Thursday, May 5, 2011

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 051713
SWODY2
SPC AC 051712

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1212 PM CDT THU MAY 05 2011

VALID 061200Z - 071200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A PROGRESSIVE/DEAMPLIFYING LARGE SCALE REGIME WILL PREVAIL INTO
FRIDAY OVER THE CONUS AS AN INCREASINGLY ZONAL UPPER FLOW PATTERN
DEVELOPS. WITHIN THIS REGIME...THE SOUTHERNMOST PORTION OF AN UPPER
TROUGH CURRENTLY OVER THE UPPER MIDWEST IS EXPECTED TO PIVOT
EAST-NORTHEASTWARD FROM THE TN VALLEY TOWARD THE COASTAL
MID-ATLANTIC STATES/CAROLINAS ON FRIDAY. FARTHER WEST...AMID
WEST-NORTHWESTERLY LOW AMPLITUDE FLOW ALOFT...LEE TROUGH DEVELOPMENT
IS EXPECTED ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS WHILE AIRMASS
MODIFICATION OCCURS/LOW LEVEL MOISTURE BEGINS TO RETURN INLAND
ACROSS THE LOWER/MIDDLE TX COAST FRIDAY INTO SATURDAY.

...EASTERN CAROLINAS...
AS THE AFOREMENTIONED SHORTWAVE TROUGH SHIFTS EASTWARD TOWARD THE
MID-ATLANTIC STATES/CAROLINAS...RELATIVELY STRONG HEATING WILL OCCUR
DURING THE DAY ON FRIDAY ACROSS PORTIONS OF THE CAROLINAS INTO VA.
SHORTWAVE TROUGH ASSOCIATED DPVA/LIFT COUPLED WITH STEEP LAPSE RATES
ALOFT/WEAK BUOYANCY WILL SUPPORT RELATIVELY LOW TOPPED TSTMS MAINLY
FRIDAY AFTERNOON FROM THE MIDDLE/UPPER OH RIVER VALLEY INTO
VA/PORTIONS OF THE CAROLINAS. HOWEVER...WITH ONLY A MODESTLY MOIST
AIRMASS /LOWER TO MIDDLE 50S F SURFACE DEWPOINTS OR LESS/ LIKELY TO
BE IN PLACE AHEAD OF AN EASTWARD ADVANCING WEAK COLD FRONT ACROSS
THE CAROLINAS/VA...THE MARGINAL MOISTURE/WEAK BUOYANCY SHOULD
GENERALLY LIMIT A SEVERE RISK. CANNOT CURRENTLY RULE A LIMITED
SEVERE WIND AND/OR MARGINALLY SEVERE HAIL THREAT MAINLY ACROSS
EASTERN NC FRIDAY AFTERNOON...BUT LOW SEVERE PROBABILITIES DO NOT
SEEM WARRANTED AT THIS JUNCTURE.

...EASTERN KS/NORTHEAST OK AND OZARKS LATE FRIDAY NIGHT...
AIDED BY A LOW AMPLITUDE SHORTWAVE TROUGH/SPEED MAX CROSSING THE
CENTRAL PLAINS AND A NOCTURNALLY STRENGTHENING LOW LEVEL
JET/ELEVATED MOISTURE TRANSPORT REGIME...TSTMS SHOULD INCREASE
FRIDAY NIGHT ACROSS THE LOWER MO VALLEY...AND THEN PORTIONS OF
EASTERN KS/NORTHEAST OK/OZARKS LATE FRIDAY NIGHT/EARLY SATURDAY.
HOWEVER...THE STRENGTH OF THE ELEVATED MIXED LAYER/CAP...AND
APPRECIABLY HIGH STORM BASES /GENERALLY ABOVE 700 MB/ IMPLIED PER
12Z NAM/GFS FORECAST SOUNDINGS...PROVIDES UNCERTAINTY REGARDING THE
EFFECTIVE MAGNITUDE OF ELEVATED INSTABILITY/RESULTANT VIGOR OF
ELEVATED STORMS ON THE EDGE OF THE CAP FRIDAY NIGHT. GIVEN THESE
UNCERTAINTIES AND PERCEIVED MARGINAL NATURE OF THE SEVERE HAIL
THREAT...WILL DEFER TO SUBSEQUENT DAY 1 OUTLOOKS FOR ANY INCLUSION
OF LOW SEVERE PROBABILITIES.

..GUYER.. 05/05/2011

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