662  
ACUS03 KWNS 220740  
SWODY3  
SPC AC 220740  
 
DAY 3 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0240 AM CDT FRI OCT 22 2021  
 
VALID 241200Z - 251200Z  
 
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER THE MIDDLE  
MISSISSIPPI VALLEY REGION...  
   
..SUMMARY
 
 
SEVERE STORMS WITH ALL HAZARDS POSSIBLE ARE EXPECTED OVER A PORTION  
OF THE MIDDLE MISSISSIPPI VALLEY REGION SUNDAY AFTERNOON AND SUNDAY  
NIGHT. A FEW STRONG TO SEVERE STORMS ARE ALSO POSSIBLE OVER COASTAL  
OREGON.  
 
...EASTERN KANSAS AND OKLAHOMA INTO THE MIDDLE MISSISSIPPI VALLEY  
REGION...  
 
A LOW-AMPLITUDE SHORTWAVE TROUGH WILL MOVE THROUGH KS AND OK DURING  
THE DAY, REACHING THE MIDDLE MS VALLEY LATER SUNDAY AFTERNOON AND  
EVENING. THE ATTENDANT SURFACE LOW WILL MOVE FROM NORTHEAST KS  
DURING THE MORNING INTO IL OVERNIGHT. TRAILING FRONT WILL SWEEP  
ACROSS KS AND OK INTO THE MS VALLEY, REACHING THE TN AND OH VALLEYS  
OVERNIGHT. A WARM FRONT WILL EXTEND EAST FROM THE LOW AND SPREAD  
NORTHWARD THROUGH THE OH VALLEY.  
 
THE PRE-FRONTAL WARM SECTOR IS EXPECTED TO BECOME MODERATELY  
UNSTABLE SUPPORTED BY THE NORTHWARD ADVECTION OF LOW TO MID 60S F  
DEWPOINTS. LOW CLOUDS MAY ACCOMPANY THIS MOISTURE RETURN, BUT SOME  
BREAKS SHOULD ALLOW FOR POCKETS OF DIURNAL HEATING OF THE BOUNDARY  
LAYER WITH MLCAPE FROM 1500-2000 J/KG MLCAPE. LOW CLOUDS AND A  
MODEST CAP MAY DELAY STORM DEVELOPMENT UNTIL MID AFTERNOON WHEN  
STORMS SHOULD INITIATE ALONG THE COLD FRONT FROM EASTERN KS INTO  
EASTERN OK. WIND PROFILES WITH UP TO 50 KT EFFECTIVE BULK SHEAR AND  
SIZEABLE LOW-LEVEL HODOGRAPHS WILL SUPPORT SUPERCELLS. STORMS MAY  
EVENTUALLY EVOLVE INTO LINES DURING THE EVENING AS THEY CONTINUE  
THROUGH THE MS AND TN VALLEY REGIONS. ALL SEVERE HAZARDS ARE  
POSSIBLE INCLUDING POTENTIAL FOR SIGNIFICANT SEVERE WEATHER.  
   
..COASTAL OREGON
 
 
A SUBSTANTIAL UPPER TROUGH WILL AMPLIFY AS IT APPROACHES THE WEST  
COAST ACCOMPANIED BY COLD AIR ALOFT AND STEEP LAPSE RATES. THIS WILL  
CONTRIBUTE TO MARGINAL SURFACE-BASED INSTABILITY, ESPECIALLY ALONG  
COASTAL OR WHERE VERTICAL WIND PROFILES WITH STRONG VERTICAL SHEAR  
WILL SUPPORT A CONDITIONAL THREAT FOR ORGANIZED STORMS INCLUDING  
LOW-TOPPED SUPERCELLS DURING THE LATE AFTERNOON INTO THE EVENING.  
THIS REGION WILL CONTINUE TO BE MONITORED FOR A POSSIBLE SLGT RISK  
IN LATER UPDATES.  
 
..DIAL.. 10/22/2021  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page