Monday, April 28, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 280544
SWODY1
SPC AC 280542

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1242 AM CDT MON APR 28 2008

VALID 281200Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN VA...ERN NC
AND SC...

...ERN SEABOARD...
AN UPPER-LEVEL TROUGH OVER THE MS VALLEY WILL AMPLIFY AND DIG SEWD
INTO THE OH AND TN VALLEYS TODAY. AT THE SFC...A COLD FRONT WILL
ADVANCE EWD OUT OF THE APPALACHIAN MTNS AND ACROSS THE ERN SEABOARD.
SOME THUNDERSTORM ACTIVITY SHOULD BE ONGOING AHEAD OF THE FRONT THIS
MORNING WITH STORM COVERAGE BECOMING WIDESPREAD BY MIDDAY FROM ERN
VA SSWWD ACROSS NC...SC INTO GA. SEVERAL THUNDERSTORM CLUSTERS WILL
LIKELY MOVE EWD INTO THE IMMEDIATE COASTAL SECTIONS BY THIS EVENING.

CONCERNING THE SEVERE POTENTIAL...A 40 KT LOW-LEVEL JET ALONG THE
ERN SEABOARD IS FORECAST TO STRENGTHEN TODAY AS THE UPPER-LEVEL
SYSTEM APPROACHES FROM THE WEST. THIS FEATURE ALONG WITH SLY FLOW AT
THE SFC WILL CREATE SOMEWHAT UNIDIRECTIONAL LOW-LEVEL WIND PROFILES
SUGGESTING A WIND DAMAGE THREAT MAY DEVELOP BY MIDDAY. THE WIND
DAMAGE THREAT WILL LIKELY BE GREATEST ACROSS SE VA...ERN NC AND ERN
SC WHERE THE MODELS FORECAST AN AXIS OF SLIGHTLY GREATER
INSTABILITY. HOWEVER...FORECAST SOUNDINGS ACROSS MOST OF THE SLIGHT
RISK AREA KEEP SBCAPE VALUES BELOW 500 J/KG SUGGESTING THE MAGNITUDE
OF THE WIND DAMAGE THREAT REMAINS UNCERTAIN ATTM.

...LOWER OH VALLEY...
THE CORE OF AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE ESEWD ACROSS
THE OH VALLEY TODAY. IN RESPONSE...A POCKET OF COLD AIR ALOFT WILL
DRIFT SEWD INTO THE LOWER OH VALLEY. THIS COMBINED WITH STRONG
LARGE-SCALE ASCENT AND SFC HEATING WILL BE FAVORABLE FOR SCATTERED
THUNDERSTORM DEVELOPMENT EARLY THIS AFTERNOON. STEEP LAPSE RATES AND
STRONG VERTICAL SHEAR PROFILES EVIDENT ON REGIONAL FORECAST
SOUNDINGS SHOULD SUPPORT A HAIL THREAT WITH THE STRONGER CORES.

..BROYLES/HURLBUT.. 04/28/2008

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