DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 280035
SWODY1
SPC AC 280032

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0732 PM CDT THU SEP 27 2007

VALID 280100Z - 281200Z

..NO SVR TSTM AREAS FORECAST...

..NERN STATES...

A VORT MAX IS MOVING ENEWD THROUGH WRN PA AND WRN NY THIS EVENING.
STORMS HAVE ORGANIZED INTO A MULTICELL LINE FROM NRN VA NWD THROUGH
ERN PA AND CNTRL NY WITHIN ZONE OF LOW LEVEL CONVERGENCE AND MID
LEVEL ASCENT ATTENDING THIS FEATURE. FARTHER DOWNSTREAM...NUMEROUS
MULTICELL STORMS PERSIST WITHIN WEAKLY CAPPED WARM SECTOR FROM ERN
NY INTO PARTS OF NEW ENGLAND WHERE MODEST SWLY UNIDIRECTIONAL WIND
PROFILES EXIST. STRONGER DEEP LAYER SHEAR SUFFICIENT FOR SUPERCELL
STRUCTURES EXISTS OVER NRN NY INTO NRN NEW ENGLAND...BUT INSTABILITY
IN THIS REGION IS MORE LIMITED. PRIMARY THREATS WILL CONTINUE TO BE
ISOLATED STRONG TO DAMAGING WIND GUSTS AND MARGINALLY SEVERE HAIL
THIS EVENING. STORMS WILL LIKELY PERSIST INTO MUCH OF TONIGHT...BUT
A GRADUAL DECREASE IN INTENSITY IS EXPECTED AS THE BOUNDARY LAYER
STABILIZES.

..SRN HIGH PLAINS...

WIDELY SCATTERED STORMS PERSIST OVER PARTS OF WRN AND NWRN TX THIS
EVENING WITH NUMEROUS OUTFLOW INTERACTIONS OBSERVED. FLOW ALOFT IS
RATHER MODEST WITH 20 KT AT 500 MB...BUT ELY LOW LEVEL WINDS VEERING
TO WNWLY AT 6 KM IS RESULTING IN SUFFICIENT DIRECTIONAL SHEAR FOR
STORMS TO DEVELOP SOME SUPERCELL STRUCTURES. WEAK FLOW ALOFT
SUGGESTS STORMS SHOULD REMAIN OUTFLOW DOMINANT. THE ATMOSPHERE IS
MODERATELY UNSTABLE WITH MLCAPE FROM 2000 TO 2500 J/KG ALONG WITH
6.5-7 C/KM 700-500 MB LAPSE RATES. THIS ENVIRONMENT WILL CONTINUE TO
SUPPORT A THREAT OF ISOLATED LARGE HAIL AND STRONG WIND GUSTS AS
STORMS DEVELOP NEXT FEW HOURS.

..MI...

LINE OF LOW TOPPED STORMS IS MOVING EWD INTO SRN LOWER MI IN
ASSOCIATION WITH ZONE OF ASCENT AND STEEP LAPSE RATES ATTENDING A
STRONG VORTICITY MAXIMUM. COLD AIR ALOFT WITH -20C AT 500 MB AND
STEEP MID LEVEL LAPSE RATES WILL SUPPORT A MARGINAL SEVERE THREAT
NEXT HOUR OR TWO. HOWEVER...ACTIVITY IS EXPECTED TO WEAKEN AS THE
BOUNDARY LAYER COOLS.

.DIAL.. 09/28/2007

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