949  
ACUS48 KWNS 220919  
SWOD48  
SPC AC 220917  
 
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0417 AM CDT WED MAY 22 2019  
 
VALID 251200Z - 301200Z  
   
..DISCUSSION
 
 
MODELS REMAIN IN REASONABLE AGREEMENT WITH REGARD TO EVOLUTION OF  
THE SYNOPTIC PATTERN THROUGH DAY 5, BUT CONSIDERABLE DIFFERENCES  
ARISE BY DAY 6 AND BEYOND ESPECIALLY REGARDING EVOLUTION OF WESTERN  
U.S. CUTOFF UPPER LOW.  
 
DAY 4 (SATURDAY) SHORTWAVE TROUGH WILL CREST UPPER RIDGE AND MOVE  
THROUGH THE GREAT LAKES DURING THE DAY BEFORE TURNING SOUTHEAST INTO  
THE NORTHEAST STATES SATURDAY NIGHT. SURFACE LOW ACCOMPANYING THIS  
FEATURE WILL MOVE THROUGH EASTERN CANADA WHILE TRAILING COLD FRONT  
ADVANCES SOUTHEAST THROUGH THE GREAT LAKES AND NORTHEAST STATES.  
WESTERN EXTENSION OF FRONT SHOULD STALL ACROSS THE CENTRAL PLAINS. A  
DRYLINE WILL RESIDE NEAR THE TX/NM BORDER. LOW 60S F DEWPOINTS WILL  
ADVECT THROUGH THE OH VALLEY WARM SECTOR SATURDAY CONTRIBUTING TO  
MODEST INSTABILITY. THUNDERSTORMS MAY DEVELOP ALONG AND AHEAD OF THE  
COLD FRONT LOCATED ACROSS THE SOUTHERN GREAT LAKES AND SPREAD  
SOUTHEAST INTO THE OH VALLEY AND A PORTION OF THE NORTHEAST STATES.  
STRONG UNIDIRECTIONAL WIND PROFILES ATTENDING THE NORTHERN-STREAM  
TROUGH WILL BE SUFFICIENT FOR A FEW ORGANIZED SEVERE STORMS. OTHER  
STRONG TO SEVERE STORMS WILL BE POSSIBLE ALONG PORTION OF THE FRONT  
OVER THE CENTRAL PLAINS WHERE STRONG INSTABILITY WILL RESIDE.  
DEVELOPMENT ALONG WEST TEXAS DRYLINE REMAINS UNCERTAIN AT THIS TIME  
GIVEN APPARENT WEAK CONVERGENCE AND PRESENCE OF LOW-AMPLITUDE RIDGE.  
 
DAY 5 (SUNDAY) SOME SEVERE STORM POTENTIAL WILL PERSIST IN VICINITY  
OF EAST-WEST FRONT FROM THE PLAINS TO THE OH VALLEY AS WELL AS ALONG  
SOUTHERN PLAINS DRYLINE. BUT LOCATION OF BEST SEVERE STORM POTENTIAL  
WILL BE DEPENDENT ON PREVIOUS DAY'S STORMS AND OUTFLOW.  
 
BY DAY 7 (TUESDAY) BOTH GFS AND ECMWF AS WELL AS SOME SREF MEMBERS  
INDICATE AN UPPER SPEED MAX WILL ROTATE THROUGH THE BASE OF THE  
WESTERN U.S. UPPER TROUGH AND INTO THE SOUTHERN AND CENTRAL PLAINS.  
THIS WOULD SUGGEST INCREASING SEVERE POTENTIAL OVER THE PLAINS BY  
THAT TIME, AND SEVERE PROBABILITIES WILL NEED TO BE INTRODUCED IN  
LATER UPDATES IF MODELS BECOME MORE CONSISTENT.  
 
..DIAL.. 05/22/2019  
 
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