881  
FXUS61 KRNK 190830  
AFDRNK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BLACKSBURG VA  
430 AM EDT THU SEP 19 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE AT THE SURFACE AND ALOFT WILL CONTINUE TO BUILD  
OVER THE AREA THROUGH THE WEEKEND. A WEAK COLD FRONT WILL DRIFT  
INTO THE AREA FROM THE NORTHWEST EARLY NEXT WEEK. WEATHER  
CONDITIONS WILL REMAIN DRY THROUGH THE PERIOD WITH COOL NIGHTS  
AND WARM AFTERNOONS.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 400 AM EDT THURSDAY...  
 
HIGH PRESSURE WILL BE THE DOMINATE SYNOPTIC FACTOR THROUGH THE  
WEEKEND AND AT LEAST INTO EARLY NEXT WEEK. A BROAD HIGH  
AMPLITUDE RIDGE OVER THE CENTRAL U.S. WILL SLOWLY SHIFT EASTWARD  
INTO EARLY NEXT WEEK, FINALLY DRIFTING OFF THE MID-ATLANTIC  
COAST BY MONDAY OR TUESDAY. MEANWHILE, A LARGE SURFACE HIGH OVER  
THE NORTHEAST U.S. WILL DRIFT SOUTHWEST AND BE OVERHEARD  
SOUTHWEST VA EARLY NEXT WEEK.  
 
THE EASTERLY UPSLOPE FLOW ALONG THE SOUTHERN BLUE RIDGE WILL  
SLOWLY ERODE THROUGH THE PERIOD, ALLOWING THE ASSOCIATED CLOUD  
COVER TO REFOCUS FURTHER SOUTHWEST WITH TIME. ALTHOUGH CLOUDS  
ARE EVIDENT AGAIN THIS MORNING ACROSS NORTHWEST NC INTO  
SOUTHWEST VA, CEILINGS OVERALL ARE HIGHER THAN YESTERDAY AND ALL  
MODELS SHOW THIS CLOUD COVER ERODING FROM THE NORTHEAST AS DRY  
AIR WITH DEWPOINTS IN THE 40S AND 50S CONTINUES TO ADVECT  
SOUTHWEST INTO THE REGION. EXPECT MOSTLY SUNNY SKIES BY  
AFTERNOON ACROSS ALL AREAS EXCEPT POSSIBLY PARTLY CLOUDY YET  
ACROSS WATAUGA INTO GRAYSON COUNTIES AND PERHAPS EASTWARD TOWARD  
UKF AND MWK. CLOUD COVER IN THESE AREAS COULD LINGER OVERNIGHT  
AND INTO EARLY FRIDAY. FOG DEVELOPMENT IS QUESTIONABLE AS A  
RESULT OF THE DRY AIR MASS IN PLACE AS WELL AS LINGERING CLOUD  
COVER DURING THE NIGHTTIME HOURS. WINDS WILL CONTINUE TO BE  
NORTHEAST TO EAST-SOUTHEAST THROUGH THE PERIOD AT SPEEDS MOSTLY  
8KTS OR LESS. 850MB TEMPERATURES RANGE FROM AROUND +16C VIA THE  
GFS TO 18C ECMWF. THIS WILL YIELD NEAR NORMAL TEMPERATURES  
ACROSS THE AREA (~ 55 TO 75 ON AVERAGE). THE INCREASINGLY DRY  
AIR MASS WILL RESULT IN LARGE DIURNAL TEMPERATURE SWINGS. LOOK  
FOR LOWS MOSTLY IN THE 50S AND HIGHS MOSTLY IN THE 70S TODAY  
WITH LOWS TONIGHT IN THE 40S AND 50S (40S CONFINED TO DEEP  
VALLEYS [I.E., BURKES GARDEN, LWB, AND THE I-64 CORRIDOR AREA]).  
 
/CONFIDENCE IN FORECAST PARAMETERS/  
TEMPERATURES - MODERATE TO HIGH,  
PRECIPITATION PROBABILITIES - NONE (0% POPS)  
WINDS - HIGH,  
THUNDERSTORM THREAT - NONE.  
 

 
   
SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/
 
 
AS OF 315 AM EDT THURSDAY...  
 
HIGH PRESSURE WILL BE NEARLY OVERHEAD EARLY FRIDAY WITH VERY DRY AIR  
IN PLACE ACROSS THE REGION, GFS FORECAST SOUNDING NEAR KRNK AT 12Z  
FRIDAY SHOWS ONLY 0.36 PWAT ACROSS THE REGION. VERY LITTLE CHANGE IS  
EXPECTED OVER THE WEEKEND AS HIGH PRESSURE DRIFTS SLOWLY SOUTHEAST  
TOWARD THE NC COAST BY EARLY SUNDAY. TEMPS WILL CLIMB FROM NEAR  
NORMAL LEVELS FOR MID-SEPTEMBER FRIDAY SLOWLY BACK TO ABOVE NORMAL  
LEVELS BY SUNDAY. NO RELIEF FROM THE INCREASINGLY DRY CONDITIONS  
EXPECTED THROUGH THE WEEKEND.  
 

 
   
LONG TERM /MONDAY THROUGH WEDNESDAY/
 
 
AS OF 315 PM EDT WEDNESDAY...  
 
