MD 1792 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR N CNTRL MO...CNTRL IA INTO FAR SERN MN
MESOSCALE DISCUSSION 1792 NWS STORM PREDICTION CENTER NORMAN OK 0538 PM CDT MON SEP 06 2010 AREAS AFFECTED...N CNTRL MO...CNTRL IA INTO FAR SERN MN CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 062238Z - 070015Z STORMS WERE DEVELOPING/STRENGTHENING ALONG THE COLD FRONT FROM CNTRL IA SWWD INTO NWRN MO. THESE STORMS COULD QUICKLY BECOME SEVERE AS THEY TRACK E/NEWD AND A WW MAY BE NEEDED WITHIN THE NEXT HOUR OR SO. LARGE HAIL WOULD BE THE INITIAL THREAT. ANY STORMS THAT CAN BECOME SFC BASED WOULD THEN POSE A THREAT FOR DAMAGING WINDS. GIVEN STRONG...WEAKLY VEERING DEEP LAYER FLOW...AN ISOLATED TORNADO COULD ALSO BE POSSIBLE. A MODERATELY UNSTABLE AIR MASS WITH MLCAPE VALUES AROUND 1500 J/KG FOR NWRN MO INTO CNTRL IA IS BECOMING LESS CAPPED AS COLD FRONT AND STRONGER MID LEVEL FLOW NOSES INTO THE REGION. MID LEVEL WARM NOSE BETWEEN 850-700 MB IS LIKELY BEING ERODED DUE TO STRONG LIFT ALONG THE FRONT AND SFC MOISTURE INCREASING /DEWPOINTS IN THE MID/UPPER 60S/. WHILE STORMS MAY INITIALLY BE ELEVATED...AS THE ELEVATED WARM LAYER ERODES THEY WILL QUICKLY BECOME ROOTED IN THE BOUNDARY LAYER. THIS WILL ALLOW DAMAGING WINDS AND POSSIBLY AN ISOLATED TORNADO THREAT TO DEVELOP IN ADDITION TO LARGE HAIL IN A CORRIDOR FROM N CNTRL MO INTO CNTRL IA NEAR DSM. FURTHER NE INTO NERN IA AND SERN MN...THE AIR MASS IS LESS LIKELY TO SUPPORT VIGOROUS SFC BASED CONVECTION GIVEN THE QUALITY OF THE AIR MASS. COOLER TEMPERATURES AND LOWER DEWPOINTS WILL LIKELY INHIBIT THE WIND/TORNADO THREAT BUT LARGE HAIL MAY STILL BE POSSIBLE. ..STOPPKOTTE.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...DVN...ARX...MPX...DMX...EAX... LAT...LON 41779169 42299126 42749101 43209093 43729106 44079123 44279159 44399233 44429289 44369326 44229329 43939345 43229382 40879468 40399484 40079458 39909383 40109288 40689224 41779169 Read more

MD 1791 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS LOWER-MIDDLE TX COASTAL PLAIN
MESOSCALE DISCUSSION 1791 NWS STORM PREDICTION CENTER NORMAN OK 0501 PM CDT MON SEP 06 2010 AREAS AFFECTED...PORTIONS LOWER-MIDDLE TX COASTAL PLAIN CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 062201Z - 062300Z THREAT FOR TORNADOES PRODUCED BY TS HERMINE IS MRGL NOW BUT FCST TO INCREASE GRADUALLY FROM S-N ACROSS THIS AREA THROUGH REMAINDER AFTERNOON AND INTO EVENING. TIME SERIES OF LOW-LEVEL VWP HODOGRAPHS AT BRO SHOW STEADY TENDENCY FOR ENLARGEMENT...WITH 0-1 KM SRH NOW IN 100-200 J/KG RANGE DEPENDING ON INPUT CELL MOTION USED. THIS TENDENCY SHOULD CONTINUE FOR A FEW MORE HOURS UNTIL CENTER GETS CLOSER TO ANY GIVEN POINT...WHEREUPON INCREASING TREND IN BOUNDARY