SWODY1
SPC AC 281754
DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
1254 PM CDT SAT MAY 28 2011
VALID 282000Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF MN/WI...
...THERE IS A SLGT RISK OF SVR TSTMS FROM KS INTO IL/IND...
...THERE IS A SLGT RISK OF SVR TSTMS NORTHEAST NY AND MUCH OF VT...
AMENDED TO ADD SLIGHT RISK IN NY/NEW ENGLAND
...NY/NEW ENGLAND...
WEAKENING CYCLONIC FLOW REMAINS ACROSS PORTIONS OF NY AND WESTERN
NEW ENGLAND TODAY. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO FORM IN THIS AREA THIS AFTERNOON. TEMPERATURES IN THE 70S AND
DEWPOINTS IN THE MID 60S WILL YIELD SUFFICIENT CAPE FOR A RISK OF A
FEW SEVERE CELLS CAPABLE OF HAIL AND DAMAGING WINDS. PLEASE REFER
TO MCD 1004 AND WW 391 FOR FURTHER DETAILS.
...MN/WI...
A WEAKENING UPPER LOW IS CURRENTLY OVER ND/SRN MANITOBA. A SERIES
OF SHORTWAVE TROUGHS ARE ROTATING AROUND THE LOW...INCLUDING ONE
OVER WESTERN ND/SD. THIS FEATURE IS FORECAST TO MOVE EASTWARD AND
AFFECT MN/WI LATER TODAY. THUNDERSTORMS ARE EXPECTED TO FORM IN
WESTERN MN BY MID AFTERNOON AND SPREAD EASTWARD TOWARD WESTERN LAKE
SUPERIOR...NORTHERN WI...AND THE ARROWHEAD REGION THIS EVENING.
INSTABILITY IS ONLY MARGINAL FOR AN ORGANIZED SEVERE EVENT.
HOWEVER...STEEP MID LEVEL LAPSE RATES...COLD TEMPERATURES AND FAST
FLOW ALOFT WILL SUPPORT A RISK OF A FEW FAST-MOVING CLUSTERS OF
THUNDERSTORMS CAPABLE OF HAIL AND LOCALLY DAMAGING WINDS. STORMS
SHOULD DIMINISH A FEW HOURS AFTER SUNSET.
...CENTRAL PLAINS INTO MID MS VALLEY...
CONVECTIVE EVOLUTION IS UNCERTAIN ACROSS THIS AREA TODAY. WEAK MID
LEVEL HEIGHT RISES AND WEAK FORCING MECHANISMS SUGGEST CONVECTIVE
COVERAGE WILL BE QUITE LIMITED THROUGH MOST OF THE FORECAST PERIOD.
THROUGH THE AFTERNOON AND EARLY EVENING...MOST LIKELY AREA FOR
ISOLATED SEVERE STORMS WOULD BE FROM EASTERN KS INTO PORTIONS OF
MO/IL WHERE STRONG HEATING AND RESIDUAL BOUNDARIES FROM MORNING
CONVECTION MIGHT AID DEVELOPMENT. IF STORMS CAN FORM...STRONG
INSTABILITY AND SUFFICIENT EFFECTIVE SHEAR WOULD SUPPORT A RISK OR
ORGANIZED OR EVEN SUPERCELL STORMS CAPABLE OF LARGE HAIL AND
DAMAGING WINDS.
OVERNIGHT...STRENGTHENING SOUTHERLY LOW LEVEL WINDS WILL ENHANCE
WARM ADVECTION AND POSSIBLY LEAD TO MORE WIDESPREAD THUNDERSTORMS
ALONG THE SLIGHT RISK AXIS. LARGE HAIL WOULD BE THE MAIN THREAT
WITH THESE STORMS FROM KS INTO IND.
...SC/GA/FL...
STRONG DAYTIME HEATING IS OCCURRING FROM SC INTO THE FL
PENINSULA...WHERE AFTERNOON MLCAPE VALUES WILL EXCEED 3000 J/KG.
WIND FIELDS ARE RELATIVELY WEAK...BUT COMBINATION OF COOL
TEMPERATURES ALOFT AND MOIST THERMODYNAMIC PROFILE MAY BE SUFFICIENT
FOR A FEW WET-MICROBURSTS IN STRONGER CELLS.
..HART.. 05/28/2011
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