DAY1SVR: Day 1 Convective Outlook Corr 1

ACUS01 KWNS 261610
SWODY1
SPC AC 261608

DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1108 AM CDT FRI SEP 26 2008

VALID 261630Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE UPPER MS VALLEY...

CORRECTED FOR THUNDER LINE IN FL

..NRN MN AND ADJACENT PORTIONS OF LS AND NRN WI...
AIR MASS SAMPLED BOTH BY INL 12Z SOUNDING AND MN ACARS THIS AM
CONFIRM THAT STEEP MID LEVEL LAPSE RATES...8C/KM...AND A PLUME OF
MOISTURE WITH PWS NEAR 1.25 INCHES ARE IN PLACE AHEAD OF APPROACHING
S/W TROUGH NOW MOVING ACROSS ND.

MLCAPES CURRENTLY ABOVE 1000 J/KG AND EXPECTED TO INCREASE TO NEAR
2000 J/KG BY EARLY AFTERNOON IN RESPONSE TO STRONG SURFACE HEATING.
ONGOING ELEVATED STRONG/SEVERE STORMS JUST S OF CANADIAN
BORDER...WILL CONTINUE...DRIVEN BY ASCENT AND WARM ADVECTION AHEAD
OF APPROACHING S/WV TROUGH AND 50-60KT MID LEVEL SPEED MAX.

SEVERE THUNDERSTORMS PRIMARILY A LARGE HAIL THREAT...WILL INCREASE
ACROSS NRN MN EARLY THIS AFTERNOON AS CIN WEAKENS AND INSTABILITY
INCREASES. ACTIVITY WILL SPREAD E AND S POSSIBLY INTO CENTRAL
MN...NWRN WI BY THIS EVENING PRIOR TO WEAKENING WITH THE PASSAGE OF
UPPER TROUGH AND LOSS OF HEATING.

REF MCD 2292 FOR ADDITIONAL INFO ON THIS AREA.

...MID ATLANTIC COASTAL AREAS...
WELL DEFINED STACKED LOW OVER NRN SC CONTINUES TO DRIFT WWD AND
SLOWLY FILL. PLUME OF TROPICAL AIR /WITH SFC DEWPOINTS AROUND 70/
WILL CONTINUE TO SPREAD ACROSS NRN/ERN NC AND SE VA ON ERN SIDE OF
SYSTEM... BENEATH MID LVL DRY SLOT.

DIURNAL DESTABILIZATION IN DRY SLOT SUPPORTING DEVELOPMENT OF
BANDS/CLUSTERS OF SHOWERS AND STORMS IN AN ARC FROM THE OUTER BANKS
OF NC NW INTO S CNTRL/SE VA. COUPLED WITH RICH MOISTURE AND
RESIDUAL BAND OF MODERATE FLOW...SETUP COULD YIELD ONE OR TWO ISOLD
TORNADOES THROUGH THIS AFTERNOON. THIS IS SUPPORTED BY THE PRESENT
25-30KT OF LOW LEVEL SHEAR COUPLED WITH MLCAPES TO 1000 J/KG.
HOWEVER WITH THE WWD MOVEMENT AND WEAKENING OF THE LOW...SHEAR
PROFILES ACROSS ERN NC/SERN VA SHOULD BECOME LESS FAVORABLE FOR
ROTATING STORMS BY LATER THIS AFTERNOON.

..HALES.. 09/26/2008

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