[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 111953
SWOMCD
SPC MCD 111952 
MTZ000-WYZ000-112115-

MESOSCALE DISCUSSION 1618
NWS STORM PREDICTION CENTER NORMAN OK
0252 PM CDT SUN JUL 11 2004

AREAS AFFECTED...CENTRAL/ERN MT AND NERN WY

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 111952Z - 112115Z

EARLIER THOUGHTS OF DEEP CONVECTION DEVELOPING OVER ERN MT/WRN ND
FROM HIGH BASED CONVECTION HAS BECOME MORE UNCERTAIN.
HOWEVER...SEVERE CONVECTION SHOULD DEVELOP AND INTENSIFY OVER
CENTRAL MT ALONG LEE TROUGH/COLD FRONT WITHIN THE NEXT FEW HOURS.
THEREFORE WW ISSUANCE IS NOW LIKELY TO OCCUR AROUND 21Z.

LARGE SCALE SUBSIDENCE IN THE WAKE OF THE LEAD SHORTWAVE SHOULD
LIMIT CONVECTIVE DEVELOPMENT ALONG LEE TROUGH EXTENDING ACROSS
CENTRAL MT FOR THE NEXT HOUR OR TWO.  MODIFIED 18Z SOUNDING FROM GTF
INDICATES THAT THERE EXISTS ABOUT 50 J/KG OF MLCINH OVER CENTRAL MT
AHEAD OF THE COLD FRONT. BUT A LITTLE MORE HEATING IN THE BOUNDARY
LAYER AND MID LEVEL COOLING AHEAD OF UPPER TROUGH SUGGESTS DEEP
CONVECTIVE DEVELOPMENT SHOULD OCCUR WITHIN THE HOUR ALONG THE COLD
FRONT EXTENDING FROM BOZEMAN NEWD TO JUST WEST OF GTF AND OVER THE
MTNS OF SWRN MT. OVERALL SEVERE THREAT WEST OF LEE TROUGH AND EAST
OF COLD FRONT FROM AREAS AROUND GTF SWD TO NEAR LIVINGSTON SHOULD
REMAIN MARGINAL DUE TO THE HIGH BASED NATURE OF CONVECTION AND
MLCAPES FROM 500-1000 J/KG. UNLIKE ALONG THE COLD FRONT...IF
CONVECTION DEVELOPS ALONG THE LEE TROUGH BEFORE THE COLD FRONT
OVERTAKES THIS BOUNDARY...IT WILL LIKELY BECOME QUICKLY SEVERE AS
MLCAPES AROUND 1500 J/KG AND BETTER LOW LEVEL INFLOW EXIST EAST OF
THE BOUNDARY. ADDITIONALLY ... CONVECTION DEVELOPING OVER THE HIGHER
TERRAIN OF NERN WY JUST EAST OF THE BIG HORNS...SHOULD QUICKLY
BECOME SEVERE ONCE THEY BECOME SURFACE BASED AND EVENTUALLY MOVE
INTO FAR SERN MT.

..CROSBIE.. 07/11/2004

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

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

44950895 45321006 46571083 47341081 49020986 48980730
48940514 44630423 44430666 44850774 

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