No Mesoscale Discussions are in effect as of Sat Sep 4 12:30:02 UTC 2010.

No watches are valid as of Sat Sep 4 12:30:02 UTC 2010.

SPC 1300Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0721 AM CDT SAT SEP 04 2010 VALID 041300Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...NRN INTERMOUNTAIN REGION INTO NRN HIGH PLAINS... LARGE-SCALE TROUGH CENTERED OVER BRITISH COLUMBIA EARLY THIS MORNING WILL SHIFT EWD THROUGH THE PERIOD IN RESPONSE TO APPROACH OF NEXT UPSTREAM SYSTEM THROUGH THE GULF OF AK. AS THIS OCCURS...AN UPSTREAM VORTICITY MAXIMUM AND ATTENDANT MID TO UPPER-LEVEL STREAKS ALONG THE BRITISH COLUMBIA COAST WILL PROPAGATE SEWD...CONTRIBUTING TO A NET SEWD DEVELOPMENT/AMPLIFICATION OF BROADER-SCALE TROUGH THROUGH THE PACIFIC NW AND NRN INTERMOUNTAIN REGION. AT THE SURFACE...AN ASSOCIATED COLD FRONT WILL PROGRESS EWD ACROSS THE REGION...SERVING AS THE FOCUS FOR STRONG TO MARGINALLY SEVERE STORMS THIS AFTERNOON THROUGH EVENING. SATELLITE-DERIVED PW IMAGERY SHOWS A SLIGHT INCREASE IN MOISTURE FROM THE ERN PACIFIC THIS MORNING...THOUGH IN GENERAL...AIR MASS WILL REMAIN RATHER DRY WITH DEW POINTS IN THE 40S AND PW VALUES LESS THAN AN INCH. HOWEVER...REGION WILL RESIDE WITHIN A PLUME OF STEEP MIDLEVEL LAPSE RATES...WHICH WHEN COUPLED WITH DAYTIME HEATING...SHOULD YIELD AFTERNOON MLCAPE OF 250-500 J/KG. THIS DESTABILIZATION COMBINED WITH INCREASED HEIGHT FALLS/DYNAMIC FORCING FOR ASCENT IN ADVANCE OF MIDLEVEL TROUGH SHOULD FOSTER SCATTERED STORM FORMATION ALONG THE FRONT THIS AFTERNOON OVER WRN AND CNTRL MT. AMBIENT INFLOW AIR MASS WILL BE CHARACTERIZED BY A DEEPLY-MIXED PBL WITH 40-50 KT OF WLY DEEP-LAYER SHEAR WHICH WILL BE SUPPORTIVE OF HIGH-BASED STORMS /INCLUDING POSSIBLE SUPERCELLS/ WITH THE THREAT FOR ISOLATED STRONG WIND GUSTS AND MARGINALLY SEVERE HAIL. TSTMS SHOULD TEND TO WEAKEN BY MID TO LATE EVENING AS THE BOUNDARY LAYER COOLS AND SURFACE-BASED CONVECTIVE INHIBITION RAPIDLY ACCUMULATES. ..MEAD/GRAMS.. 09/04/2010 Read more

SPC Day 2 Fire Weather Outlook
DAY 2 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0458 AM CDT SAT SEP 04 2010 VALID 051200Z - 061200Z ...CRITICAL FIRE WEATHER AREA FOR MOST OF THE ERN GREAT BASIN TO THE CNTRL ROCKIES... ...SYNOPSIS... A LARGE-SCALE UPPER-LEVEL TROUGH WILL CONTINUE TO DIG ACROSS THE NWRN CONUS AND PROGRESS EWD TOWARDS THE NRN/CNTRL ROCKIES THROUGH EARLY MON. MID-LEVEL WLYS WILL STRENGTHEN WITH A BELT OF 50 TO 70 MPH FLOW AT 500 MB CENTERED ACROSS NRN NV/SRN ID INTO WY ON SUN AFTERNOON. AT THE SURFACE...A SHARP COLD FRONT WILL SWEEP SWD THROUGH THE GREAT BASIN...WITH TIGHT THERMAL AND PRESSURE GRADIENTS DEVELOPING IN ITS WAKE. ...MOST OF THE ERN GREAT BASIN TO THE CNTRL ROCKIES... WIDESPREAD CRITICAL CONDITIONS APPEAR LIKELY SUN AFTERNOON AHEAD OF A SHARP COLD FRONT ACROSS NRN AZ...SRN/ERN UT...NRN/WRN CO AND CNTRL/SRN WY. SUSTAINED SURFACE WINDS WILL INCREASE TO 20 TO 30 MPH...WITH WIND GUSTS LOCALLY REACHING 40 TO 50 MPH OVER PORTIONS OF SRN WY/NWRN CO. THIS WILL COINCIDE WITH AN ANTECEDENT VERY WARM/DRY AIR MASS /RH VALUES OF 5 TO 15 PERCENT/. THE CRITICAL AREA HAS BEEN EXTENDED FARTHER NW INTO NERN NV/NWRN UT/SERN ID. HERE...STRONG SURFACE WINDS /FROM 20 TO 30 MPH/ DURING THE AFTERNOON WILL PERSIST INTO THE EVENING AS THE POST-FRONTAL PRESSURE GRADIENT STRENGTHENS. DESPITE COOLING TEMPERATURES WITH WINDS VEERING TO THE N/NW...CONSENSUS OF MODEL FORECASTS SUGGESTS RH RECOVERY WILL INITIALLY BE POOR DURING THE EARLY EVENING AS GUSTS AOA 30 MPH CONTINUE. ALTHOUGH MIN RH VALUES MAY BE MARGINAL /AROUND 15 PERCENT/...THE STRENGTH AND DURATION OF WINDS WARRANT A CRITICAL DELINEATION. ...PORTIONS OF THE TX/OK PANHANDLES...SWRN KS...NWRN OK... MARGINAL TO LOCALIZED CRITICAL CONDITIONS MAY DEVELOP AROUND PEAK HEATING ON SUN. THE STRONGEST LOW-LEVEL SLYS SHOULD PRIMARILY BE CONFINED E OF A DRYLINE MIXING ACROSS THE CNTRL/SRN PLAINS...WHERE RH VALUES WILL BE INCREASINGLY MARGINAL WITH ERN EXTENT. HOWEVER...AS LEE CYCLOGENESIS ENSUES INVOF NERN CO...A TIGHTENING SURFACE PRESSURE GRADIENT W OF THE DRYLINE WILL OCCUR ACROSS THE TX/OX PANHANDLES DURING MID TO LATE AFTERNOON. SUSTAINED SURFACE WINDS SHOULD REACH 15 TO 20 MPH WITH RH VALUES OF 10 TO 20 PERCENT. ...NRN SACRAMENTO VALLEY IN NRN CA... A HIGHLY LOCALIZED ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP LATE SUN AFTERNOON THROUGH THE EVENING. GUSTY NLY WINDS WILL DEVELOP AS LOW-LEVEL PRESSURE GRADIENTS TIGHTEN SUBSTANTIALLY WITH A RIDGE BUILDING INTO THE PACIFIC NW. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE...REACHING 15 MPH. THIS WOULD BE INITIALLY JUXTAPOSED WITH LOW RH VALUES OF 6 TO 12 PERCENT...AND POOR RH RECOVERY IS EXPECTED THROUGH MUCH OF THE NIGHT. ..GRAMS.. 09/04/2010 ...