MESO: Mesoscale Discussion 1790

ACUS11 KWNS 282054
SWOMCD
SPC MCD 282054
NDZ000-MTZ000-282230-

MESOSCALE DISCUSSION 1790
NWS STORM PREDICTION CENTER NORMAN OK
0354 PM CDT WED AUG 28 2013

AREAS AFFECTED...PORTIONS CENTRAL/ERN MT.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 282054Z - 282230Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...CONVECTION IS GRADUALLY INCREASING IN COVERAGE OVER MUCH
OF CENTRAL/SRN MT...AS AIR MASS DESTABILIZES. AT LEAST ISOLATED
DAMAGING GUSTS AND LARGE HAIL WILL BECOME POSSIBLE THROUGH REMAINDER
AFTN. GREATER TSTM ORGANIZATION AND POTENTIAL FOR WW APPEARS TO BE
OVER ERN MT WHERE LOW-LEVEL MOISTURE WILL REMAIN RELATIVELY
MAXIMIZED.

DISCUSSION...SFC MESOANALYSIS SHOWS DIFFUSE LOW ROUGHLY LOCATED
BETWEEN GTF-LWT...WITH COLD FRONT SSWWD NEAR NW TIP OF WY AND INTO
SERN ID. FRONT IS FCST TO MOVE EWD ACROSS CENTRAL MT THROUGH
REMAINDER AFTN...CATCHING UP TO DRYLINE THAT WAS DRAWN FROM LOW SEWD
OVER TREASURE COUNTY TO NERN WY. MOISTURE CHANNEL IMAGERY INDICATES
SHORTWAVE TROUGH EJECTING NEWD ACROSS WRN MT AND SERN ID. VIS
IMAGERY AND LTG DATA SHOW SCATTERED TCU/CB WITH WIDELY SCATTERED
EMBEDDED TSTMS ALONG AND BEHIND COLD FRONT...IN REGIME OF
LARGE-SCALE DCVA/LIFT THAT PRECEDES EJECTING SHORTWAVE TROUGH. THIS
ACTIVITY MAY STRENGTHEN AND BECOME MORE DENSE AS IT ACCESSES
BETTER-HEATED/MIXED AIR LOCATED AHEAD OF COLD FRONT AND OVER HIGH
TERRAIN OF S-CENTRAL/SWRN MT...WHERE MODIFIED RAOBS AND MODEL
SOUNDINGS SUGGEST AROUND 500 J/KG MLCAPE.

FARTHER E...BAND OF CONVECTION INVOF DRYLINE HAS BEEN BUILDING AND
MIXING OUT ROUGHLY IN BALANCE FOR LAST COUPLE HOURS.
HOWEVER...COVERAGE AND DEPTH ARE BEGINNING TO INCREASE...AND LTG IS
EVIDENT FROM ASSOCIATED CELL EMBEDDED WITHIN PERSISTENT CONVECTIVE
REGIME ALONG GARFIELD/PETROLEUM COUNTY LINE. SOME OF THIS ACTIVITY
MAY LAST LONG ENOUGH AND/OR GROW SUFFICIENTLY UPSCALE TO SURVIVE
INTO FAVORABLY MOIST AIR MASS OVER ERN MT...WITH SFC DEW POINTS IN
MID 50S/60S F...SUPPORTING 1000-2000 J/KG MLCAPE. EFFECTIVE SHEAR
MAGNITUDES OF ONLY 30-35 KT ARE APPARENT OVER THIS AREA...BUT MAY
STRENGTHEN SOMEWHAT AS MID-UPPER WAVE APCHS THIS EVENING.

..EDWARDS/THOMPSON.. 08/28/2013

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

ATTN...WFO...BIS...BYZ...GGW...TFX...

LAT...LON 45311115 46401097 47681140 48560850 48370519 47130388
45330493 45311115

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