MESO: Mesoscale Discussion 0526

ACUS11 KWNS 212233
SWOMCD
SPC MCD 212232
OKZ000-TXZ000-KSZ000-COZ000-NMZ000-220030-

MESOSCALE DISCUSSION 0526
NWS STORM PREDICTION CENTER NORMAN OK
0532 PM CDT SAT APR 21 2007

AREAS AFFECTED...OK/TX PANHANDLES...TX SOUTH PLAINS AND PORTIONS OF
THE PERMIAN BASIN

CONCERNING...TORNADO WATCH 157...

VALID 212232Z - 220030Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 157 WILL INCREASE
THROUGH 01Z.

LEADING EDGE OF MID LEVEL COOLING/HEIGHT FALLS WAS SPREADING OVER
THE WRN EDGE OF THE INSTABILITY AXIS /JUST EAST OF A DRYLINE
EXTENDING FROM NEAR DHT TO HOB/. INCREASING CONVECTIVE TRENDS SEEN
ON VISIBLE SATELLITE IMAGERY OVER THE LAST 30 MIN TO 1 HR WILL
CONTINUE OVER THE NEXT SEVERAL HRS...WITH SEVERAL SUPERCELLS
EXPECTED TO DEVELOP OVER WRN PORTIONS OF WW 157 BY 00Z. A REMNANT
DIFFERENTIAL HEATING BOUNDARY GENERATED BY THE LOW CLOUD COVER OVER
THE ERN TX PANHANDLE FOR MUCH OF THE DAY HAS PUSHED WSWWD THROUGH
PORTIONS OF THE CENTRAL/SRN TX PANHANDLE AND NRN SOUTH PLAINS OVER
THE LAST FEW HRS. THIS BOUNDARY WAS EVIDENT BY SATELLITE AND RECENT
OBS AT AMA WHERE WINDS BACKED TO AROUND 130 DEG ALONG WITH A SLIGHT
COOLING. 22Z PLACEMENT OF THIS BOUNDARY WAS FROM JUST WEST OF AMA
SSWWD TO BRISCOE AND HALL COUNTIES. ANY SUPERCELLS THAT DEVELOP WEST
OF THIS BOUNDARY OVER THE WRN PANHANDLE AND WRN SOUTH PLAINS MAY
BECOME TORNADIC NEAR OF JUST EAST OF THIS BOUNDARY ACROSS THE
CENTRAL/SRN TX PANHANDLE AND NRN SOUTH PLAINS AREA BETWEEN 23-01Z
GIVEN THE PRESENCE OF VERY STRONG LOW LEVEL SHEAR /200-300 M2/S2 OF
0-1 KM SRH PER AMA VWP/ AND INCREASING 0-3 KM CAPE /AROUND 100 J/KG/
AS MID LEVEL COOLING OVERSPREADS THE AREA.

.CROSBIE.. 04/21/2007

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

ATTN...WFO...OUN...DDC...SJT...LUB...AMA...MAF...PUB...ABQ...

32070304 37000302 37009998 32929998 32930069 32080066

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