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 0458 AM CDT SAT SEP 04 2010 VALID 051200Z - 061200Z ...CRITICAL FIRE WEATHER AREA FOR MOST OF THE ERN GREAT BASIN TO THE CNTRL ROCKIES... ...SYNOPSIS... A LARGE-SCALE UPPER-LEVEL TROUGH WILL CONTINUE TO DIG ACROSS THE NWRN CONUS AND PROGRESS EWD TOWARDS THE NRN/CNTRL ROCKIES THROUGH EARLY MON. MID-LEVEL WLYS WILL STRENGTHEN WITH A BELT OF 50 TO 70 MPH FLOW AT 500 MB CENTERED ACROSS NRN NV/SRN ID INTO WY ON SUN AFTERNOON. AT THE SURFACE...A SHARP COLD FRONT WILL SWEEP SWD THROUGH THE GREAT BASIN...WITH TIGHT THERMAL AND PRESSURE GRADIENTS DEVELOPING IN ITS WAKE. ...MOST OF THE ERN GREAT BASIN TO THE CNTRL ROCKIES... WIDESPREAD CRITICAL CONDITIONS APPEAR LIKELY SUN AFTERNOON AHEAD OF A SHARP COLD FRONT ACROSS NRN AZ...SRN/ERN UT...NRN/WRN CO AND CNTRL/SRN WY. SUSTAINED SURFACE WINDS WILL INCREASE TO 20 TO 30 MPH...WITH WIND GUSTS LOCALLY REACHING 40 TO 50 MPH OVER PORTIONS OF SRN WY/NWRN CO. THIS WILL COINCIDE WITH AN ANTECEDENT VERY WARM/DRY AIR MASS /RH VALUES OF 5 TO 15 PERCENT/. THE CRITICAL AREA HAS BEEN EXTENDED FARTHER NW INTO NERN NV/NWRN UT/SERN ID. HERE...STRONG SURFACE WINDS /FROM 20 TO 30 MPH/ DURING THE AFTERNOON WILL PERSIST INTO THE EVENING AS THE POST-FRONTAL PRESSURE GRADIENT STRENGTHENS. DESPITE COOLING TEMPERATURES WITH WINDS VEERING TO THE N/NW...CONSENSUS OF MODEL FORECASTS SUGGESTS RH RECOVERY WILL INITIALLY BE POOR DURING THE EARLY EVENING AS GUSTS AOA 30 MPH CONTINUE. ALTHOUGH MIN RH VALUES MAY BE MARGINAL /AROUND 15 PERCENT/...THE STRENGTH AND DURATION OF WINDS WARRANT A CRITICAL DELINEATION. ...PORTIONS OF THE TX/OK PANHANDLES...SWRN KS...NWRN OK... MARGINAL TO LOCALIZED CRITICAL CONDITIONS MAY DEVELOP AROUND PEAK HEATING ON SUN. THE STRONGEST LOW-LEVEL SLYS SHOULD PRIMARILY BE CONFINED E OF A DRYLINE MIXING ACROSS THE CNTRL/SRN PLAINS...WHERE RH VALUES WILL BE INCREASINGLY MARGINAL WITH ERN EXTENT. HOWEVER...AS LEE CYCLOGENESIS ENSUES INVOF NERN CO...A TIGHTENING SURFACE PRESSURE GRADIENT W OF THE DRYLINE WILL OCCUR ACROSS THE TX/OX PANHANDLES DURING MID TO LATE AFTERNOON. SUSTAINED SURFACE WINDS SHOULD REACH 15 TO 20 MPH WITH RH VALUES OF 10 TO 20 PERCENT. ...NRN SACRAMENTO VALLEY IN NRN CA... A HIGHLY LOCALIZED ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP LATE SUN AFTERNOON THROUGH THE EVENING. GUSTY NLY WINDS WILL DEVELOP AS LOW-LEVEL PRESSURE GRADIENTS TIGHTEN SUBSTANTIALLY WITH A RIDGE BUILDING INTO THE PACIFIC NW. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE...REACHING 15 MPH. THIS WOULD BE INITIALLY JUXTAPOSED WITH LOW RH VALUES OF 6 TO 12 PERCENT...AND POOR RH RECOVERY IS EXPECTED THROUGH MUCH OF THE NIGHT. ..GRAMS.. 09/04/2010 ...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 0458 AM CDT SAT SEP 04 2010 VALID 051200Z - 061200Z ...CRITICAL FIRE WEATHER AREA FOR MOST OF THE ERN GREAT BASIN TO THE CNTRL ROCKIES... ...SYNOPSIS... A LARGE-SCALE UPPER-LEVEL TROUGH WILL CONTINUE TO DIG ACROSS THE NWRN CONUS AND PROGRESS EWD TOWARDS THE NRN/CNTRL ROCKIES THROUGH EARLY MON. MID-LEVEL WLYS WILL STRENGTHEN WITH A BELT OF 50 TO 70 MPH FLOW AT 500 MB CENTERED ACROSS NRN NV/SRN ID INTO WY ON SUN AFTERNOON. AT THE SURFACE...A SHARP COLD FRONT WILL SWEEP SWD THROUGH THE GREAT BASIN...WITH TIGHT THERMAL AND PRESSURE GRADIENTS DEVELOPING IN ITS WAKE. ...MOST OF THE ERN GREAT BASIN TO THE CNTRL ROCKIES... WIDESPREAD CRITICAL CONDITIONS APPEAR LIKELY SUN AFTERNOON AHEAD OF A SHARP COLD FRONT ACROSS NRN AZ...SRN/ERN UT...NRN/WRN CO AND CNTRL/SRN WY. SUSTAINED SURFACE WINDS WILL INCREASE TO 20 TO 30 MPH...WITH WIND GUSTS LOCALLY REACHING 40 TO 50 MPH OVER PORTIONS OF SRN WY/NWRN CO. THIS WILL COINCIDE WITH AN ANTECEDENT VERY WARM/DRY AIR MASS /RH VALUES OF 5 TO 15 PERCENT/. THE CRITICAL AREA HAS BEEN EXTENDED FARTHER NW INTO NERN NV/NWRN UT/SERN ID. HERE...STRONG SURFACE WINDS /FROM 20 TO 30 MPH/ DURING THE AFTERNOON WILL PERSIST INTO THE EVENING AS THE POST-FRONTAL PRESSURE GRADIENT STRENGTHENS. DESPITE COOLING TEMPERATURES WITH WINDS VEERING TO THE N/NW...CONSENSUS OF MODEL FORECASTS SUGGESTS RH RECOVERY WILL INITIALLY BE POOR DURING THE EARLY EVENING AS GUSTS AOA 30 MPH CONTINUE. ALTHOUGH MIN RH VALUES MAY BE MARGINAL /AROUND 15 PERCENT/...THE STRENGTH AND DURATION OF WINDS WARRANT A CRITICAL DELINEATION. ...PORTIONS OF THE TX/OK PANHANDLES...SWRN KS...NWRN OK... MARGINAL TO LOCALIZED CRITICAL CONDITIONS MAY DEVELOP AROUND PEAK HEATING ON SUN. THE STRONGEST LOW-LEVEL SLYS SHOULD PRIMARILY BE CONFINED E OF A DRYLINE MIXING ACROSS THE CNTRL/SRN PLAINS...WHERE RH VALUES WILL BE INCREASINGLY MARGINAL WITH ERN EXTENT. HOWEVER...AS LEE CYCLOGENESIS ENSUES INVOF NERN CO...A TIGHTENING SURFACE PRESSURE GRADIENT W OF THE DRYLINE WILL OCCUR ACROSS THE TX/OX PANHANDLES DURING MID TO LATE AFTERNOON. SUSTAINED SURFACE WINDS SHOULD REACH 15 TO 20 MPH WITH RH VALUES OF 10 TO 20 PERCENT. ...NRN SACRAMENTO VALLEY IN NRN CA... A HIGHLY LOCALIZED ENHANCED FIRE WEATHER THREAT SHOULD DEVELOP LATE SUN AFTERNOON THROUGH THE EVENING. GUSTY NLY WINDS WILL DEVELOP AS LOW-LEVEL PRESSURE GRADIENTS TIGHTEN SUBSTANTIALLY WITH A RIDGE BUILDING INTO THE PACIFIC NW. SUSTAINED SURFACE WINDS SHOULD BECOME MODERATE...REACHING 15 MPH. THIS WOULD BE INITIALLY JUXTAPOSED WITH LOW RH VALUES OF 6 TO 12 PERCENT...AND POOR RH RECOVERY IS EXPECTED THROUGH MUCH OF THE NIGHT. ..GRAMS.. 