DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281239
SWODY1
SPC AC 281236

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0736 AM CDT MON APR 28 2008

VALID 281300Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS ALONG THE MID AND S ATLANTIC
CST...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LWR OH AND TN
VLY...

...SYNOPSIS...
AMPLIFIED BUT PROGRESSIVE PATTERN WILL PREVAIL ACROSS THE LWR 48
THROUGH TUESDAY. POTENT UPR VORT NOW OVER SRN IA EXPECTED TO
CONTINUE SE TO NEAR EVV THIS EVENING BEFORE TURNING MORE E TO THE
WV/VA BORDER AREA EARLY TUESDAY. THIS WILL FURTHER AMPLIFY EXISTING
LARGER-SCALE TROUGH OVER THE ERN U.S. AS LEAD IMPULSE NOW CROSSING
THE TN VLY IS ABSORBED WITHIN STRENGTHENING SW FLOW OVER THE MID
ATLANTIC STATES.

AT LWR LEVELS...COLD FRONT NOW OVER THE SRN/CNTRL APPALACHIANS WILL
CONTINUE E ACROSS THE SRN AND MID ATLANTIC CSTL PLN LATER TODAY AS
UPSTREAM FRONT...ASSOCIATED WITH IA VORT...SURGES SE ACROSS THE LWR
OH AND TN VLYS.

...ERN SEABOARD...
CLOUDS WILL LIMIT DIURNAL DESTABILIZATION ALONG AND AHEAD OF COLD
FRONT CROSSING ERN PORTIONS OF THE MID AND S ATLANTIC STATES TODAY.
NEVERTHELESS...GIVEN PERSISTENT LOW-LVL MOISTURE INFLOW /PWS AOA
1.25 IN/ AND INCREASING ASCENT/CONVERGENCE ON E SIDE OF PROGRESSIVE
LARGER-SCALE TROUGH...EVEN MODEST HEATING SHOULD SUPPORT
BANDS/CLUSTERS OF STORMS OVER THE REGION THIS AFTN AND EVE. THE
STRONGEST/MOST SUSTAINED ACTIVITY MAY FOCUS ALONG PRE-FRONTAL
TROUGH/WIND SHIFT LINE FROM THE DELMARVA PENINSULA SSW ALONG THE
CSTL PLN INTO THE ERN CAROLINAS/SE GA.

LOW TO MID-LVL LAPSE RATES WILL BE WEAK. BUT HEATING/MOISTURE
INFLOW SHOULD BOOST SBCAPE TO AOA 500 J/KG. COUPLED WITH
STRENGTHENING LOW- TO MID-LVL WIND FIELD /500 MB SW FLOW AOA 50 KTS
ATOP A 40 KT SSWLY LLJ/...SETUP COULD YIELD A FEW EMBEDDED ROTATING
STORMS/SUPERCELLS. BOWING SEGMENTS WITH ANY SUCH STRUCTURES WILL
POSE A THREAT FOR LOCALLY DMGG WIND AND PERHAPS A BRIEF TORNADO OR
TWO. THE STRONGEST STORMS SHOULD CLEAR THE CST BY EARLY TONIGHT.

...LWR OH/TN VLYS...
A LINE OF LOW-TOPPED STORMS WILL FORM EARLY THIS AFTN ALONG COLD
FRONT CROSSING THE LWR OH AND TN VLYS. DESPITE SPARSE MOISTURE...
VERY COLD AIR ALOFT /AROUND MINUS 28C AT 500 MB/ ASSOCIATED WITH UPR
VORT WILL CONTRIBUTE TO CONSIDERABLE STATIC INSTABILITY. THIS
...COMBINED WITH STRONG SFC HEATING AND ASCENT...WILL BE FAVORABLE
FOR STORMS WITH HAIL. MODERATE UNIDIRECTIONAL WIND PROFILES...
SIZABLE TEMPERATURE-DEWPOINT SPREADS...AND LINEAR FORCING FOR ASCENT
MAY ALSO SUPPORT LOCALLY DMGG WIND.

..CORFIDI/HURLBUT.. 04/28/2008

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