238  
ACUS02 KWNS 231727  
SWODY2  
SPC AC 231726  
 
DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1226 PM CDT SUN APR 23 2017  
 
VALID 241200Z - 251200Z  
 
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MONDAY ACROSS  
THE CAROLINA COASTAL PLAIN AND PARTS OF THE ADJACENT PIEDMONT...  
   
..SUMMARY
 
 
THUNDERSTORMS ACCOMPANIED BY AT LEAST SOME SEVERE WEATHER POTENTIAL  
MAY IMPACT THE CAROLINA COASTAL PLAIN AND PORTIONS OF THE ADJACENT  
PIEDMONT MONDAY.  
   
..SYNOPSIS
 
 
MODELS INDICATE THAT A STRONG BELT OF WESTERLIES, TRAVERSING MUCH OF  
THE MID-LATITUDE PACIFIC INTO THE INTERIOR WESTERN U.S., WILL  
UNDERGO SOME AMPLIFICATION DURING THIS PERIOD. AS BROAD MID/UPPER  
RIDGING BUILDS ACROSS THE EASTERN PACIFIC THROUGH THE U.S. PACIFIC  
COAST, BROAD DOWNSTREAM TROUGHING APPEARS LIKELY TO EVOLVE NEAR THE  
NOSE OF THE STRONGER FLOW, ACROSS THE GREAT BASIN AND ROCKIES. IN  
LOWER LEVELS, AN INITIAL SURFACE CYCLONE, DEVELOPING TO THE LEE OF  
THE ROCKIES IN ASSOCIATION WITH THIS REGIME, APPEARS LIKELY TO  
MIGRATE NORTHEAST OF THE BLACK HILLS REGION AND WEAKEN DURING THE  
DAY MONDAY, WITH NEW SURFACE CYCLOGENESIS TAKING PLACE NEAR/NORTH OF  
THE TEXAS/OKLAHOMA PANHANDLE REGION LATE MONDAY THROUGH MONDAY  
NIGHT.  
 
MEANWHILE, WITHIN SPLIT WESTERLIES DOWNSTREAM OF THE ROCKIES, BROAD  
RIDGING WITHIN THE NORTHERN STREAM IS EXPECTED TO BUILD ACROSS AND  
NORTHEAST OF THE GREAT LAKES REGION. WITHIN THE SOUTHERN STREAM,  
TROUGHING OVER THE SOUTHEAST MAY GRADUALLY PIVOT FROM A NEUTRAL TO  
NEGATIVE TILT WHILE PROGRESSING EAST OF THE ATLANTIC COAST. AS IT  
DOES, A MODEST EMBEDDED LOWER/MID TROPOSPHERIC CYCLONE IS FORECAST  
TO REDEVELOP FROM NEAR OR JUST SOUTH OF THE SOUTHERN APPALACHIANS  
INTO AREAS NEAR OR EAST OF THE CAROLINA COAST BY 12Z TUESDAY.  
APPRECIABLE SPREAD IS EVIDENT AMONG THE VARIOUS MODELS, AND WITHIN  
THEIR RESPECTIVE ENSEMBLE OUTPUT, CONCERNING THESE DEVELOPMENTS AND  
POSSIBLE INTERACTION/CONSOLIDATION WITH AN IMPULSE WITHIN THE  
SUBTROPICAL WESTERLIES (NOW PROGRESSING ACROSS/NORTHEAST OF SOUTHERN  
FLORIDA AND THE BAHAMAS).  
   
..SOUTH ATLANTIC COAST
 
 
IT REMAINS UNCLEAR WHAT, IF ANY, IMPACT THAT THE MODEL SPREAD  
CONCERNING THE EVOLUTION OF THE SYNOPTIC SYSTEM WILL HAVE ON THE  
FORECAST FOR THIS PERIOD. EVEN THOUGH IT APPEARS THAT THE HIGHEST  
MOISTURE CONTENT AIR (CHARACTERIZED BY 70F+ SURFACE DEW POINTS) WILL  
GENERALLY REMAIN CONFINED TO AREAS WELL OFFSHORE, A SUBSTANTIVE  
INFLUX OF MOISTURE STILL SEEMS LIKELY ACROSS/INLAND OF THE CAROLINA  
COAST. THIS IS EXPECTED TO CONTRIBUTE TO SUFFICIENT DESTABILIZATION  
FOR CONSIDERABLE CONVECTIVE DEVELOPMENT. THE EXTENT TO WHICH  
MID-LEVEL COOLING IS ABLE TO STEEPEN LOWER/MID TROPOSPHERIC LAPSE  
RATES REMAINS UNCERTAIN, AND IT IS NOT CLEAR THAT THERE WILL BE  
SUFFICIENT BREAKS IN THE OVERCAST ACROSS INLAND AREAS TO ALLOW FOR  
APPRECIABLE SURFACE HEATING. DEEP LAYER MEAN WIND FIELDS AND SHEAR  
WITHIN THE WARM SECTOR OF THE LOW MAY NOT BE MUCH MORE THAN 30 KT.  
HOWEVER, IT MAY NOT BE OUT OF THE QUESTION THAT THE ENVIRONMENT  
COULD BECOME CONDUCIVE TO THUNDERSTORMS WITH AT LEAST SOME SEVERE  
WEATHER POTENTIAL, MAINLY ACROSS PARTS OF THE SOUTH CAROLINA  
PIEDMONT INTO COASTAL PLAIN DURING THE DAY MONDAY, AND PERHAPS THE  
NORTH CAROLINA COASTAL PLAIN MONDAY NIGHT.  
   
..NRN INTERMOUNTAIN REGION/ROCKIES INTO NORTH CENTRAL PLAINS
 
 
STEEPENING OF LAPSE RATES ASSOCIATED WITH MID-LEVEL COOLING, AND THE  
NORTHEASTWARD ADVECTION OF ELEVATED MIXED LAYER AIR TO THE LEE OF  
THE SOUTHERN ROCKIES, MAY CONTRIBUTE TO SUFFICIENT DESTABILIZATION  
FOR AT LEAST WIDELY SCATTERED THUNDERSTORM ACTIVITY, IN THE PRESENCE  
OF FAVORABLE OROGRAPHIC AND SYNOPTIC FORCING FOR ASCENT. THIS  
PROBABLY WILL BE ACCOMPANIED BY AT LEAST SOME POTENTIAL FOR HAIL IN  
STRONGER CELLS, INCLUDING ACTIVITY BASED WITHIN LOWER/MID  
TROPOSPHERIC WARM ADVECTION ACROSS PARTS OF THE NORTH CENTRAL PLAINS  
MONDAY INTO MONDAY NIGHT. HOWEVER, DESTABILIZATION, IN GENERAL,  
WILL BE SUBSTANTIALLY INHIBITED ACROSS THE PLAINS BY THE LACK OF A  
SUBSTANTIVE RETURN FLOW OF MOISTURE OFF THE GULF OF MEXICO, IN THE  
WAKE OF THE SOUTHEASTERN SYSTEM. AND POCKETS OF POTENTIALLY  
SUBSTANTIVE DESTABILIZATION ACROSS THE ROCKIES AND INTERMOUNTAIN  
REGION REMAIN TOO UNCERTAIN (AND LIKELY TO REMAIN RATHER SPARSE) TO  
ALLOW A FORECAST OF 5 PERCENT SEVERE PROBABILITIES AT THIS TIME.  
 
..KERR.. 04/23/2017  
 

 
 
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