09/04/2010 ...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 0228 AM CDT SAT SEP 04 2010 VALID 041200Z - 051200Z ...CRITICAL FIRE WEATHER AREA FOR S-CNTRL ID...NERN NV... ...SYNOPSIS... AN UPPER-LEVEL TROUGH WILL AMPLIFY FROM BRITISH COLUMBIA INTO THE PACIFIC NW THROUGH EARLY SUN...AS A DOWNSTREAM RIDGE MOVES FROM THE NRN ROCKIES TO THE NRN PLAINS. A WEAK MID-LEVEL IMPULSE JUST OFF THE SWRN ORE COAST WILL PROGRESS INLAND REACHING THE NRN GREAT BASIN THIS AFTERNOON. IN THE EAST...SEVERAL IMPULSES EMBEDDED WITHIN A LARGE-SCALE UPPER-LEVEL TROUGH CENTERED OVER THE GREAT LAKES/MIDWEST WILL EJECT ACROSS THE NRN/CNTRL APPALACHIANS THROUGH NEW ENGLAND. ...S-CNTRL ID...NERN NV... THE APPROACH OF A WEAK MID-LEVEL IMPULSE OFF THE SWRN ORE COAST AND ASSOCIATED SPEED MAX WILL BE FAVORABLY TIMED WITH THE DIURNAL HEATING CYCLE AND SHOULD RESULT IN AREAS OF LOW-END CRITICAL CONDITIONS. DEEP VERTICAL MIXING WILL PROMOTE SUSTAINED SURFACE WINDS NEAR 20 MPH WITH GUSTS OF 30 TO 35 MPH...AS RH VALUES BECOME LOW /BETWEEN 6 AND 12 PERCENT/. ...SERN ID...SRN WY... EAST OF THE CRITICAL AREA IN S-CNTRL ID...SIMILAR METEOROLOGICAL CONDITIONS ARE EXPECTED TO EXTEND ACROSS SERN ID INTO SWRN WY. HOWEVER...ABOVE-NORMAL RAINFALL DURING THE PAST WEEK SHOULD HELP MARGINALIZE THE OVERALL THREAT. ACROSS SERN WY...RECENT RAINFALL HAS BEEN LACKING...BUT WIND SPEEDS SHOULD REMAIN SLIGHTLY MORE MODERATE /AROUND 15 TO 20 MPH/ AND THIS WILL PRECLUDE A CRITICAL AREA DELINEATION ATTM. ...PIEDMONT AND COASTAL PLAIN OF THE MID-ATLANTIC INTO NC... MARGINAL TO LOCALIZED CRITICAL CONDITIONS SHOULD DEVELOP THIS AFTERNOON IN THE WAKE OF A COLD FRONT PASSAGE LATE FRI INTO EARLY SAT. WLY LOW-LEVEL FLOW WILL BE STRONG OVER THE UPPER MID-ATLANTIC/NORTHEAST AND PROGRESSIVELY WEAKEN WITH SRN EXTENT WHERE THE PRESSURE GRADIENT WILL BECOME MORE RELAXED. SUSTAINED SURFACE WINDS SHOULD RANGE FROM 15 TO 25 MPH N TO BETWEEN 10 TO 15 MPH S. MEANWHILE...WARM/DRY CONDITIONS WILL OCCUR OVER NC/SRN VA...WHERE RH VALUES SHOULD FALL INTO THE 20S. PROGRESSIVELY COOLER/MORE MOIST CONDITIONS ARE EXPECTED WITH NWD EXTENT...WITH RH VALUES LARGELY IN THE 30S. THE RELATIVELY GREATEST THREAT SHOULD EXIST OVER PORTIONS OF NRN/CNTRL VA WHERE MODERATE TO SEVERE DROUGHT PERSISTS. ...E-CNTRL NV...W-CNTRL/SWRN UT... ALTHOUGH THIS REGION WILL REMAIN ON THE SRN PERIPHERY OF STRONGER MID-LEVEL FLOW ASSOCIATED WITH THE IMPULSE OFF THE SWRN ORE COAST...DEEP BOUNDARY LAYER MIXING WILL SUPPORT SUSTAINED SURFACE WINDS OF 15 TO 20 MPH WITH GUSTS OF 25 TO 30 MPH. THIS WILL BE JUXTAPOSED WITH VERY LOW RH VALUES OF 4 TO 8 PERCENT AND SHOULD RESULT IN AN ENHANCED FIRE WEATHER THREAT. ...LEE OF THE NRN SIERRAS IN FAR NERN CA/NWRN NV... LOCALIZED MARGINAL CONDITIONS SHOULD DEVELOP DURING THE LATE AFTERNOON ALONG THE LEE OF THE NRN SIERRAS. ALTHOUGH THE MAGNITUDE OF MID-LEVEL FLOW WILL BE SIMILAR TO THE AFOREMENTIONED CRITICAL AREA...MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE THAT THE DEPTH OF VERTICAL MIXING WILL REMAIN LOWER. THIS SHOULD HELP HOLD SUSTAINED SURFACE SPEEDS TO AROUND 15 MPH WITH GUSTS OF 25 MPH...AS RH VALUES FALL TO BETWEEN 5 TO 10 PERCENT. ..GRAMS.. 09/04/2010 ...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 0228 AM CDT SAT SEP 04 2010 VALID 041200Z - 051200Z ...CRITICAL FIRE WEATHER AREA FOR S-CNTRL ID...NERN NV... ...SYNOPSIS... AN UPPER-LEVEL TROUGH WILL AMPLIFY FROM BRITISH COLUMBIA INTO THE PACIFIC NW THROUGH EARLY SUN...AS A DOWNSTREAM RIDGE MOVES FROM THE NRN ROCKIES TO THE NRN PLAINS. A WEAK MID-LEVEL IMPULSE JUST OFF THE SWRN ORE COAST WILL PROGRESS INLAND REACHING THE NRN GREAT BASIN THIS AFTERNOON. IN THE EAST...SEVERAL IMPULSES EMBEDDED WITHIN A LARGE-SCALE UPPER-LEVEL TROUGH CENTERED OVER THE GREAT LAKES/MIDWEST WILL EJECT ACROSS THE NRN/CNTRL APPALACHIANS THROUGH NEW ENGLAND. ...S-CNTRL ID...NERN NV... THE APPROACH OF A WEAK MID-LEVEL IMPULSE OFF THE SWRN ORE COAST AND ASSOCIATED SPEED MAX WILL BE FAVORABLY TIMED WITH THE DIURNAL HEATING CYCLE AND SHOULD RESULT IN AREAS OF LOW-END CRITICAL CONDITIONS. DEEP VERTICAL MIXING WILL PROMOTE SUSTAINED SURFACE WINDS NEAR 20 MPH WITH GUSTS OF 30 TO 35 MPH...AS RH VALUES BECOME LOW /BETWEEN 6 AND 12 PERCENT/. ...SERN ID...SRN WY... EAST OF THE CRITICAL AREA IN S-CNTRL ID...SIMILAR METEOROLOGICAL CONDITIONS ARE EXPECTED TO EXTEND ACROSS SERN ID INTO SWRN WY. HOWEVER...ABOVE-NORMAL RAINFALL DURING THE PAST WEEK SHOULD HELP MARGINALIZE THE OVERALL THREAT. ACROSS SERN WY...RECENT RAINFALL HAS BEEN LACKING...BUT WIND SPEEDS SHOULD REMAIN SLIGHTLY MORE MODERATE /AROUND 15 TO 20 MPH/ AND THIS WILL PRECLUDE A CRITICAL AREA DELINEATION ATTM. ...PIEDMONT AND COASTAL PLAIN OF THE MID-ATLANTIC INTO