MESO: Mesoscale Discussion 0329

ACUS11 KWNS 212237
SWOMCD
SPC MCD 212237
WYZ000-UTZ000-IDZ000-MTZ000-212330-

MESOSCALE DISCUSSION 0329
NWS STORM PREDICTION CENTER NORMAN OK
0537 PM CDT WED APR 21 2010

AREAS AFFECTED...PORTIONS OF ERN/SERN ID AND NRN UT

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 212237Z - 212330Z

ISOLATED STRONG/DAMAGING WIND GUSTS ALONG WITH HAIL GENERALLY LESS
THAN 1 INCH IN DIAMETER WILL BE POSSIBLE WITH STORMS MOVING NNW
ACROSS NRN UT AND ERN/SERN ID THROUGH THE REMAINDER OF THE AFTERNOON
AND INTO THE EARLY EVENING. GIVEN THE MARGINAL/ISOLATED NATURE OF
THE SEVERE WEATHER THREAT...A WW DOES NOT APPEAR NECESSARY AT THIS
TIME.

THUNDERSTORMS CONTINUE TO DEVELOP/EVOLVE OFF OF A COLD FRONT MOVING
EWD ACROSS UT...WITH ADDITIONAL ACTIVITY FORMING ALONG APPARENT
TROUGH AXIS EXTENDING NNW INTO ERN/SERN ID. MIXED MODE OF CONVECTION
HAS BEEN OBSERVED THUS FAR...WITH SEVERAL CELLS EVOLVING INTO FAST
MOVING SHORT BOWING LINE SEGMENTS...WHICH IS SUPPORTED BY AN
ENVIRONMENT CHARACTERIZED BY STRONG DEEP LAYER MEAN WIND AND SHEAR
VECTORS ALIGNED PARALLEL TO THE SURFACE COLD FRONT. THERMODYNAMIC
ENVIRONMENT IS CHARACTERIZED BY AN AXIS OF SURFACE TEMPERATURES IN
THE 60S LOCATED IMMEDIATELY AHEAD OF THE FRONT AND ID SURFACE
TROUGH...AIDING IN THE DEVELOPMENT OF STEEP LOW TO MID LEVEL LAPSE
RATES AND MLCAPE VALUES AROUND 500-1000 J/KG. RECENT TRENDS IN SFCOA
DATA ALSO INDICATE DESTABILIZATION TAKING PLAINS E OF THE CNTRL
MOUNTAINS AND S OF THE BITTEROOT RANGE IN ID...WHERE INCREASING
LARGE SCALE ASCENT AND STEEPENING MID LEVEL LAPSE RATES APPEAR TO
COINCIDE. THIS MAY ALLOW STRONG STORMS TO EXPAND NNW ACROSS ERN ID
DURING THE NEXT FEW HOURS. HOWEVER...AS THE EVENING
APPROACHES...MODEL GUIDANCE INDICATES THAT THE BOUNDARY LAYER WILL
BEGIN TO STABILIZE ACROSS THE REGION...WHICH WILL LIKELY LEAD TO A
REDUCED POTENTIAL FOR DAMAGING WIND GUSTS AT THE SURFACE.

.GARNER.. 04/21/2010

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

ATTN...WFO...RIW...TFX...SLC...PIH...MSO...BOI...

LAT...LON 41661201 42761321 45171481 45461423 43541119 41981101
41661201

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