MESO: Mesoscale Discussion 0477

ACUS11 KWNS 131034
SWOMCD
SPC MCD 131034
OKZ000-TXZ000-131200-

MESOSCALE DISCUSSION 0477
NWS STORM PREDICTION CENTER NORMAN OK
0534 AM CDT FRI APR 13 2007

AREAS AFFECTED...PARTS OF WRN/NW TX...TX/OK PNHDLS...WRN AND CNTRL
OK

CONCERNING...SEVERE THUNDERSTORM WATCH 132...

VALID 131034Z - 131200Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 132
CONTINUES. SOME UNCERTAINTY EXISTS AS TO WHETHER A NEW WW WILL BE
NEEDED AT 12Z...BUT TRENDS ARE BEING MONITORED FOR THIS POSSIBILITY.

LATEST RUC GUIDANCE INDICATES THAT 90-100 KT CORE OF A CYCLONIC 500
MB JET STREAK IS NOW PROGRESSING ACROSS NORTHERN SONORA/CHIHUAHUA.
THIS IS SUPPORTED BY WATER VAPOR IMAGERY...AND MOST MODEL GUIDANCE
INDICATES THAT THIS FEATURE WILL BEGIN NOSING INTO SOUTHWEST TEXAS
BY THE 12-15Z TIME FRAME. AS THIS OCCURS...DIVERGENT UPPER FLOW
FIELD IN ITS LEFT EXIT REGION WILL OVERSPREAD THE TEXAS/OKLAHOMA
PANHANDLE REGION AND THE TEXAS SOUTH PLAINS. THIS IS EXPECTED TO
MAINTAIN VIGOROUS CONVECTIVE DEVELOPMENT ACROSS PARTS OF THE TEXAS
PANHANDLE INTO WESTERN OKLAHOMA...WHERE CAPE FOR PARCELS BASED IN
ELEVATED MOIST LAYER RETURNING ABOVE DEVELOPING SURFACE FRONT IS
INCREASING INTO THE 500-1000 J/KG RANGE. AN EXPANDING CONVECTIVE
CLUSTER APPEARS POSSIBLE THROUGH THE MORNING HOURS...WITH PERSISTENT
HEAVY RAINFALL BECOMING AN INCREASING THREAT...IN ADDITION TO A
CONTINUING RISK FOR MOSTLY MARGINALLY SEVERE HAIL.

UNCERTAINTY EXISTS CONCERNING PROSPECTS FOR CONVECTIVE DEVELOPMENT
TO THE SOUTH OF SURFACE FRONTAL ZONE...ROUGHLY SOUTHEAST OF A LAWTON
OK/LUBBOCK TX LINE. IT APPEARS THAT VEERING LOW-LEVEL FLOW MAY
CONTRIBUTE TO A ZONE OF ENHANCED LOW-LEVEL WARM ADVECTION SOUTH OF
CHILDRESS INTO THE ABILENE AREA...WHERE ADDITIONAL CONVECTIVE
DEVELOPMENT IS POSSIBLE DURING THE 12-15Z TIME FRAME. IF THIS
OCCURS...HODOGRAPHS WILL BE MORE THAN SUPPORTIVE OF SUPERCELLS.
BUT...THROUGH AT LEAST MID MORNING...STORMS PROBABLY WILL BE ROOTED
ABOVE A COOLER/DRIER BOUNDARY LAYER...WITH LARGE HAIL THE PRIMARY
SEVERE THREAT.

.KERR.. 04/13/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FWD...OUN...SJT...LUB...AMA...

36090176 36780091 36950001 36689855 36019793 34879821
34409849 33969850 32919806 32269846 32109960 32860015
33490115 34200186 35330189

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