119  
ACUS48 KWNS 220846  
SWOD48  
SPC AC 220845  
 
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0345 AM CDT THU AUG 22 2019  
 
VALID 251200Z - 301200Z  
   
..DISCUSSION
 
 
HEIGHT FALLS AND COOLING ALOFT WILL SPREAD SOUTHEASTWARD ACROSS THE  
NORTHERN PLAINS ON SUNDAY/D4 AND TOWARD THE UPPER MS VALLEY BY  
MONDAY/D5, WITH A COLD FRONT AFFECTING MUCH OF THE NORTHERN AND  
CENTRAL PLAINS. DUE TO A RATHER LARGE SURFACE RIDGE OVER THE GREAT  
LAKES AND NORTHEAST, THE MOIST PLUME PRECEDING THIS SYSTEM OVER THE  
PLAINS WILL REMAIN NARROW, COMPRISED PRIMARILY OF MID 60S F  
DEWPOINTS.  
MODEL DIFFERENCES EXIST REGARDING THE POSITION (OR EXISTENCE) OF  
UPPER DISTURBANCES PRECEDING THE MAIN SHORTWAVE TROUGH, SUCH AS THE  
ECMWF DEPICTION OF A WEAK LOW OVER MO ON SUNDAY/D4. QUESTIONS  
REGARDING INSTABILITY ALSO EXIST AS EARLY DAY STORMS ARE LIKELY OVER  
PARTS OF THE NORTHERN PLAINS. AS SUCH, WILL DEFER SEVERE  
PROBABILITIES TO LATER OUTLOOKS.  
 
FOR THE D6-D8 PERIOD, A DEEP UPPER LOW WILL FORM OVER NORTHERN  
ONTARIO WITH A BROAD REGION OF STRONG CYCLONIC FLOW ALOFT ENVELOPING  
MUCH OF THE NORTHERN CONUS AND EASTERN CANADA. THIS WILL DRIVE A  
COLD FRONT RATHER FAR SOUTH, PERHAPS TO THE NORTHERN GULF COAST BY  
THURSDAY/D8. THIS WILL REDUCE THE POTENTIAL AREA OF THUNDERSTORMS  
OVER MUCH OF THE PLAINS AND MS VALLEY.  
 
..JEWELL.. 08/22/2019  
 
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