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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