MESO: Mesoscale Discussion 1890

ACUS11 KWNS 180030
SWOMCD
SPC MCD 180029
NDZ000-SDZ000-MTZ000-WYZ000-180130-

MESOSCALE DISCUSSION 1890
NWS STORM PREDICTION CENTER NORMAN OK
0729 PM CDT TUE SEP 17 2013

AREAS AFFECTED...PORTIONS OF THE NRN HIGH PLAINS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 180029Z - 180130Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...SOME POTENTIAL FOR STRONG WIND GUSTS IS EXPECTED INTO THE
LATE EVENING...BUT SHOULD REMAIN TOO MARGINAL FOR A WW.

DISCUSSION...INCREASING LARGE-SCALE FORCING FOR ASCENT AHEAD OF A
PACIFIC NW UPPER TROUGH IS CONTRIBUTING TO TSTM DEVELOPMENT OVER THE
NRN HIGH PLAINS THIS EVENING. LATEST SUBJECTIVE SFC ANALYSIS PLACES
A COLD FRONT FROM NEAR ISN S-SWWD TO JUST E OF SHR...WITH WIDESPREAD
LOWER-MID 50S F DEWPOINTS. OF NOTE...MOST RECENT MODEL FORECAST
GUIDANCE /INCLUDING 23Z RAP/ APPEAR TO BE UNDERESTIMATING THE
QUALITY OF BOUNDARY LAYER MOISTURE...AND SUBSEQUENTLY THE AMOUNT OF
AVAILABLE INSTABILITY...WITH MODIFIED FORECAST SOUNDINGS SUGGESTING
NEAR 1000 J/KG OF SBCAPE MAY ACTUALLY BE PRESENT NEAR/E OF THE FRONT
ACROSS WRN ND INTO SERN MT.

ALTHOUGH THE LOSS OF DIURNAL HEATING AND INCREASING CINH WILL BE
UNFAVORABLE FOR SUSTAINING SFC-BASED STORMS BEYOND THE IMMEDIATE
TIME FRAME...THIS MAY BE SOMEWHAT OFFSET BY A MODEST INCREASE IN THE
LLJ THROUGH THE LATE EVENING. BUT GIVEN THE CURRENT PHASING OF PEAK
SFC-BASED INSTABILITY WITH RATHER WEAK LOW-LEVEL FLOW...THE
POTENTIAL FOR DMGG WIND GUSTS APPEARS TO BE RATHER LIMITED...AND
WILL LIKELY BE CONTINGENT ON TSTMS CONGEALING AND FORMING AN
ORGANIZED COLD POOL WITH ACTIVITY SPREADING NEWD OUT OF SERN MT. A
THREAT FOR SMALL HAIL MAY ALSO EXIST GIVEN STEEP MIDLEVEL LAPSE
RATES AND EFFECTIVE SHEAR NEAR 20-30 KT.

..ROGERS/GOSS.. 09/18/2013

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

ATTN...WFO...BIS...UNR...BYZ...GGW...

LAT...LON 47950260 46850281 45220312 44250411 44040475 44550580
45250685 46900661 48160385 47950260

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.