NC... MARGINAL TO LOCALIZED CRITICAL CONDITIONS SHOULD DEVELOP THIS AFTERNOON IN THE WAKE OF A COLD FRONT PASSAGE LATE FRI INTO EARLY SAT. WLY LOW-LEVEL FLOW WILL BE STRONG OVER THE UPPER MID-ATLANTIC/NORTHEAST AND PROGRESSIVELY WEAKEN WITH SRN EXTENT WHERE THE PRESSURE GRADIENT WILL BECOME MORE RELAXED. SUSTAINED SURFACE WINDS SHOULD RANGE FROM 15 TO 25 MPH N TO BETWEEN 10 TO 15 MPH S. MEANWHILE...WARM/DRY CONDITIONS WILL OCCUR OVER NC/SRN VA...WHERE RH VALUES SHOULD FALL INTO THE 20S. PROGRESSIVELY COOLER/MORE MOIST CONDITIONS ARE EXPECTED WITH NWD EXTENT...WITH RH VALUES LARGELY IN THE 30S. THE RELATIVELY GREATEST THREAT SHOULD EXIST OVER PORTIONS OF NRN/CNTRL VA WHERE MODERATE TO SEVERE DROUGHT PERSISTS. ...E-CNTRL NV...W-CNTRL/SWRN UT... ALTHOUGH THIS REGION WILL REMAIN ON THE SRN PERIPHERY OF STRONGER MID-LEVEL FLOW ASSOCIATED WITH THE IMPULSE OFF THE SWRN ORE COAST...DEEP BOUNDARY LAYER MIXING WILL SUPPORT SUSTAINED SURFACE WINDS OF 15 TO 20 MPH WITH GUSTS OF 25 TO 30 MPH. THIS WILL BE JUXTAPOSED WITH VERY LOW RH VALUES OF 4 TO 8 PERCENT AND SHOULD RESULT IN AN ENHANCED FIRE WEATHER THREAT. ...LEE OF THE NRN SIERRAS IN FAR NERN CA/NWRN NV... LOCALIZED MARGINAL CONDITIONS SHOULD DEVELOP DURING THE LATE AFTERNOON ALONG THE LEE OF THE NRN SIERRAS. ALTHOUGH THE MAGNITUDE OF MID-LEVEL FLOW WILL BE SIMILAR TO THE AFOREMENTIONED CRITICAL AREA...MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE THAT THE DEPTH OF VERTICAL MIXING WILL REMAIN LOWER. THIS SHOULD HELP HOLD SUSTAINED SURFACE SPEEDS TO AROUND 15 MPH WITH GUSTS OF 25 MPH...AS RH VALUES FALL TO BETWEEN 5 TO 10 PERCENT. ..GRAMS.. 09/04/2010 ...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 0351 AM CDT SAT SEP 04 2010 VALID 071200Z - 121200Z ...DISCUSSION... AS GOOD AGREEMENT CONTINUES AMONG LATEST ECMWF/GEFS GUIDANCE...IT IS LIKELY THAT A RELATIVELY MORE ACTIVE PATTERN WILL DEVELOP ACROSS THE NORTH CENTRAL STATES DURING THE MIDDLE TO LATTER PART OF NEXT WEEK. THIS WILL BE IN ASSOCIATION WITH THE EASTWARD ADVANCEMENT OF A WESTERN STATES UPPER TROUGH...ALONG WITH THE ANTICIPATED AVAILABILITY OF A BROAD/HIGHER QUALITY MOIST SECTOR GIVEN A STALLING/RETREATING CENTRAL STATES FRONT DURING THE MIDDLE PART OF THE WEEK. INITIALLY...IT APPEARS THAT SOME SEVERE RISK MAY EXIST ON DAY 5/WEDNESDAY ACROSS THE NORTH-CENTRAL HIGH PLAINS. A MORE APPRECIABLE SEVERE RISK SHOULD UNFOLD INTO DAYS 6/7...MAINLY THE DAKOTAS AND WESTERN/NORTHERN NEB ON DAY 6/THURSDAY...AND PERHAPS THE UPPER MS RIVER VALLEY ON DAY 7/FRIDAY. WHILE CURRENT THINKING IS THAT CATEGORICAL SLIGHT RISKS WILL ULTIMATELY BE WARRANTED IN THIS TIME FRAME...LARGE SCALE TIMING UNCERTAINTY/INHERENT UNKNOWNS CURRENTLY PRECLUDE DELINEATION OF ANY HIGHER PROBABILITY /30 PERCENT AND GREATER/ SEVERE RISK AREAS. Read more

Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0351 AM CDT SAT SEP 04 2010 VALID 071200Z - 121200Z ...DISCUSSION... AS GOOD AGREEMENT CONTINUES AMONG LATEST ECMWF/GEFS GUIDANCE...IT IS LIKELY THAT A RELATIVELY MORE ACTIVE PATTERN WILL DEVELOP ACROSS THE NORTH CENTRAL STATES DURING THE MIDDLE TO LATTER PART OF NEXT WEEK. THIS WILL BE IN ASSOCIATION WITH THE EASTWARD ADVANCEMENT OF A WESTERN STATES UPPER TROUGH...ALONG WITH THE ANTICIPATED AVAILABILITY OF A BROAD/HIGHER QUALITY MOIST SECTOR GIVEN A STALLING/RETREATING CENTRAL STATES FRONT DURING THE MIDDLE PART OF THE WEEK. INITIALLY...IT APPEARS THAT SOME SEVERE RISK MAY EXIST ON DAY 5/WEDNESDAY ACROSS THE NORTH-CENTRAL HIGH PLAINS. A MORE APPRECIABLE SEVERE RISK SHOULD UNFOLD INTO DAYS 6/7...MAINLY THE DAKOTAS AND WESTERN/NORTHERN NEB ON DAY 6/THURSDAY...AND PERHAPS THE UPPER MS RIVER VALLEY ON DAY 7/FRIDAY. WHILE CURRENT THINKING IS THAT CATEGORICAL SLIGHT RISKS WILL ULTIMATELY BE WARRANTED IN THIS TIME FRAME...LARGE SCALE TIMING UNCERTAINTY/INHERENT UNKNOWNS CURRENTLY PRECLUDE DELINEATION OF ANY HIGHER PROBABILITY /30 PERCENT AND GREATER/ SEVERE RISK AREAS. Read more

Day 4-8 Outlook
DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0351 AM CDT SAT SEP 04 2010 VALID 071200Z - 121200Z ...DISCUSSION... AS GOOD AGREEMENT CONTINUES AMONG LATEST ECMWF/GEFS GUIDANCE...IT IS LIKELY THAT A RELATIVELY MORE ACTIVE PATTERN WILL DEVELOP ACROSS THE NORTH CENTRAL STATES DURING THE MIDDLE TO LATTER PART OF NEXT WEEK. THIS WILL BE IN ASSOCIATION WITH THE EASTWARD ADVANCEMENT OF A WESTERN STATES UPPER TROUGH...ALONG WITH THE ANTICIPATED AVAILABILITY OF A BROAD/HIGHER QUALITY MOIST SECTOR GIVEN A STALLING/RETREATING CENTRAL STATES FRONT DURING THE MIDDLE PART OF THE WEEK. INITIALLY...IT APPEARS THAT SOME SEVERE RISK MAY EXIST ON DAY 5/WEDNESDAY ACROSS THE NORTH-CENTRAL HIGH PLAINS. A MORE APPRECIABLE SEVERE RISK SHOULD UNFOLD INTO DAYS 6/7...MAINLY THE DAKOTAS AND WESTERN/NORTHERN NEB ON DAY 6/THURSDAY...AND PERHAPS THE UPPER MS RIVER VALLEY ON DAY 7/FRIDAY. WHILE CURRENT THINKING IS THAT CATEGORICAL SLIGHT RISKS WILL ULTIMATELY BE WARRANTED IN THIS TIME FRAME...LARGE SCALE TIMING UNCERTAINTY/INHERENT UNKNOWNS CURRENTLY PRECLUDE DELINEATION OF ANY HIGHER PROBABILITY /30 PERCENT AND GREATER/ SEVERE RISK AREAS. Read more

