DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 241230
SWODY1
SPC AC 241229

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0729 AM CDT SAT OCT 24 2009

VALID 241300Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OF NC INTO THE MID
ATLANTIC...

...PIEDMONT OF NC/VA INTO THE MID ATLANTIC...
ONLY MINOR MODIFICATIONS NEEDED ATTM AS ENHANCED FLOW ALOFT WILL
CONTINUE OVERSPREADING THE NORTHEASTERN U.S. AHEAD OF EJECTING
POSITIVELY-TILTED LONGWAVE TROUGH. AREA OF ASCENT EVIDENT ON
SATELLITE IMAGERY THIS MORNING...SUPPORTING TSTM CLUSTER OVER THE
CENTRAL APPALACHIANS/PA...WILL LIKELY CONTINUE NEWD THROUGH THE
EARLY AFTERNOON. MORE PRONOUNCED/INTENSE IMPULSE APPEARED TO BE
OVER THE MID-SOUTH EARLY THIS MORNING WHICH SHOULD EJECT INTO THE
CENTRAL APPALACHIANS BY LATER TODAY. EXPECT MAIN EWD PUSH TO THE
SURFACE COLD FRONT WILL AWAIT THIS LATTER FEATURE WITH COLD FRONT
MOVING OFFSHORE DURING THE MID TO LATE EVENING.

OVERNIGHT AND EARLY MORNING SURFACE ANALYSES INDICATE PERSISTENT
WARMING/MOISTENING WITHIN WARM SECTOR NOSING INTO THE MID ATLANTIC
REGION AT DAYBREAK. EXPECT AXIS OF 60+F SURFACE DEW POINTS WILL
EVENTUALLY LIFT NWD INTO FAR SRN NY AND POSSIBLY SWRN NEW ENGLAND AS
WEDGE OF COLD/STABLE AIR BEGINS TO ERODE NWD AS STRONG SWLY FLOW
JUST OFF THE SURFACE BEGINS TO MIX DOWN...WHILE UPPER 60F DEW POINTS
HOLD OVER THE CAROLINAS. DESPITE THE ENHANCED SHEAR ATOP SEASONABLY
WARM/MOIST SURFACE AIRMASS FORECAST TO BE MAINTAINED IN ADVANCE OF
SURFACE COLD FRONT NOW OVER THE APPALACHIANS...LIMITED
INSTABILITY/LAPSE RATES WILL BE PRIMARY INHIBITING FACTOR FOR
WIDESPREAD SEVERE THUNDERSTORM DEVELOPMENT. REGARDLESS...FORECAST
SOUNDINGS SUGGEST AXIS OF MARGINAL INSTABILITY FROM PORTIONS OF
NC/VA INTO THE MID ATLANTIC GIVEN MODEST PEAK HEATING. SHEAR
PROFILES WILL BE QUITE FAVORABLE FOR SUPERCELLS AND BOWING SEGMENTS
AS STORMS INCREASE DURING THE AFTERNOON...WITH NWD EXTENT OF ENSUING
SVR THREAT MITIGATED BY MORE LIMITED INSTABILITY. DAMAGING WINDS
SHOULD BE PRIMARY SEVERE THREAT AS ACTIVITY EVOLVES INTO SMALL
FAST-MOVING LINES...ALTHOUGH SFC-1 SRH IN EXCESS OF 250 M2/S2 AND
LOW LCLS INDICATE THREAT OF A FEW TORNADOES WITH ANY PERSISTENT
ROTATION.

..EVANS/BOTHWELL.. 10/24/2009

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