490
FXUS61 KRNK 172331
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
731 PM EDT SUN OCT 17 2021
SYNOPSIS
CANADIAN HIGH PRESSURE WILL DRIFT SLOWLY FROM THE MIDWEST INTO
THE MID-ATLANTIC REGION THROUGH TUESDAY. THIS WILL BRING MOSTLY
SUNNY CONDITIONS TO THE REGION ALONG WITH SEASONABLY COOL
TEMPERATURES. PATCHY FROST CAN BE EXPECTED IN THE WESTERN
MOUNTAIN VALLEYS TONIGHT AND TUESDAY MORNING. THE NEXT FRONTAL
SYSTEM WILL ARRIVE BY THE END OF THE WEEK BRINGING THE NEXT
CHANCE FOR ANY PRECIPITATION TO THE REGION.
NEAR TERM /THROUGH MONDAY/
AS OF 645 PM EDT SUNDAY...
SEASONABLY COOL TONIGHT WITH SOME FROST POSSIBLE IN THE MOUNTAINS.
HIGH PRESSURE TO OUR WEST WILL BUILD INTO OUR REGION TONIGHT INTO
MONDAY BEHIND THE DEPARTING TROUGH. THE PROXIMITY OF THE HIGH
PRESSURE AS WELL AS VERY DRY AIR ALOFT AND DIMINISHING WINDS SHOULD
LEAD TO GOOD RADIATIONAL COOLING CONDITIONS OVERNIGHT AND THE
DEVELOPMENT OF FROST IN SOME AREAS. FROST ADVISORY HAS BEEN POSTED
FOR LOCATIONS WHERE FROST COULD BE MORE WIDESPREAD IN THE WEST.
PATCHY FROST MAY ALSO DEVELOP IN THE MOUNTAINS VALLEYS
ESPECIALLY THE GREENBRIER VALLEY. MODIFIED TEMPERATURES FOR THIS
EVENING INTO TONIGHT UTILIZING THE LATEST SURFACE OBS,THEIR
TRENDS AND BLENDED IN NBM. OVERNIGHT LOW TEMPERATURES WILL
VARIED FROM AROUND 30 DEGREES IN MOUNTAINS TO THE LOWER 40S
IN THE EAST. AFTER A CHILLY START, HIGH TEMPERATURES MONDAY
WILL RANGE FROM MID 50S IN THE MOUNTAINS TO THE LOWER 70S IN THE
PIEDMONT.
MODERATE CONFIDENCE IN NEAR TERM FORECAST PERIOD.
PREVIOUS DISCUSSION:
AS OF 145 PM EDT SUNDAY...
CHILLY TONIGHT WITH SOME FROST POSSIBLE IN THE MOUNTAINS.
UPPER TROUGH WITH A CUTOFF LOW CENTERED NEAR JAMES BAY WILL RETREAT
EAST-NORTHEAST OVER THE NEXT 24 HOURS. OVERALL THE OMEGA BLOCK
PATTERN THAT IS IN PLACE WILL TRANSLATE EAST, PUTTING THE SOUTHERN
APPALACHIANS MORE SQUARELY INTO THE NE FLOW ON THE WEST SIDE OF THE
TROUGH. HIGH PRESSURE AT THE SURFACE STRENGTHENS AND MOVES TOWARDS
THE TN VALLEY.
TODAY HAS BEEN QUITE COOL WITH READINGS IN THE 40S AND 50S IN THE
MOUNTAINS, AND IN THE MID 50S TO LOWER 60S IN THE PIEDMONT. PWATS ON
THIS MORNING'S SOUNDINGS WERE AROUND A QUARTER INCH, AND THIS WILL
NOT IMPROVE APPRECIABLY OVERNIGHT. THE PROXIMITY OF THE HIGH
PRESSURE AS WELL AS VERY DRY AIR ALOFT AND DIMINISHING WINDS SHOULD
LEAD TO AGREEABLE RADIATIONAL COOLING CONDITIONS AND THE DEVELOPMENT
OF FROST IN SOME AREAS. MOST LIKELY SPOTS TO HAVE WIDESPREAD FROST
ARE THE GRAYSON AND ALLEGHANY HIGHLANDS WHERE A FROST ADVISORY HAS
BEEN ISSUED. PATCHY FROST MAY APPEAR ELSEWHERE, INCLUDING THE
GREENBRIER VALLEY, FOR A COUPLE OF HOURS, BUT IT SHOULD NOT BE
WIDESPREAD ENOUGH FOR AN ADVISORY. CURRENTLY THE ONLY LOCATIONS THAT
MAY SEE FREEZING TEMPERATURES IS THE BURKE'S GARDEN AREA.
OTHERWISE, SITES WEST OF THE BLUE RIDGE WILL SEE A CLEAR AND VERY
CHILLY NIGHT WITH LOWS A FEW DEGREES ABOVE FREEZING. TO THE EAST,
TEMPERATURES WILL BE IN THE UPPER 30S TO LOWER 40S. WINDS
DECREASE OVERNIGHT BUT TO GENERALLY 5-10 MPH OUTSIDE OF THE
ADVISORY AREA. AFTER A COLD START HIGHS REBOUND DURING THE DAY
TUESDAY, AND SHOULD BE A FEW DEGREES WARMER THAN TODAY, REACHING
THE UPPER 50S TO LOWER 70S WEST TO EAST. DAYTIME MIXING WILL
AGAIN CREATE GUSTY WINDS AROUND 10-20 MPH.