SPC Day 1 Fire Weather Outlook
DAY 1 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0228 AM CDT SAT SEP 04 2010 VALID 041200Z - 051200Z ...CRITICAL FIRE WEATHER AREA FOR S-CNTRL ID...NERN NV... ...SYNOPSIS... AN UPPER-LEVEL TROUGH WILL AMPLIFY FROM BRITISH COLUMBIA INTO THE PACIFIC NW THROUGH EARLY SUN...AS A DOWNSTREAM RIDGE MOVES FROM THE NRN ROCKIES TO THE NRN PLAINS. A WEAK MID-LEVEL IMPULSE JUST OFF THE SWRN ORE COAST WILL PROGRESS INLAND REACHING THE NRN GREAT BASIN THIS AFTERNOON. IN THE EAST...SEVERAL IMPULSES EMBEDDED WITHIN A LARGE-SCALE UPPER-LEVEL TROUGH CENTERED OVER THE GREAT LAKES/MIDWEST WILL EJECT ACROSS THE NRN/CNTRL APPALACHIANS THROUGH NEW ENGLAND. ...S-CNTRL ID...NERN NV... THE APPROACH OF A WEAK MID-LEVEL IMPULSE OFF THE SWRN ORE COAST AND ASSOCIATED SPEED MAX WILL BE FAVORABLY TIMED WITH THE DIURNAL HEATING CYCLE AND SHOULD RESULT IN AREAS OF LOW-END CRITICAL CONDITIONS. DEEP VERTICAL MIXING WILL PROMOTE SUSTAINED SURFACE WINDS NEAR 20 MPH WITH GUSTS OF 30 TO 35 MPH...AS RH VALUES BECOME LOW /BETWEEN 6 AND 12 PERCENT/. ...SERN ID...SRN WY... EAST OF THE CRITICAL AREA IN S-CNTRL ID...SIMILAR METEOROLOGICAL CONDITIONS ARE EXPECTED TO EXTEND ACROSS SERN ID INTO SWRN WY. HOWEVER...ABOVE-NORMAL RAINFALL DURING THE PAST WEEK SHOULD HELP MARGINALIZE THE OVERALL THREAT. ACROSS SERN WY...RECENT RAINFALL HAS BEEN LACKING...BUT WIND SPEEDS SHOULD REMAIN SLIGHTLY MORE MODERATE /AROUND 15 TO 20 MPH/ AND THIS WILL PRECLUDE A CRITICAL AREA DELINEATION ATTM. ...PIEDMONT AND COASTAL PLAIN OF THE MID-ATLANTIC INTO NC... MARGINAL TO LOCALIZED CRITICAL CONDITIONS SHOULD DEVELOP THIS AFTERNOON IN THE WAKE OF A COLD FRONT PASSAGE LATE FRI INTO EARLY SAT. WLY LOW-LEVEL FLOW WILL BE STRONG OVER THE UPPER MID-ATLANTIC/NORTHEAST AND PROGRESSIVELY WEAKEN WITH SRN EXTENT WHERE THE PRESSURE GRADIENT WILL BECOME MORE RELAXED. SUSTAINED SURFACE WINDS SHOULD RANGE FROM 15 TO 25 MPH N TO BETWEEN 10 TO 15 MPH S. MEANWHILE...WARM/DRY CONDITIONS WILL OCCUR OVER NC/SRN VA...WHERE RH VALUES SHOULD FALL INTO THE 20S. PROGRESSIVELY COOLER/MORE MOIST CONDITIONS ARE EXPECTED WITH NWD EXTENT...WITH RH VALUES LARGELY IN THE 30S. THE RELATIVELY GREATEST THREAT SHOULD EXIST OVER PORTIONS OF NRN/CNTRL VA WHERE MODERATE TO SEVERE DROUGHT PERSISTS. ...E-CNTRL NV...W-CNTRL/SWRN UT... ALTHOUGH THIS REGION WILL REMAIN ON THE SRN PERIPHERY OF STRONGER MID-LEVEL FLOW ASSOCIATED WITH THE IMPULSE OFF THE SWRN ORE COAST...DEEP BOUNDARY LAYER MIXING WILL SUPPORT SUSTAINED SURFACE WINDS OF 15 TO 20 MPH WITH GUSTS OF 25 TO 30 MPH. THIS WILL BE JUXTAPOSED WITH VERY LOW RH VALUES OF 4 TO 8 PERCENT AND SHOULD RESULT IN AN ENHANCED FIRE WEATHER THREAT. ...LEE OF THE NRN SIERRAS IN FAR NERN CA/NWRN NV... LOCALIZED MARGINAL CONDITIONS SHOULD DEVELOP DURING THE LATE AFTERNOON ALONG THE LEE OF THE NRN SIERRAS. ALTHOUGH THE MAGNITUDE OF MID-LEVEL FLOW WILL BE SIMILAR TO THE AFOREMENTIONED CRITICAL AREA...MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE THAT THE DEPTH OF VERTICAL MIXING WILL REMAIN LOWER. THIS SHOULD HELP HOLD SUSTAINED SURFACE SPEEDS TO AROUND 15 MPH WITH GUSTS OF 25 MPH...AS RH VALUES FALL TO BETWEEN 5 TO 10 PERCENT. ..GRAMS.. 09/04/2010 ...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 1208 AM CDT SAT SEP 04 2010 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE NRN-STREAM PATTERN FCST TO CONTINUE...LED BY MID-UPPER LEVEL CYCLONE NOW CENTERED OVER NRN ONT THAT IS FCST TO SHIFT/REDEVELOP NNEWD ACROSS ERN HUDSON BAY AND NWRN QUE. UPSTREAM RIDGING WILL MOVE EWD ACROSS CANADIAN PRAIRIE PROVINCES AND NRN HIGH PLAINS OF CONUS. MEANWHILE...STG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY MOVING ASHORE BC -- IS FCST TO EVOLVE INTO CLOSED LOW OVER NRN BC AND THEN NRN AB. SPEED MAX DIGGING SEWD W OF THIS FEATURE WILL LEAD TO OVERALL AMPLIFICATION OF TROUGH S OF LOW...WITH STG HEIGHT FALLS ACROSS PAC NW AND NRN ROCKIES THROUGH MUCH OF PERIOD. BY 5/12Z...TROUGH POSITION SHOULD EXTEND FROM CANADIAN ROCKIES SSWWD ACROSS ERN WA...CENTRAL ORE AND NRN CA. AT SFC...LEE CYCLOGENESIS WILL OCCUR AHEAD OF UPPER LOW OVER AB...WITH TROUGHING SEWD ACROSS MT. THIS LOW SHOULD MOVE EWD TOWARD SK...WHILE FRONTOGENESIS OCCURS TO ITS SW OVER NRN ROCKIES. BY END OF PERIOD...FRONT SHOULD BE MOVING EWD/SEWD ACROSS NERN MT...SWRN MT AND WRN ID. WEAKER/SECONDARY LOW MAY FORM ALONG LEE TROUGH OVER CENTRAL/SRN MT AROUND 5/00Z...AND MOVE ESEWD TO SEWD TO WRN SD. ...NRN HIGH PLAINS REGION... WIDELY SCATTERED TSTMS SHOULD INITIATE THIS AFTERNOON ON HIGHER TERRAIN OF MOUNTAINS/FOOTHILLS...AND POSSIBLY IN CONVERGENT AREAS NEAR FRONT AND LEE TROUGH AS WELL. MOST INTENSE TSTMS MAY PRODUCE ISOLATED SVR/DAMAGING GUSTS. AS TROUGHING AND RELATED HEIGHT FALLS APCH...STRONG MID-UPPER WINDS