DAY48SVR: Nws Storm Prediction Center Norman Ok

ACUS48 KWNS 030916
SWOD48
SPC AC 030916

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0316 AM CST SAT JAN 03 2009

VALID 061200Z - 111200Z

...DISCUSSION...

LATEST MEDIUM-RANGE GUIDANCE REMAINS IN REASONABLY GOOD AGREEMENT IN
THE EVOLUTION OF THE LARGE-SCALE PATTERN THROUGH THE FIRST PART OF
THE EXTENDED PERIOD. THEREAFTER...DIFFERENCES BEGIN TO ARISE IN THE
HANDLING OF THE NEXT WRN U.S. TROUGH.

...D4 /TUE JAN 6TH/...

SHORT WAVE TROUGH OVER TX AT THE BEGINNING OF THE PERIOD WILL
RAPIDLY EJECT NEWD INTO THE OH VALLEY DURING THE DAY IN ADVANCE OF
POWERFUL...FULL-LATITUDE TROUGH SHIFTING EWD THROUGH THE CNTRL
CONUS. IN THE LOW LEVELS...BROAD LOW PRESSURE OVER THE PLAINS INTO
GULF STATES WILL EVENTUALLY CONSOLIDATE INTO A PRIMARY CYCLONE
TUESDAY NIGHT OVER THE UPPER OH VALLEY OR CUMBERLAND PLATEAU.
HOWEVER...IT STILL APPEARS THAT A WEAKER LOW PRESSURE CENTER WILL
TRACK ACROSS THE CNTRL AND ERN GULF STATES TUESDAY.

PLAN VIEW FIELDS AND FORECAST SOUNDINGS SUGGEST THAT WARM SECTOR AIR
MASS WILL BECOME ONLY WEAKLY UNSTABLE LARGELY DUE TO WEAK MIDLEVEL
LAPSE RATES. HOWEVER...THE PRESENCE OF 60+ F DEWPOINTS...VERY
STRONG WIND SHEAR AND INCREASED FORCING FOR ASCENT ALL SUGGEST THE
POTENTIAL FOR AN ORGANIZED SEVERE WEATHER EPISODE AHEAD OF COLD
FRONT AND SURFACE LOW FROM PORTIONS OF THE LOWER MS VALLEY INTO ERN
GULF STATES.

...D5 /WED JAN 7TH/...

ANY LINGERING SEVERE THREAT ALONG THE SERN ATLANTIC COAST SHOULD
QUICKLY MOVE OFF THE COAST EARLY IN THE PERIOD WITH PASSAGE OF COLD
FRONT. FARTHER S OVER THE FL PENINSULA...DECREASING CONVERGENCE
ALONG FRONT SHOULD TEND TO LIMIT A MORE SUBSTANTIAL SEVERE THREAT.

...D6 /THU JAN 8TH/ THROUGH D8 /SAT JAN 10TH/...

A RETURN FLOW REGIME WILL BECOME ESTABLISHED OVER THE WRN GULF OF
MEXICO ON D6 INTO D7 AS HEIGHTS BEGIN TO FALL OVER THE WRN STATES.
WHILE THERE DOES APPEAR TO BE SOME POTENTIAL FOR TSTMS OVER ERN TX
INTO LOWER MS VALLEY TOWARD THE END OF THE PERIOD WITH THE ARRIVAL
OF ANOTHER COLD FRONT...UNCERTAINTIES EXIST IN THE EVOLUTION OF
ASSOCIATED MIDLEVEL TROUGH AND FRONTAL MOTION. THEREFORE...NO
ADDITIONAL AREAS WILL BE DELINEATED.

..MEAD.. 01/03/2009

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