LAYER SHEAR VECTOR SHOULD BEGIN TO LEVEL OFF. MEANWHILE SIMILAR TREND IN HODOGRAPHS SHOULD OCCUR FARTHER N TOWARD TX COASTAL BEND...BUT DELAYED BY SEVERAL HOURS IN STEP WITH RELATIVE PROXIMITY TO HERMINE. MOST FAVORABLE JUXTAPOSITION OF BUOYANCY AND SHEAR SHOULD OCCUR OVER MIDDLE-OUTER SECTOR FROM NNW-SE OF CENTER. MLCAPE CURRENTLY IN 1000-1500 J/KG RANGE AWAY FROM THICK CLOUDS/HEAVY PRECIP WILL DIMINISH SOMEWHAT WITH LOSS OF SFC DIABATIC HEATING INLAND...HOWEVER WEAK CINH AND VERY RICH LOW-LEVEL THETAE SHOULD KEEP EFFECTIVE INFLOW PARCELS SFC-BASED EXCEPT IN CLOSE PROXIMITY TO LARGE PRECIP CORES. MAIN LIMITING FACTOR WILL BE SMALL AREA COVERED BY BEST OVERLAP OF SHEAR AND AT LEAST MRGL INSTABILITY. GIVEN NHC FCST TRACK OF CENTER AND STRENGTH/RADII OF WIND FIELDS...FAVORABLE NNW-SE SECTOR WILL SPREAD NNWWD/INLAND WITH SOME EXPANSION ALSO POSSIBLE IN EVENT OF ANY INTENSIFICATION. RADAR SRM TRENDS ALREADY INDICATE BRIEF/SPORADIC AND MAINLY WEAK SHEAR COUPLETS WITH CELLS OFFSHORE AND OVER MEX...BUT WITHOUT SUSTAINED/WELL-ORGANIZED SUPERCELL STRUCTURES UP TO THIS POINT. STG-SVR TSTM GUSTS ALSO ARE POSSIBLE FROM MOST INTENSE OUTER CELLS AND BANDS...OUTSIDE RADIUS OF DAMAGING AMBIENT/GRADIENT WINDS. REF NHC ADVISORIES FOR LATEST TRACK/INTENSITY FCST GUIDANCE ON TS HERMINE. ..EDWARDS.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...HGX...CRP...EWX...BRO... LAT...LON 27099845 27799882 28679900 28859767 28669577 28289648 27889700 27439728 27039737 26639729 26399720 25969713 25949725 25939731 25799735 25909757 26009766 26099799 26359812 27099845 Read more

SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0239 PM CDT MON SEP 06 2010 VALID 062000Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN MN/WRN WI/IA... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER-MIDDLE TX COAST... HAVE MADE MINOR CHANGES TO 1630Z OUTLOOK AND THOSE ARE PRIMARILY TO ADDRESS THE DIMINISHING CONVECTIVE POTENTIAL WITHIN POST-FRONTAL ENVIRONMENT ACROSS THE NRN-CNTRL PLAINS. LATEST RADAR AND SATELLITE IMAGERY SUGGEST CONVECTION IS GRADUALLY INCREASING WITHIN REGION OF STRONG ASCENT ALONG THE SD/MN BORDER...SWD INTO THE MID MO VALLEY. AN EVOLVING SQUALL LINE WITH BOW-TYPE CHARACTERISTICS APPEARS TO REFLECT THIS INCREASING ASCENT AS IT PROPAGATES TOWARD WCNTRL/SWRN MN. SWD EXTENT OF THIS ACTIVITY IS STRUGGLING DUE PRIMARILY TO A STRONG CAP THAT HAS YET TO ERODE - PER 18Z SOUNDINGS AT OAX AND TOP. IN THE ABSENCE OF SIGNIFICANT MID LEVEL COOLING FARTHER SOUTH...INTENSE BOUNDARY LAYER HEATING WILL BE REQUIRED ALONG TRAILING FRONTAL ZONE INTO KS FOR ROBUST UPDRAFT DEVELOPMENT. FOR THIS REASON IT APPEARS THE MORE CONCENTRATED ACTIVITY WILL HOLD ACROSS THE UPPER MS VALLEY AS INDICATED