AND NEARLY UNIDIRECTIONAL DEEP-LAYER WIND FIELDS ARE EXPECTED...WITH AT LEAST MRGL BUOYANCY DEVELOPING DIURNALLY ATOP DEEP/WELL-MIXED BOUNDARY LAYER. LARGE-SCALE ASCENT -- RELATED TO VARIOUS EXTENTS TO MIDLEVEL DPVA...AGEOSTROPHICALLY FORCED ASCENT IN LEFT-EXIT REGION OF UPPER JET MAX...AND LOW-LEVEL WAA...WILL CONTRIBUTE TO DESTABILIZATION ALOFT. DESPITE RELATIVELY MEAGER MOISTURE -- I.E. SFC DEW POINTS MAINLY 30S AND 40S F -- DEEP-LAYER LAPSE RATES SHOULD BE STEEP ENOUGH DURING MID-LATE AFTERNOON TO SUPPORT MLCAPE IN 250-500 J/KG RANGE. GUST POTENTIAL WITH THIS ACTIVITY SHOULD DIMINISH AFTER DARK ACROSS ERN MT AS IT MOVES INTO PROGRESSIVELY MORE STABLE BOUNDARY-LAYER AIR MASS...BOTH WITH TIME AND WITH EWD EXTENT. ..EDWARDS/STOPPKOTTE.. 09/04/2010 Read more

SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1208 AM CDT SAT SEP 04 2010 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE NRN-STREAM PATTERN FCST TO CONTINUE...LED BY MID-UPPER LEVEL CYCLONE NOW CENTERED OVER NRN ONT THAT IS FCST TO SHIFT/REDEVELOP NNEWD ACROSS ERN HUDSON BAY AND NWRN QUE. UPSTREAM RIDGING WILL MOVE EWD ACROSS CANADIAN PRAIRIE PROVINCES AND NRN HIGH PLAINS OF CONUS. MEANWHILE...STG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY MOVING ASHORE BC -- IS FCST TO EVOLVE INTO CLOSED LOW OVER NRN BC AND THEN NRN AB. SPEED MAX DIGGING SEWD W OF THIS FEATURE WILL LEAD TO OVERALL AMPLIFICATION OF TROUGH S OF LOW...WITH STG HEIGHT FALLS ACROSS PAC NW AND NRN ROCKIES THROUGH MUCH OF PERIOD. BY 5/12Z...TROUGH POSITION SHOULD EXTEND FROM CANADIAN ROCKIES SSWWD ACROSS ERN WA...CENTRAL ORE AND NRN CA. AT SFC...LEE CYCLOGENESIS WILL OCCUR AHEAD OF UPPER LOW OVER AB...WITH TROUGHING SEWD ACROSS MT. THIS LOW SHOULD MOVE EWD TOWARD SK...WHILE FRONTOGENESIS OCCURS TO ITS SW OVER NRN ROCKIES. BY END OF PERIOD...FRONT SHOULD BE MOVING EWD/SEWD ACROSS NERN MT...SWRN MT AND WRN ID. WEAKER/SECONDARY LOW MAY FORM ALONG LEE TROUGH OVER CENTRAL/SRN MT AROUND 5/00Z...AND MOVE ESEWD TO SEWD TO WRN SD. ...NRN HIGH PLAINS REGION... WIDELY SCATTERED TSTMS SHOULD INITIATE THIS AFTERNOON ON HIGHER TERRAIN OF MOUNTAINS/FOOTHILLS...AND POSSIBLY IN CONVERGENT AREAS NEAR FRONT AND LEE TROUGH AS WELL. MOST INTENSE TSTMS MAY PRODUCE ISOLATED SVR/DAMAGING GUSTS. AS TROUGHING AND RELATED HEIGHT FALLS APCH...STRONG MID-UPPER WINDS AND NEARLY UNIDIRECTIONAL DEEP-LAYER WIND FIELDS ARE EXPECTED...WITH AT LEAST MRGL BUOYANCY DEVELOPING DIURNALLY ATOP DEEP/WELL-MIXED BOUNDARY LAYER. LARGE-SCALE ASCENT -- RELATED TO VARIOUS EXTENTS TO MIDLEVEL DPVA...AGEOSTROPHICALLY FORCED ASCENT IN LEFT-EXIT REGION OF UPPER JET MAX...AND LOW-LEVEL WAA...WILL CONTRIBUTE TO DESTABILIZATION ALOFT. DESPITE RELATIVELY MEAGER MOISTURE -- I.E. SFC DEW POINTS MAINLY 30S AND 40S F -- DEEP-LAYER LAPSE RATES SHOULD BE STEEP ENOUGH DURING MID-LATE AFTERNOON TO SUPPORT MLCAPE IN 250-500 J/KG RANGE. GUST POTENTIAL WITH THIS ACTIVITY SHOULD DIMINISH AFTER DARK ACROSS ERN MT AS IT MOVES INTO PROGRESSIVELY MORE STABLE BOUNDARY-LAYER AIR MASS...BOTH WITH TIME AND WITH EWD EXTENT. ..EDWARDS/STOPPKOTTE.. 09/04/2010 Read more

SPC 1200Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1208 AM CDT SAT SEP 04 2010 VALID 041200Z - 051200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE NRN-STREAM PATTERN FCST TO CONTINUE...LED BY MID-UPPER LEVEL CYCLONE NOW CENTERED OVER NRN ONT THAT IS FCST TO SHIFT/REDEVELOP NNEWD ACROSS ERN HUDSON BAY AND NWRN QUE. UPSTREAM RIDGING WILL MOVE EWD ACROSS CANADIAN PRAIRIE PROVINCES AND NRN HIGH PLAINS OF CONUS. MEANWHILE...STG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY MOVING ASHORE BC -- IS FCST TO EVOLVE INTO CLOSED LOW OVER NRN BC AND THEN NRN AB. SPEED MAX DIGGING SEWD W OF THIS FEATURE WILL LEAD TO OVERALL AMPLIFICATION OF TROUGH S OF LOW...WITH STG HEIGHT FALLS ACROSS PAC NW AND NRN ROCKIES THROUGH MUCH OF PERIOD. BY 5/12Z...TROUGH POSITION SHOULD EXTEND FROM CANADIAN ROCKIES SSWWD ACROSS ERN WA...CENTRAL ORE AND NRN CA. AT SFC...LEE CYCLOGENESIS WILL OCCUR AHEAD OF UPPER LOW OVER AB...WITH TROUGHING SEWD ACROSS MT. THIS LOW SHOULD MOVE EWD TOWARD SK...WHILE FRONTOGENESIS OCCURS TO ITS SW OVER NRN ROCKIES. BY END OF PERIOD...FRONT SHOULD BE MOVING EWD/SEWD ACROSS NERN MT...SWRN MT AND WRN ID. WEAKER/SECONDARY LOW MAY FORM ALONG LEE TROUGH OVER CENTRAL/SRN MT AROUND 5/00Z...AND MOVE ESEWD TO SEWD TO WRN SD. ...NRN HIGH PLAINS REGION... WIDELY SCATTERED TSTMS SHOULD INITIATE THIS AFTERNOON ON HIGHER TERRAIN OF MOUNTAINS/FOOTHILLS...AND POSSIBLY IN CONVERGENT AREAS NEAR FRONT AND LEE TROUGH AS WELL. MOST INTENSE TSTMS MAY PRODUCE ISOLATED SVR/DAMAGING GUSTS. AS TROUGHING AND RELATED HEIGHT FALLS APCH...STRONG MID-UPPER WINDS AND NEARLY UNIDIRECTIONAL DEEP-LAYER WIND FIELDS ARE EXPECTED...WITH AT LEAST MRGL BUOYANCY DEVELOPING DIURNALLY ATOP DEEP/WELL-MIXED BOUNDARY LAYER. LARGE-SCALE ASCENT -- RELATED TO VARIOUS EXTENTS TO MIDLEVEL DPVA...AGEOSTROPHICALLY FORCED ASCENT IN LEFT-EXIT REGION OF UPPER JET MAX...AND LOW-LEVEL WAA...WILL CONTRIBUTE TO DESTABILIZATION ALOFT. DESPITE RELATIVELY MEAGER MOISTURE -- I.E. SFC DEW POINTS MAINLY 30S AND 40S F -- DEEP-LAYER LAPSE RATES SHOULD BE STEEP ENOUGH DURING MID-LATE AFTERNOON TO SUPPORT MLCAPE IN 250-500 J/KG RANGE. GUST POTENTIAL WITH THIS ACTIVITY SHOULD DIMINISH AFTER DARK ACROSS ERN MT AS IT MOVES INTO PROGRESSIVELY MORE STABLE BOUNDARY-LAYER AIR MASS...BOTH WITH TIME AND WITH EWD EXTENT. ..EDWARDS/STOPPKOTTE.. 09/04/2010 Read more

