760  
ACUS11 KWNS 122205  
SWOMCD  
SPC MCD 122205  
MTZ000-WYZ000-130030-  
 
MESOSCALE DISCUSSION 1045  
NWS STORM PREDICTION CENTER NORMAN OK  
0505 PM CDT THU JUL 12 2018  
 
AREAS AFFECTED...PORTIONS OF NORTHEASTERN/EAST-CENTRAL WY AND FAR  
SOUTHEASTERN MT  
 
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY  
 
VALID 122205Z - 130030Z  
 
PROBABILITY OF WATCH ISSUANCE...20 PERCENT  
 
SUMMARY...AN ISOLATED SEVERE HAIL/WIND THREAT SHOULD CONTINUE  
THROUGH THE EARLY EVENING. THE COVERAGE OF SEVERE THUNDERSTORMS WILL  
LIKELY REMAIN TOO ISOLATED TO WARRANT WATCH ISSUANCE.  
 
DISCUSSION...ISOLATED THUNDERSTORMS HAVE DEVELOPED THIS AFTERNOON  
ALONG AND JUST EAST OF THE BIGHORN MOUNTAINS DUE TO WEAK LOW-LEVEL  
UPSLOPE FLOW AND A LOW-AMPLITUDE SHORTWAVE TROUGH MOVING OVER THIS  
AREA. A WEAK SURFACE FRONT RESIDES TO THE SOUTH OF THIS REGION, AND  
LIMITED MOISTURE REMAINS IN THE POST-FRONTAL ENVIRONMENT. STILL,  
AMPLE SURFACE HEATING ACROSS MUCH OF NORTHEASTERN INTO EAST-CENTRAL  
WY HAS ALLOWED SURFACE TEMPERATURES TO WARM INTO THE UPPER 70S TO  
LOWER 80S. MLCAPE HAS LIKEWISE INCREASED INTO THE 500-1000 J/KG  
RANGE WITH MODESTLY STEEP MID-LEVEL LAPSE RATES AROUND 7 C/KM  
PRESENT. ALTHOUGH THE LOW AND MID-LEVEL FLOW WILL LIKELY REMAIN  
LIMITED THROUGH THE EVENING, THERE IS ENOUGH VEERING WITH HEIGHT TO  
SUPPORT GENERALLY 30-40 KT OF EFFECTIVE BULK SHEAR. MULTICELL TO  
MARGINAL SUPERCELL STRUCTURES SHOULD BE THE PREDOMINANT STORM MODES,  
WITH AN ASSOCIATED LARGE HAIL AND LOCALLY DAMAGING WIND THREAT.  
CURRENT RADAR/SATELLITE TRENDS SUGGEST THE SEVERE THREAT WILL LIKELY  
REMAIN QUITE ISOLATED THROUGH THE EVENING, BEFORE DIMINISHING WITH  
THE LOSS OF DAYTIME HEATING AND INCREASING CONVECTIVE INHIBITION.  
THEREFORE, WATCH ISSUANCE WILL PROBABLY NOT BE NEEDED.  
 
..GLEASON/HART.. 07/12/2018  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...UNR...CYS...BYZ...RIW...  
 
LAT...LON 43910652 44460650 45100633 45330590 45390495 45150419  
44420412 43680406 42970415 42560465 42480562 43410640  
43910652  
 
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