IN CURRENT OUTLOOK SUITE. SEVERE THREAT WILL CONTINUE TO INCREASE ALONG THE LOWER AND MIDDLE TX COAST AS THE CENTER OF HERMINE LIFTS NNWWD TOWARD BRO. OUTER-MOST BANDS OF STRONG CONVECTION ARE BEGINNING TO ROTATE INTO DEEP SOUTH TX AND ISOLATED SUPERCELLS SHOULD BECOME MORE COMMON INTO THE OVERNIGHT HOURS. HAVE ADJUSTED THE RISK OF ISOLATED TORNADOES WWD TO INCLUDE MORE OF COASTAL SOUTH TX. ..DARROW.. 09/06/2010 .PREV DISCUSSION... /ISSUED 1127 AM CDT MON SEP 06 2010/ ...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. Read more

SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0239 PM CDT MON SEP 06 2010 VALID 062000Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN MN/WRN WI/IA... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER-MIDDLE TX COAST... HAVE MADE MINOR CHANGES TO 1630Z OUTLOOK AND THOSE ARE PRIMARILY TO ADDRESS THE DIMINISHING CONVECTIVE POTENTIAL WITHIN POST-FRONTAL ENVIRONMENT ACROSS THE NRN-CNTRL PLAINS. LATEST RADAR AND SATELLITE IMAGERY SUGGEST CONVECTION IS GRADUALLY INCREASING WITHIN REGION OF STRONG ASCENT ALONG THE SD/MN BORDER...SWD INTO THE MID MO VALLEY. AN EVOLVING SQUALL LINE WITH BOW-TYPE CHARACTERISTICS APPEARS TO REFLECT THIS INCREASING ASCENT AS IT PROPAGATES TOWARD WCNTRL/SWRN MN. SWD EXTENT OF THIS ACTIVITY IS STRUGGLING DUE PRIMARILY TO A STRONG CAP THAT HAS YET TO ERODE - PER 18Z SOUNDINGS AT OAX AND TOP. IN THE ABSENCE OF SIGNIFICANT MID LEVEL COOLING FARTHER SOUTH...INTENSE BOUNDARY LAYER HEATING WILL BE REQUIRED ALONG TRAILING FRONTAL ZONE INTO KS FOR ROBUST UPDRAFT DEVELOPMENT. FOR THIS REASON IT APPEARS THE MORE CONCENTRATED ACTIVITY WILL HOLD ACROSS THE UPPER MS VALLEY AS INDICATED IN CURRENT OUTLOOK SUITE. SEVERE THREAT WILL CONTINUE TO INCREASE ALONG THE LOWER AND MIDDLE TX COAST AS THE CENTER OF HERMINE LIFTS NNWWD TOWARD BRO. OUTER-MOST BANDS OF STRONG CONVECTION ARE BEGINNING TO ROTATE INTO DEEP SOUTH TX AND ISOLATED SUPERCELLS SHOULD BECOME MORE COMMON INTO THE OVERNIGHT HOURS. HAVE ADJUSTED THE RISK OF ISOLATED TORNADOES WWD TO INCLUDE MORE OF COASTAL SOUTH TX. ..DARROW.. 09/06/2010 .PREV DISCUSSION... /ISSUED 1127 AM CDT MON SEP 06 2010/ ...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. Read more

SPC 2000Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0239 PM CDT MON SEP 06 2010 VALID 062000Z - 071200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN MN/WRN WI/IA... