363  
ACUS11 KWNS 041927  
SWOMCD  
SPC MCD 041926  
ILZ000-MOZ000-IAZ000-ARZ000-OKZ000-KSZ000-042100-  
 
MESOSCALE DISCUSSION 1778  
NWS STORM PREDICTION CENTER NORMAN OK  
0126 PM CST MON DEC 04 2017  
 
AREAS AFFECTED...SOUTHEAST KS...NORTHEAST OK...NORTHWEST  
AR...SOUTHWEST TO NORTHEAST MO...AND PART OF WESTERN IL...AND  
SOUTHEAST IA  
 
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE  
 
VALID 041926Z - 042100Z  
 
PROBABILITY OF WATCH ISSUANCE...60 PERCENT  
 
SUMMARY...THUNDERSTORMS ARE EXPECTED TO DEVELOP BY LATE AFTERNOON  
ALONG A COLD FRONT ADVANCING EAST/SOUTHEAST THROUGH EASTERN KS AND  
WESTERN MO. DAMAGING WINDS WILL BE THE PRIMARY SEVERE-WEATHER  
THREAT INTO THE EARLY EVENING, WITH A MARGINAL RISK FOR A TORNADO,  
AS STORMS CONTINUE TO FORM ALONG THIS BOUNDARY SWEEPING ACROSS THIS  
REGION.  
 
DISCUSSION...DESPITE CLOUDINESS OBSERVED ON VISIBLE SATELLITE  
IMAGERY ACROSS MUCH OF EASTERN KS AND FAR EASTERN OK INTO AR AND MO,  
THERE IS LIKELY FILTERED SUNSHINE OCCURRING WITHIN THINNER AREAS OF  
CIRRUS CLOUDS IN EASTERN KS TO WESTERN/CENTRAL MO. THIS IS BOOSTING  
SURFACE TEMPERATURES TO WELL ABOVE NORMAL AS DEW POINTS CLIMB INTO  
THE UPPER 50S ACROSS MUCH OF THE DISCUSSION AREA, WITH VALUES INTO  
THE LOWER 60S FROM EASTERN OK INTO SOUTHEAST KS. AS STEEPENING  
MIDLEVEL LAPSE RATES SPREAD EAST, WITH THE APPROACH OF A CENTRAL  
PLAINS TROUGH, SURFACE-BASED CAPE IS EXPECTED REACH NEAR 1000 J/KG  
WITHIN A NARROW CORRIDOR JUST AHEAD OF THE FRONT.  
 
FORCING FOR ASCENT WITH THE FRONT AND AS THE TROUGH ADVANCES EAST  
WILL FURTHER WEAKEN ANY REMAINING LOW-MID LEVEL CAPPING EVIDENT IN  
12Z SOUNDINGS FOR STORMS TO FORM. SOME DEEPENING OF CUMULUS CLOUDS  
HAS ALREADY BEEN NOTED JUST AHEAD OF THE FRONT IN NORTHWEST MO TO  
EAST-CENTRAL KS. EFFECTIVE BULK SHEAR IS ALREADY SUFFICIENT FOR  
ORGANIZED STORMS (35-40 KT), THOUGH FURTHER STRENGTHENING OF  
WEST/SOUTHWESTERLY 500-MB WINDS IS EXPECTED INTO THE EVENING,  
SUPPORTING THE EASTWARD PROGRESSION OF THE COLD FRONT ACROSS THE  
NARROW INSTABILITY CORRIDOR. THIS SHEAR COMBINED WITH VERTICALLY  
VEERING AND STRENGTHENING OF WINDS IN THE LOW-LEVELS, PER RECENT  
AREA WSR-88D VWPS, SUGGESTS A TORNADO THREAT CANNOT BE RULED OUT.  
THE STRENGTH OF THE LOW-LEVEL WINDS FAVOR A RISK FOR DAMAGING WINDS.  
 
..PETERS/THOMPSON.. 12/04/2017  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...ILX...LSX...DVN...LZK...SGF...SHV...DMX...EAX...  
TSA...  
 
LAT...LON 36389530 38239422 39659343 40499279 40919215 40929166  
40769115 40169081 38619150 36489249 35249311 34509384  
34289435 34479505 34669547 35219560 35509575 36389530  
 
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