SPC 0100Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0758 PM CDT FRI SEP 03 2010 VALID 040100Z - 041200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE NRN-STREAM PATTERN FEATURES SHARPLY DEFINED RIDGING FROM LOWER CO RIVER VALLEY NNEWD ACROSS NRN ROCKIES TO SK...BRACKETED BY STRONG TROUGHS OVER AK PANHANDLE AND UPPER GREAT LAKES REGION. LATTER TROUGH IS ANCHORED BY 500 MB CYCLONE OVER NRN ONT NEAR LS...WHICH IS PREDICTED TO MOVE SLOWLY EWD ACROSS ONT. RELATED SFC FRONTAL ZONE -- ANALYZED AT 23Z FROM CENTRAL NY TO WRN VA...CENTRAL MS...AND S-CENTRAL TX -- WILL MOVE EWD ACROSS REMAINDER MID-ATLANTIC REGION AND ONTO CAROLINAS/GA PIEDMONT. TRAILING PORTION OF FRONT WILL MOVE SWD ACROSS S TX AND LOWER MS VALLEY REGION. ...COASTAL SERN MA AND ADJACENT ISLANDS... A FEW SHALLOW/SHORT-LIVED CELLS EMBEDDED WITHIN OUTER FRINGES OF HURRICANE EARL...THOUGH MOSTLY DEVOID OF LIGHTNING...HAVE SHOWN BRIEF/WEAK CYCLONIC SHEAR IN SRM IMAGERY. LOW-LEVEL SHEAR ENVIRONMENT NNW-NE OF CENTER WILL BE FAVORABLE FOR SUPERCELLS...WITH ENHANCED 0-1 KM AGL HODOGRAPHS. BRIEF WINDOW OF OPPORTUNITY EXISTS DURING NEXT FEW HOURS WHERE THAT SECTOR OF EARL WILL AFFECT THIS AREA...FOR A TRANSIENT SUPERCELL OR TWO TO DEVELOP AND MOVE ASHORE. HOWEVER...THERMODYNAMIC CHARACTER OF AIR MASS IS IN QUESTION GIVEN SHALLOW STABLE LAYER EVIDENT IN CHH RAOB...LOSS OF ALREADY WEAK DIURNAL HEATING INLAND...AND CONTINUED WEAKENING OF EARL OVERALL AS IT MOVES OVER COLDER WATER...PER NHC DISCUSSIONS. OVERALL PROBABILITIES ARE TOO SMALL/CONDITIONAL FOR CATEGORICAL OUTLOOK. REF NHC ADVISORIES FOR LATEST TRACK/INTENSITY GUIDANCE ON THIS SYSTEM. ...FRONTAL ZONE FROM NERN CONUS TO CENTRAL APPALACHIANS... POCKETS OF MARGINAL BUOYANCY LINGER ACROSS PORTIONS OF INLAND MID-ATLANTIC REGION AND CENTRAL APPALACHIANS...SUPPORTING ISOLATED TO WIDELY SCATTERED TSTMS INVOF COLD FRONT IN THOSE AREAS. CONVECTIVE POTENTIAL WILL DIMINISH MARKEDLY IN NEXT 2-3 HOURS...HOWEER...AS PREFRONTAL AIR MASS EXPERIENCES DIABATIC SFC COOLING AND AS FRONT MOVES ACROSS MOUNTAINS INTO DRIER...DOWNSLOPING WLY FLOW REGIME. ...LOWER MS VALLEY TO S TX... CONVECTIVE POTENTIAL MAY PERSIST OVER THIS REGION ALONG AND AHEAD OF COLD FRONT LONGER THAN FARTHER NE...GIVEN MORE ROBUST BOUNDARY LAYER THETAE AND SLIGHTLY STEEPER LAPSE RATES ALOFT. HOWEVER...NLY FLOW COMPONENT ACROSS ENTIRE REGION WILL RESULT IN VERY WEAK CONVERGENCE INVOF FRONTAL ZONE...WHILE SFC AIR MASS COOLS AFTER DARK. THEREFORE...EXPECT CONVECTIVE COVERAGE TO DIMINISH IN THIS AREA AS WELL. DEEP-LAYER WINDS AND SHEAR ARE TOO WEAK TO SUPPORT ORGANIZED SVR PROBABILITIES. ...AZ/NM... WIDELY SCATTERED TSTMS FCST TO PERSIST INTO EARLY EVENING OVER SERN AZ AND HIGHER TERRAIN FROM NEAR MOGOLLON RIM NEWD TO WRN NM...SUPPORTED BY POCKETS OF 250-500 J/KG MLCAPE. EXPECT CONVECTIVE COVERAGE TO DIMINISH THROUGH EVENING...AS MLCINH INCREASES DUE TO COMBINATION OF SFC COOLING AND SPREADING OUTFLOWS. ...INLAND NWRN CONUS... MRGL THUNDER POTENTIAL LINGERS OVER THIS REGION...PRIMARILY TIED TO REMAINING AREAS OF HEATING OF HIGHER TERRAIN FOR ANOTHER 1-2 HOURS. VIS IMAGERY SHOWS TCU AND ISOLATED CB. MODIFIED RAOBS AND RUC SOUNDINGS SUGGEST MLCAPE WILL REMAIN BELOW 300 J/KG...LIMITED BY RELATIVELY WEAK SFC THETAE. ..EDWARDS.. 09/04/2010 Read more

SPC 0100Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0758 PM CDT FRI SEP 03 2010 VALID 040100Z - 041200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... PROGRESSIVE NRN-STREAM PATTERN FEATURES SHARPLY DEFINED RIDGING FROM LOWER CO RIVER VALLEY NNEWD ACROSS NRN ROCKIES TO SK...BRACKETED BY STRONG TROUGHS OVER AK PANHANDLE AND UPPER GREAT LAKES REGION. LATTER TROUGH IS ANCHORED BY 500 MB CYCLONE OVER NRN ONT NEAR LS...WHICH IS PREDICTED TO MOVE SLOWLY EWD ACROSS ONT. RELATED SFC FRONTAL ZONE -- ANALYZED AT 23Z FROM CENTRAL NY TO WRN VA...CENTRAL MS...AND S-CENTRAL TX -- WILL MOVE EWD ACROSS REMAINDER MID-ATLANTIC REGION AND ONTO CAROLINAS/GA PIEDMONT. TRAILING PORTION OF FRONT WILL MOVE SWD ACROSS S TX AND LOWER MS VALLEY REGION. ...COASTAL SERN MA AND ADJACENT ISLANDS... A FEW SHALLOW/SHORT-LIVED CELLS EMBEDDED WITHIN OUTER FRINGES OF HURRICANE EARL...THOUGH MOSTLY DEVOID OF LIGHTNING...HAVE SHOWN BRIEF/WEAK CYCLONIC SHEAR IN SRM IMAGERY. LOW-LEVEL SHEAR ENVIRONMENT NNW-NE OF CENTER WILL BE FAVORABLE FOR SUPERCELLS...WITH ENHANCED 0-1 KM AGL HODOGRAPHS. BRIEF WINDOW OF