917  
FXUS61 KRNK 150552  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
152 AM EDT SUN SEP 15 2019  
   
SYNOPSIS
 
 
A COLD FRONT TO OUR WEST WILL MOVE EAST TONIGHT INTO SUNDAY.  
HIGH PRESSURE WILL BUILD SOUTH INTO OUR REGION EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TODAY/
 
 
AS OF 830 PM EDT SATURDAY...  
 
CONVECTION IN ADVANCE OF A COLD FRONT CONTINUED TO LINGER  
ACROSS THE ROANOKE VALLEY. THIS ACTIVITY WAS SLOWLY MOVING TO  
THE EAST, BUT STRUGGLING TO MAKE IT MUCH FARTHER THAN THE CREST  
OF THE BLUE RIDGE. EXPECTATION IS FOR THIS ACTIVITY TO DISSIPATE  
AS WE HEAD THROUGH THE EVENING HOURS...FALLING APART AS IT MOVES  
INTO BEDFORD AND NORTHERN FRANKLIN. MESOANALYSIS FROM SPC SHOWS  
LITTLE OR NO CAPE EAST OF THE BLUE RIDGE, ALTHOUGH THERE IS  
STILL A FINGER OF MODEST SBCAPE (1500 J/KG) WHICH LINGERS  
FROM ROANOKE SOUTHWEST INTO THE NORTHWEST PIEDMONT OF NC, RIGHT  
ALONG THE BLUE RIDGE ESCARPMENT. CURRENT THINKING, IS IF THERE  
IS ANY LINGERING SHOWERS IT WILL BE WITHIN THIS CORRIDOR, AND IT  
TOO SHOULD DISSIPATE AS WE HEAD INTO THE OVERNIGHT.  
 
A COLD FRONT EXTENDS FROM CENTRAL PENNSYLVANIA EXTENDING  
SOUTHWARD ALONG THE SPINE OF THE APPALACHIANS TO NORTHERN  
ALABAMA. THIS FRONT IS FORECAST TO SLOWLY MOVE EAST AND INTO THE  
PIEDMONT BY SUNDAY.  
 
THE COMBINATION OF LIGHT WINDS AND LOW LEVEL MOISTURE WILL  
RESULT IN AREAS OF FOG OVERNIGHT INTO SUNDAY MORNING. LOW  
TEMPERATURES TONIGHT WILL RANGE FROM THE MID 50S IN THE  
MOUNTAINS TO THE MID 60S IN THE PIEDMONT. HIGH PRESSURE WILL  
BUILD IN FROM THE NORTH ON SUNDAY AND PUSH DOWN THE SPINE OF THE  
APPALACHIANS AS TROPICAL CYCLONE HUMBERTO SPINS OFF THE COAST  
OF THE CAROLINAS. ISOLATED SHOWERS AND THUNDERSTORMS MAY BE  
POSSIBLE ON SUNDAY MAINLY IN THE SOUTHEAST. WITH THE TREND OF  
THE MODELS LIGHTER WITH POTENTIAL FOR CONVECTION ON SUNDAY,  
DECIDED TO DECREASE POPS ON SUNDAY. HIGH TEMPERATURES ON SUNDAY  
WILL VARY FROM THE UPPER 70S IN THE MOUNTAINS TO THE MID 80S IN  
THE PIEDMONT.  
 

 
   
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
 
 
AS OF 215 PM EDT SATURDAY...  
 
GENERALLY QUIET AND MOSTLY DRY WEATHER CONDITIONS EXPECTED  
THROUGH THIS PERIOD AS THE REGION INCREASINGLY COMES UNDER THE  
INFLUENCE OF A HIGH AMPLITUDE SUBTROPICAL RIDGE DRIFTING SLOWLY  
EASTWARD FROM THE CENTRAL U.S. THE WEAK FRONT THAT IS MOVING  
THROUGH THE FORECAST AREA TODAY WILL STALL AND EVENTUALLY WASH  
OUT JUST TO OUR SOUTH ACROSS NORTH CAROLINA. MEANWHILE, TROPICAL  
STORM HUMBERTO WILL BE MOVING NORTHEASTWARD OFF THE GA/SC COAST,  
WHICH WILL LIKELY HELP INDUCE SUBSIDENCE TO SOME EXTENT ACROSS  
OUR AREA.  
 
THE ONLY REAL POTENTIAL FOR PRECIPITATION DURING THIS TIME FRAME  
WILL BE ACROSS THE NORTHWEST NC MOUNTAINS AND THE FAR SOUTHWEST  
CORNER OF VA WHERE TERRAIN INFLUENCE AND DIFFERENTIAL HEATING  
ALONG WITH THE LINGERING FRONT, NORTHEAST SURFACE FLOW BEHIND  
THE DISSIPATING FRONT, AND IMPROVED MOISTURE CONVERGENCE, COULD  
LEAD TO A FEW AFTERNOON SHOWERS OR THUNDERSTORMS. A WEAK UPPER  
TROUGH WILL BE MOVING THROUGH THE MEAN FLOW ACROSS OH/PA/MD  
AREA, WHICH MAY RESULT IN AN ISOLATED THREAT FOR  
SHOWERS/THUNDERSTORMS NORTH OF I-64, AGAIN MAINLY  
AFTERNOON/EVENING. THUS, AT THIS POINT, POPS THROUGH THE PERIOD  
ARE 30% AT BEST, CONFINED TO THE FAR SOUTHWEST. MUCH OF THE  
PERIOD WILL BE DRY WITH POPS BELOW 15%.  
 
