MESO: Mesoscale Discussion 1253

ACUS11 KWNS 232049
SWOMCD
SPC MCD 232049
MTZ000-IDZ000-WAZ000-232245-

MESOSCALE DISCUSSION 1253
NWS STORM PREDICTION CENTER NORMAN OK
0349 PM CDT SAT JUN 23 2012

AREAS AFFECTED...PORTIONS OF NRN ID INTO NW MT

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 232049Z - 232245Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...SEVERE THREAT INCREASING ACROSS PORTIONS OF NRN ID AND NW
MT. STORMS WILL LIKELY FORM OVER THE BITTERROOT AND SAPPHIRE RANGES
AND TRACK NWD THROUGH THIS EVENING. LARGE HAIL AND STRONG/LOCALLY
DAMAGING WINDS WILL BE THE MAIN THREAT BUT A TORNADO CAN NOT BE
RULED OUT. TRENDS WILL BE MONITORED OVER THE NEXT 1-2 HOURS FOR WW
ISSUANCE AS SOME UNCERTAINTY REMAINS AS TO CONVECTIVE INITIATION AND
STABILITY ISSUES FURTHER NORTH.

DISCUSSION...20Z TFX RAOB AND SFC OBJECTIVE ANALYSIS INDICATED
INSTABILITY ACROSS THE REGION WITH SBCAPE VALUES AROUND 500-1000
J/KG. THIS SEEMS REASONABLE BASED ON TEMPERATURES WARMING INTO THE
MID 70S AND LOW 80S ACROSS NW MT /COOLER ACROSS NRN ID AND IN THE
LEE OF THE DIVIDE UNDER STRATUS/ WITH DEWPOINTS IN THE MID 50S.
WHILE VIS SATELLITE SUGGESTS INITIAL DEVELOPMENT OVER THE MOUNTAINS
SOUTH OF MSO...CLOUD STRUCTURE CONTINUES TO INDICATE LOW LEVEL
STABILITY ACROSS THE NRN HALF OF THE MCD AREA. THEREFORE...STORMS
MAY INITIALLY DEVELOP FURTHER SOUTH AND MOVE NWD AS THE AIRMASS
DESTABILIZES FURTHER THIS AFTERNOON.

DEEP LAYER SHEAR AROUND 40-50 KTS WILL FAVOR ORGANIZED SUPERCELL
STRUCTURES AND WITH STEEP LAPSE RATES...LARGE HAIL AND
STRONG/LOCALLY DAMAGING WINDS WILL BE POSSIBLE. ATTM MSX WSR-88D VWP
PROFILES INDICATE ABOUT 100 M2/S2 0-1KM SRH. THEREFORE A WEAK
TORNADO OR TWO CAN NOT BE RULED OUT AS WELL. CONVECTIVE TRENDS WILL
CONTINUE TO BE MONITORED FOR WW ISSUANCE IN THE NEXT 1-2 HOURS.

..LEITMAN/WEISS.. 06/23/2012

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

ATTN...WFO...TFX...MSO...OTX...

LAT...LON 48961297 47021184 45741319 45561452 46251563 47121646
48411696 48981714 48961297

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