MESO: Mesoscale Discussion 0510

ACUS11 KWNS 132040
SWOMCD
SPC MCD 132039
OKZ000-TXZ000-132215-

MESOSCALE DISCUSSION 0510
NWS STORM PREDICTION CENTER NORMAN OK
0339 PM CDT FRI APR 13 2012

AREAS AFFECTED...CNTRL/WRN OK...PARTS OF WRN NORTH TX

CONCERNING...TORNADO WATCH 160...

VALID 132039Z - 132215Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 160 CONTINUES.

SCATTERED SUPERCELLS OVER SWRN/CNTRL OK AND PARTS OF WRN NORTH TX
WILL CONTINUE TO TRACK ENEWD/EWD AND APPROACH THE I-35 CORRIDOR
DURING THE NEXT COUPLE OF HOURS. THESE STORMS WILL PERSIST IN AN
ENVIRONMENT CHARACTERIZED BY SBCAPE VALUES OF 2500-3500 J/KG AND
EFFECTIVE BULK SHEAR MAGNITUDES OF 35-50 KT...WITH SUSTAINED
MID-LEVEL MESOCYCLONES NOTED ON AREA RADAR IMAGERY. VERY LARGE HAIL
WILL BE A CONCERN WITH ANY PERSISTENT SUPERCELL STRUCTURES THROUGH
LATE AFTERNOON. ONE SUPERCELL EXHIBITING NOTABLE EWD DEVIANT MOTION
FROM THE MEAN FLOW IS APPROACHING PARTS OF THE OKC/NORMAN
AREAS...WHICH WILL LIKELY BE IMPACTED BETWEEN 2050 AND 2130Z. A
LOCAL EWD EXTENSION OF THE TORNADO WATCH HAS BEEN COORDINATED WITH
THE NORMAN WFO TO ADDRESS A SHORT-TERM THREAT OUTSIDE OF WW160 IN
CNTRL OK...AND AN ADDITIONAL WW TO THE EAST MAY EVENTUALLY BE
REQUIRED.

DESPITE LOW-LEVEL SHEAR CURRENTLY BEING SOMEWHAT MARGINAL FOR
TORNADOES -- 0-1 KM SRH OF 135 M2/S2 PER TWIN LAKES VWP DATA --
LOW-LEVEL SHEAR WILL LIKELY INCREASE LATER THIS AFTERNOON INTO THIS
EVENING COMMENSURATE WITH THE STRENGTHENING NOCTURNAL BOUNDARY-LAYER
WIND MAXIMUM. AS SUCH...THE THREAT FOR TORNADOES WILL INCREASE.
ALSO...ADDITIONAL STORMS...INCLUDING SUPERCELLS...WILL LIKELY
DEVELOP W/NW OF THE ONGOING SUPERCELLS DURING THE NEXT FEW HOURS.
THIS WILL OCCUR AS THE FRINGES OF THE RICHER LOW-LEVEL MOISTURE
EXPAND WWD/NWWD OWING TO THE ISALLOBARIC FLOW ASSOCIATED WITH SFC
PRESSURE FALLS OVER NM/SRN CO. AS SUCH...A CORRESPONDING INCREASE IN
THE THREAT FOR SVR STORMS INCLUDING TORNADOES WILL BUILD INTO PARTS
OF W-CNTRL...NWRN...AND N-CNTRL OK AFTER 2230Z.

..COHEN.. 04/13/2012

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

ATTN...WFO...TSA...OUN...

LAT...LON 36779599 36039627 34889694 33919845 34079986 35409974
36479885 36919818 36939680 36779599

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