SWODY2
SPC AC 190558
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1158 PM CST TUE DEC 18 2007
VALID 201200Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS PORTIONS E TX...LA TO WRN FL
PANHANDLE...
..SYNOPSIS...
PROGRESSIVE MID/UPPER LEVEL PATTERN WILL CONTINUE...WITH MOST
CRITICAL FEATURE BEING SHORTWAVE TROUGH NOW EVIDENT IN MOISTURE
CHANNEL IMAGERY OVER SRN CA SWD TO JUST OFFSHORE NRN BAJA. THIS
TROUGH IS FCST TO MOVE EWD TO ERN OK AND N-CENTRAL/CENTRAL TX BY
20/12Z...THEN REACHING SC...ERN GA AND PERHAPS NRN FL BY 21/12Z. AT
SFC...LEE TROUGHING WITH WEAK EMBEDDED LOWS -- NOW ANALYZED FROM ERN
CO SWD ACROSS ERN NM AND SW TX -- IS EXPECTED TO CONSOLIDATE INTO
DISCRETE LOW DAY-1 BEFORE MOVING ESEWD/SEWD TOWARD RED RIVER N-NE OF
DAL BY 20/12Z. THIS LOW THEN SHOULD MOVE EWD ACROSS NRN MS BETWEEN
21/00-21/06Z BEFORE BECOMING DIFFUSE INVOF NWRN AL/NERN MS. DRYLINE
WILL BECOME BETTER DEFINED AND MOVE EWD ACROSS WRN/CENTRAL TX
THROUGH BEGINNING OF PERIOD AS DEW POINTS INCREASE TO ITS E...WITH
SIGNIFICANT WLY WIND COMPONENT TO ITS W.
..SE TX TO CENTRAL GULF COAST REGION...
ONGOING POTENTIAL EXISTS FROM END OF DAY-1 PERIOD OVER PORTIONS E TX
AND LA...WITH ADDITIONAL DEVELOPMENT OF SCATTERED TSTMS POSSIBLE IN
EWD-SHIFTING BANDS AND CLUSTERS DURING DAY. MAIN THREATS WILL
TRANSITION FROM ISOLATED HAIL OVER PARTS OF NE TX...AR AND NWRN
NS...TO WIND DAMAGE AND A FEW TORNADOES WITH PROXIMITY TO COAST.
THIS IS BECAUSE SFC-BASED DESTABILIZATION IS EXPECTED TO DIMINISH
WITH INLAND EXTENT...ESPECIALLY N OF I-20 IN LA/MS...GIVEN BOTH
INCOMPLETENESS OF RETURN FLOW MODIFICATION FROM GULF AND EFFECTS OF
CLOUDS/PRECIP. STRONG BUT NARROW ZONE OF MIDLEVEL DPVA IS FCST TO
PRECEDE TROUGH AS IT MOVES EWD OVER ARKLATEX REGION AND INTO MS.
THIS WILL COINCIDE WITH DIURNAL HEATING ACROSS PORTIONS NRN CENTRAL
LA AND PERHAPS SWRN MS...PROVIDING ADDITIONAL CONTRIBUTION TO
STEEPENING OF DEEP-LAYER LAPSE RATES. INFLOW LAYER IS EXPECTED TO
BECOME PROGRESSIVELY MORE ELEVATED WITH NWD EXTENT OVER NRN
LA...AR...NRN MS AND WRN TN...THOUGH ISOLATED HAIL MAY BE POSSIBLE.
AIR MASS MODIFICATION IS WELL UNDERWAY OVER ROUGHLY WRN HALF OF GULF
BASED ON PW DATA AND SFC-850 MB ISODROSOTHERMAL ANALYSIS TRENDS.
LATEST BRO/CRP RAOBS AND GPS DATA INDICATE 1-1.25 INCH PW...WITH
CIRA SATELLITE BASED INDICATIONS OF 1.25-1.5 INCH OVER SHELF WATERS
BETWEEN BRO-TAMPICO...AND OBSERVED 66-70 DEG F SFC DEW POINTS OVER
WRN GULF S OF 26N. PRIND LOW-MID 60S F DEW POINTS WILL SPREAD NEWD
ACROSS CATEGORICAL OUTLOOK AREA BENEATH INCREASING FLOW ALOFT. LOW
LEVEL HODOGRAPHS SHOULD BE FAVORABLE FOR BOTH SUPERCELLS AND SMALL
BOWS...GIVEN ANTICIPATED BLEND OF LINEAR AND CLUSTERED CONVECTIVE
MODES. SVR POTENTIAL EFFECTIVELY WILL BE SHUNTED SEWD WITH
TIME...AS STRONGEST DEEP-LAYER FORCING OUTRUNS MOST FAVORABLE
BOUNDARY LAYER DESTABILIZATION AND MOVES OVER SMALLER THETAE IN LOW
LEVELS.
.EDWARDS.. 12/19/2007
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