SERVE AS THE FOCUS FOR STRONG TO SEVERE TSTM DEVELOPMENT LATER THIS AFTERNOON INTO TONIGHT. NW-SE ORIENTED BAND OF ELEVATED STRONG TO MARGINALLY SEVERE TSTMS IS ONGOING THIS MORNING OVER WI...DRIVEN BY WAA/ISENTROPIC ASCENT IN EXIT REGION OF 45-60 KT SWLY...NOCTURNAL LLJ AND DEEPER-LAYER FORCING ATTENDANT TO A LOW AMPLITUDE PERTURBATION PROGRESSING ESEWD THROUGH MN/WI. GIVEN THE PRESENCE OF MODEST INSTABILITY AND RELATIVELY STRONG CLOUD-BEARING SHEAR...THE MOST INTENSE STORMS WILL BE CAPABLE OF MARGINALLY SEVERE HAIL THIS MORNING. ACTIVITY SHOULD GRADUALLY WEAKEN WITH THE CESSATION OF THE NOCTURNAL LLJ. MEANWHILE...12Z UPSTREAM OBSERVED SOUNDINGS INDICATE THE PRESENCE OF A STRONG CAP ASSOCIATED WITH A WELL-DEFINED EML WHICH HAS BEEN ADVECTED EWD INTO THE PLAINS IN ADVANCE OF THE NRN/CNTRL ROCKIES UPPER TROUGH. BENEATH THE EML...THE 12Z SOUNDING DATA AND SATELLITE-DERIVED PW IMAGERY SHOW SIMILAR MOISTURE CONTENT EXTENDING SWWD INTO NRN TX. THIS WOULD SUGGEST THAT THE HORIZONTAL ADVECTION OF MOISTURE IN THE LOWER TROPOSPHERE WILL CONTRIBUTE LITTLE TO THE DESTABILIZATION PROCESS WITHIN THE WARM SECTOR TODAY. AS SUCH...IT APPEARS THAT THE CAP WILL REMAIN ROBUST AND LIKELY INHIBIT SURFACE-BASED STORM DEVELOPMENT THROUGH MUCH OF THE DIURNAL HEATING CYCLE. LATEST MESOSCALE AND CONVECTION-ALLOWING MODEL GUIDANCE INDICATES THAT TSTMS WILL BECOME INCREASINGLY LIKELY BY 07/00Z FROM VICINITY OF SURFACE LOW SEWD ALONG BENT BACK PORTION OF COLD FRONT OVER W-CNTRL INTO SRN MN AND NRN IA AS STRONG DYNAMIC FORCING FOR ASCENT ASSOCIATED WITH THE APPROACHING UPPER WAVE BEGINS TO RAPIDLY ERODE THE CAP. FARTHER SWD/SWWD ALONG THE FRONT --I.E. CNTRL/SRN IA INTO NERN KS/NRN AND WRN MO-- STORM INITIATION AND SUSTENANCE BECOME MORE UNCERTAIN DUE TO THE COMPACT NATURE OF THE UPPER TROUGH AND TENDENCY FOR LARGE-SCALE FORCING TO RAPIDLY DIMINISH ON THE ANTICYCLONIC SIDE OF THE ATTENDANT MIDLEVEL JET STREAK. AMBIENT WARM SECTOR ENVIRONMENT --PARTICULARLY OVER SRN MN INTO IA-- WILL BE QUITE SUPPORTIVE OF ORGANIZED STORMS WHERE MLCAPE OF 1000-1500 J/KG WILL COINCIDE WITH 150-300 M2/S2 0-1 KM SRH AND 50-70 KT OF DEEP-LAYER SHEAR. A LARGELY NORMAL ORIENTATION OF THE DEEP-LAYER SHEAR VECTOR TO THE SURFACE FRONT SUGGESTS THAT INITIAL STORM MODE WOULD BE SUPERCELLULAR WITH THE THREAT FOR HAIL...DAMAGING WINDS AND A FEW TORNADOES. SHOULD ACTIVITY GROW UPSCALE INTO A LINEAR CONVECTIVE SYSTEM...THEN A RISK FOR DAMAGING WIND GUSTS WILL CONTINUE AFTER DARK...MAINLY ALONG AND AHEAD OF THE MIDLEVEL JET STREAK. CURRENTLY...UNCERTAINTIES