[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 262323
SWOMCD
SPC MCD 262322 
ARZ000-LAZ000-TXZ000-OKZ000-270045-

MESOSCALE DISCUSSION 2158
NWS STORM PREDICTION CENTER NORMAN OK
0622 PM CDT THU OCT 26 2006

AREAS AFFECTED...NERN TX...EXTREME SERN OK...EXTREME SWRN AR AND
EXTREME NWRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 262322Z - 270045Z

LARGE SCALE HEIGHT FALLS ASSOCD WITH THE TX PNHDL UPPER LOW APPEAR
TO BE IMPINGING ON THE SUB-TROPICAL CONVEYOR ACROSS CNTRL/NERN TX
PER INCREASE IN MID-LEVEL CONVECTIVE ELEMENTS. THIS MAY BE THE
BEGINNING OF A LONG TERM TSTM THREAT THAT WILL LAST INTO EARLY FRI
ACROSS THE ARKLATEX REGION.  SEVERE PROBABILITIES AND TYPE REMAIN IN
QUESTION...HOWEVER.

PASSAGE OF THE SUB-TROPICAL WAVE EARLIER TODAY HAS LARGELY MODIFIED
THE TROPOSPHERIC WIND PROFILE WITH A DECIDEDLY VEERED REGIME JUST
OFF THE SFC...THEN A GRADUALLY BACKING UPPER FLOW AHEAD OF THE
PRIMARY UPPER LOW.  FURTHERMORE...MID-TROPOSPHERIC LAPSE RATES WERE
RATHER POOR GIVEN SUB-TROPICAL NATURE TO THE CONVEYOR. 0-3KM LAPSE
RATES WERE BETTER WHERE BOUNDARY LAYER HEATING WAS MORE SIGNIFICANT
ACROSS ECNTRL THROUGH NERN TX.

ATTM...IT APPEARS THAT TSTMS WILL INDEED EXPAND AS THE UPPER LOW
APPROACHES IN THE 00-03Z TIME FRAME FROM PARTS OF ECNTRL TX NEWD
INTO THE ARKLATEX.  STRONGEST STORM POTENTIAL WILL EXIST S OF THE
RED RVR VLY AND EAST OF TEMPLE-CORSICANA AS MID-LEVEL STORMS BEGIN
TO ROOT INTO THE MORE UNSTABLE BOUNDARY LAYER. DAMAGING WIND GUSTS
APPEAR TO BE THE PRIMARY SEVERE THREAT.  BUT...THE LOW-LEVEL
FLOW...ALBEIT RATHER WEAK...WAS REGIONALLY BACKED IN A CORRIDOR FROM
TYLER TO LUFKIN.  AS STORMS MATURE...AN ISOLD TORNADO CANNOT BE
RULED OUT IN THIS REGION THROUGH MID-EVENING.

ACTIVITY WILL DEVELOP/MOVE ENEWD TOWARD SRN AR AND LA LATER THIS
EVENING WITH PERHAPS AN ATTENDANT DAMAGING WIND THREAT.  BUT...IT
APPEARS THAT HEAVY RAINFALL MAY BE THE EVOLVING PROBLEM AS NE-SW
ORIENTED LINES TRAIN OVER THE SAME REGIONS.

..RACY.. 10/26/2006

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

ATTN...WFO...LZK...SHV...TSA...HGX...FWD...

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