637  
ACUS01 KWNS 052001  
SWODY1  
SPC AC 051959  
 
DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0159 PM CST SUN NOV 05 2017  
 
VALID 052000Z - 061200Z  
 
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS  
OF ILLINOIS...INDIANA...AND OHIO...  
 
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDWEST  
AND OHIO VALLEY...  
 
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE  
MIDWEST AND OHIO VALLEY...  
   
..SUMMARY
 
 
SEVERE THUNDERSTORMS CAPABLE OF LARGE HAIL, DAMAGING WINDS, AND  
TORNADOES WILL CONTINUE FROM PARTS OF THE MID MISSISSIPPI VALLEY  
EAST-NORTHEASTWARD INTO THE LOWER GREAT LAKES THIS AFTERNOON INTO  
TONIGHT.  
   
..20Z UPDATE
 
 
LITTLE CHANGES TO PRIOR FORECAST REASONING WITH THE 20Z UPDATE --  
SEE LATEST MESOSCALE DISCUSSIONS FOR THE MOST CONTEMPORARY DETAILS  
-- ALTHOUGH MADE SOME ADJUSTMENTS ACROSS ILLINOIS AND INDIANA IN  
ACCORDANCE WITH THE SOUTHEAST-PROGRESSING COLD FRONT. MULTIPLE  
TORNADOES HAVE ALREADY BEEN REPORTED THIS AFTERNOON IN SEVERAL  
DISTINCT CORRIDORS ACROSS SOUTHERN INDIANA, EASTERN INDIANA INTO  
WESTERN OHIO, AS WELL AS FAR NORTH-CENTRAL OHIO AS OF 20Z. OVERALL  
SCENARIO CONTINUES TO REMAIN FAVORABLE FOR SEVERE WEATHER/TORNADOES,  
PARTICULARLY IN THE ENHANCED CORRIDOR SPANNING DOWNSTATE PORTIONS OF  
ILLINOIS/INDIANA EAST-NORTHEASTWARD INTO MUCH OF OHIO. A RECENT  
SPECIAL 19Z OBSERVED SOUNDING FROM WILMINGTON OHIO SAMPLED 1000+  
J/KG SBCAPE ALONG WITH 47 KT EFFECTIVE SHEAR AND 0-1 KM SRH IN  
EXCESS OF 200 M2/S2.  
 
..GUYER.. 11/05/2017  
   
PREV DISCUSSION
 
/ISSUED 1015 AM CST SUN NOV 05 2017/  
   
..IN/OH/PA
 
 
HAVE EXPANDED THE EHH RISK AREA EASTWARD TO INCLUDE MORE OF CENTRAL  
AND EASTERN OH. TRENDS IN SURFACE OBSERVATIONS AND SATELLITE  
IMAGERY SUGGEST DESTABILIZATION WILL CONTINUE OVER THIS REGION, WITH  
12Z CAM SOLUTIONS INDICATING ROBUST THUNDERSTORM DEVELOPMENT THROUGH  
THE AFTERNOON AND EVENING. FORECAST SOUNDINGS SHOW SUBSTANTIAL LOW  
LEVEL WIND SPEEDS AND VERTICAL SHEAR, PROMOTING A SQUALL LINE WITH  
EMBEDDED BOWING/ROTATING STORMS CAPABLE OF DAMAGING WINDS AND  
ISOLATED TORNADOES. LARGE HAIL MAY ALSO OCCUR IN ANY SUPERCELLS  
THAT CAN BECOME ESTABLISHED. THE THREAT SHOULD SLOWLY DIMINISH AS  
THE STORMS MOVE INTO A PROGRESSIVELY MORE STABLE AIR MASS OVER  
WESTERN PA.  
   
..IL/IN
 
 
ANOTHER AREA OF INTENSE THUNDERSTORM DEVELOPMENT IS EXPECTED THIS  
AFTERNOON ALONG THE PRIMARY COLD FRONT SAGGING INTO PARTS OF MO/IL.  
MOST MODEL GUIDANCE SUGGESTS DEVELOPMENT WILL BEGIN NEAR THE STL  
AREA AND SPREAD EASTWARD ACROSS PARTS OF SOUTHERN IL INTO CENTRAL  
AND SOUTHERN IN. THERMODYNAMIC PARAMETERS WILL BE STRONGER IN THIS  
AREA COMPARED TO FARTHER NORTHEAST, PROMOTING A GREATER RISK OF  
LARGE (POSSIBLY VERY LARGE) HAIL. MODEL GUIDANCE ALONG SUGGESTS A  
SLIGHTLY HIGHER PROBABILITY OF DISCRETE SUPERCELLS IN THIS AREA,  
WITH A FEW TORNADOES EXPECTED. EVENTUALLY, THESE STORMS WILL ALSO  
CONGEAL INTO A SQUALL LINE AS THEY BUILD SOUTHEASTWARD TOWARD THE OH  
RIVER.  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page