IN THE DAYTIME INITIATION OF STORMS WITHIN THE ZONE OF MOST FAVORABLE PARAMETERS PRECLUDES AN INCREASE IN SEVERE WEATHER PROBABILITIES. HOWEVER...AN UPGRADE MAY BE NECESSARY IN SUBSEQUENT OUTLOOKS. ...TX... RECENTLY NAMED TS HERMINE IS FORECAST TO MOVE NWWD THROUGH THE WRN GULF OF MEXICO TODAY AND INTO DEEP S TX TONIGHT. AN ASSOCIATED INCREASE IN LOWER-TROPOSPHERIC SHEAR AND MOISTURE WILL ACCOMPANY THIS SYSTEM INLAND...AND AT LEAST A MARGINAL RISK FOR A BRIEF TORNADO OR TWO WILL EXIST ALONG THE LOWER TO MIDDLE COASTAL PLAIN DURING THE LATTER HALF OF THE FORECAST PERIOD. ..MEAD/GRAMS.. 09/06/2010 Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0456 AM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO CRITICAL AREAS... ...SYNOPSIS... POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE UPPER MS VALLEY WILL TRANSLATE EWD ACROSS THE GREAT LAKES/SRN ONTARIO THROUGH EARLY WED. ATTENDANT SURFACE COLD FRONT WILL MARCH EWD ACROSS THE UPPER GREAT LAKES AND MIDWEST BY TUE AFTERNOON. IN THE WEST...A LARGE-SCALE UPPER-LEVEL TROUGH WILL BECOME ANCHORED ACROSS THE PACIFIC NW INTO NRN CA. ...PORTIONS OF CNTRL/ERN NV... LATEST MODEL FORECASTS ARE FAIRLY CONSISTENT WITH THE DEPICTION OF A WEAK MID-LEVEL IMPULSE EJECTING OUT AHEAD OF A LARGE-SCALE TROUGH AMPLIFYING OVER THE PACIFIC NW. ASSOCIATED SPEED MAX WILL AID IN STRENGTHENING BOUNDARY LAYER FLOW TUE AFTERNOON. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING. 06Z NAM AND ASSOCIATED WRF MEMBERS IN THE 03Z SREF APPEAR STRONGER THAN 00Z GFS/ECMWF GUIDANCE. IN ADDITION...BOTH THE GFS/ECMWF INDICATE MORE ROBUST SUB-TROPICAL MOISTURE EMANATING NWD FROM NWRN MEXICO/AZ...SUGGESTING THE JUXTAPOSITION OF STRONG WINDS/LOW RH WOULD BE NARROW BOTH SPATIALLY AND TEMPORALLY. AS SUCH...CONFIDENCE IS LOWER THAN AVERAGE FOR DELINEATING A CRITICAL AREA ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... LOW/MID-LEVEL SWLYS WILL STRENGTHEN WITH APPROACH OF AN UPPER-LEVEL TROUGH DIGGING ACROSS THE PACIFIC NW. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING DURING THE DIURNAL HEATING CYCLE...WITH THE NAM/WRF-BASED SREF MEMBERS STRONGER THAN THE GFS/ECMWF. CONSENSUS OF MODEL GUIDANCE SUGGESTS THE STRONGEST FLOW WILL DEVELOP DURING THE EARLY EVENING WHICH MAY MARGINALIZE THE DURATION OF POTENTIALLY STRONG WINDS OVERLAPPING WITH LOW RH. