867  
ACUS02 KWNS 041656  
SWODY2  
SPC AC 041655  
 
DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1055 AM CST MON DEC 04 2017  
 
VALID 051200Z - 061200Z  
   
..NO SEVERE THUNDERSTORM AREAS FORECAST
 
 
   
..SUMMARY
 
 
THE RISK FOR SEVERE STORMS APPEARS NEGLIGIBLE ACROSS THE U.S.,  
TUESDAY THROUGH TUESDAY NIGHT.  
   
..DISCUSSION
 
 
MODELS INDICATE THAT A DEEP LOWER/MID TROPOSPHERIC CYCLONE WILL  
PROGRESS NORTHEAST OF THE UPPER GREAT LAKES, THROUGH THE JAMES BAY  
REGION OF CANADA DURING THIS PERIOD. ASSOCIATED WITH THIS FEATURE,  
BROAD CYCLONIC MID/UPPER FLOW WILL OVERSPREAD MOST OF THE OHIO  
VALLEY AND NORTHEAST, WHILE BEING MAINTAINED ACROSS THE NORTHERN AND  
CENTRAL PLAINS THROUGH THE ADJACENT MISSISSIPPI VALLEY, AS ANOTHER  
COUPLE OF SHORT WAVE TROUGHS DIG TO THE LEE OF AMPLIFYING RIDGING  
NEAR THE PACIFIC COAST NORTHWARD THROUGH THE WESTERN CANADIAN  
PROVINCES. IN LOWER LEVELS, A SIGNIFICANT COLD FRONT IS FORECAST TO  
SURGE ACROSS THE LOWER GREAT LAKES/OHIO VALLEY/LOWER MISSISSIPPI  
VALLEY AND SOUTHERN PLAINS THROUGH THE NORTHERN AND MIDDLE ATLANTIC  
COAST/SOUTHEAST AND NORTHWESTERN GULF OF MEXICO BY LATE TUESDAY  
NIGHT.  
 
AS THE FRONT ADVANCES SOUTHEASTWARD, IT APPEARS LIKELY TO UNDERCUT,  
THEN INCREASINGLY CUT-OFF, THE ONGOING SEASONABLY MOIST RETURN FLOW  
OFF THE GULF OF MEXICO. BEFORE IT DOES, GUIDANCE SUGGESTS THAT WEAK  
DESTABILIZATION COULD CONTINUE TO SUPPORT A RISK FOR THUNDERSTORM  
ACTIVITY BEYOND 12Z TUESDAY, ACROSS PORTIONS OF THE MID SOUTH  
THROUGH THE UPPER OHIO VALLEY, WHERE A PERTURBATION PIVOTING AROUND  
THE MID-LEVEL CYCLONE MAY CONTRIBUTE TO FAVORABLE LARGE-SCALE  
FORCING FOR ASCENT. HOWEVER, ANY SUCH ACTIVITY SEEMS LIKELY TO BE  
BASED ABOVE/TO THE COOL SIDE OF THE SURFACE FRONT, WITH NEGLIGIBLE  
RISK FOR SEVERE WEATHER.  
 
ALTHOUGH MID/UPPER SUPPORT REMAINS MORE UNCLEAR, ADDITIONAL  
THUNDERSTORM DEVELOPMENT APPEARS POSSIBLE ACROSS PARTS OF  
SOUTH/SOUTHEAST TEXAS THROUGH THE CENTRAL GULF COAST LATER  
TUESDAY/TUESDAY NIGHT. SOME OF THIS, MAINLY NEAR THE CENTRAL GULF  
COAST, MAY INITIATE NEAR OR JUST AHEAD OF THE COLD FRONT. HOWEVER,  
GIVEN GENERALLY MODEST CAPE, RELATIVELY WEAK LOWER/MID TROPOSPHERIC  
FLOW ACROSS THIS REGION (AMONG OTHER FACTORS) IS EXPECTED TO RESULT  
IN NEGLIGIBLE RISK FOR SEVERE WEATHER.  
 
..KERR.. 12/04/2017  
 

 
 
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