216  
FXUS62 KRAH 131046  
AFDRAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE RALEIGH NC  
645 AM EDT TUE APR 13 2021  
   
SYNOPSIS
 
 
WEAK HIGH PRESSURE WILL SETTLE OVER THE AREA TODAY AS A COLD FRONT  
STALLS SOUTH OF THE AREA. AN AREA OF LOW PRESSURE IS EXPECTED TO  
TRACK ACROSS NC ON WEDNESDAY, FOLLOWED BY THE PASSAGE OF A COLD FRONT  
LATE WEDNESDAY NIGHT AND EARLY THURSDAY MORNING. COOLER AND DRIER  
HIGH PRESSURE WILL FOLLOW FOR LATE WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 400 AM TUESDAY...  
 
MID AND UPPER LEVEL HEIGHTS WILL INCREASE ALOFT AS SHORTWAVE RIDGING  
MOVES INTO THE REGION, DOWNSTREAM OF YET ANOTHER SLOW MOVING UPPER  
LEVEL LOW MOVING OVER THE GREAT LAKES REGION. WEAK UPPER LEVEL  
IMPULSES AND ASSOCIATED MID-LEVEL WAA SPILLING ATOP THE BUILDING  
RIDGE AXIS WILL LEAD TO AN INFLUX OF MID AND HIGH CLOUDS BY THE  
AFTERNOON. IT'S POSSIBLE SOME VERY LIGHT SPRINKLES COULD REACH THE  
GROUND ACROSS THE FAR NW ZONES, BUT GIVEN RIDGING ALOFT, ANY  
MEASURABLE PRECIP WILL BE HARD TO COME BY.  
 
OTHERWISE, CONTINUED DRY WITH SLIGHTLY COOLER DAYTIME HIGHS, THANKS  
TO THE LOW-LEVEL NORTHERLY FLOW AND AFOREMENTIONED CLOUD OVER. HIGHS  
RANGING FROM LOWER 70S NE TO UPPER 70S SOUTH. LOWS 50 TO 55, WITH  
SOME MID/UPPER 40S POSSIBLE ACROSS THE FAR NE ZONES.  
 

 
   
SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/
 
 
AS OF 400 AM TUESDAY...  
 
...A FEW STRONG TO SEVERE STORMS POSSIBLE WEDNESDAY AFTERNOON AND  
EVENING...  
 
THE UPPER LOW OVER THE UPPER GREAT LAKES WILL DEEPEN AS IT MOVES  
SLOWLY SEWD TOWARD THE UPPER OHIO VALLEY. A SERIES OF SHORTWAVE  
IMPULSES EMBEDDED WITHIN THE BROADENING CYCLONIC FLOW ALOFT WILL  
EJECT EAST ACROSS THE AREA DURING THE LATE AFTERNOON AND INTO THE  
OVERNIGHT HOURS. AT THE SURFACE, A COLD FRONT WILL BE DRAPED FROM  
THE CENTRAL/SOUTHERN APPALACHIANS TO THE LOWER MS VALLEY TO START  
THE DAY. HOWEVER, AS THE UPPER LOW DEEPENS AND THE ASSOCIATED MODEST  
H5 FALLS BEGIN TO OVERSPREAD THE AREA FROM THE WEST, AN AREA OF LOW  
PRESSURE IS FORECAST TO DEVELOP INVOF THE CAROLINAS, ALONG/AHEAD OF  
THE COLD FRONT. THIS SURFACE LOW AND COLD FRONT WILL MOVE EAST  
THROUGH THE AREA DURING THE EVENING AND OVERNIGHT HOURS, BEFORE  
MOVING OFFSHORE EARLY THURSDAY MORNING.  
 
SURPRISINGLY, MODELS ARE INDICATING RATHER ROBUST HEATING/INSOLATION  
BEFORE THE ARRIVAL OF THE DEEPER MOISTURE/CLOUD COVER, WITH STEEP  
LOW-LEVEL LAPSE RATES OF 8-8.5 C/KM ACROSS THE AREA BY 18Z AS  
AFTERNOON TEMPS WARM IN THE MID/UPPER 70S NORTH TO LOWER 80S SE.  
HOWEVER, MODELS INDICATE ONLY WEAK LOW-LEVEL MOISTURE ADVECTION INTO  
THE AREA, WITH BL DEWPOINTS FORECAST TO REMAIN IN THE 50S. THESE  
LOWER DEWPOINTS WILL LIKELY LIMIT DESTABILIZATION TO WEAK  
INSTABILITY.  
 