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY DELINEATE A CRITICAL AREA ATTM. ...SRN LOWER MI... A SHORT-DURATION PERIOD OF CRITICAL CONDITIONS MAY DEVELOP DURING MID AFTERNOON ON TUE. CONSENSUS OF MODEL GUIDANCE INDICATES SUBSTANTIAL LOWER-TROPOSPHERIC DRYING WILL OCCUR AS A MID-LEVEL DRY SLOT OVERSPREADS THE UPPER GREAT LAKES AND A SURFACE COLD FRONT PUSHES EWD TOWARDS THE LOWER GREAT LAKES. RH VALUES SHOULD BECOME MARGINALLY LOW FOR A FEW HOURS /FROM 25 TO 35 PERCENT/ UNTIL MORE PRONOUNCED COOLING OCCURS LATE IN THE DAY. WITH 40 TO 50 MPH LOW-LEVEL FLOW...SUSTAINED SURFACE WINDS OF 25 TO 30 MPH APPEAR LIKELY. RAINFALL DURING THE PAST WEEK AND THE SHORT DURATION OF MARGINALLY LOW RH SHOULD HELP MITIGATE THE OVERALL THREAT. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... MARGINAL FIRE WEATHER CONDITIONS SHOULD DEVELOP TUE AFTERNOON AS A RELATIVELY WARM/DRY AIR MASS REMAINS WITHIN A NARROW SW TO NE CORRIDOR DOWNSTREAM OF AN APPROACHING COLD FRONT. AS SWLY LOW-LEVEL FLOW INCREASES...SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/. ABOVE-NORMAL TEMPERATURES IN THE MIDDLE 80S TO LOWER 90S WILL SUPPORT RH VALUES BECOMING MARGINALLY LOW /AROUND 25 TO 30 PERCENT/. GIVEN BELOW-NORMAL RAINFALL ACROSS THE REGION DURING THE PAST FEW WEEKS...AN ENHANCED FIRE WEATHER THREAT APPEARS PROBABLE. ..GRAMS.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0456 AM CDT MON SEP 06 2010 VALID 071200Z - 081200Z ...NO CRITICAL AREAS... ...SYNOPSIS... POTENT UPPER-LEVEL SHORT WAVE TROUGH OVER THE UPPER MS VALLEY WILL TRANSLATE EWD ACROSS THE GREAT LAKES/SRN ONTARIO THROUGH EARLY WED. ATTENDANT SURFACE COLD FRONT WILL MARCH EWD ACROSS THE UPPER GREAT LAKES AND MIDWEST BY TUE AFTERNOON. IN THE WEST...A LARGE-SCALE UPPER-LEVEL TROUGH WILL BECOME ANCHORED ACROSS THE PACIFIC NW INTO NRN CA. ...PORTIONS OF CNTRL/ERN NV... LATEST MODEL FORECASTS ARE FAIRLY CONSISTENT WITH THE DEPICTION OF A WEAK MID-LEVEL IMPULSE EJECTING OUT AHEAD OF A LARGE-SCALE TROUGH AMPLIFYING OVER THE PACIFIC NW. ASSOCIATED SPEED MAX WILL AID IN STRENGTHENING BOUNDARY LAYER FLOW TUE AFTERNOON. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING. 06Z NAM AND ASSOCIATED WRF MEMBERS IN THE 03Z SREF APPEAR STRONGER THAN 00Z GFS/ECMWF GUIDANCE. IN ADDITION...BOTH THE GFS/ECMWF INDICATE MORE ROBUST SUB-TROPICAL MOISTURE EMANATING NWD FROM NWRN MEXICO/AZ...SUGGESTING THE JUXTAPOSITION OF STRONG WINDS/LOW RH WOULD BE NARROW BOTH SPATIALLY AND TEMPORALLY. AS SUCH...CONFIDENCE IS LOWER THAN AVERAGE FOR DELINEATING A CRITICAL AREA ATTM. ...NRN SIERRA MTNS OF NERN CA/NWRN NV... LOW/MID-LEVEL SWLYS WILL STRENGTHEN WITH APPROACH OF AN UPPER-LEVEL TROUGH DIGGING ACROSS THE PACIFIC NW. HOWEVER...MODEL FORECASTS DIFFER WITH