094  
ACUS02 KWNS 281731  
SWODY2  
SPC AC 281730  
 
DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1230 PM CDT SAT MAR 28 2020  
 
VALID 291200Z - 301200Z  
 
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF  
THE UPPER OH VALLEY...LOWER GREAT LAKES...CENTRAL APPALACHIANS...AND  
MID-ATLANTIC...  
   
..SUMMARY
 
 
ISOLATED STRONG TO SEVERE THUNDERSTORMS APPEAR POSSIBLE SUNDAY  
ACROSS PARTS OF THE UPPER OHIO VALLEY, LOWER GREAT LAKES, CENTRAL  
APPALACHIANS, AND MID-ATLANTIC.  
 
...UPPER OHIO VALLEY INTO THE LOWER GREAT LAKES AND CENTRAL  
APPALACHIANS...  
A STRONG, CLOSED UPPER LOW WILL MIGRATE EAST-NORTHEASTWARD FROM THE  
UPPER MIDWEST ACROSS THE GREAT LAKES SUNDAY, EVENTUALLY REACHING  
SOUTHERN ONTARIO/QUEBEC BY THE END OF THE PERIOD. A BELT OF 70-90+  
KT MID-LEVEL SOUTHWESTERLY FLOW WILL OVERSPREAD MUCH OF THE UPPER OH  
VALLEY, LOWER GREAT LAKES, AND CENTRAL APPALACHIANS BY SUNDAY  
AFTERNOON. AT THE SURFACE, A LOW WILL ALSO DEVELOP OVER THE SAME  
REGIONS WHILE GRADUALLY OCCLUDING. A SURFACE WARM FRONT WILL LIKELY  
MAKE ONLY MODEST NORTHWARD PROGRESS ACROSS WESTERN/CENTRAL PA  
THROUGH THE DAY.  
 
A LOW-TOPPED CONVECTIVE LINE ALONG OR JUST AHEAD OF AN  
EASTWARD-MOVING COLD FRONT SHOULD BE ONGOING AT THE START OF THE  
PERIOD SUNDAY MORNING ROUGHLY FROM LAKE ERIE SOUTHWARD ACROSS OH AND  
INTO PARTS OF EASTERN KY. ALTHOUGH INSTABILITY ACROSS THESE AREAS  
WILL LIKELY REMAIN LIMITED DUE TO MODEST LOW-LEVEL MOISTURE (MID 50S  
TO LOWER 60S SURFACE DEWPOINTS), THERE WILL BE VERY STRONG LOW TO  
MID-LEVEL SHEAR PRESENT. THIS WILL SUPPORT THE POTENTIAL FOR  
CONTINUED STORM ORGANIZATION AS THEY MOVE QUICKLY EAST-NORTHEASTWARD  
THROUGH THE MORNING AND EARLY AFTERNOON. STRONG TO LOCALLY DAMAGING  
WINDS APPEAR TO BE THE MAIN THREAT GIVEN THE VERY STRONG FLOW  
EXPECTED IN THE BOUNDARY LAYER, BUT A TORNADO CANNOT BE RULED OUT  
MAINLY SUNDAY MORNING ACROSS PARTS OF EASTERN OH INTO WV AND WESTERN  
PA. STORMS WILL LIKELY WEAKEN AS THEY REACH THE CREST OF THE  
APPALACHIANS BY SUNDAY AFTERNOON.  
   
..MID-ATLANTIC
 
 
LARGE-SCALE ASCENT IS FORECAST TO REMAIN FAIRLY WEAK SUNDAY ACROSS  
THE MID-ATLANTIC. HOWEVER, SOME MODEST MID-LEVEL HEIGHT FALLS SHOULD  
OVERSPREAD THIS REGION BY SUNDAY AFTERNOON. LATEST MODEL GUIDANCE  
ALSO SUGGESTS THE POSSIBILITY OF A WEAK, SECONDARY SURFACE LOW  
DEVELOPING OVER MD AND VICINITY THROUGH THE DAY. MORE ROBUST DIURNAL  
HEATING IS EXPECTED ACROSS THIS REGION, AND WEAK TO POTENTIALLY  
MODERATE INSTABILITY (MLCAPE 500-1500 J/KG) SHOULD DEVELOP  
ALONG/SOUTH OF A SURFACE WARM FRONT THAT WILL LIKELY BE LOCATED  
ACROSS PARTS OF CENTRAL/EASTERN PA INTO SOUTHERN/CENTRAL NJ.  
EFFECTIVE BULK SHEAR OF 50-70+ KT WOULD EASILY SUPPORT SUPERCELLS,  
WITH ALL SEVERE HAZARDS POSSIBLE. THE MAIN UNCERTAINTY IS WHETHER  
ANY STORMS WILL FORM ALONG/AHEAD OF THE COLD FRONT. LATEST GUIDANCE  
SHOWS SUBSTANTIAL VARIABILITY REGARDING OVERALL CONVECTIVE COVERAGE  
ACROSS THIS REGION. FOR NOW, HAVE OPTED TO EXPAND THE MARGINAL RISK  
EASTWARD ACROSS MUCH OF THE MID-ATLANTIC TO ACCOUNT FOR THIS  
SOMEWHAT CONDITIONAL POTENTIAL.  
   
..NORTH CAROLINA
 
 
THE POSSIBILITY OF SURFACE-BASED STORM DEVELOPMENT EVEN FARTHER  
SOUTH INTO NC APPEARS VERY QUESTIONABLE/UNCERTAIN, SINCE LARGE-SCALE  
ASCENT WILL LIKELY BE VERY WEAK. FORECAST INSTABILITY/SHEAR  
PARAMETERS WOULD CONDITIONALLY SUPPORT A SEVERE THREAT WITH ANY  
STORMS THAT FORM ALONG/AHEAD OF THE COLD FRONT. BUT, THE POTENTIAL  
FOR CONVECTIVE DEVELOPMENT SUNDAY AFTERNOON REMAINS TOO LOW TO  
EXTEND MARGINAL HAIL/WIND PROBABILITIES INTO NC AT THIS TIME.  
   
..TENNESSEE/ALABAMA/GEORGIA
 
 
A SHALLOW, BROKEN LINE OF STORMS WILL LIKELY BE ONGOING SUNDAY  
MORNING ALONG THE COLD FRONT. THESE STORMS SHOULD WEAKEN THROUGH THE  
MORNING AS LARGE-SCALE ASCENT REMAINS FOCUSED FARTHER NORTH.  
ACCORDINGLY, THIS REGION DOES NOT APPEAR TO WARRANT LOW SEVERE  
PROBABILITIES FOR WIND.  
 
..GLEASON.. 03/28/2020  
 

 
 
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