MESO: Mesoscale Discussion 1880

ACUS11 KWNS 140224
SWOMCD
SPC MCD 140224
MTZ000-WYZ000-140330-

MESOSCALE DISCUSSION 1880
NWS STORM PREDICTION CENTER NORMAN OK
0924 PM CDT THU AUG 13 2009

AREAS AFFECTED...PARTS OF CENTRAL/ERN MT

CONCERNING...SEVERE THUNDERSTORM WATCH 701...

VALID 140224Z - 140330Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 701
CONTINUES.

WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH TRACKING NEWD THROUGH
WRN MT. STRONGEST FORCING FOR ASCENT...EVIDENT BY DEEPER
CONVECTION/COLD CLOUD TOPS OVER CENTRAL MT...SUGGESTS STRONGEST
ACTIVITY THIS EVENING SHOULD PROGRESS ENEWD OVER ERN PART OF WW
701...WITH PRIMARY SEVERE THREAT OVER EAST CENTRAL/SRN PART OF THIS
WATCH. THIS SEVERE THREAT IS SUPPORTED BY OBJECTIVE ANALYSES
INDICATING A CORRIDOR OF MODERATE INSTABILITY RESIDING OVER SRN
MT/FAR NRN WY AND EXPANDING EWD INTO THE NRN PLAINS.

STRONGEST STORMS...THUS FAR...HAVE TENDED TO OCCUR WITHIN THE
STRONGER INSTABILITY AXIS INCLUDING THE RIGHT SPLIT STORM NOW
TRACKING ENEWD THROUGH ERN GOLDEN VALLEY/MUSSELSHELL COUNTIES MT.
EFFECTIVE BULK SHEAR AROUND 50 KT IS SUFFICIENT FOR STORM
ORGANIZATION...BUT STORMS MOVING AWAY FROM THE STRONGER INSTABILITY
SHOULD TEND TO WEAKEN.

MEANWHILE...PERSISTENT STORM OVER FAR NERN WY/SERN MT IS MOVING INTO
A MOIST/MODERATELY UNSTABLE ENVIRONMENT WITH EFFECTIVE BULK SHEAR
30-35 KT SUPPORTING THIS STORM. ALTHOUGH THIS AIR MASS...
ESPECIALLY OVER SERN MT INTO WRN DAKOTAS IS SUPPORTIVE OF STORM
ORGANIZATION...STRONGER FORCING FOR ASCENT SHOULD SPREAD INTO NORTH
CENTRAL/NERN MT WHERE INSTABILITY IS WEAKER.

..PETERS.. 08/14/2009

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

ATTN...WFO...UNR...BYZ...GGW...RIW...TFX...

LAT...LON 44981034 46151015 46491021 47911073 49000922 48970720
47510690 46340719 45430618 45810512 44970457 44570600
44560735 44990832 44981034

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