OPPORTUNITY EXISTS DURING NEXT FEW HOURS WHERE THAT SECTOR OF EARL WILL AFFECT THIS AREA...FOR A TRANSIENT SUPERCELL OR TWO TO DEVELOP AND MOVE ASHORE. HOWEVER...THERMODYNAMIC CHARACTER OF AIR MASS IS IN QUESTION GIVEN SHALLOW STABLE LAYER EVIDENT IN CHH RAOB...LOSS OF ALREADY WEAK DIURNAL HEATING INLAND...AND CONTINUED WEAKENING OF EARL OVERALL AS IT MOVES OVER COLDER WATER...PER NHC DISCUSSIONS. OVERALL PROBABILITIES ARE TOO SMALL/CONDITIONAL FOR CATEGORICAL OUTLOOK. REF NHC ADVISORIES FOR LATEST TRACK/INTENSITY GUIDANCE ON THIS SYSTEM. ...FRONTAL ZONE FROM NERN CONUS TO CENTRAL APPALACHIANS... POCKETS OF MARGINAL BUOYANCY LINGER ACROSS PORTIONS OF INLAND MID-ATLANTIC REGION AND CENTRAL APPALACHIANS...SUPPORTING ISOLATED TO WIDELY SCATTERED TSTMS INVOF COLD FRONT IN THOSE AREAS. CONVECTIVE POTENTIAL WILL DIMINISH MARKEDLY IN NEXT 2-3 HOURS...HOWEER...AS PREFRONTAL AIR MASS EXPERIENCES DIABATIC SFC COOLING AND AS FRONT MOVES ACROSS MOUNTAINS INTO DRIER...DOWNSLOPING WLY FLOW REGIME. ...LOWER MS VALLEY TO S TX... CONVECTIVE POTENTIAL MAY PERSIST OVER THIS REGION ALONG AND AHEAD OF COLD FRONT LONGER THAN FARTHER NE...GIVEN MORE ROBUST BOUNDARY LAYER THETAE AND SLIGHTLY STEEPER LAPSE RATES ALOFT. HOWEVER...NLY FLOW COMPONENT ACROSS ENTIRE REGION WILL RESULT IN VERY WEAK CONVERGENCE INVOF FRONTAL ZONE...WHILE SFC AIR MASS COOLS AFTER DARK. THEREFORE...EXPECT CONVECTIVE COVERAGE TO DIMINISH IN THIS AREA AS WELL. DEEP-LAYER WINDS AND SHEAR ARE TOO WEAK TO SUPPORT ORGANIZED SVR PROBABILITIES. ...AZ/NM... WIDELY SCATTERED TSTMS FCST TO PERSIST INTO EARLY EVENING OVER SERN AZ AND HIGHER TERRAIN FROM NEAR MOGOLLON RIM NEWD TO WRN NM...SUPPORTED BY POCKETS OF 250-500 J/KG MLCAPE. EXPECT CONVECTIVE COVERAGE TO DIMINISH THROUGH EVENING...AS MLCINH INCREASES DUE TO COMBINATION OF SFC COOLING AND SPREADING OUTFLOWS. ...INLAND NWRN CONUS... MRGL THUNDER POTENTIAL LINGERS OVER THIS REGION...PRIMARILY TIED TO REMAINING AREAS OF HEATING OF HIGHER TERRAIN FOR ANOTHER 1-2 HOURS. VIS IMAGERY SHOWS TCU AND ISOLATED CB. MODIFIED RAOBS AND RUC SOUNDINGS SUGGEST MLCAPE WILL REMAIN BELOW 300 J/KG...LIMITED BY RELATIVELY WEAK SFC THETAE. ..EDWARDS.. 09/04/2010 Read more

No watches are valid as of Fri Sep 3 21:36:01 UTC 2010.

No Mesoscale Discussions are in effect as of Fri Sep 3 21:36:01 UTC 2010.

SPC Day 3-8 Fire Weather Outlook
DAY 3-8 FIRE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0346 PM CDT FRI SEP 03 2010 VALID 051200Z - 111200Z A SEASONABLY STRONG UPPER-LEVEL SHORTWAVE TROUGH IS FORECAST TO DROP SEWD OUT OF THE PAC NW AND MOVE ACROSS THE NRN GREAT BASIN/INTERMOUNTAIN W ON SUNDAY/D3. STRONG MID-LEVEL WLY WIND FIELDS /50+ KT AT 500 MB...30+ KT AT 700 MB/ ARE EXPECTED TO SPREAD EWD AHEAD OF THE TROUGH ACROSS MUCH OF UT/CO/WY...WHILE SLIGHTLY WEAKER FLOW RESIDES AT THE BASE OF THE TROUGH OVER NRN AZ. IN RESPONSE TO THIS UPPER FEATURE...SUSTAINED SURFACE WIND SPEEDS WILL INCREASE TO 20-30 MPH...WITH WIND GUSTS LOCALLY REACHING 40 MPH OVER PORTIONS OF WY. IN ADDITION...MODEL GUIDANCE INDICATES THAT A DRY LOW-LEVEL AIR MASS WILL RESIDE ACROSS THE REGION...WITH AFTERNOON RH VALUES AOB 15 PERCENT. GIVEN THESE CONDITIONS...THE CRITICAL FIRE WEATHER AREA HAS BEEN EXTENDED SWD FROM CNTRL WY ACROSS MUCH OF UT /WHERE FUEL CONDITIONS BELOW 7000 FEET WILL BE FAVORABLE FOR WILDFIRES...AND ONGOING PRESCRIBED BURNS WILL HAVE THE POTENTIAL TO ESCAPE CONTROL/ AND INTO NRN AZ. ELSEWHERE...POST FRONTAL SURFACE PRESSURE GRADIENT WILL STRENGTHEN OVER NERN NV INTO SERN ID DURING SUNDAY AFTERNOON. LOCALLY CRITICAL FIRE WEATHER CONDITIONS WILL BE POSSIBLE OVER THE REGION...BUT WILL WAIT FOR ADDITIONAL MODEL GUIDANCE BEFORE DELINEATING AN OUTLOOK AREA. OFFSHORE WIND REGIME IS ALSO FORECAST TO DEVELOP OVER PORTIONS OF NRN/NWRN CA ON SUNDAY...AND GUSTY ONSHORE FLOW IS INDICATED OVER SRN CA. THESE AREAS WILL ALSO BE MONITORED IN FUTURE OUTLOOKS FOR INCREASING CRITICAL FIRE POTENTIAL GIVEN LOW RH VALUES DEPICTED IN LATEST MODEL GUIDANCE. ON MONDAY/D4...THE WRN UPPER TROUGH WILL MOVE QUICKLY ACROSS THE GREAT PLAINS...WITH BREEZY POST FRONTAL NWLY WINDS DEVELOPING OVER PORTIONS OF THE CENTRAL HIGH PLAINS /SERN WY...NERN CO...WRN NEB/. HOWEVER...CURRENT MODEL GUIDANCE INDICATES THAT THE STRONGER WIND SPEEDS WILL OCCUR BEFORE DRIER AFTERNOON RH VALUES DEVELOP...PRECLUDING A MORE SIGNIFICANT CRITICAL FIRE WEATHER THREAT. A SECOND UPPER-LEVEL TROUGH IS THEN FORECAST TO DIG SWD ALONG THE PAC COAST DURING THE MIDDLE OF NEXT WEEK. THIS WILL AID IN RE-ESTABLISHING SLY LOW-LEVEL FLOW OVER MUCH OF THE WRN CONUS...LEADING TO INCREASING TEMPERATURES AND LOWER RH VALUES. THOUGH MODEL OUTPUT SUGGESTS THIS TROUGH WILL EJECT EWD ACROSS THE GREAT BASIN DURING THE THURSDAY/FRIDAY TIME FRAME...CERTAINTY IN THIS SCENARIO IS NOT GREAT ENOUGH ATTM TO OUTLINE A WIND DRIVEN WILDFIRE THREAT AREA. ..GARNER.. 09/03/2010 ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT... Read more