FORECAST CONFIDENCE IS HIGH FOR POPS AND QPF, MODERATE FOR WINDS
AND TEMPERATURES.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/
AS OF 145 PM EDT SUNDAY...
TRANQUIL WEATHER CONTINUES...
500MB PATTERN IS PROGRESSIVE AND MOVES LONG WAVE TROUGH OFF THE EAST
COAST MONDAY NIGHT AND TUESDAY. BY WEDNESDAY MUCH OF THE EAST WILL
HAVE HIGHER 500 MB HEIGHTS AND UPPER RIDGING. AT THE SURFACE, HIGH
PRESSURE MOVES OFFSHORE ON WEDNESDAY. AIR MASS SHOULD BE WARMING TO
AROUND +12 AT 850MB BY WEDNESDAY. STILL SOME 45 KNOT 850 MB WINDS
OVER THE HIGHER ELEVATIONS OF THE ALLEGHANY HIGHLANDS AND SOUTHEAST
WEST VIRGINIA ON MONDAY EVENING. LITTLE CLOUD COVER IS EXPECTED
THROUGH WEDNESDAY NIGHT AS AIR MASS REMAINS DRY.
LONG TERM /THURSDAY THROUGH SUNDAY/
AS OF 140 PM EDT SUNDAY..
KEEPING FORECAST DRY UNTIL FRONT ARRIVES THURSDAY..
TROUGH OFF THE WEST COAST MOVES ACROSS THE CONUS, REACHING THE OHIO
VALLEY ON THURSDAY. HEIGHTS CONTINUE TO FALL AS THE LONG WAVE TROUGH
OVER THE EAST AMPLIFIES BY SATURDAY. BY THURSDAY, REGION IS BETWEEN
THE SURFACE HIGH OFFSHORE AND LOW PRESSURE OVER THE GREAT LAKES AND
OHIO VALLEY. THIS LOW PRESSURE SYSTEM BRINGS A FRONT THROUGH THE MID
ATLANTIC REGION LATE THURSDAY. CANADIAN, ECMWF AND GFS ARE IN DECENT
AGREEMENT FOR THE TIMING OF THE FRONT. SURFACE HIGH PRESSURE WILL
BUILD IN BEHIND THE FRONT ON SATURDAY AND SUNDAY. HIGHEST
PROBABILITY OF PRECIPITATION WILL BE ON THURSDAY AND THURSDAY NIGHT
IN THE MOUNTAINS. WILL BE REMOVING PROBABILITY OF PRECIPITATION FOR
SATURDAY. EVEN THE UPSLOPE CLOUDS IN THE MOUNTAINS WILL ERODE BY
SATURDAY AFTERNOON.
AVIATION /00Z MONDAY THROUGH FRIDAY/
AS OF 731 PM EDT SUNDAY...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD.
HIGH PRESSURE FROM THE MIDWEST WILL BUILD ACROSS THE REGION
THROUGH MONDAY. CONDITIONS ARE EXPECTED TO BE VFR THROUGH THE
TAF CYCLE. WESTERLY WINDS WILL DIMINISH THIS EVENING INTO
TONIGHT, AND THEN RETURN AFTER SUNRISE TUESDAY. GUSTS SHOULD
STAY IN THE 10-20 MPH RANGE FOR TAF SITES.
/CONFIDENCE LEVELS IN FORECAST PARAMETERS/
- HIGH CONFIDENCE IN CEILINGS,
- HIGH CONFIDENCE IN VISIBILITIES,
- MODERATE TO HIGH CONFIDENCE IN WIND DIRECTION AND SPEED.
EXTENDED AVIATION DISCUSSION...
MOSTLY VFR CONDITIONS EXPECTED THROUGH THE PERIOD. HIGH
PRESSURE REMAINS OVERHEAD THROUGH AT LEAST WEDNESDAY BOTH AT THE
SURFACE AND ALOFT. THE NEXT COLD FRONT WILL ARRIVE LATE IN THE
WEEK. MOISTURE WILL BE LIMITED BUT A FEW MVFR SHOWERS ARE
EXPECTED WITH THAT FRONT LATE THURSDAY OR FRIDAY. SOME LATE
NIGHT/EARLY MORNING FOG WILL BE POSSIBLE IN VERY ISOLATED
LOCATIONS MONDAY MORNING (E.G., LWB) AND IN OTHER AREAS NEAR
RIVERS/MOUNTAIN VALLEYS TOWARD MIDWEEK.
RNK WATCHES/WARNINGS/ADVISORIES
VA...FROST ADVISORY FROM 4 AM TO 9 AM EDT MONDAY FOR VAZ007-009-010-
012-015.
NC...FROST ADVISORY FROM 4 AM TO 9 AM EDT MONDAY FOR NCZ001-002-018.
WV...NONE.
SYNOPSIS...SH
NEAR TERM...KK/SH
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...KK/SH
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