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LOWER-MIDDLE TX COAST... HAVE MADE MINOR CHANGES TO 1630Z OUTLOOK AND THOSE ARE PRIMARILY TO ADDRESS THE DIMINISHING CONVECTIVE POTENTIAL WITHIN POST-FRONTAL ENVIRONMENT ACROSS THE NRN-CNTRL PLAINS. LATEST RADAR AND SATELLITE IMAGERY SUGGEST CONVECTION IS GRADUALLY INCREASING WITHIN REGION OF STRONG ASCENT ALONG THE SD/MN BORDER...SWD INTO THE MID MO VALLEY. AN EVOLVING SQUALL LINE WITH BOW-TYPE CHARACTERISTICS APPEARS TO REFLECT THIS INCREASING ASCENT AS IT PROPAGATES TOWARD WCNTRL/SWRN MN. SWD EXTENT OF THIS ACTIVITY IS STRUGGLING DUE PRIMARILY TO A STRONG CAP THAT HAS YET TO ERODE - PER 18Z SOUNDINGS AT OAX AND TOP. IN THE ABSENCE OF SIGNIFICANT MID LEVEL COOLING FARTHER SOUTH...INTENSE BOUNDARY LAYER HEATING WILL BE REQUIRED ALONG TRAILING FRONTAL ZONE INTO KS FOR ROBUST UPDRAFT DEVELOPMENT. FOR THIS REASON IT APPEARS THE MORE CONCENTRATED ACTIVITY WILL HOLD ACROSS THE UPPER MS VALLEY AS INDICATED IN CURRENT OUTLOOK SUITE. SEVERE THREAT WILL CONTINUE TO INCREASE ALONG THE LOWER AND MIDDLE TX COAST AS THE CENTER OF HERMINE LIFTS NNWWD TOWARD BRO. OUTER-MOST BANDS OF STRONG CONVECTION ARE BEGINNING TO ROTATE INTO DEEP SOUTH TX AND ISOLATED SUPERCELLS SHOULD BECOME MORE COMMON INTO THE OVERNIGHT HOURS. HAVE ADJUSTED THE RISK OF ISOLATED TORNADOES WWD TO INCLUDE MORE OF COASTAL SOUTH TX. ..DARROW.. 09/06/2010 .PREV DISCUSSION... /ISSUED 1127 AM CDT MON SEP 06 2010/ ...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. Read more

No Mesoscale Discussions are in effect as of Mon Sep 6 19:43:04 UTC 2010.

SPC Day 3-8 Fire Weather Outlook
DAY 3-8 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 PM CDT MON SEP 06 2010 VALID 081200Z - 141200Z LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH FRIDAY/D5 AS AN UPPER TROUGH MOVES ACROSS THE GREAT BASIN AND INTO THE GREAT PLAINS. ON WEDNESDAY/D3...THE UPPER LEVEL SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS CA AND TOWARD THE WRN GREAT BASIN. THIS WILL FOCUS STRENGTHENING LOW/MID-LEVEL SWLY WIND FIELDS ACROSS ERN/SRN NV...WRN UT...AND NWRN AZ. AS A RESULT...SUSTAINED SURFACE WINDS UP TO 25 MPH ARE EXPECTED TO OCCUR IN THE MIDST OF A WARM/DEEPLY MIXED BOUNDARY LAYER AIR MASS FAVORING AFTERNOON RH VALUES AOB 15 PERCENT...WHICH CONTINUES TO SUPPORT A CRITICAL OUTLOOK AREA. THE TROUGH IS THEN FORECAST TO MOVE ACROSS THE GREAT BASIN ON THURSDAY/D4...WHICH WILL AID IN NEAR CRITICAL WIND SPEEDS FROM WY S-SWWD ACROSS PORTIONS OF CO/UT INTO AZ. ATTM...CONDITIONS APPEAR TO BE TOO MARGINAL TO SUPPORT AN OUTLOOK AREA...BUT AN UPGRADE REMAINS POSSIBLE IN FUTURE FORECASTS. MODEL GUIDANCE THEN EJECTS THE TROUGH INTO THE GREAT PLAINS ON FRIDAY/D5...FAVORING A WARM/DRY DOWNSLOPE WIND REGIME OVER THE CNTRL HIGH PLAINS...WHICH MAY LEAD TO A PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS DURING THE AFTERNOON. BEYOND FRIDAY/D5...MREF GUIDANCE SUGGESTS THE UPPER AIR PATTERN WILL EVOLVE TO QUASI-ZONAL...WHILE THE ECMWF INDICATES A MORE AMPLIFIED PATTERN WILL PREVAIL /WITH ANOTHER TROUGH ENTERING THE PAC NW OVER THE WEEKEND/. DUE TO LOW FORECAST CONFIDENCE INDICATED BY THE MODEL OUTPUT...ADDITIONAL CRITICAL OUTLOOK AREAS CANNOT BE DELINEATED ATTM. ..GARNER.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 3-8 Fire Weather Outlook