THE AMPLITUDE OF THIS STRENGTHENING DURING THE DIURNAL HEATING CYCLE...WITH THE NAM/WRF-BASED SREF MEMBERS STRONGER THAN THE GFS/ECMWF. CONSENSUS OF MODEL GUIDANCE SUGGESTS THE STRONGEST FLOW WILL DEVELOP DURING THE EARLY EVENING WHICH MAY MARGINALIZE THE DURATION OF POTENTIALLY STRONG WINDS OVERLAPPING WITH LOW RH. PREDICTABILITY REMAINS TOO LOW TO CONFIDENTLY DELINEATE A CRITICAL AREA ATTM. ...SRN LOWER MI... A SHORT-DURATION PERIOD OF CRITICAL CONDITIONS MAY DEVELOP DURING MID AFTERNOON ON TUE. CONSENSUS OF MODEL GUIDANCE INDICATES SUBSTANTIAL LOWER-TROPOSPHERIC DRYING WILL OCCUR AS A MID-LEVEL DRY SLOT OVERSPREADS THE UPPER GREAT LAKES AND A SURFACE COLD FRONT PUSHES EWD TOWARDS THE LOWER GREAT LAKES. RH VALUES SHOULD BECOME MARGINALLY LOW FOR A FEW HOURS /FROM 25 TO 35 PERCENT/ UNTIL MORE PRONOUNCED COOLING OCCURS LATE IN THE DAY. WITH 40 TO 50 MPH LOW-LEVEL FLOW...SUSTAINED SURFACE WINDS OF 25 TO 30 MPH APPEAR LIKELY. RAINFALL DURING THE PAST WEEK AND THE SHORT DURATION OF MARGINALLY LOW RH SHOULD HELP MITIGATE THE OVERALL THREAT. ...PORTIONS OF THE ALLEGHENY PLATEAU IN SERN OH...WRN WV/PA... MARGINAL FIRE WEATHER CONDITIONS SHOULD DEVELOP TUE AFTERNOON AS A RELATIVELY WARM/DRY AIR MASS REMAINS WITHIN A NARROW SW TO NE CORRIDOR DOWNSTREAM OF AN APPROACHING COLD FRONT. AS SWLY LOW-LEVEL FLOW INCREASES...SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/. ABOVE-NORMAL TEMPERATURES IN THE MIDDLE 80S TO LOWER 90S WILL SUPPORT RH VALUES BECOMING MARGINALLY LOW /AROUND 25 TO 30 PERCENT/. GIVEN BELOW-NORMAL RAINFALL ACROSS THE REGION DURING THE PAST FEW WEEKS...AN ENHANCED FIRE WEATHER THREAT APPEARS PROBABLE. ..GRAMS.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0236 AM CDT MON SEP 06 2010 VALID 061200Z - 071200Z ...NO CRITICAL AREAS... ...SYNOPSIS... A VIGOROUS UPPER-LEVEL SHORT WAVE TROUGH WILL PROGRESS EWD FROM THE NRN HIGH PLAINS/CNTRL ROCKIES TOWARDS THE UPPER MS VALLEY THROUGH EARLY TUE. ATTENDANT SURFACE CYCLONE OVER THE CNTRL HIGH PLAINS WILL TRACK NEWD TO MN...WHILE A COLD FRONT PUSHES SEWD ACROSS THE CNTRL HIGH PLAINS INTO THE OK/TX PANHANDLES BY EARLY EVENING. IN THE WEST...AN UPPER-LEVEL SHORT WAVE TROUGH WILL DIG ALONG THE BRITISH COLUMBIA COAST WITH A SURFACE RIDGE WEAKENING OVER THE PACIFIC NW. ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... AREAS OF SHORT-DURATION CRITICAL CONDITIONS TO LONGER-DURATION MARGINAL CONDITIONS APPEAR PROBABLE FROM LATER THIS MORNING INTO THE AFTERNOON. RELATIVELY LARGE SPREAD PERSISTS AMONGST LATEST NAM/GFS/SREF GUIDANCE WITH THE DEGREE OF DRYING OCCURRING IN THE WAKE OF A COLD FRONT PASSAGE THIS MORNING. 