982  
ACUS02 KWNS 201727  
SWODY2  
SPC AC 201725  
 
DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1125 AM CST MON FEB 20 2017  
 
VALID 211200Z - 221200Z  
   
..NO SEVERE THUNDERSTORM AREAS FORECAST
 
 
   
..SUMMARY
 
 
ORGANIZED SEVERE THUNDERSTORMS ARE NOT FORECAST ACROSS THE  
CONTIGUOUS UNITED STATES ON TUESDAY OR TUESDAY NIGHT.  
   
..DISCUSSION
 
 
AN UPPER-LEVEL LOW WILL MOVE EASTWARD FROM THE ARKLATEX INTO THE  
LOWER MISSISSIPPI VALLEY ON TUESDAY AS UPPER-LEVEL TROUGH APPROACHES  
THE WEST COAST. AHEAD OF THE WEST COAST TROUGH, SOUTHWEST LOW TO  
MID-LEVEL FLOW WILL BE IN PLACE ACROSS CALIFORNIA. STRONG  
LARGE-SCALE ASCENT, STEEP LAPSE RATES AND COLD AIR ALOFT AHEAD OF  
THE UPPER-LEVEL TROUGH WILL CREATE CONDITIONS SUPPORTIVE OF  
THUNDERSTORM DEVELOPMENT FROM NORTHERN CALIFORNIA EAST NORTHEASTWARD  
INTO SOUTHERN IDAHO DURING THE MORNING AND AFTERNOON. CONDITIONS  
WILL BE MOST FAVORABLE FOR THUNDERSTORM DEVELOPMENT DURING THE  
MORNING ACROSS NORTHERN CALIFORNIA FROM EUREKA SOUTHWARD TO SAN  
FRANCISCO ALONG THE AXIS OF A 40 TO 50 KT LOW-LEVEL JET. RAP  
FORECAST SOUNDINGS NEAR EUREKA AT 12Z/TUESDAY SHOW 0-6 KM SHEAR OF  
90 TO 100 KNOTS WITH STEEP LOW TO MID-LEVEL LAPSE RATES EXCEEDING  
7.0 C/KM SUGGESTING A THREAT FOR SMALL HAIL AND STRONG WIND GUSTS  
MAY EXIST AS CELLS MOVE INLAND. AFTER COORDINATING WITH WFO EUREKA,  
THE DECISION HAS BEEN MADE TO NOT INTRODUCE LOW END HAIL  
PROBABILITIES FOR THIS OUTLOOK MAINLY DUE TO UNCERTAINTIES  
CONCERNING THE MAGNITUDE OF THE THREAT WHICH COULD REMAIN BELOW  
MARGINAL CRITERIA. ELSEWHERE, ISOLATED THUNDERSTORMS MAY OCCUR  
ACROSS THE CENTRAL GULF COAST ALONG A CORRIDOR OF LOW-LEVEL MOISTURE  
TO THE SOUTHEAST OF THE LOWER MISSISSIPPI VALLEY UPPER-LEVEL LOW.  
THE CONVECTION IN THE CENTRAL GULF COAST REGION IS NOT EXPECTED TO  
BE ASSOCIATED WITH A SEVERE THREAT.  
 
..BROYLES.. 02/20/2017  
 

 
 
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