MESO: Mesoscale Discussion 1979

ACUS11 KWNS 292048
SWOMCD
SPC MCD 292048
TXZ000-292215-

MESOSCALE DISCUSSION 1979
NWS STORM PREDICTION CENTER NORMAN OK
0348 PM CDT TUE OCT 29 2013

AREAS AFFECTED...SWRN TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 292048Z - 292215Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER SWRN PORTIONS
OF TX THROUGH LATE AFTERNOON AND EVENING. ONE OR TWO SUPERCELLS WILL
BE POSSIBLE POSING A THREAT FOR LARGE HAIL. WW DOES NOT APPEAR
NECESSARY ATTM.

DISCUSSION...AFTERNOON SURFACE OBSERVATIONS SHOW A SHARPENING
DRYLINE BOUNDARY ORIENTED N-S FROM THE PERMIAN BASIN TO THE SIERRA
DEL BURRO MOUNTAINS IN NRN MEXICO. STRONGER HEATING /WITH
TEMPERATURES IN THE LOW 80S/ AND BOUNDARY LAYER MIXING IS AIDING IN
REDUCING CINH ALONG THIS BOUNDARY...WHILE DEWPOINTS IN MID/UPPER 60S
ARE PRESENT TO ITS E. MODEL FORECAST SOUNDINGS APPEAR TO BE
ERRONEOUSLY TOO STEEP WITH MIDLEVEL LAPSE RATES /RAP AND NAM AOA 7.0
C PER KM IN THE 700-500 MB LAYER/...WITH MORNING RAOBS INDICATING
VALUES CLOSER TO 6.5-7.0 C/KM. NEVERTHELESS...THE SEASONALLY
WARM/MOIST BOUNDARY LAYER LOCATED NEAR THE DRYLINE COMBINED WITH
GRADUAL MIDLEVEL COOLING SUPPORT MLCAPE VALUES AROUND 500-1500 J/KG.


PRIMARY LARGE-SCALE FORCING FOR ASCENT WILL LAG WELL TO THE W WITH A
SHORTWAVE TROUGH PIVOTING ACROSS THE LOWER CO RIVER VALLEY.
HOWEVER...A MINOR UPPER IMPULSE PRECEDING THE WRN TROUGH IS QUICKLY
MOVING NE OVER NWRN MEXICO THIS AFTERNOON. SUBTLE
ASCENT/DESTABILIZATION ASSOCIATED WITH THIS FEATURE...COMBINED WITH
TERRAIN-INDUCED CIRCULATIONS OVER SWRN TX/SIERRA DEL BURRO/S IS
EXPECTED TO SUPPORT ISOLATED/SCATTERED THUNDERSTORM DEVELOPMENT
DURING THE LATE AFTERNOON INTO THE EVENING. WEAK LOW-LEVEL SELYS
VEERING TO 40+ KT OUT OF THE SW IN THE MID/UPPER-LEVELS WILL YIELD
LONG HODOGRAPHS FAVORABLE FOR SUPERCELLS. ANY PERSISTENT SUPERCELL
STRUCTURES WILL POSE A THREAT FOR LARGE HAIL...AND PERHAPS AN
ISOLATED DAMAGING WIND GUST.

..GARNER/CORFIDI.. 10/29/2013

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

ATTN...WFO...EWX...SJT...MAF...

LAT...LON 31710337 31870195 30700098 29200067 29760147 29820217
29610276 28970315 29520377 31710337

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