00Z NAM AND 03Z SREF MEAN INDICATE CRITICALLY LOW RH VALUES WILL BE RELEGATED TO ALONG THE LEE OF THE FRONT RANGE IN N-CNTRL CO...WHILE THE 00Z GFS SUGGESTS LOW RH WILL ALSO BE PREVALENT TO THE N/E ACROSS SERN WY INTO WRN NEB/KS. MODEL FORECASTS ARE MORE CONSISTENT WITH THE DEPICTION OF A SURGE IN LOW-LEVEL W/NWLYS ACCOMPANYING SHORT WAVE TROUGH PASSAGE LATER THIS MORNING. THIS SHOULD LEAD TO A FEW HOURS OF CRITICAL CONDITIONS AROUND NOON ALONG THE FRONT RANGE IN N-CNTRL CO...PRIOR TO WINDS DIMINISHING THROUGH THE AFTERNOON AS A SURFACE RIDGE QUICKLY BUILDS ACROSS THE HIGH PLAINS. FARTHER E INTO WRN NEB/KS...LONGER DURATIONS OF STRONG N/NWLY WINDS /FROM 20 TO 30 MPH/ APPEAR LIKELY. HOWEVER...BASED ON UPSTREAM OBSERVATIONS OF MUCH COOLER/HIGHER RH VALUES...AFTERNOON RH VALUES MAY ONLY BECOME MARGINALLY LOW /FROM 20 TO 30 PERCENT/. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... AN ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP THIS AFTERNOON AS SLY SURFACE WINDS INCREASE WITHIN AN ANTECEDENT WARM/DRY AIR MASS ACROSS THE LOWER MS/OH VALLEY...WHERE ABNORMAL DRYNESS AND MODERATE DROUGHT PERSIST. MODEL FORECASTS REMAIN HIGHLY CONSISTENT THAT TEMPERATURES WILL WARM INTO THE MIDDLE TO UPPER 80S...WITH RH VALUES DROPPING TO BETWEEN 18 AND 25 PERCENT. ALTHOUGH S/SWLY LOW-LEVEL WINDS WILL STRENGTHEN...THIS REGION OF LOW RH VALUES SHOULD REMAIN TO THE E/SE OF STRONGER LOW-LEVEL FLOW CENTERED OVER THE MID-MO VALLEY. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/...WITH GUSTS TO AROUND 25 MPH. ...NRN SACRAMENTO VALLEY OF NRN CA... RECENT MESONET OBSERVATIONS CONFIRM AREAS OF GUSTY NLY WINDS /AROUND 2O TO 30 MPH/ OCCURRING ACROSS THE NRN SACRAMENTO VALLEY AND SURROUNDING FOOTHILLS. THIS HAS SUPPORTED POOR OVERNIGHT RH RECOVERY...WITH 12 TO 20 PERCENT READINGS COMMON AS OF 07Z. AS THE TIGHT LOW-LEVEL PRESSURE GRADIENT RELAXES WITH THE RIDGE AXIS OVER THE PACIFIC NW WEAKENING...WINDS WILL GRADUALLY DIMINISH DURING THE LATE MORNING/EARLY AFTERNOON AND SHOULD REMAIN WEAK THROUGH THE REST OF THE PERIOD. NEVERTHELESS...LONG DURATIONS OF LOW RH APPEAR LIKELY WITH MIN VALUES NEAR 5 PERCENT AT PEAK HEATING. ..GRAMS.