445  
ACUS48 KWNS 220801  
SWOD48  
SPC AC 220759  
 
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0259 AM CDT FRI SEP 22 2017  
 
VALID 251200Z - 301200Z  
   
..DISCUSSION
 
 
THE SLOW-MOVING LONGWAVE TROUGH OVER THE WEST WILL FINALLY BEGIN TO  
WEAKEN AND EJECT NORTHEASTWARD TOWARD THE WESTERN GREAT LAKES REGION  
AROUND D5/TUESDAY. AHEAD OF THIS TROUGH, SURFACE CYCLOGENESIS  
SHOULD OCCUR IN WISCONSIN THAT, WHEN COMBINED WITH WEAK  
SURFACE-BASED DESTABILIZATION, MAY RESULT IN A RISK FOR ISOLATED  
SEVERE STORMS DURING THE AFTERNOON AND EVENING.  
 
BEYOND THIS PERIOD, MODELS DIVERGE SUBSTANTIALLY WITH REGARD TO A  
REMNANT CUT-OFF LOW OVER THE SOUTHWEST AND A DOWNSTREAM TROUGH NEAR  
THE GREAT LAKES. DESPITE DIFFERENCES IN THE MID/UPPER SYNOPTIC  
PATTERN, MODELS GENERALLY SUGGEST VARYING DEGREES OF SURFACE RIDGING  
ACROSS THE NORTHERN ROCKIES AND CENTRAL PLAINS THAT SHOULD RESULT IN  
A COOLER, DRIER AIRMASS SPREADING INTO THESE AREAS. WITH MODIFIED  
MARITIME AIR SHUNTED SOUTH OF MORE ACTIVE WESTERLIES (NEARER THE  
GREAT LAKES AND VICINITY), IT APPEARS THAT ANY ORGANIZED SEVERE RISK  
SHOULD BE ON THE DECREASE.  
 
..COOK.. 09/22/2017  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page