Sunday, June 21, 2009

MESO: Mesoscale Discussion 1261

ACUS11 KWNS 211806
SWOMCD
SPC MCD 211806
IDZ000-UTZ000-NVZ000-211930-

MESOSCALE DISCUSSION 1261
NWS STORM PREDICTION CENTER NORMAN OK
0106 PM CDT SUN JUN 21 2009

AREAS AFFECTED...NWRN UT...SRN ID...NERN NV

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 211806Z - 211930Z

THE POTENTIAL FOR AT LEAST ISOLATED LARGE HAIL/DAMAGING WINDS IS
EXPECTED TO INCREASE AHEAD OF A COLD UPPER LEVEL S/W TROUGH THROUGH
THE AFTERNOON ACROSS NWRN UT...SRN ID AND NERN NV. CONVECTIVE TRENDS
WILL BE MONITORED FOR A WW.

SIMILAR TO THE PAST SEVERAL DAYS...ANOTHER SMALL AMPLITUDE COLD
MID/UPPER LEVEL TROUGH /500 MB TEMPERATURES PER 12Z RAOBS AOB -15
DEG C/ WILL PROGRESS ENE ACROSS THE GREAT BASIN THROUGH THIS
AFTERNOON. STEEP MID LEVEL LAPSE RATES COMBINED WITH MID 40S
DEWPOINTS WILL AID IN THE DEVELOPMENT OF 500-1000 J/KG OF MLCAPE.
THOUGH POST COLD FRONTAL AIRMASS /WHICH AT 16Z WAS LOCATED FROM SRN
NV NE INTO CENTRAL WY/ WILL REMAIN RELATIVELY COOL...THE COLD
TEMPERATURES ALOFT AS WELL AS FAVORABLE LARGE SCALE ASCENT AHEAD OF
THE UPPER TROUGH WILL RESULT IN FAVORABLE DESTABILIZATION FOR
THUNDERSTORM DEVELOPMENT BY 18-19Z ACROSS THE REGION.

MODERATE MID/UPPER LEVEL FLOW /AOA 30-40 KT ABOVE 6 KM/ WILL
CONTRIBUTE TOWARD SUFFICIENT VERTICAL WIND SHEAR FOR ORGANIZED
THUNDERSTORM DEVELOPMENT. HOWEVER...IT IS UNCERTAIN AT THIS POINT
WHETHER SEVERE WEATHER POTENTIAL WILL BE WIDESPREAD ENOUGH TO
WARRANT A WATCH. REGARDLESS...AT LEAST SOME POTENTIAL WILL EXIST FOR
ISOLATED LARGE HAIL/DAMAGING WINDS THROUGH THE AFTERNOON.

..GARNER.. 06/21/2009

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

ATTN...WFO...SLC...PIH...BOI...LKN...

LAT...LON 41281174 39951254 39361397 39431577 40091701 41081724
42191686 43601474 43351205 42411165 41281174

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