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0356 AM CDT MON SEP 06 2010 VALID 091200Z - 141200Z ...DISCUSSION... AMPLE AGREEMENT CONTINUES AMONG 00Z ECMWF/GEFS GUIDANCE ASIDE FROM RELATIVELY MINOR TIMING/MAGNITUDE DIFFERENCES INTO THE WEEKEND. THE MAIN FOCUS WILL BE ON THE NORTHEASTWARD EJECTING WESTERN STATES TROUGH ON DAYS 4/5...AS IT INTERACTS WITH A BROAD WARM/MOIST SECTOR ACROSS THE NORTHERN AND CENTRAL PLAINS TO MIDWEST. THE REMNANTS OF CURRENT TROPICAL SYSTEM HERMINE MAY ALSO BE A FACTOR INTO DAY 4/THURSDAY ACROSS THE SOUTH-CENTRAL PLAINS/OZARKS VICINITY...BUT A CONSIDERABLY LIMITED FORECAST PREDICTABILITY EXISTS BY THIS TIME FRAME /REFERENCE LATEST NHC FORECASTS/. WITH THE ADVANCEMENT OF THE WESTERN STATES UPPER TROUGH OVER THE NORTH CENTRAL STATES...A SEVERE THREAT IS EXPECTED TO INCREASE BY DAY 4/THURSDAY ACROSS THE NORTHERN HIGH PLAINS...INCLUDING THE WESTERN DAKOTAS TO WESTERN/NORTHERN NEB. WHILE LARGE SCALE TIMING UNCERTAINTY INCREASES SOMEWHAT INTO DAY 5/FRIDAY...IT IS PROBABLE THAT A SEVERE RISK WILL EXIST WITHIN A CORRIDOR ACROSS THE EASTERN DAKOTAS/MIDDLE MO VALLEY TO THE UPPER MS VALLEY/UPPER MIDWEST...PERHAPS CENTERED ACROSS EASTERN SD/EASTERN NEB TO IA/SOUTHERN MN. LARGE SCALE TIMING UNCERTAINTY/INHERENT MODEL VARIABILITY...ALONG WITH THE POSSIBILITY OF A SOMEWHAT ANA-FRONTAL TYPE SCENARIO BY DAY 5...PROVIDES UNCERTAINTY REGARDING THE MAGNITUDE OF SPECIFIC DAY SEVERE POTENTIAL. WHILE CATEGORICAL SEVERE RISKS ARE A DISTINCT POSSIBILITY FOR DAY 4/THURSDAY AND DAY 5/FRIDAY...DELINEATION OF ANY HIGHER PROBABILITY /30 PERCENT AND GREATER/ RISK AREAS ARE NOT CURRENTLY WARRANTED. Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0236 AM CDT MON SEP 06 2010 VALID 061200Z - 071200Z ...NO CRITICAL AREAS... ...SYNOPSIS... A VIGOROUS UPPER-LEVEL SHORT WAVE TROUGH WILL PROGRESS EWD FROM THE NRN HIGH PLAINS/CNTRL ROCKIES TOWARDS THE UPPER MS VALLEY THROUGH EARLY TUE. ATTENDANT SURFACE CYCLONE OVER THE CNTRL HIGH PLAINS WILL TRACK NEWD TO MN...WHILE A COLD FRONT PUSHES SEWD ACROSS THE CNTRL HIGH PLAINS INTO THE OK/TX PANHANDLES BY EARLY EVENING. IN THE WEST...AN UPPER-LEVEL SHORT WAVE TROUGH WILL DIG ALONG THE BRITISH COLUMBIA COAST WITH A SURFACE RIDGE WEAKENING OVER THE PACIFIC NW. ...SERN WY/N-CNTRL CO E/SEWD ACROSS THE CNTRL HIGH PLAINS... AREAS OF SHORT-DURATION CRITICAL CONDITIONS TO LONGER-DURATION MARGINAL CONDITIONS APPEAR PROBABLE FROM LATER THIS MORNING INTO THE AFTERNOON. RELATIVELY LARGE SPREAD PERSISTS AMONGST LATEST NAM/GFS/SREF GUIDANCE WITH THE DEGREE OF DRYING OCCURRING IN THE WAKE OF A COLD FRONT PASSAGE THIS MORNING. 