MESO: Mesoscale Discussion 1099

ACUS11 KWNS 082053
SWOMCD
SPC MCD 082052
MTZ000-082145-

MESOSCALE DISCUSSION 1099
NWS STORM PREDICTION CENTER NORMAN OK
0352 PM CDT FRI JUN 08 2012

AREAS AFFECTED...NERN MT

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 082052Z - 082145Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...A GRADUAL INCREASE IN TSTM COVERAGE IS EXPECTED THROUGH
LATE AFTERNOON ACROSS NERN MT. THE ENVIRONMENT WILL BECOME
INCREASINGLY FAVORABLE FOR LARGE HAIL AND ISOLATED DMGG WIND
GUSTS...AND CONVECTIVE TRENDS WILL BE MONITORED FOR POTENTIAL WW
ISSUANCE LATER THIS AFTERNOON AND EVENING.

DISCUSSION...RECENT VISIBLE SATELLITE LOOP SHOWS INCREASING TOWERING
CU FIELD /PRIMARILY ANCHORED TO THE HIGHER TERRAIN/ OVER PORTIONS OF
CNTRL MT. ONE EXCEPTION IS A PERSISTENT/REGENERATING STORM OVER
BLAINE COUNTY...WHICH HAS SHOWN RADAR INDICATIONS FOR POTENTIALLY
SUB-SEVERE HAIL. STRONG SFC HEATING /TEMPS IN THE UPPER 70S AT 20Z/
...UPSLOPE E-SELY LOW-LEVEL FLOW...AND INCREASING LARGE-SCALE
ASCENT/HEIGHT FALLS ASSOCIATED WITH A POWERFUL NWRN CONUS UPPER
TROUGH...SHOULD SUPPORT AN INCREASE IN TSTM COVERAGE DURING THE NEXT
2-3 HRS. THE EXACT EVOLUTION OF CONVECTION IS SOMEWHAT
UNCERTAIN...BUT RECENT CONVECTION-ALLOWING GUIDANCE /INCLUDING THE
18Z WRF-HRRR/ INDICATES DISCRETE STORMS OR SMALL CLUSTERS SHOULD
EVENTUALLY MOVE OFF THE HIGHER TERRAIN EWD TOWARDS THE HIGH PLAINS
OF ERN MT.

ALTHOUGH INSTABILITY APPEARS RATHER MARGINAL /MLCAPE VALUES AOB 500
J/KG PER MODIFIED 20Z GGW SOUNDING/...FURTHER HEATING AND MOISTURE
ADVECTION FROM THE SE WILL CONTINUE TO DESTABILIZE THE ENVIRONMENT
THROUGH THIS EVENING...BECOMING MORE FAVORABLE FOR SUSTAINING STRONG
UPDRAFTS. ADDITIONALLY...ESELY LOW-LEVEL FLOW BENEATH MODERATE
MIDLEVEL SWLYS WILL YIELD EFFECTIVE SHEAR VALUES OF 50-60 KTS. THIS
ENVIRONMENT WILL BE FAVORABLE FOR SUPERCELLS CAPABLE OF PRODUCING
LARGE HAIL AND DMGG WIND GUSTS...AND MAY NECESSITATE ISSUANCE OF A
WW BY THE EARLY EVENING.

..ROGERS/MEAD.. 06/08/2012

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

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

LAT...LON 48990556 48080527 47200534 46560592 46270739 46340860
46760963 47760980 48970926 48990556

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