SPC AC 180057
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0757 PM CDT WED MAY 17 2006
VALID 180100Z - 181200Z
...THERE IS A SLGT RISK OF SVR TSTMS CENTRAL IL TO WRN PA...
...SYNOPSIS...
BASIC SYNOPTIC PATTERN ALOFT FEATURES WRN CONUS RIDGE -- WHICH IS
PART OF REX BLOCK INVOLVING BAJA CA CYCLONE...AND ERN TROUGH.
STRONG SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY
OVER WI/LM -- IS FCST TO DIG SEWD ACROSS LOWER MI AND DEVELOP INTO
DISCRETE MIDLEVEL LOW OVERNIGHT. MEANWHILE SFC CYCLONE OVER ONT/QUE
BORDER WILL RETROGRADE WWD TO BECOME MORE VERTICALLY STACKED WITH
MID/UPPER LOW. ASSOCIATED COLD FRONT -- INITIALLY ANALYZED FROM SRN
ONT SWWD ACROSS NRN PORTIONS IL/INDIANA -- WILL CONTINUE TO MOVE
SEWD INTO LOWER-MIDDLE OH VALLEY OVERNIGHT.
...GREAT LAKES/OH VALLEY REGION...
REF WW 362 AND ASSOCIATED MESOSCALE DISCUSSIONS FOR NOWCAST
DEVELOPMENTS. LARGE SCALE ASCENT AND ASSOCIATED COLD MIDLEVEL AIR
AHEAD OF TROUGH -- I.E. -17 TO -18 DEG C AT 500 MB -- ARE EXPECTED
TO SHIFT EWD AND SOMEWHAT SWD OVER OUTLOOK AREA. THIS WILL COMBINE
WITH LOW LEVEL WAA ABOVE SFC HELP TO MAINTAIN STEEP LAPSE RATES AND
CONVECTIVE POTENTIAL THROUGH MUCH OF TONIGHT OVER OH VALLEY
REGION...DESPITE DIABATICALLY COOLING BOUNDARY LAYER. SEVERE WIND
POTENTIAL SHOULD DIMINISH WITH TIME...HOWEVER HAIL AND OCCASIONAL
STRONG/DAMAGING GUSTS WILL REMAIN POSSIBLE FROM MOST INTENSE CELLS
THROUGH REMAINDER PERIOD.
...CA...
SUBTLE SHORTWAVE PERTURBATION IS EVIDENT IN ANIMATIONS OF BOTH
MOISTURE CHANNEL IMAGERY AND MIDLEVEL VWP PLOTS OVER THIS
REGION...MOVING NNWWD APPROXIMATELY 10-15 KT ACROSS CENTRAL CA
BETWEEN FAT-MRY. WIDELY SCATTERED TSTMS MAY CONTINUE FOR ANOTHER
2-3 HOURS ACROSS SIERRAS GENERALLY N OF LINE FROM BIH-FAT...ROUGHLY
ALONG AND N OF LATITUDE OF MOST FAVORABLE LARGE SCALE ASCENT
ESTIMATED FROM THAT TROUGH. RUC APPEARS TO BE OVERESTIMATING MLCAPE
BY UP TO 800 J/KG OVER THIS REGION WITH SFC THETAE TOO HIGH FOR
MODEL ELEVATIONS...HOWEVER MODIFIED RNO RAOB SUGGESTS LEGITIMATE
300-500 J/KG MLCAPES AMIDST INVERTED-V PROFILES SUITABLE FOR
MAINTAINING INTENSITY TO SFC OF ANY STRONG-SEVERE GUSTS OR HAIL
GENERATED ALOFT.
..EDWARDS.. 05/18/2006
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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