00Z NAM AND 03Z SREF MEAN INDICATE CRITICALLY LOW RH VALUES WILL BE RELEGATED TO ALONG THE LEE OF THE FRONT RANGE IN N-CNTRL CO...WHILE THE 00Z GFS SUGGESTS LOW RH WILL ALSO BE PREVALENT TO THE N/E ACROSS SERN WY INTO WRN NEB/KS. MODEL FORECASTS ARE MORE CONSISTENT WITH THE DEPICTION OF A SURGE IN LOW-LEVEL W/NWLYS ACCOMPANYING SHORT WAVE TROUGH PASSAGE LATER THIS MORNING. THIS SHOULD LEAD TO A FEW HOURS OF CRITICAL CONDITIONS AROUND NOON ALONG THE FRONT RANGE IN N-CNTRL CO...PRIOR TO WINDS DIMINISHING THROUGH THE AFTERNOON AS A SURFACE RIDGE QUICKLY BUILDS ACROSS THE HIGH PLAINS. FARTHER E INTO WRN NEB/KS...LONGER DURATIONS OF STRONG N/NWLY WINDS /FROM 20 TO 30 MPH/ APPEAR LIKELY. HOWEVER...BASED ON UPSTREAM OBSERVATIONS OF MUCH COOLER/HIGHER RH VALUES...AFTERNOON RH VALUES MAY ONLY BECOME MARGINALLY LOW /FROM 20 TO 30 PERCENT/. ...SERN MO...NERN AR...SRN IL/IND...WRN KY/TN... AN ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP THIS AFTERNOON AS SLY SURFACE WINDS INCREASE WITHIN AN ANTECEDENT WARM/DRY AIR MASS ACROSS THE LOWER MS/OH VALLEY...WHERE ABNORMAL DRYNESS AND MODERATE DROUGHT PERSIST. MODEL FORECASTS REMAIN HIGHLY CONSISTENT THAT TEMPERATURES WILL WARM INTO THE MIDDLE TO UPPER 80S...WITH RH VALUES DROPPING TO BETWEEN 18 AND 25 PERCENT. ALTHOUGH S/SWLY LOW-LEVEL WINDS WILL STRENGTHEN...THIS REGION OF LOW RH VALUES SHOULD REMAIN TO THE E/SE OF STRONGER LOW-LEVEL FLOW CENTERED OVER THE MID-MO VALLEY. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE /NEAR 15 MPH/...WITH GUSTS TO AROUND 25 MPH. ...NRN SACRAMENTO VALLEY OF NRN CA... RECENT MESONET OBSERVATIONS CONFIRM AREAS OF GUSTY NLY WINDS /AROUND 2O TO 30 MPH/ OCCURRING ACROSS THE NRN SACRAMENTO VALLEY AND SURROUNDING FOOTHILLS. THIS HAS SUPPORTED POOR OVERNIGHT RH RECOVERY...WITH 12 TO 20 PERCENT READINGS COMMON AS OF 07Z. AS THE TIGHT LOW-LEVEL PRESSURE GRADIENT RELAXES WITH THE RIDGE AXIS OVER THE PACIFIC NW WEAKENING...WINDS WILL GRADUALLY DIMINISH DURING THE LATE MORNING/EARLY AFTERNOON AND SHOULD REMAIN WEAK THROUGH THE REST OF THE PERIOD. NEVERTHELESS...LONG DURATIONS OF LOW RH APPEAR LIKELY WITH MIN VALUES NEAR 5 PERCENT AT PEAK HEATING. ..GRAMS.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1237 AM CDT MON SEP 06 2010 VALID 061200Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN MN/WRN WI/IA... ...SYNOPSIS... MID-LEVEL TROUGH/LOW -- INITIALLY OVER MT/WY/CO -- IS FORECAST TO SHIFT QUICKLY ENEWD WITH TIME ACROSS THE CENTRAL AND NRN PLAINS THROUGH THE AFTERNOON...AND THEN INTO/ACROSS THE UPPER MS VALLEY THROUGH THE LATTER HALF OF THE PERIOD. AS THIS OCCURS...SUBSTANTIAL CYCLOGENESIS IS FORECAST ACROSS THE CENTRAL/N CENTRAL CONUS...WITH THE LOW SHIFTING FROM NEB INTO SRN MN THROUGH THE DAY...AND THEN INTO THE WRN UPPER