Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 172321
SWOMCD
SPC MCD 172320
TXZ000-180045-

MESOSCALE DISCUSSION 1726
NWS STORM PREDICTION CENTER NORMAN OK
0620 PM CDT WED SEP 17 2014

AREAS AFFECTED...PORTIONS OF W TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 172320Z - 180045Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...THE RISK FOR ISOLATED STRONG THUNDERSTORMS WILL CONTINUE
TO SPREAD EWD/ESEWD ACROSS PORTIONS OF W TX INTO THE EARLY EVENING.
WHILE A MARGINALLY SVR TSTM CANNOT BE RULED OUT...THE ISSUANCE OF A
WW IS NOT NEEDED.

DISCUSSION...AN OUTFLOW BOUNDARY FROM CROSBY COUNTY TO NRN GAINES
COUNTY IS SURGING SWD ACROSS SRN PORTIONS OF THE TX S
PLAINS...UNDERCUTTING INCIPIENT UPDRAFTS THAT HAVE FORMED IN ITS
PROXIMITY. THE AIR MASS AHEAD OF THE BOUNDARY IS CHARACTERIZED BY
MODERATE INSTABILITY...WITH MLCAPE VALUES AROUND 1000-2000 J/KG
AIDED BY RICH BOUNDARY-LAYER MOISTURE -- E.G. SFC DEWPOINTS IN THE
UPPER 60S. DESPITE POOR TROPOSPHERIC LAPSE RATES...THIS DEGREE OF
BUOYANCY WILL BE SUFFICIENT FOR ROBUST CONVECTIVE ELEMENTS TO THRIVE
DURING THE NEXT FEW HOURS AS 25-35 KT OF MID-LEVEL WLYS GLANCE THE
AREA. THIS ENHANCED FLOW AND RELATED DEEP SHEAR ARE ASSOCIATED WITH
A LOCALLY TIGHTENED MID-LEVEL HEIGHT GRADIENT ON THE ERN EDGE OF A
LONG-LIVED VORT MAX...WHICH EMERGED OVER W TX FROM NM PER A LONG
LOOP OF MOSAIC RADAR IMAGERY. THE MOST INTENSE STORMS COULD PRODUCE
AN ISOLATED DMGG WIND GUST AIDED BY WATER LOADING...ASSOCIATED WITH
PW AROUND 1.75 INCHES PER GPS DATA. MARGINALLY SVR HAIL ALSO CANNOT
BE RULED OUT...THOUGH POOR LAPSE RATES WILL BE A DETERRENT TO HAIL
GROWTH ALOFT. STORMS SHOULD WEAKEN QUICKLY AFTER SUNSET OWING TO THE
LOSS OF DIABATIC SFC-LAYER HEATING.

..COHEN/EDWARDS.. 09/17/2014

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

ATTN...WFO...SJT...LUB...MAF...

LAT...LON   32330110 32550212 32940214 33620071 33340004 32739999
            32330110




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