Thursday, February 21, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 211302
SWODY1
SPC AC 211300

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0700 AM CST THU FEB 21 2008

VALID 211300Z - 221200Z

..THERE IS A SLGT RISK OF SVR TSTMS OVER THE WRN AND CNTRL GULF CST
REGION...

..SYNOPSIS...
PROGRESSIVE SPLIT FLOW PATTERN WILL PERSIST OVER THE CONUS THROUGH
FRIDAY. TWO DISTURBANCES IN THE SRN STREAM.../1/ THE MAIN TROUGH
NOW ALONG THE AZ-NM BORDER AND.../2/ SUBTROPICAL IMPULSE NOW NEARING
THE TX BIG BEND...WILL BE DOMINANT FEATURES AFFECTING TSTM
DEVELOPMENT DOWNSTREAM ACROSS PARTS OF TX AND THE GULF CST REGION
THIS PERIOD.

THE LWR LEVELS WILL REMAIN FAIRLY COMPLEX. SHALLOW ARCTIC FRONT
SHOULD CONTINUE NOSING S/SSE ACROSS NW AND CNTRL TX TODAY...WHILE
ERN PART OF THE BOUNDARY BECOMES MORE OR LESS STATIONARY FROM E
CNTRL TX INTO NRN LA/MS. RESULTING INFLECTION POINT OVER E CNTRL TX
LIKELY WILL BE THE SEAT OF DEVELOPMENT OF A SFC WAVE...WITH THE
WAVE TRACKING ENE INTO NRN MS BY THE END OF THE PERIOD. S OF THE
WAVE... A DRY LINE/WIND SHIFT LINE WILL MOVE E ACROSS S CNTRL/ SE
TX. FARTHER E/SE...DEVELOPMENT OF WAVE AND CONTINUED EWD
PROGRESSION OF UPR TROUGHS SHOULD ALLOW MARITIME WARM FRONT NOW IN
THE NWRN GULF TO LIFT NE INTO LA TODAY...AND INTO MS/SRN AL AND THE
FL PANHANDLE EARLY FRIDAY.

..WRN/CNTRL GULF CST REGION...
SCTD AREAS/BANDS OF ELEVATED CONVECTION/TSTMS LIKELY WILL PERSIST
THROUGH THE DAY FROM E TX NWD AND EWD INTO ERN OK...SE KS...SRN
MO...AR AND MS. THIS ACTIVITY WILL BE SUPPORTED BY GRADUALLY
INCREASING WAA DOWNSTREAM FROM AFOREMENTIONED UPR TROUGHS AND MAY
YIELD ISOLATED/PERIODIC HAIL. WITH POCKETS OF MUCAPE AROUND 1000
J/KG...ESPECIALLY OVER E TX/LA AND AR...AND WITH UNIDIRECTIONAL
CLOUD-LAYER SHEAR AROUND 50 KTS...SOME OF THE HAIL COULD EXCEED SVR
LIMITS.

A POTENTIALLY MORE WIDESPREAD/SUSTAINED SVR THREAT MAY EVOLVE THIS
AFTN AND EVENING OVER SE TX AND LA...SPREADING INTO PARTS OF
MS...SRN AL AND THE FL PANHANDLE TONIGHT/EARLY FRIDAY. COMBINATION
OF INCREASING UVV DOWNSTREAM FROM APPROACHING UPR
DISTURBANCES...COUPLED WITH MODEST SFC HEATING AND CONTINUED
MOISTURE INFLOW...MAY YIELD STORM DEVELOPMENT INVOF AFOREMENTIONED
SFC WAVE AND SWD ALONG ASSOCIATED WIND SHIFT LINE OVER E CNTRL...
SE AND POSSIBLY S CNTRL TX. THE DOMINANT SVR THREAT WITH THESE
STORMS WILL BE HAIL AND LOCALLY DMGG WIND AS THEY MERGE INTO BROKEN
LINES AND/OR SEVERAL SMALL CLUSTERS.

OTHER STRONG TO SVR STORMS LIKELY WILL CONTINUE TO FORM ALONG AND N
OF WARM/MARITIME FRONT NOW APPROACHING THE LA GULF CST. EXPECTED
VEERING OF LLJ OVER THE WRN/CNTRL GULF CST REGION LATER TODAY/
TONIGHT WILL MAXIMIZE LOW-LEVEL SPEED/DIRECTIONAL SHEAR ACROSS THIS
REGION RELATIVE TO POINTS FARTHER W. THIS MAY SUPPORT AN ENHANCED
THREAT FOR TORNADOES...IN ADDITION TO SVR WIND/HAIL AS SFC DEWPOINTS
RISE INTO THE MID/UPR 60S...YIELDING SBCAPE UP TO 1000-1500 J/KG.
THIS SVR THREAT LIKELY WILL CONTINUE THROUGH MUCH OF THE NIGHT EWD
INTO PARTS OF MS/AL AND THE WRN FL PANHANDLE AS MARITIME FRONT
CONTINUES TO LIFT NEWD.

.CORFIDI.. 02/21/2008

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