GREAT LAKES REGION BY 07/12. THIS LOW -- AND THE ASSOCIATED SWWD-TRAILING COLD FRONT -- SHOULD FOCUS A LINE OF VIGOROUS/SEVERE STORMS FROM LATE AFTERNOON INTO THE EVENING HOURS. ELSEWHERE...T.D. 10 IS FORECAST TO SHIFT NNWWD ACROSS THE WRN GULF OF MEXICO TOWARD S TX -- POSSIBLY STRENGTHENING TO TROPICAL STORM LEVELS DURING THE PERIOD. ...SRN MN AND PARTS OF WI SWWD INTO THE MID MO VALLEY REGION... CAPPING LAYER OF WARM AIR IN THE 850 TO 700 MB LEVEL IS FORECAST ACROSS THE SLIGHT RISK AREA INTO THE AFTERNOON...AS A DEEPENING CYCLONE SHIFTS NEWD ACROSS THE MID MO VALLEY AND INTO SRN MN. COOLING ALOFT WILL CONTRIBUTE TO SOME CAPE DEVELOPMENT ABOVE THE WARM LAYER...WHILE FLOW FIELD THROUGH THE LOWER HALF OF THE TROPOSPHERE STRENGTHENS. AFOREMENTIONED CAPPING SHOULD SUPPRESS DEEP CONVECTION FOR MUCH OF THE AFTERNOON. HOWEVER...STRONG UVV ASSOCIATED WITH THE ROBUST/COMPACT UPPER SYSTEM -- FOCUSED AT THE SURFACE NEAR THE LOW AND ALONG THE TRAILING COLD FRONT -- SHOULD EVENTUALLY ALLOW STORMS TO DEVELOP IN THE ERN SD/SRN MN/IA VICINITY...AND THEN SWWD ACROSS NWRN MO/KS. WHILE WIND PROFILES ACROSS THE SLIGHT RISK AREA -- FEATURING SUBSTANTIAL VEERING/STRENGTHENING WITH HEIGHT -- WILL BE SUPPORTIVE OF SUPERCELLS...LINEAR FORCING AND DEGREE OF WARM SECTOR CAPPING SUGGEST THAT CONVECTION SHOULD REMAIN CONFINED TO THE IMMEDIATE FRONTAL ZONE...GROWING UPSCALE INTO A MORE LINEAR CONFIGURATION RATHER QUICKLY AFTER INITIAL STORM DEVELOPMENT. THUS -- WHILE SOME TORNADO THREAT APPEARS TO EXIST ACROSS IA AND NWD/NWWD TO THE N OF THE LOW/WARM FRONT WHERE ELY/SELY LOW-LEVEL FLOW WILL EXIST...MAIN THREATS WILL LIKELY BE HAIL AND/OR LOCALLY DAMAGING WINDS. FARTHER SWWD ALONG THE FRONT...STORMS WHICH DEVELOP ACROSS KS AND VICINITY WILL LIKELY REMAIN LESS VIGOROUS GIVEN WEAKER SHEAR PROFILES. STILL...ISOLATED STRONGER CELLS COULD PRODUCING BRIEF GUSTY WINDS AND/OR MARGINAL HAIL. STORMS SHOULD CONTINUE INTO THE EVENING ALONG THE ADVANCING FRONT...BUT WITH THE LOSS OF HEATING AND GRADUAL REDEVELOPMENT OF CAPPING...A DECREASING TREND IN STORM ACTIVITY AND ASSOCIATED SEVERE POTENTIAL IS EXPECTED. ...COASTAL SRN/SERN TX... TROPICAL DEPRESSION #10 HAS FORMED IN THE SWRN GULF OF MEXICO...AND IS FORECAST TO APPROACH S TX LATER IN THE DAY 1 PERIOD. AS THIS OCCURS...INCREASING LOW-LEVEL FLOW FIELD COULD EVENTUALLY SUPPORT WEAK UPDRAFT ROTATION WITH STRONGER CELLS WITHIN THE CONVECTIVE BANDS SURROUNDING THIS SYSTEM. THEREFORE...WILL MAINTAIN LOW TORNADO PROBABILITY ACROSS THIS AREA. ..GOSS/STOPPKOTTE.. 09/06/2010 Read more