CONVECTIVE RAIN CHANCES WILL INCREASE FROM WEST TO EAST DURING THE  
AFTERNOON AND EVENING, WITH THE HIGHEST QPF AND BEST COVERAGE OF  
SHOWERS AND STORMS EXPECTED NEAR THE VA BORDER WHERE MODELS INDICATE  
THE DEEPEST MOISTURE AND ALONG JUST NORTH OF THE WARM/OCCLUDED FRONT  
AND POTENTIAL LOW TRACK. THIS WILL ALSO BE THE FAVORED AREA FOR A  
FEW STRONG TO SEVERE STORMS, ESPECIALLY WITH ANY STORMS THAT RIDE  
EAST ALONG THE FRONT DRAPED ACROSS THE AREA. DESPITE THE WEAK  
INSTABILITY, 0-1KM SHEAR OF 20 TO 25 KTS COUPLED WITH THE POTENTIAL  
FOR LOCALLY ENHANCED LOW-LEVEL SHEAR/HELICITY ALONG THE FRONT, COULD  
SUPPORT A FEW SUPERCELLS CAPABLE OF PRODUCING ISOLATED DAMAGING  
WINDS AND HAIL. AT THIS TIME IT IS BELIEVED THAT HIGHER LCL HEIGHTS,  
DUE TO THE DRIER AIR IN THE LOW-LEVELS, WILL GREATLY REDUCE THE RISK  
OF ANY STORM'S CIRCULATION OF REACHING THE GROUND. THUS, MAKING  
FUNNEL CLOUD SIGHTINGS A REAL POSSIBILITY WEDNESDAY  
AFTERNOON/EVENING.  
 
WHILE THE SEVERE THREAT LOOKS TO BE OVER BY LATE EVENING, RAIN  
CHANCES WILL LINGER THROUGH THURSDAY MORNING UNTIL THE PASSAGE OF  
THE COLD FRONT AND UNDER THE CONTINUED MOIST PERTURBED FLOW ALOFT.  
LOWS RANGING FROM LOWER/MID 50S NW TO LOWER 60S SE.  
 

 
   
LONG TERM /THURSDAY THROUGH MONDAY/
 
 
AS OF 330 AM TUESDAY...  
 
AS THE SURFACE LOW MOVES OFF THE NEW ENGLAND COAST THURSDAY  
AFTERNOON, DRIER AND COOLER AIR MASS TAKES OVER CENTRAL NC THURSDAY  
AND FRIDAY. RELATIVE HUMIDITIES WILL BE DOWN AS WELL TO AROUND 30-  
40 PERCENT IN THE AFTERNOONS THURSDAY AND FRIDAY. EXPECT FRIDAY AND  
SATURDAY TO BE DRY (BESIDES A FEW SPRINKLES POSSIBLE IN THE SOUTHERN  
PART OF THE CWA ON SATURDAY) BEFORE THE NEXT SYSTEM MOVES INTO THE  
REGION FOR THE LATTER HALF OF THE WEEKEND. ANOTHER RIDGE, WEAKER  
THAN THE LAST, WILL MOVES ACROSS THE REGION SATURDAY NIGHT/SUNDAY  
MORNING AHEAD OF A DEEPENING LOW IN THE MIDWEST MOVING IN FROM  
CANADA. MODEL DISCREPANCY CONTINUES FOR TIMING AND AMOUNT OF PRECIP  
FOR SATURDAY ONWARD THEREFORE CONFIDENCE IS STILL TOO LOW FOR ANY  
FORECAST SPECIFICS. ALTHOUGH, SHOWERS SHOULD REMAIN WEAK AND  
SCATTERED THROUGH THE LATTER PART OF THE WEEKEND AS ZONAL FLOW KEEPS  
WEAK MOISTURE AROUND. THERE IS A SLIGHT CHANCE OF RAIN SUNDAY  
MORNING THROUGH AT LEAST MONDAY EVENING. TEMPERATURES FOR THE  
WEEKEND WILL BE A TAD BELOW NORMAL WITH HIGHS IN THE UPPER 60S IN  
THE NORTH AND LOW 70S IN THE SOUTH. MONDAYS TEMPERATURES WILL WARM  
UP TO LOW/MID 70S DURING THE DAY AND CONTINUE WITH MID 40S LOW 50S  
AT NIGHT.  
 

 
   
AVIATION /12Z TUESDAY THROUGH SATURDAY/
 
 
AS OF 645 AM TUESDAY...  
 
NELY LOW-FLOW IN THE WAKE OF THE BACK-DOOR COLD FRONT IS PRODUCING  
BRIEF PERIOD OF IFR TO MVFR RESTRICTIONS IN FOG AND/OR CEILINGS AT  
RWI. OTHERWISE, CONDITIONS SHOULD REMAIN VFR THROUGH THE TAF PERIOD  
WITH INTERMITTENT MID AND HIGH CLOUDS STREAMING ACROSS THE AREA,  
ESPECIALLY AT KGSO/KINT THE LOWER MID-LEVEL CEILINGS COULD ALSO  
SUPPORT SOME SPRINKLES.  
 
OUTLOOK: AN AREA OF LOW PRESSURE WILL TRACK ACROSS THE REGION  
WEDNESDAY AFTERNOON AND EVENING, BRINGING WIDESPREAD SHOWERS, ALONG  
WITH AND A FEW STORMS TO THE AREA. A COLD FRONTAL PASSAGE THURSDAY  
MORNING WILL USHER IN MUCH DRIER AND WILL MARK A RETURN TO VFR  
CONDITIONS THAT WILL LAST THROUGH SATURDAY.  
 

 
 
   
RAH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
SYNOPSIS...CBL  
NEAR TERM...CBL  
SHORT TERM...CBL  
LONG TERM...CA  
AVIATION...CBL  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab NC Page Main Text Page