DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 090824
SWODY3
SPC AC 090822

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0222 AM CST SUN DEC 09 2012

VALID 111200Z - 121200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE SPREAD AMONG THE VARIOUS MODEL ENSEMBLE DATA BECOMES SIZABLE
DURING THIS FORECAST PERIOD CONCERNING SHORT WAVE DEVELOPMENTS
WITHIN A BRANCH OF WESTERLIES EMERGING FROM THE NORTHEAST
PACIFIC...BEFORE CURVING ACROSS THE U.S. IN A BROADLY CYCLONIC
FASHION. GENERALLY...HOWEVER...IT APPEARS THAT A SIGNIFICANT SHORT
WAVE TROUGH WILL GRADUALLY DIG MORE SHARPLY SOUTHWARD NEAR THE
PACIFIC COAST...AS SHORT WAVE RIDGING AMPLIFIES UPSTREAM...ACROSS
THE NORTHEAST PACIFIC. MEANWHILE...AS SHORT WAVE RIDGING BUILDS
ACROSS THE SOUTHERN AND CENTRAL INTERMOUNTAIN REGION/ROCKIES AND
PLAINS...IT APPEARS THAT ONE MORE FAIRLY SIGNIFICANT IMPULSE WILL
PIVOT THROUGH THE BASE OF LINGERING BROADER SCALE UPPER TROUGHING
SHIFTING EAST OF THE MISSISSIPPI VALLEY.

THIS LATTER FEATURE COULD PROVIDE SUPPORT FOR CONVECTIVE DEVELOPMENT
ALONG AND AHEAD OF A SLOW MOVING FRONTAL ZONE ADVANCING SOUTHEAST OF
SOUTH ATLANTIC/EASTERN GULF COASTAL AREAS...INTO THE FLORIDA
PENINSULA. WEAK DESTABILIZATION APPEARS POSSIBLE ABOVE/TO THE COOL
SIDE OF THE SURFACE FRONT...WITH WEAK TO MODERATE DESTABILIZATION
POSSIBLE TO THE SOUTH...AIDED BY LOW-LEVEL MOISTENING WITHIN A PLUME
OF PRECIPITABLE WATER WITH VALUES AS HIGH AS 1.5+ INCHES. THIS IS
EXPECTED TO ADVECT NORTHEASTWARD FROM THE CENTRAL AND SOUTHERN GULF
OF MEXICO...ON A MODERATELY STRONG AND SHEARED SOUTHWESTERLY DEEP
LAYER MEAN FLOW.

...FLORIDA...
FRONTAL CONVECTION...WITH AN EXPECTED TENDENCY TO BECOME UNDERCUT BY
A COOL STABLE SURFACE-BASED AIR MASS...SEEMS LIKELY TO REMAIN
SUB-SEVERE TUESDAY. HOWEVER...MODELS ARE SUGGESTIVE THAT A
PRE-FRONTAL CONFLUENT ZONE...BECOMING ORIENTED SOUTHWEST TO
NORTHEAST ACROSS THE CENTRAL PENINSULA...COULD BECOME THE FOCUS FOR
BOUNDARY LAYER BASED STORM DEVELOPMENT DURING THE AFTERNOON AND
EVENING. ALTHOUGH LOW/MID-LEVEL LAPSE RATES WILL PROBABLY NOT BE
PARTICULARLY STEEP...VERTICAL SHEAR MAY BE SUFFICIENT FOR AT LEAST
MODEST UPDRAFT ROTATION...PERHAPS ONE OR TWO SUPERCELL STRUCTURES
WITH SOME SEVERE WEATHER POTENTIAL.

..KERR.. 12/09/2012

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