DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 021253
SWODY1
SPC AC 021251

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT SUN SEP 02 2007

VALID 021300Z - 031200Z

..NO SVR TSTM AREAS FORECAST...

..NRN PLAINS THROUGH TONIGHT...
A SURFACE COLD FRONT WILL MOVE SEWD ACROSS THE UPPER MS VALLEY AND
UPPER GREAT LAKES IN THE WAKE OF A STRONG MID LEVEL TROUGH OVER
ONTARIO/QUEBEC. THE WRN EXTENT OF THE SURFACE FRONT WILL STALL THIS
AFTERNOON INVOF THE NEB/SD BORDER...AND THEN LIFT NWD AS A WARM
FRONT LATER TONIGHT.

THE ONGOING CONVECTION ACROSS NEB/IA IS ASSOCIATED WITH WAA IN
ADVANCE OF A WEAKENING MID LEVEL WAVE...AND INSTABILITY BASED IN THE
800-700 MB LAYER. THIS CONVECTION WILL LIKELY DISSIPATE BY MID-LATE
MORNING. A 30-40 KT LLJ IS FORECAST TO DEVELOP TONIGHT OVER THE
DAKOTAS AS THE BOUNDARY LIFTS NWD...WITH PRONOUNCED WAA IN THE
850-700 MB LAYER EXPECTED OVER CENTRAL/ERN ND FROM 06-12Z. MID
LEVEL LAPSE RATES IN EXCESS OF 7 C/KM WILL ACCOMPANY THE DEVELOPING
WAA PATTERN...THOUGH UPSTREAM LOW-LEVEL MOISTURE WILL BE LIMITED TO
A NARROW CORRIDOR OF 58-62 F BOUNDARY LAYER DEWPOINTS ALONG THE
STALLED FRONT. SOME ELEVATED CONVECTION WILL BE POSSIBLE EARLY
MONDAY OVER ND...BUT THE DEGREE OF MOISTURE/INSTABILITY WILL LIKELY
REMAIN INSUFFICIENT FOR SEVERE STORMS.

..FOUR CORNERS STATES INTO SRN CA...
RESIDUAL LOW-MID LEVEL MOISTURE AND DAYTIME HEATING WILL RESULT IN
SCATTERED THUNDERSTORM DEVELOPMENT THIS AFTERNOON INTO EARLY TONIGHT
ACROSS THE FOUR CORNERS STATES INTO INTERIOR SRN CA. WHILE VERY
ISOLATED DOWNBURSTS AND STRONG OUTFLOW WINDS CANNOT BE RULED
OUT...THE OVERALL THREAT APPEARS TO BE TOO LOW TO WARRANT A
NECESSARILY LARGE 5% WIND PROBABILITY AREA.

..TX TO THE SE ATLANTIC COAST...
THE MID LEVEL CYCLONIC SHEAR AXIS OVER THIS AREA FOR THE PAST FEW
DAYS IS EVOLVING INTO A TUTT LOW NEAR THE BIG BEND...AND A SMALLER
SCALE VORTICITY MAXIMUM AND ASSOCIATED CONVECTIVE SYSTEM JUST OFF
THE GA COAST. HIGH PW VALUES IN EXCESS OF 2 INCHES AND
WEAK-MODERATE INSTABILITY WILL AGAIN SUPPORT SCATTERED-NUMEROUS
/MAINLY DIURNAL/ THUNDERSTORMS ACROSS THE GULF COASTAL PLAIN AND FL.

.THOMPSON/BRIGHT.. 09/02/2007

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