SPC AC 140820
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0220 AM CST THU FEB 14 2008
VALID 161200Z - 171200Z
...THERE IS A SLGT RISK OF SVR TSTMS SAT/SAT NIGHT ACROSS MUCH OF
CENTRAL/SOUTHEAST TEXAS....
...SYNOPSIS...
AMPLIFICATION WITHIN THE UPPER PATTERN...EXPECTED TO BE ONGOING AT
12Z SATURDAY ACROSS THE NORTHEAST PACIFIC INTO THE LEE OF THE
CANADIAN/U.S. ROCKIES...IS PROGGED TO PROCEED/TRANSLATE EASTWARD
THROUGH 12Z SUNDAY. AND...THE 14/00Z OPERATIONAL NAM/GFS/ECMWF
...NCEP SREF AND MREF...ALL INDICATE THAT THE SOUTHERN BRANCH CLOSED
LOW WILL FINALLY ACCELERATE EASTWARD OUT OF THE NORTHWESTERN MEXICAN
PLATEAU...AS A VIGOROUS SHORT WAVE TROUGH CONTINUES TO DIG THROUGH
THE NORTH CENTRAL STATES. CONSIDERABLE SPREAD DOES EXIST AMONG THE
MODELS CONCERNING THE RATE AT WHICH THIS OCCURS. BUT...THE NCEP
SREF/MREF MEANS ARE QUITE SIMILAR WITH TRACK OF THE MID-LEVEL
CIRCULATION ACROSS THE TEXAS BIG BEND REGION INTO CENTRAL TEXAS BY
LATE SATURDAY NIGHT.
...SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY...
PERHAPS THE BIGGEST SOURCE OF FORECAST UNCERTAINTY FOR THIS PERIOD
CONCERNS JUST HOW FAST THE SHALLOW COLD SURFACE BASED AIR MASS
MODIFIES ACROSS CENTRAL TEXAS INTO TEXAS GULF COASTAL AREAS...IN THE
WAKE OF THE ANTICIPATED COLD INTRUSION LATE THIS WEEK. ASIDE FROM
BOUNDARY LAYER DESTABILIZATION ISSUES...THIS WILL IMPACT THE
STRENGTH/LOCATION OF SURFACE CYCLOGENESIS...WHICH SHOULD INITIATE
WITH THE APPROACH OF THE UPPER SYSTEM. IT CURRENTLY SEEMS A BIT
MORE PROBABLE THAT THIS PROCESS WILL BE WEAKER/SLOWER AND ALONG A
BAROCLINIC ZONE IN CLOSER PROXIMITY TO COASTAL AREAS...THAN
CURRENTLY INDICATED BY EITHER THE ECMWF OR GFS.
REGARDLESS...THIS SHOULD ONLY IMPACT THE TORNADO POTENTIAL. IF NOT
NEAR THE SURFACE...JUST ABOVE...THERMODYNAMIC PROFILES ACROSS MUCH
OF TEXAS ARE EXPECTED TO BECOME CONVECTIVELY UNSTABLE. AND...A
LOADED GUN TYPE STRUCTURE SHOULD EVOLVE...PARTICULARLY ACROSS PARTS
OF SOUTH CENTRAL INTO SOUTHEAST TEXAS...AS A SOUTHERLY LOW-LEVEL JET
CONTINUES TO STRENGTHEN OFF THE WESTERN GULF OF MEXICO...BENEATH AN
ELEVATED MIXED LAYER. BY LATE SATURDAY AFTERNOON...VERY LARGE
CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS ARE FORECAST TO EVOLVE BENEATH
50+ KT SOUTHERLY 850 FLOW...WHILE DEEP LAYER SHEAR INTENSIFIES AS A
STRONG SOUTHWESTERLY UPPER JET NOSES THROUGH THE LOWER RIO GRANDE
VALLEY.
THIS ENVIRONMENT WILL BE FAVORABLE FOR SUPERCELLS...AT LEAST CAPABLE
OF PRODUCING VERY LARGE HAIL AND DAMAGING WIND GUSTS. WHILE
DISCRETE ACTIVITY IS POSSIBLE...STRONG MID-LEVEL FORCING ASSOCIATED
WITH THE APPROACHING IMPULSE IS EXPECTED TO SUPPORT A SEVERE SQUALL
LINE...WHICH SHOULD DEVELOP EASTWARD OUT OF CENTRAL TEXAS ACROSS
TEXAS COASTAL AREAS AND PARTS OF THE SABINE VALLEY BEFORE WEAKENING
SATURDAY NIGHT.
..KERR.. 02/14/2008
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1100Z
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