SWODY1
SPC AC 131233
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0733 AM CDT FRI APR 13 2007
VALID 131300Z - 141200Z
..THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT FROM CENTRAL/NE TX INTO NW LA AND EXTREME SW AR...
..THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...FROM
CENTRAL TX AND SRN OK EWD TO THE LOWER MS VALLEY...
..SYNOPSIS...
A STRONG MID LEVEL TROUGH OVER SE AZ HAS NOW TURNED TO THE E AND
WILL CONTINUE EWD OVER SRN NM THE FIRST PART OF THE DAY...AND THEN
NEWD OVER NW TX AND OK BY TONIGHT. AN ASSOCIATED SURFACE LOW INVOF
THE TX/NM BORDER WILL DEVELOP EWD ACROSS NW INTO N CENTRAL TX BY
THIS EVENING...AND THEN CONTINUE TO THE ENE OVER SRN AR TONIGHT. A
MOIST WARM SECTOR /BOUNDARY LAYER DEWPOINTS OF 65-70 F/ NOW ACROSS S
TX WILL SPREAD NWD INTO N CENTRAL AND NE TX BY MID-LATE AFTERNOON AS
A RESULT OF ADVECTION ON A 40 KT SLY LLJ IN ADVANCE OF THE SURFACE
LOW AND MID LEVEL WAVE...AND VERTICAL MIXING WITH DAYTIME HEATING.
THE INCREASING LOW-LEVEL MOISTURE WILL CONTRIBUTE TO SUBSTANTIAL
DESTABILIZATION ACROSS CENTRAL AND E TX...WHILE VERTICAL SHEAR WILL
BECOME QUITE FAVORABLE FOR SUPERCELLS IN THE WARM SECTOR.
..CENTRAL/NE TX TODAY EWD ACROSS SRN AR AND NRN LA TONIGHT...
ONE CONCERN TODAY WILL BE THE EXTENT OF ELEVATED CONVECTION ACROSS
N/NE TX...WHERE RAINFALL AND EVAPORATIVE COOLING WITHIN THE
INITIALLY DRIER BOUNDARY LAYER COULD TEND TO LIMIT THE NWD EXTENT OF
THE UNSTABLE WARM SECTOR. HOWEVER...CONSENSUS OF SHORT RANGE MODELS
SUGGESTS THAT THE MAJORITY OF CONVECTION FROM THIS MORNING INTO MID
AFTERNOON SHOULD BE NEAR AND N OF THE RED RIVER WHERE ASCENT WILL BE
FOCUSED N OF THE DEEP BAROCLINIC ZONE. THEREFORE...MODERATE
INSTABILITY WILL LIKELY DEVELOP IN THE WARM SECTOR ROUGHLY ALONG AND
S OF A LINE FROM THE DFW METROPLEX TO THE TXK-SHV AREA BY THIS
EVENING.
VERTICAL SHEAR PROFILES ARE FORECAST TO BECOME QUITE FAVORABLE FOR
TORNADIC SUPERCELLS IN ADVANCE OF THE SURFACE LOW AND EWD ALONG AND
EVEN S OF THE WARM FRONT INTO E/NE TX. A FEW DISCRETE SUPERCELLS
WILL LIKELY DEVELOP ALONG THE DRYLINE AND PERHAPS IN THE OPEN WARM
SECTOR BY MID AFTERNOON AND MOVE ENEWD INTO THE REGION OF STRONGER
LOW-LEVEL SHEAR. BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 60S AND
LARGE HODOGRAPHS WITH EFFECTIVE SRH OF 400-500 M2/S2 APPEAR
SUPPORTIVE OF SUPERCELLS WITH STRONG TORNADOES LATE THIS AFTERNOON
INTO THIS EVENING ACROSS NE TX.
BY TONIGHT...CONVECTION SHOULD TEND TOWARD A MORE LINEAR STRUCTURE
AS THE DEEP LAYER SHEAR AND BOUNDARY ORIENTATIONS BECOME MORE
PARALLEL /SW TO NE/. THE NET RESULT WILL BE A TRANSITION TO MORE OF
A DAMAGING WIND THREAT ACROSS LA...THOUGH VERTICAL SHEAR WILL STILL
FAVOR A FEW EMBEDDED MESOCYCLONES/LEWPS WITHIN THE BAND OF
STORMS...AND AN ASSOCIATED THREAT FOR A FEW TORNADOES OVERNIGHT.
..NW TX AND SRN OK TODAY...
A LARGE CLUSTER OF ELEVATED THUNDERSTORMS IS DEVELOPING FROM NW TX
INTO CENTRAL OK IN ASSOCIATION WITH INCREASINGLY MOIST WAA AND A
LEAD SHORTWAVE TROUGH EJECTING NEWD IN ADVANCE OF THE MAIN WAVE OVER
AZ/NM. MUCAPE OF 750-1250 J/KG BASED IN THE 800-700 MB LAYER AND
STEEP MID LEVEL LAPSE RATES WILL SUPPORT A FEW STORMS WITH LARGE
HAIL THROUGH THE DAY SPREADING EWD OVER SRN OK AND ADJACENT RED
RIVER COUNTIES IN N TX.
.THOMPSON/CROSBIE.. 04/13/2007
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write chris@lib.siu.edu.
No comments:
Post a Comment