638  
ACUS48 KWNS 160852  
SWOD48  
SPC AC 160850  
 
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0350 AM CDT WED OCT 16 2019  
 
VALID 191200Z - 241200Z  
   
..DISCUSSION
 
 
DAY 4/SATURDAY: A WEAK UPPER SHORTWAVE TROUGH OVER EASTERN PORTIONS  
OF THE PLAINS ON SATURDAY WILL QUICKLY LIFT NORTHEAST. AT THE  
SURFACE, A WEAK COLD FRONT WILL SWEEP ACROSS THE UPPER MIDWEST/GREAT  
LAKES WHILE STALLING OVER THE SOUTHERN PLAINS. MEANWHILE, GUIDANCE  
VARIES ON THE INTENSITY OF A TROPICAL DISTURBANCE AS IT TRACKS NEAR  
THE NORTHERN GULF COAST/SOUTHEASTERN U.S. ON SATURDAY. REFERENCE THE  
TROPICAL WEATHER OUTLOOKS FROM THE NATIONAL HURRICANE CENTER FOR  
MORE DETAILS ON THIS SYSTEM. HOW THIS LOW EVOLVES COULD INFLUENCE  
SEVERE POTENTIAL ACROSS PARTS OF THE NORTHERN AND EASTERN GULF COAST  
STATES INTO GA/SC ON SATURDAY, THOUGH SEVERE POTENTIAL APPEARS LOW  
AT THIS TIME.  
 
DAYS 5-7/SUNDAY-TUESDAY: SEVERE POTENTIAL IS EXPECTED TO INCREASE  
ON SUNDAY AS A MORE INTENSE SHORTWAVE TROUGH EJECTS EASTWARD FROM  
THE ROCKIES INTO THE PLAINS ON MONDAY. STRONG DEEP-LAYER  
SOUTHWESTERLY FLOW WILL DEVELOP FROM THE SOUTHERN PLAINS TO THE  
UPPER MIDWEST AS THE TROUGH DEEPENS OVER THE PLAINS. THE ECMWF AND  
GFS ARE IN BETTER AGREEMENT OVER THE POSITION OF AN INTENSIFYING  
SURFACE LOW COMPARED TO YESTERDAY, WITH THE LOW TRACKING ACROSS SD  
THROUGH THE AFTERNOON BEFORE LIFTING NORTHEAST INTO MN OVERNIGHT. A  
TRAILING COLD FRONT WILL PUSH EASTWARD ACROSS THE PLAINS, WITH SOME  
TIMING DIFFERENCES AMONG VARIOUS GUIDANCE. DESPITE THIS, MODELS ARE  
FAIRLY CONSISTENT IN MOIST RETURN FLOW BRINGING 60S SURFACE  
DEWPOINTS NORTHWARD TO AT LEAST THE OZARK PLATEAU EASTWARD TOWARD  
THE MID-SOUTH. AT LEAST A NARROW CORRIDOR OF SEVERE POTENTIAL IS  
EXPECTED AHEAD OF THE COLD FRONT WHERE A FAVORABLE COMBINATION OF  
INSTABILITY, STEEPENING MIDLEVEL LAPSE RATES, STRONG SHEAR AND UPPER  
FORCING FOR ASCENT WILL ALIGN. OVER THE PAST FEW DAYS, THIS CORRIDOR  
HAS BEEN MOST CONSISTENTLY INDICATED BY MEDIUM-RANGE GUIDANCE ACROSS  
PARTS OF NORTH TX, EASTERN OK INTO ADJACENT PARTS OF KS/MO/AR.  
CONFIDENCE HAS INCREASED SUFFICIENTLY TO INCLUDE 15% SEVERE  
PROBABILITIES, THROUGH THIS AREA LIKELY WILL CHANGE SOME IN COME  
DAYS AS FORECAST DETAILS HOPEFULLY BECOME MORE CLEAR.  
 
A SEVERE THREAT COULD CONTINUE INTO MONDAY ACROSS PARTS OF THE  
MID/LOWER MS VALLEY VICINITY EASTWARD TOWARD THE APPALACHIANS AS THE  
COLD FRONT CONTINUES TO SURGE EASTWARD. A VERY MOIST AIRMASS WILL BE  
IN PLACE DOWNSTREAM OF THE FRONT, BUT TIMING DIFFERENCES IN THE  
EASTWARD PROGRESSION OF THE FRONT AMONG VARIOUS MODEL OUTPUT IS  
LARGE, DECREASING FORECAST CONFIDENCE. THE COLD FRONT WILL CONTINUE  
TO SHIFT EASTWARD ACROSS THE EASTERN U.S. AND IS EXPECTED TO MOVE  
OFFSHORE MOST OF THE ATLANTIC COAST BY WEDNESDAY MORNING. DEPENDING  
ON TIMING, SOME SEVERE THREAT IS POSSIBLE ACROSS PARTS OF THE  
CAROLINAS AND MID-ATLANTIC, BUT AGAIN, CONFIDENCE REMAINS LOW.  
 
BY DAY 8/WEDNESDAY, MEDIUM RANGE GUIDANCE VARIES GREATLY, BUT SEVERE  
POTENTIAL SHOULD BE LOW WITH STRONG SURFACE HIGH PRESSURE  
ENCOMPASSING MUCH OF THE PLAINS TO THE SOUTHEAST.  
 
..LEITMAN.. 10/16/2019  
 
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