DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 100717
SWODY3
SPC AC 100715

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0215 AM CDT WED APR 10 2013

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR ERN NC...FAR SERN VA ON FRI
MORNING...

...SYNOPSIS...
MEAN POSITION OF A LARGE-SCALE UPPER-LEVEL TROUGH SHOULD REMAIN
CENTERED ACROSS THE GREAT LAKES WITH SEVERAL EMBEDDED SHORTWAVE
IMPULSES GYRATING AROUND THE CENTER. THE MOST PROMINENT IMPULSE TO
INFLUENCE SEVERE POTENTIAL WILL BE ONE EXPECTED TO REACH THE
MID-ATLANTIC EITHER LATE D2 OR EARLY D3. A SURFACE COLD FRONT WILL
CONTINUE TO MOVE EWD AND SHOULD EXIT THE MID/SOUTH ATLANTIC COAST BY
FRI EVENING.

...MID/SOUTH ATLANTIC COAST...
GUIDANCE CONTINUES TO DIFFER WITH THE HANDLING OF A QUICK-MOVING
SHORTWAVE IMPULSE /CURRENTLY LOCATED WITHIN THE BASAL PORTION OF THE
BROAD UPPER-LEVEL TROUGH OVER NWRN MEXICO/. THE CONSISTENT...BUT
UNIQUE ECMWF DEPICTS A MORE PROMINENT NEGATIVE-TILT IMPULSE THAN THE
GFS/NAM/CMC/UKMET...ACROSS THE SRN APPALACHIANS AT 12Z/FRI. WITH
MORE INTENSE LOW/MID-LEVEL FLOW AND ROBUST CONVECTIVE SIGNAL IN THE
ECMWF...THERE REMAINS CONCERN THAT DAMAGING WIND/TORNADO THREATS
FROM D2 COULD PERSIST INTO EARLY D3 ACROSS PARTS OF THE COASTAL
PLAIN. BUT THE BULK OF GUIDANCE DEPICTS THIS IMPULSE TO BE
WEAKER/FASTER WHICH SUGGESTS THAT FORCING FOR ASCENT WILL BE
DIMINISHING FRI MORNING AND THAT SLIGHT RISK POTENTIAL WILL REMAIN
CONDITIONAL ON THERE BEING ONGOING TSTMS. BY MIDDAY/EARLY
AFTERNOON...MID-LEVEL LAPSE RATES SHOULD BE POOR AND WITH
INCREASINGLY VEERED/WEAKENING LOW-LEVEL WIND PROFILES...CONVERGENCE
ALONG THE FRONT SHOULD BE MODEST WITHIN A MARGINAL ENVIRONMENT FOR
LOCALLY DAMAGING WINDS.

..GRAMS.. 04/10/2013

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