BOTH THE GFS AND ECMWF MODELS REVEAL HIGH PRESSURE EDGING OFFSHORE  
WHILE A NOTABLE UPPER LEVEL RIDGE REMAINS OVERHEAD DURING SUNDAY.  
THUS, THE UNSEASONABLY WARM AND DRY WEATHER WILL CONTINUE THROUGH  
THE REMAINDER OF THIS WEEKEND. THE MODELS DIVERGE WITH RESPECT TO  
THE TIMING OF AN APPROACHING UPPER LEVEL TROUGH AND ASSOCIATED COLD  
FRONT OVER THE GREAT LAKES BEYOND SUNDAY NIGHT. WHILE THE GFS BRINGS  
THE COLD FRONT OVER THE MID ATLANTIC DURING MONDAY INTO MONDAY  
NIGHT, THE ECWMF DOES NOT BRING THE COLD FRONT OVERHEAD UNTIL MONDAY  
NIGHT INTO TUESDAY. BECAUSE OF THE FAST BIAS THAT THE GFS NORMALLY  
HAS FOR WEATHER SYSTEMS IN THE EXTENDED PORTION OF THE FORECAST, THE  
ECMWF WAS FAVORED FOR THE TIMING AND THE OVERALL BIG PICTURE.  
 
THE COLD FRONT APPEARS RATHER WEAK AS MOST OF THE DYNAMICAL ENERGY  
AND SUPPORT WILL PASS WELL TO THE NORTH IN BOTH MODELS. IT IS QUITE  
POSSIBLE THAT THE PIEDMONT MAY NOT SEE ANY RAINFALL AT ALL FROM THIS  
FRONTAL PASSAGE. THE BEST CHANCE FOR ANY RAIN WILL REMAIN ALONG AND  
WEST OF THE BLUE RIDGE, BUT CONFIDENCE IS LOW THAT ANY SIGNIFICANT  
RAINFALL WILL OCCUR THAT COULD HELP TO REVERSE THE OVERALL DRY TREND  
FROM THE PAST COUPLE MONTHS IN THE CWA. ANY SHOWERS SHOULD DISSIPATE  
BY TUESDAY EVENING ACCORDING TO THE ECWMF MODEL, AND HIGH PRESSURE  
WILL RETURN OVER THE MID ATLANTIC BY WEDNESDAY.  
 

 
   
AVIATION /08Z THURSDAY THROUGH MONDAY/
 
 
AS OF 245 AM EDT THURSDAY...  
 
MVFR CEILINGS ARE MAINLY CONFINED TO THE BLUE RIDGE MOUNTAINS  
SOUTHWEST OF ROANOKE AND INTO WESTERN NC. ELSEWHERE SKIES HAVE  
CLEARED OUT OR AT LEAST HAVE BECOME SCATTERED AT VFR LEVELS.  
EXPECTATION IS THAT THE CLOUDS WILL WORK THEIR WAY BACK SOME TO  
THE EAST AND LIKELY INVOLVE ROA AT A MINIMUM, LESS LIKELY LYH  
AND DAN. HOWEVER, THESE CEILINGS MAY REMAIN ABOVE 030, THUS VFR.  
FOG DEVELOPMENT SEEMS TO BE VERY QUESTIONABLE THIS MORNING  
BECAUSE OF ADVECTION OF DRIER AIR AND 40-50 DEGREE DEWPOINTS  
ACROSS THE NORTHERN AREAS. HAVE REDUCED FOG THREAT IN THE 06Z  
TAFS.  
 
REGARDLESS OF THE FOG/STRATUS OUTCOME THIS MORNING, STRONG  
SUBSIDENCE AND ADVECTION OF DRY AIR INTO THE REGION THURSDAY  
UNDER HIGH PRESSURE SURFACE AND ALOFT SHOULD RESULT IN QUICK  
DISSIPATION OF CLOUD/FOG ELEMENTS LEAVING US WITH WIDESPREAD  
CLEAR AIR AND VFR.  
 
WINDS REMAINING NORTHEAST TO EAST-SOUTHEAST THROUGH THE PERIOD  
AT SPEEDS MOSTLY 9KTS OR LESS.  
 
/CONFIDENCE IN FORECAST PARAMETERS/  
CEILINGS - MODERATE TO HIGH,  
VISIBILITIES - MODERATE,  
WINDS - HIGH,  
THUNDERSTORM THREAT - NONE.  
   
EXTENDED AVIATION DISCUSSION
 
 
HIGH PRESSURE TO OUR NORTHEAST WILL CONTINUE TO BUILD SOUTHWEST  
OVER THE REGION PROMOTING VFR INTO THE UPCOMING WEEKEND.  
ONLY EXCEPTIONS WILL BE LATE NIGHT AND EARLY MORNING FOG IN THE  
MOUNTAIN VALLEYS WHICH WOULD IMPACT THE USUAL TERMINALS (E.G.,  
KLWB AND KBCB).  
 
CONFIDENCE IS HIGH THAT VFR WILL BE THE DOMINANT FLIGHT  
CATEGORY INTO THE UPCOMING WEEKEND. NEXT CHANCE SCATTERED MVFR  
SHOWERS WOULD ACCOMPANY A FRONT ON TUESDAY, AND MAINLY IMPACT  
THE MOUNTAINS.  
 

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

 
 

 
SYNOPSIS...RAB  
NEAR TERM...RAB  
SHORT TERM...PC  
LONG TERM...PC/PW  
AVIATION...PM/RAB  
 
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