SPC AC 210730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT MON MAY 21 2007
VALID 231200Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS WED...WED NIGHT ACROSS PARTS OF
THE CNTRL/SRN PLAINS....
...THERE IS A SLGT RISK OF SVR TSTMS LATE WED AFTN/EVE ACROSS PARTS
OF THE UPPER MS VLY/UPPER GREAT LAKES....
...SYNOPSIS...
MODELS INDICATE THAT THE AMPLIFIED POLAR TROUGH WILL CONTINUE TO
GRADUALLY LIFT NORTHEAST OF THE ROCKIES DURING THIS FORECAST PERIOD.
CONFIDENCE IS LOW WITH REGARD TO THE SPECIFIC DETAILS...BUT THIS
SEEMS LIKELY TO CONTINUE IN PHASES...AS RIDGING...PARTICULARLY IN
LOWER/MID-LEVELS...IS PROGGED TO REMAIN STRONG ACROSS MUCH OF THE
EASTERN STATES.
AN ELONGATED MID-LEVEL CIRCULATION LIKELY TO DEVELOP NORTH NORTHEAST
OF THE CENTRAL ROCKIES EARLY TUESDAY...MAY FINALLY LIFT NORTH OF THE
CENTRAL CANADIAN/U.S. BORDER AREA BY LATE WEDNESDAY/ WEDNESDAY
NIGHT. MODELS SUGGEST THAT THIS WILL BE FOLLOWED BY AT LEAST A
COUPLE OF ADDITIONAL IMPULSES...THE LAST OF WHICH MAY TURN NORTHEAST
OF THE CENTRAL ROCKIES BY WEDNESDAY AFTERNOON...BEFORE CONTINUING
NORTHEASTWARD WEDNESDAY NIGHT...WITH BROADER SCALE TROUGHING TAKING
ON AN INCREASINGLY NEGATIVE TILT ACROSS THE UPPER MISSISSIPPI
VALLEY.
AN ASSOCIATED SURFACE FRONT SEEMS LIKELY TO PROGRESS THROUGH MUCH OF
THE REMAINDER OF THE MIDDLE/UPPER MISSISSIPPI VALLEY...THE OZARK
PLATEAU...AND THE SOUTHERN PLAINS DURING THIS PERIOD. BUT...THIS
FEATURE WILL PROBABLY BE PRECEDED BY CONSIDERABLE CLOUD
COVER/PRECIPITATION AND/OR CONVECTIVE OUTFLOW...PARTICULARLY FROM
THE LOWER MISSOURI VALLEY NORTHEASTWARD INTO THE UPPER GREAT LAKES.
...PARTS OF THE CENTRAL AND SOUTHERN PLAINS...
A LARGE CONVECTIVE COMPLEX MAY BE IN THE PROCESS OF WEAKENING EARLY
WEDNESDAY ACROSS PARTS OF NORTHERN OKLAHOMA INTO EASTERN KANSAS. AS
THIS OCCURS...A STEADILY MOISTENING GULF RETURN FLOW IS EXPECTED TO
CONTRIBUTE TO DESTABILIZATION BENEATH STRONGER CAPPING TO ITS
SOUTH/SOUTHWEST...ACROSS THE REMAINDER OF SOUTHEAST KANSAS... PARTS
OF SOUTHWEST MISSOURI...AND THE REMAINDER OF OKLAHOMA INTO MUCH OF
NORTHERN/WESTERN TEXAS. MODELS ARE SUGGESTIVE THAT EVOLVING UPPER
FLOW PATTERN WILL RESULT IN WEAKENING MID-LEVEL INHIBITION
SOUTH/SOUTHWESTWARD ACROSS MUCH OF THE REMAINDER OF THE PLAINS
DURING THE DAY WEDNESDAY...ALLOWING FOR INCREASINGLY WIDESPREAD
STRONG/SEVERE CONVECTIVE DEVELOPMENT IN AN ENVIRONMENT WITH STEEP
LAPSE RATES AND CAPE AT OR ABOVE 2000 J/KG. UNSATURATED
LOWER/MID-LEVELS WILL ALLOW FOR CONSIDERABLE EVAPORATIVE COOLING
NEAR HEAVY PRECIPITATION CORES...ENHANCING POTENTIAL FOR LARGE HAIL
AND A FEW DOWNBURSTS...WITH AN EXPANDING AND SOUTHWARD SURGING
CONGLOMERATE SURFACE COLD POOL LIKELY THROUGH LATE
WEDNESDAY/WEDNESDAY NIGHT.
...UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES...
ALTHOUGH INSTABILITY IS EXPECTED TO BE RATHER WEAK...FORCING AHEAD
OF COLD FRONT MAY BE SUFFICIENT TO SUPPORT AT LEAST A BROKEN
INTENSIFYING PRE-FRONTAL LINE OF STORMS THROUGH THE LATE AFTERNOON
AND EARLY EVENING HOURS. IF THIS OCCURS...40+ KT SOUTHERLY MEAN
ENVIRONMENT FLOW WILL CONTRIBUTE TO POTENTIAL FOR...PRIMARILY...
DAMAGING WIND GUSTS ACROSS PARTS OF EASTERN MINNESOTA/WISCONSIN AND
THE UPPER PENINSULA OF MICHIGAN.
..KERR.. 05/21/2007
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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