SWODY2
SPC AC 031728
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT TUE APR 03 2012
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE LOWER MS
VALLEY AND TN VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF SERN VA
THROUGH ERN NC...
...SYNOPSIS...
BLOCKING PATTERN WILL PREVAIL OVER THE U.S. WEDNESDAY WITH AN UPPER
RIDGE OVER THE NRN PLAINS AND SRN CANADA FLANKED BY UPPER TROUGHS
OVER THE PACIFIC NW AND NERN STATES. CUTOFF LOW NOW CENTERED OVER
THE SRN HIGH PLAINS WILL DRIFT SLOWLY EWD AND IS FORECAST TO BE
CENTERED OVER THE LOWER MS VALLEY BY THE END OF THE PERIOD. IMPULSE
CURRENTLY MOVING NEWD INTO THE MID MS VALLEY WILL CONTINUE THROUGH
THE OH VALLEY AND MID ATLANTIC AREA.
AT THE SURFACE AN EAST-WEST ORIENTED COLD FRONT WILL SETTLE SWD
THROUGH KY AND VA. PACIFIC FRONT ACCOMPANYING THE SRN STREAM CUTOFF
LOW WILL ADVANCE SLOWLY THROUGH ERN PORTIONS OF THE SRN PLAINS INTO
THE LOWER MS VALLEY REGION.
...LOWER MS VALLEY THROUGH TN VALLEY REGION...
A MOIST WARM SECTOR WITH DEWPOINTS IN THE 60S WILL PERSIST OVER THE
LOWER MS AND TN VALLEYS WEDNESDAY BENEATH 7-7.5 MID LEVEL LAPSE
RATES. THIS WILL RESULT IN AREAS OF MODERATE INSTABILITY OUTSIDE OF
ANY AREAS OF ONGOING CONVECTION WHICH MAY BE IN PROGRESS FROM ERN
PARTS OF THE SRN PLAINS INTO THE LOWER MS VALLEY. AS THE BOUNDARY
LAYER WARMS AND DESTABILIZES ADDITIONAL STORMS SHOULD DEVELOP EAST
OF THE PACIFIC FRONT PROMOTED BY RESIDUAL OUTFLOW BOUNDARIES AND
ZONES OF DEEPER ASCENT ACCOMPANYING VORTICITY MAXIMA ROTATING
THROUGH THE UPPER LOW. VERTICAL DEEP LAYER SHEAR WILL INCREASE TO
AOA 40 KT AS MID LEVEL JET ADVANCES THROUGH BASE OF UPPER TROUGH.
THIS WILL SUPPORT POTENTIAL FOR ORGANIZED STORMS INCLUDING
SUPERCELLS WITH LARGE HAIL AND DAMAGING WIND THE MAIN THREATS.
...SERN VA THROUGH ERN NC...
RICHER BOUNDARY LAYER MOISTURE WILL ADVECT NEWD THROUGH ERN NC INTO
SERN VA WITH DEWPOINTS IN THE UPPER 50S TO NEAR 60F. THROUGH MID
LEVEL LAPSE RATES WILL REMAIN MODEST...POTENTIAL WILL EXIST FOR
1000-1500 J/KG MLCAPE AS THE BOUNDARY LAYER DESTABILIZES DURING THE
AFTERNOON. STORMS ARE EXPECTED TO FORM INITIALLY ALONG RESIDUAL
OUTFLOW BOUNDARIES AND OR E-W FRONT ACROSS VA AND SUBSEQUENTLY
DEVELOP SEWD. STORM COVERAGE MAY BE ENHANCED BY PROGRESSIVE IMPULSE
ADVANCING THROUGH THE CNTRL APPALACHIANS AND MID ATLANTIC.
INVERTED-V BOUNDARY LAYERS AND INCREASING DEEP LAYER WINDS
ASSOCIATED WITH AMPLIFYING NERN U.S. TROUGH WILL PROMOTE A THREAT OF
MAINLY ISOLATED DAMAGING WIND.
...CNTRL AND ERN OK THROUGH SRN KS...
COLD TEMPERATURES ALOFT WITH TEMPERATURES NEAR -20C NEAR UPPER LOW
CENTER AND BOUNDARY LAYER WARMING WILL PROMOTE STEEP LAPSE RATES AND
AT LEAST MARGINAL INSTABILITY DURING THE AFTERNOON IN POST FRONTAL
REGIME. A FEW STORMS MAY DEVELOP WITHIN THIS WEAKLY CAPPED
ENVIRONMENT WITH A POTENTIAL FOR ISOLATED HAIL AND GUSTY WINDS.
..DIAL.. 04/03/2012
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