DAY 3-8 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 PM CDT MON SEP 06 2010 VALID 081200Z - 141200Z LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH FRIDAY/D5 AS AN UPPER TROUGH MOVES ACROSS THE GREAT BASIN AND INTO THE GREAT PLAINS. ON WEDNESDAY/D3...THE UPPER LEVEL SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS CA AND TOWARD THE WRN GREAT BASIN. THIS WILL FOCUS STRENGTHENING LOW/MID-LEVEL SWLY WIND FIELDS ACROSS ERN/SRN NV...WRN UT...AND NWRN AZ. AS A RESULT...SUSTAINED SURFACE WINDS UP TO 25 MPH ARE EXPECTED TO OCCUR IN THE MIDST OF A WARM/DEEPLY MIXED BOUNDARY LAYER AIR MASS FAVORING AFTERNOON RH VALUES AOB 15 PERCENT...WHICH CONTINUES TO SUPPORT A CRITICAL OUTLOOK AREA. THE TROUGH IS THEN FORECAST TO MOVE ACROSS THE GREAT BASIN ON THURSDAY/D4...WHICH WILL AID IN NEAR CRITICAL WIND SPEEDS FROM WY S-SWWD ACROSS PORTIONS OF CO/UT INTO AZ. ATTM...CONDITIONS APPEAR TO BE TOO MARGINAL TO SUPPORT AN OUTLOOK AREA...BUT AN UPGRADE REMAINS POSSIBLE IN FUTURE FORECASTS. MODEL GUIDANCE THEN EJECTS THE TROUGH INTO THE GREAT PLAINS ON FRIDAY/D5...FAVORING A WARM/DRY DOWNSLOPE WIND REGIME OVER THE CNTRL HIGH PLAINS...WHICH MAY LEAD TO A PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS DURING THE AFTERNOON. BEYOND FRIDAY/D5...MREF GUIDANCE SUGGESTS THE UPPER AIR PATTERN WILL EVOLVE TO QUASI-ZONAL...WHILE THE ECMWF INDICATES A MORE AMPLIFIED PATTERN WILL PREVAIL /WITH ANOTHER TROUGH ENTERING THE PAC NW OVER THE WEEKEND/. DUE TO LOW FORECAST CONFIDENCE INDICATED BY THE MODEL OUTPUT...ADDITIONAL CRITICAL OUTLOOK AREAS CANNOT BE DELINEATED ATTM. ..GARNER.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 3-8 Fire Weather Outlook
DAY 3-8 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 PM CDT MON SEP 06 2010 VALID 081200Z - 141200Z LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH FRIDAY/D5 AS AN UPPER TROUGH MOVES ACROSS THE GREAT BASIN AND INTO THE GREAT PLAINS. ON WEDNESDAY/D3...THE UPPER LEVEL SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS CA AND TOWARD THE WRN GREAT BASIN. THIS WILL FOCUS STRENGTHENING LOW/MID-LEVEL SWLY WIND FIELDS ACROSS ERN/SRN NV...WRN UT...AND NWRN AZ. AS A RESULT...SUSTAINED SURFACE WINDS UP TO 25 MPH ARE EXPECTED TO OCCUR IN THE MIDST OF A WARM/DEEPLY MIXED BOUNDARY LAYER AIR MASS FAVORING AFTERNOON RH VALUES AOB 15 PERCENT...WHICH CONTINUES TO SUPPORT A CRITICAL OUTLOOK AREA. THE TROUGH IS THEN FORECAST TO MOVE ACROSS THE