SPC AC 160600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT THU AUG 16 2012
VALID 171200Z - 181200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE TN VALLEY/SOUTHERN
APPALACHIANS/SOUTHEAST STATES...
...SYNOPSIS...
AN EXTENSIVE LONGWAVE TROUGH WILL CONTINUE TO SHIFT SLOWLY EASTWARD
ON FRIDAY...WITH A DEGREE OF HEIGHT FALLS ACROSS THE NORTHEAST
STATES/CENTRAL APPALACHIANS AS BROAD CYCLONIC UPPER FLOW OTHERWISE
ENCOMPASSES MOST AREAS EAST OF THE ROCKIES. TSTM POTENTIAL WILL BE
FOCUSED ALONG/AHEAD OF AN ASSOCIATED COLD FRONT AS IT SPREADS
EASTWARD TOWARD/EAST OF THE APPALACHIANS...WHILE THE PORTION OF THE
FRONT OVER THE TN VALLEY/MID-SOUTH/SOUTHERN PLAINS MOVES SLOWLY
SOUTHWARD AND EVENTUALLY STALLS.
...TN VALLEY/SOUTHERN APPALACHIANS/SOUTHEAST STATES...
AS HEIGHT FALLS GRADUALLY OCCUR AND THE COLD FRONT SPREADS
EASTWARD...THE BOUNDARY LAYER AHEAD OF THE COLD FRONT AND ANY EARLY
DAY CONVECTIVE REMNANTS SHOULD AT LEAST BECOME WEAK TO MODESTLY
UNSTABLE...ALTHOUGH THINKING IS THAT MLCAPE MAY NOT EXCEED 750-1500
J/KG IN MOST AREAS. EVEN AS THE STRONGER CYCLONIC FLOW
ALOFT/VERTICAL SHEAR LAGS THE COLD FRONT /TO THE WEST/...SOME
SEMI-SUSTAINED/ORGANIZED MULTICELLS CAPABLE OF DAMAGING WINDS AND
PERHAPS SOME MARGINAL HAIL WILL BE POSSIBLE FRIDAY AFTERNOON/EARLY
EVENING.
...MUCH OF THE NORTHEAST STATES...
IN SPITE OF RELATIVELY FAVORABLE VERTICAL SHEAR...CLOUD COVER/EARLY
PRECIPITATION AND RELATIVELY LESSER MOISTURE CONTENT PUTS INTO
QUESTION THE DEGREE OF DESTABILIZATION/EXTENT OF ANY SEVERE THREAT.
SHOULD CONFIDENCE IN DESTABILIZATION INCREASE...A CATEGORICAL SLIGHT
RISK COULD BE WARRANTED FOR AREAS SUCH AS EASTERN NY AND ADJACENT
PA/NJ INTO WESTERN NEW ENGLAND.
...MID-SOUTH/ARKLATEX/SOUTHERN PLAINS TO CO/NM FRONT RANGE...
STRONG/POSSIBLY SEVERE TSTMS WILL ALSO BE POSSIBLE GENERALLY NEAR
AND SOUTH /EXCEPT FRONT RANGE/ ALONG AN EXTENSIVE PART OF THE
FRONTAL ZONE THAT IS EXPECTED TO DECELERATE/STALL ACROSS THE REGION.
VERTICAL SHEAR WILL BE LIMITED OWING TO WEAK TROPOSPHERIC FLOW...BUT
AMPLE MOISTURE/HEATING SOUTH THE FRONT MAY ACCOUNT FOR AT LEAST
SPORADIC DOWNBURST POTENTIAL FRIDAY AFTERNOON/EARLY EVENING...WITH
SOME HAIL ACROSS POSSIBLE NEAR THE FRONT RANGE/ADJACENT HIGH PLAINS.
...SOUTHERN AZ...
A RELATIVELY MOIST AIRMASS WILL PERSIST ACROSS SOUTHERN AZ WITH SOME
STRONGER STORMS CAPABLE OF GUSTY WINDS POSSIBLE FRIDAY COINCIDENT
WITH A MORE LIKELY HEAVY RAINFALL THREAT. HOWEVER...THE
LIKELIHOOD/EXTENT OF A GUSTY WIND THREAT IS STILL UNCERTAIN OWING TO
POSSIBILITY OF LESSER INSTABILITY/WEAKER STEERING FLOW...AND WILL
THUS DEFER AN INTRODUCTION OF SEVERE PROBABILITIES AT THIS TIME.
..GUYER.. 08/16/2012
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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