DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 190954
SWOD48
SPC AC 190953

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0353 AM CST THU DEC 19 2013

VALID 221200Z - 271200Z

...DISCUSSION...
...SUN/D4--PORTIONS OF THE SOUTHEAST AND MID-ATLANTIC...
WIDESPREAD SHOWERS/TSTMS /MOST LIKELY IN THE FORM OF A PRE-FRONTAL
CONVECTIVE LINE/ WILL BE ONGOING AT THE START OF THE PERIOD FROM THE
OH/TN VALLEYS SWD TOWARDS THE CNTRL GULF COAST. THE PRIMARY UPPER
TROUGH AND SFC LOW WILL CONTINUE EJECTING NEWD AWAY FROM THIS
AREA...BUT AN ASSOCIATED LOW-LEVEL JET WILL EXTEND DOWN TO THE GULF
COAST AND SHOULD PERSIST ACROSS THE SOUTHEAST INTO THE
AFTERNOON/EVENING. DESPITE MODEST MIDLEVEL LAPSE RATES...RICH
BOUNDARY LAYER MOISTURE WILL YIELD MLCAPE VALUES AROUND 500 J/KG
OVER CNTRL/ERN GULF COAST STATES...DECREASING WITH NWD EXTENT. THIS
SHOULD BE SUFFICIENT TO MAINTAIN SOME SEMBLANCE OF A CONVECTIVE LINE
EWD THROUGHOUT THE DAY...INCLUDING PARTS OF AL/GA AND THE
APPALACHIANS/CAROLINAS. LOW-LEVEL SHEAR WILL LIKELY BE SUFFICIENT
FOR STRONG-SVR WIND GUSTS AND PERHAPS AN ISOLATED TORNADO
THREAT...PRIMARILY OVER AL/GA AND PERHAPS PARTS OF MIDDLE/ERN TN. A
LOWER-END WIND THREAT COULD EXTEND N OF THIS AREA AS WELL.

MID-/UPPER-LEVEL FORCING FOR ASCENT WILL BE QUITE WEAK IN THE WAKE
OF THE LEAD UPPER TROUGH MOVING ACROSS THE GREAT LAKES...AND WELL
DOWNSTREAM FROM A POSITIVE-TILT TROUGH OVER THE GREAT PLAINS. WITH
THE LACK OF FOCUSED SYNOPTIC-SCALE LIFT AND THE LIKELIHOOD OF ONLY A
MARGINALLY UNSTABLE AIR MASS...A 30 PERCENT PROBABILISTIC AREA WILL
NOT BE DELINEATED ATTM.

...MON/D5--IMMEDIATE COASTAL AREAS OF THE SERN ATLANTIC AND
MID-ATLANTIC...
SHOWERS/TSTMS COULD PERSIST ALONG/AHEAD OF THE COLD FRONT THROUGH
LATE MORNING...PRIMARILY ALONG COASTAL AREAS EXTENDING FROM NRN FL
INTO THE CAROLINAS. A NON-ZERO STRONG WIND GUST THREAT MAY EXIST
WITH THIS ACTIVITY WITH MODERATELY STRONG SWLY DEEP-LAYER FLOW
PERSISTING. THE COLD FRONT IS EXPECTED TO MOSTLY BE OFFSHORE BY
AFTERNOON...WITH EXCEPTION TO THE SEGMENT FARTHER S OVER THE FL
PENINSULA.

...TUE/D6 THROUGH THU/D8...
HIGH PRESSURE RETURNS TO MOST OF THE NATION TUE/D6 AND WED/D7.
ANOTHER SHORTWAVE UPPER TROUGH MAY MOVE ACROSS CENTRAL PORTIONS OF
THE CONUS THU/D8...BUT MOISTURE RETURN AHEAD OF THIS SYSTEM IS
LIKELY TO BE LIMITED.

..ROGERS.. 12/19/2013

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