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

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT SAT SEP 04 2010

VALID 041630Z - 051200Z

...NO SVR TSTM AREAS FORECAST...

...WRN/CENTRAL MT AREA THIS AFTERNOON/EVENING...
A MIDLEVEL SHORTWAVE TROUGH OVER BC/WA WILL AMPLIFY SEWD OVER THE
NRN ROCKIES AS AN ASSOCIATED COLD FRONT MOVES SEWD ACROSS MT THIS
AFTERNOON THROUGH TONIGHT.  THE MIDLEVEL TROUGH IS PRECEDED BY A
NARROW PLUME OF MIDLEVEL MOISTURE ACROSS NRN ID/WRN MT...AND
MODIFIED REGIONAL SOUNDINGS INDICATE THE POTENTIAL FOR AT LEAST WEAK
INSTABILITY AND DEEP INVERTED-V PROFILES THIS AFTERNOON AHEAD OF THE
FRONT.  THESE PROFILES WILL SUPPORT HIGH-BASED THUNDERSTORMS WITH
THE POTENTIAL TO PRODUCE STRONG/ISOLATED DAMAGING GUSTS THIS
AFTERNOON/EVENING ACROSS WRN/CENTRAL MT AS MIDLEVEL FLOW INCREASES. 
THE PRIMARY LIMITING FACTOR FOR A MORE ROBUST DAMAGING WIND THREAT
IS WEAK INSTABILITY.

...ELSEWHERE ACROSS THE CONUS...
DEEP DRYING IN THE WAKE OF A DEEP MIDLEVEL TROUGH OVER THE LOWER
GREAT LAKES/NEW ENGLAND...AND AN ASSOCIATED COLD FRONT MOVING OVER
THE NRN GULF OF MEXICO...WILL LIMIT THUNDERSTORM POTENTIAL ACROSS
THE MAJORITY OF THE CONUS.  THE PRIMARY EXCEPTION WILL BE NEAR THE
SLOW-MOVING FRONT ACROSS S TX AND FL...WITHIN THE REMAINING TROPICAL
MOISTURE PLUME.

..THOMPSON/HURLBUT.. 09/04/2010

DAY 1 FIRE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1154 AM CDT SAT SEP 04 2010

VALID 041700Z - 051200Z

...CRITICAL FIRE WEATHER AREA FOR S-CNTRL ID...NERN NV...

...S-CNTRL ID...NERN NV...
NO CHANGES MADE TO THE PREVIOUS FORECAST.

...SERN ID...SRN WY...
NO CHANGES MADE TO THE PREVIOUS FORECAST.

...MID-ATLANTIC REGION /NJ INTO VA/...
MID-MORNING SURFACE OBSERVATIONS AND OBJECTIVE ANALYSIS GUIDANCE
SHOW AN AXIS OF RH VALUES AROUND 30-35 PERCENT RESIDING FROM NJ
S-SWWD ACROSS THE DC METRO AREA INTO CNTRL VA...AND MODEL
GUIDANCE/MODIFIED FORECAST SOUNDINGS INDICATE VALUES WILL LIKELY
FALL INTO THE 20S DURING THE AFTERNOON. PEAK WIND SPEEDS DURING THE
PERIOD OF LOWEST RH ARE EXPECTED TO RESIDE NEAR 20 MPH OVER
VA...WITH 20-25 MPH OCCASIONALLY EXPERIENCED OVER NJ...WHICH WILL
SUPPORT LOCALLY CRITICAL FIRE WEATHER CONDITIONS.

...CAROLINAS AND NRN/CNTRL GA...
POST FRONTAL OFFSHORE FLOW REGIME WILL PREVAIL ACROSS THE CAROLINAS
INTO GA TODAY. GIVEN THE PRESENCE OF VERY DRY AIR /PWAT VALUES AOB
0.60 INCHES PER GPS TPW GUIDANCE AND BNA 12Z RAOB/ LOCATED UPSTREAM
FROM THE REGION...MIN RH VALUES BELOW 30 PERCENT APPEAR PROBABLE /AS
INDICATED BY LATEST 12Z NAM MODEL OUTPUT/. HOWEVER...STRONGER
LOW/MID-LEVEL WLY/S WILL BE LOCATED N OF THE REGION...WHICH WILL
RESULT IN SUSTAINED WIND SPEEDS AOB 10 MPH /WITH GUSTS UP TO 20
MPH/. THEREFORE...A CRITICAL OUTLOOK AREA WILL NOT BE ASSIGNED.

...E-CNTRL NV...W-CNTRLY/SWRN UT...
NO CHANGES MADE TO THE PREVIOUS FORECAST.

...LEE OF THE NRN SIERRAS IN FAR NERN CA/NWRN NV...
NO CHANGES MADE TO THE PREVIOUS FORECAST.

..GARNER.. 09/04/2010

.PREV DISCUSSION... /ISSUED 0228 AM CDT SAT SEP 04 2010/

...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.

...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...