TEMPERATURES WILL BE ON THE WARM SIDE AND WELL ABOVE NORMAL, BUT  
NOT TO THE DEGREE WE EXPERIENCED LAST WEEK. GFS/ECMWF ARE A BIT  
AT ODDS WITH REGARD TO THE 500MB TEMPERATURES, BUT AN AVERAGE  
AROUND +18C APPEARS TO BE A GOOD BET, AS COMPARED TO THE +20 TO  
+22C WE SAW EARLIER THIS WEEK. AMPLIFYING NORTHERLY FLOW ALOFT  
ON THE EAST SIDE OF THE UPPER RIDGE COULD SAVE US FROM THE  
EXTREME HEAT WE SAW LAST WEEK. THUS, NOT EXPECTING THE  
WIDESPREAD 90S LIKE LAST WEEK, MORE IN THE RANGE OF MID 80S WEST  
TO LOWER 90S EAST/PIEDMONT.  
 
/CONFIDENCE IN FORECAST PARAMETERS/  
TEMPERATURES - MODERATE,  
PRECIPITATION PROBABILITIES - LOW TO MODERATE,  
THUNDERSTORM PROBABILITIES - LOW,  
WINDS - MODERATE.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
AS OF 230 PM EDT SATURDAY...  
 
MOSTLY DRY WITH NORMAL TO SLIGHTLY ABOVE NORMAL TEMPERATURES  
THROUGH THE PERIOD. THE SYNOPTICS WILL CONTINUE TO BE A LARGE  
SCALE, HIGHLY AMPLIFIED UPPER RIDGE DOMINATING THE EASTERN HALF  
OF THE U.S., WITH THE AXIS REMAINING JUST TO OUR WEST. TROPICAL  
CYCLONE HUMBERTO WILL TURN EAST AND MOVE FURTHER AWAY FROM THE  
U.S. AND OUT TO SEA. SURFACE HIGH PRESSURE WILL LINGER OVER AND  
TO THE NORTHEAST OF THE AREA. THIS WILL RESULT IN MOSTLY SUNNY  
TO PARTLY SUNNY CONDITIONS, YET WITH A VERY WEAK WEDGE IN PLACE,  
TEMPERATURES SHOULD STAY NEAR TO JUST ABOVE NORMAL AND NOT REACH  
THE WIDESPREAD 90S OF THIS PAST WEEK. HOWEVER, THE ECMWF/GFS TO  
DIFFER NOTABLY FROM +20C ECMWF TO CLOSER TO +16C-+18C GFS.  
 
GENERALLY FOLLOWED THE NBM FOR POP GUIDANCE, WHICH PAINTS SOME  
20-30% VALUES IN THE SOUTHWESTERN AND WESTERN MOUNTAINS, BUT  
LITTLE TO NONE ELSEWHERE. CONFIDENCE IN RAINFALL IS LOW AND  
MEANINGFUL RAINFALL APPEARS HIGHLY UNLIKELY AT THIS TIME,  
LEAVING SOME AREAS IN A CONTINUING LOW-END DROUGHT.  
 
/CONFIDENCE IN FORECAST PARAMETERS/  
TEMPERATURES - MODERATE TO HIGH,  
PRECIPITATION PROBABILITIES - LOW,  
THUNDERSTORM THREAT - LOW,  
 

 
   
AVIATION /06Z SUNDAY THROUGH THURSDAY/
 
 
AS OF 150 AM EDT SUNDAY...  
 
A COLD FRONT STRETCHES FROM NORTH TO SOUTH ALONG THE SPINE OF  
THE APPALACHIANS. SOME IFR TO LIFR CLOUDS COVERED THE SOUTHERN  
BLUE RIDGE AND FOOTHILLS SOUTH AND EAST OF KPSK.  
 
MVFR TO IFR CLOUDS WILL FILL IN EAST OF THE FRONT EARLY THIS  
MORNING. FOG WILL DEVELOP IN THE MOUNTAINS, WITH MVFR TO IFR  
VISIBILITY, ESPECIALLY WHERE IT RAINED SATURDAY AFTERNOON AND  
EVENING. SOME MID AND HIGH CLOUDS MAY DELAY THE FORMATION OF FOG  
UNTIL AFTER 4AM/08Z.  
 
THE FRONT WILL SLOWLY MOVE EAST AND INTO THE PIEDMONT OF VA/NC  
BY NOON TODAY. ISOLATED SHOWERS AND A FEW THUNDERSTORMS WILL BE  
ENCOUNTERED ALONG THE FRONT. GRADUALLY IMPROVEMENT BACK TO VFR  
IS EXPECTED TODAY WITH A RETURN TO WIDESPREAD VFR FOR THE  
AFTERNOON.  
 
MEDIUM CONFIDENCE IN CEILINGS,VISIBILITIES AND WINDS.  
 
   
EXTENDED AVIATION DISCUSSION
 
 
VFR CONDITIONS WILL CONTINUE SUNDAY NIGHT. A TROPICAL CYCLONE  
ALONG THE SOUTHEAST ATLANTIC COAST EARLY IN THE WEEK, WILL  
INDUCE A DRY NORTH WIND. THIS SHOULD PROMOTE VFR FROM MONDAY  
THROUGH WEDNESDAY. ISOLATED TO SCATTERED MVFR STORMS ARE  
POSSIBLE IN THE MOUNTAINS OF THE CENTRAL APPALACHIANS ON  
THURSDAY.  
 
FORECAST CONFIDENCE THIS TIME PERIOD IS AVERAGE.  
 

 
   
RNK WATCHES/WARNINGS/ADVISORIES
 
 
VA...NONE.  
NC...NONE.  
WV...NONE.  
 

 
 

 
SYNOPSIS...KK  
NEAR TERM...DS/KK  
SHORT TERM...RAB  
LONG TERM...RAB  
AVIATION...AMS/PM  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab VA Page
The Nexlab WV Page
The Nexlab NC Page Main Text Page