Friday, April 1, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 011245
SWODY1
SPC AC 011243

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0743 AM CDT FRI APR 01 2011

VALID 011300Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

...TX...

SURFACE LOW ANALYZED N OF ABI AS OF 11Z WILL DEVELOP SEWD TOWARD THE
HILL COUNTRY TODAY...GRADUALLY WEAKENING AS IT IS OVERTAKEN BY A
COLD FRONT PROGRESSING SEWD THROUGH THE SRN PLAINS. A MODIFIED CP
AIR MASS --DELINEATED BY PW VALUES OF .75-1.00 INCH AND DEWPOINTS IN
THE LOWER TO MID 60S-- WILL BE ADVECTED NWD IN ADVANCE OF SURFACE
LOW...AND S OF A DIFFUSE WARM FRONT LIFTING INTO THE RED RIVER
VALLEY. THIS MOISTURE IN CONJUNCTION WITH STRONG DIABATIC HEATING
AND CONDITIONALLY UNSTABLE MIDLEVEL LAPSE RATES WILL YIELD A
MODERATELY UNSTABLE WARM SECTOR BY AFTERNOON WITH MLCAPE VALUES
APPROACHING 1000 J/KG.

WHILE SYNOPTIC-SCALE HEIGHT RISES IN THE MIDLEVELS ARE FORECAST
ACROSS THE REGION TODAY...LATEST MESOSCALE MODEL GUIDANCE AND WATER
VAPOR IMAGERY SUGGEST THAT A LOW-AMPLITUDE IMPULSE CURRENTLY MOVING
INTO THE CNTRL HIGH PLAINS COULD GLANCE THE REGION DURING THE PEAK
OF THE DIURNAL HEATING CYCLE. WHEN COUPLED WITH SUSTAINED
CONVERGENCE NEAR THE COLD FRONT-DRYLINE TRIPLE POINT...POTENTIAL
WILL EXIST FOR ISOLATED TO WIDELY SCATTERED TSTM DEVELOPMENT LATE
THIS AFTERNOON INTO EVENING. FORECAST HODOGRAPHS SHOW
VERTICALLY-VEERING WIND PROFILES WITH 40-50 KT OF DEEP NWLY SHEAR...
SUPPORTIVE OF SUSTAINED/ROTATING UPDRAFTS. AS SUCH...THE POTENTIAL
WILL EXIST FOR ISOLATED OCCURRENCES OF SEVERE HAIL AND LOCALLY
DAMAGING WIND GUSTS INTO THIS EVENING.

...OH VALLEY...

AN ELONGATED VORTICITY MAXIMUM AND ASSOCIATED MID- AND UPPER-LEVEL
JET STREAKS OVER THE MID MO VALLEY THIS MORNING WILL TRANSLATE
RAPIDLY SEWD THROUGH OH/TN VALLEYS...EVENTUALLY REACHING THE MID
ATLANTIC COAST BY SAT MORNING. DEEP ASCENT WITHIN LEFT EXIT REGION
OF THE UPPER JET STREAK WILL BE SUPPORTIVE OF SCATTERED...LOW-TOPPED
TSTMS TODAY OVER PORTIONS OF IL/IND...ALONG AND AHEAD OF ASSOCIATED
COLD FRONT. FORECAST SOUNDINGS INDICATE A STEEP LAPSE RATE
ENVIRONMENT WITH SBCAPE VALUES OF 100-300 J/KG. SMALL HAIL AND
LOCALLY STRING WIND GUSTS WILL ACCOMPANY THE STRONGER STORMS GIVEN
THE COLD THERMODYNAMIC PROFILES AND DEEP NWLY WIND FIELD.

...S FL...

A FEW STRONG STORMS WILL BE POSSIBLE THIS MORNING ALONG AND AHEAD OF
COLD FRONT ADVANCING SWD THROUGH THE AREA. 12Z MIA/KEY SOUNDINGS
SHOWED THE PRESENCE OF A WARM...MOIST BOUNDARY LAYER THAT WAS
LARGELY CONTRIBUTING TO MLCAPE VALUES OF 1000-1500 J/KG AND LITTLE
OR NO CONVECTIVE INHIBITION. STRONGER DEEP-LAYER WIND FIELD
ASSOCIATED WITH ERN CONUS FULL-LATITUDE TROUGH /AS OBSERVED BY 12Z
MIA SOUNDING/ IS FORECAST TO PROGRESS EWD INTO THE ATLANTIC TODAY.
THE DECREASING SHEAR AND WEAKENING CONVERGENCE ALONG SURFACE FRONT
SHOULD LIMIT THE POTENTIAL FOR AN ORGANIZED SEVERE WEATHER THREAT.

..MEAD/BOTHWELL.. 04/01/2011

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