GREAT BASIN ON THURSDAY/D4...WHICH WILL AID IN NEAR CRITICAL WIND SPEEDS FROM WY S-SWWD ACROSS PORTIONS OF CO/UT INTO AZ. ATTM...CONDITIONS APPEAR TO BE TOO MARGINAL TO SUPPORT AN OUTLOOK AREA...BUT AN UPGRADE REMAINS POSSIBLE IN FUTURE FORECASTS. MODEL GUIDANCE THEN EJECTS THE TROUGH INTO THE GREAT PLAINS ON FRIDAY/D5...FAVORING A WARM/DRY DOWNSLOPE WIND REGIME OVER THE CNTRL HIGH PLAINS...WHICH MAY LEAD TO A PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS DURING THE AFTERNOON. BEYOND FRIDAY/D5...MREF GUIDANCE SUGGESTS THE UPPER AIR PATTERN WILL EVOLVE TO QUASI-ZONAL...WHILE THE ECMWF INDICATES A MORE AMPLIFIED PATTERN WILL PREVAIL /WITH ANOTHER TROUGH ENTERING THE PAC NW OVER THE WEEKEND/. DUE TO LOW FORECAST CONFIDENCE INDICATED BY THE MODEL OUTPUT...ADDITIONAL CRITICAL OUTLOOK AREAS CANNOT BE DELINEATED ATTM. ..GARNER.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more

SPC Day 3-8 Fire Weather Outlook
DAY 3-8 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1251 PM CDT MON SEP 06 2010 VALID 081200Z - 141200Z LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH FRIDAY/D5 AS AN UPPER TROUGH MOVES ACROSS THE GREAT BASIN AND INTO THE GREAT PLAINS. ON WEDNESDAY/D3...THE UPPER LEVEL SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS CA AND TOWARD THE WRN GREAT BASIN. THIS WILL FOCUS STRENGTHENING LOW/MID-LEVEL SWLY WIND FIELDS ACROSS ERN/SRN NV...WRN UT...AND NWRN AZ. AS A RESULT...SUSTAINED SURFACE WINDS UP TO 25 MPH ARE EXPECTED TO OCCUR IN THE MIDST OF A WARM/DEEPLY MIXED BOUNDARY LAYER AIR MASS FAVORING AFTERNOON RH VALUES AOB 15 PERCENT...WHICH CONTINUES TO SUPPORT A CRITICAL OUTLOOK AREA. THE TROUGH IS THEN FORECAST TO MOVE ACROSS THE GREAT BASIN ON THURSDAY/D4...WHICH WILL AID IN NEAR CRITICAL WIND SPEEDS FROM WY S-SWWD ACROSS PORTIONS OF CO/UT INTO AZ. ATTM...CONDITIONS APPEAR TO BE TOO MARGINAL TO SUPPORT AN OUTLOOK AREA...BUT AN UPGRADE REMAINS POSSIBLE IN FUTURE FORECASTS. MODEL GUIDANCE THEN EJECTS THE TROUGH INTO THE GREAT PLAINS ON FRIDAY/D5...FAVORING A WARM/DRY DOWNSLOPE WIND REGIME OVER THE CNTRL HIGH PLAINS...WHICH MAY LEAD TO A PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS DURING THE AFTERNOON. BEYOND FRIDAY/D5...MREF GUIDANCE SUGGESTS THE UPPER AIR PATTERN WILL EVOLVE TO QUASI-ZONAL...WHILE THE ECMWF INDICATES A MORE AMPLIFIED PATTERN WILL PREVAIL /WITH ANOTHER TROUGH ENTERING THE PAC NW OVER THE WEEKEND/. DUE TO LOW FORECAST CONFIDENCE INDICATED BY THE MODEL OUTPUT...ADDITIONAL CRITICAL OUTLOOK AREAS CANNOT BE DELINEATED ATTM. ..GARNER.. 09/06/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... 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 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