SWODY1
SPC AC 031258
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT MON SEP 03 2007
VALID 031300Z - 041200Z
..NO SVR TSTM AREAS FORECAST...
..NRN MN/NW WI AREA THIS EVENING INTO EARLY TONIGHT...
A SURFACE FRONT...IN THE WAKE OF THE STRONG MID LEVEL TROUGH OVER
QUEBEC...WILL LIFT NWD AS A WARM FRONT TODAY INTO TONIGHT ACROSS SRN
ND/MN/WI. A NARROW BELT OF 60-64 F BOUNDARY LAYER DEWPOINTS IS
PRESENT ALONG THE BAROCLINIC ZONE THIS MORNING ACROSS ERN SD...AND
THIS MOISTURE WILL SPREAD NEWD TODAY INTO ND/MN/WI WHILE BEING
AUGMENTED SOME BY EVAPOTRANSPIRATION. MEANWHILE...A WARM ELEVATED
MIXED LAYER ALREADY PRESENT OVER THE NRN PLAINS WILL ACT TO CAP THE
BOUNDARY LAYER ALONG THE FRONT TODAY...ALLOWING STRONG SURFACE
HEATING OF THE WARM SECTOR.
BY LATE EVENING...WAA/FRONTOGENESIS WILL INCREASE ALONG AND NE OF
THE SURFACE FRONT ACROSS NRN MN...WHERE ELEVATED THUNDERSTORMS
SHOULD DEVELOP. THE COMBINATION OF ELEVATED INSTABILITY /MUCAPE OF
750-1500 J/KG / AND EFFECTIVE BULK SHEAR IN EXCESS OF 40 KT MAY
SUPPORT A FEW ORGANIZED STORM CLUSTERS/SUPERCELLS FOR A FEW HOURS
THIS EVENING/EARLY TONIGHT. THE STRONGEST STORMS MAY PRODUCE SOME
HAIL ACROSS NRN MN INTO NW WI TONIGHT. THIS AREA WILL CONTINUE TO
BE MONITORED IN LATER UPDATES...BUT THE SOMEWHAT LIMITED MAGNITUDE
OF MOISTURE/INSTABILITY AND THE PRESENCE OF THE WARM ELEVATED MIXED
LAYER SHOULD TEND TO LIMIT THE OVERALL SEVERE THREAT.
..CENTRAL ROCKIES/SRN GREAT BASIN...
THE MID LEVEL RIDGE AXIS PERSISTS FROM WY SWWD TOWARD SRN NV.
HOWEVER...A MID LEVEL VORTICITY MAXIMUM IS MOVING AROUND THE NWRN
PERIPHERY OF THE RIDGE OVER NW UT/SE ID...AND SUBSTANTIAL LOW-MID
LEVEL MOISTURE IS PRESENT WITHIN THE RIDGE. MODIFIED 12Z SOUNDINGS
SUGGEST THAT AFTERNOON SURFACE TEMPERATURES OF 85-90 F WILL SUPPORT
SCATTERED AFTERNOON THUNDERSTORMS...ESPECIALLY OVER THE HIGHER
TERRAIN. GUSTY OUTFLOW WINDS WILL BE POSSIBLE GIVEN THE TYPICAL
INVERTED-V PROFILES IN THE LOW LEVELS...BUT THE SEVERE STORM THREAT
IS TOO MARGINAL TO WARRANT A LARGE 5% WIND AREA.
..TX TO FL...
A BROAD PLUME OF 2-2.25 INCH PW VALUES WILL CONTINUE TO SPREAD NWD
TO THE E OF THE MID LEVEL LOW OVER THE BIG BEND. POCKETS OF DAYTIME
HEATING WILL CONTRIBUTE TO SCATTERED THUNDERSTORM ACROSS MUCH OF THE
NW GULF COAST AREA TODAY. FARTHER E...SCATTERED THUNDERSTORMS ARE
EXPECTED IN FL ALONG THE SE AND W COAST SEA BREEZE CIRCULATIONS.
THE MOST CONCENTRATED ACTIVITY SHOULD OCCUR LATE THIS AFTERNOON OVER
SW FL IN CONJUNCTION WITH MULTIPLE STORM/BOUNDARY MERGERS.
.THOMPSON/GUYER.. 09/03/2007
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