871  
ACUS48 KWNS 200936  
SWOD48  
SPC AC 200935  
 
DAY 4-8 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0335 AM CST TUE NOV 20 2018  
 
VALID 231200Z - 281200Z  
   
..DISCUSSION
 
 
MEDIUM-RANGE GUIDANCE HAS COME INTO A LITTLE BETTER AGREEMENT  
REGARDING THE EVOLUTION OF THE SHORTWAVE TROUGH EXPECTED TO BE OVER  
THE CENTRAL/SOUTHERN PLAINS AT THE BEGINNING OF THE PERIOD (I.E. 12Z  
FRIDAY). EXPECTATION IS FOR THE SYSTEM TO MOVE EASTWARD THROUGH THE  
MS VALLEY WITH THE STRONG MID-LEVEL FLOW THROUGH ITS BASE SPREADING  
ACROSS THE SOUTHEAST. ASSOCIATED WIND PROFILES ACROSS THE SOUTHEAST  
ARE FAVORABLE FOR ORGANIZED STORMS BUT THE ATTENDANT SURFACE LOW  
EXPECTED TO REMAIN CLOSE TO THE COAST, PREVENTING MUCH INLAND  
PENETRATION OF THE WARM SECTOR. ADDITIONALLY, A SMALL SHIFT IN THE  
TRACK OF THE OVERALL SYSTEM COULD PLACE THE LOW ENTIRELY OFFSHORE.  
FORECAST UNCERTAINTIES ALONG WITH A FAIRLY LIMITED THREAT AREA  
PRECLUDE THE NEED TO OUTLOOK ANY AREAS ON D4/FRIDAY.  
 
THE SAME SHORTWAVE TROUGH IS EXPECTED TO CONTINUE  
EASTWARD/NORTHEASTWARD WITH SOME RESULTING SEVERE POTENTIAL ON  
D5/SATURDAY ACROSS THE CAROLINAS. HOWEVER, LIKE D4/FRIDAY, THE RISK  
IS HEAVILY DEPENDENT ON THE TRACK OF THE SURFACE LOW, WHICH HAS  
SHOWN TOO MUCH FORECAST VARIABILITY WITHIN THE GUIDANCE FOR MUCH  
FORECAST CONFIDENCE.  
 
AFTER D5/SATURDAY, THE PROGRESSIVE UPPER PATTERN IS EXPECTED TO  
CONTINUE WITH ANOTHER SHORTWAVE TROUGH MOVING FROM THE PLAINS INTO  
THE MS VALLEY ON D6/SUNDAY. STRONG DYNAMICS WILL ACCOMPANY THE  
SYSTEM BUT GUIDANCE HAS SHOWN SIGNIFICANT VARIABILITY REGARDING THE  
LATITUDE OF THE SYSTEM. A LOWER LATITUDE SYSTEM COULD POSE A SEVERE  
RISK AS IT INTERACTS WITH GULF MOISTURE BUT MORE MODEL CONSISTENCY  
IS STILL NEEDED TO HAVE ANY CONFIDENCE ON SEVERE POTENTIAL.  
 
..MOSIER.. 11/20/2018  
 
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