620
FXUS61 KRNK 191827
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
127 PM EST THU DEC 19 2024
SYNOPSIS
LOW PRESSURE OVER THE UPPER MISSISSIPPI VALLEY WILL SWEEP ACROSS THE
OHIO VALLEY ON FRIDAY THEN OFF THE NEW ENGLAND COAST BY SATURDAY
BRINGING SNOW TO THE MOUNTAINS FRIDAY AFTERNOON THROUGH SATURDAY.
COLDER TEMPERATURES WITH HIGH PRESSURE FOLLOW FOR THE WEEKEND.
TEMPERATURES WARM ON MONDAY AND TUESDAY AHEAD OF LOW PRESSURE OVER
THE SOUTHERN PLAINS.
NEAR TERM /THROUGH FRIDAY/
AS OF 120 PM EST THURSDAY...
KEY MESSAGES:
- CLIPPER WILL BRING SNOW TO THE MOUNTAINS STARTING FRIDAY
AFTERNOON
ROBUST SHORT WAVE AND SURFACE LOW PRESSURE SYSTEM OVER THE UPPER
MISSISSIPPI VALLEY WILL REACH THE MID ATLANTIC REGION ON FRIDAY.
CLOUD COVER FILLS IN THIS EVENING AND OVERNIGHT. ISOLATED TO
SCATTERED LIGHT RAIN AND SNOW SHOWERS ARE EXPECTED TO CROSS THE
AREA FRIDAY MORNING WITH LITTLE IMPACT. THE MORE ORGANIZED AREA
OF SNOW WILL REMAIN CONFINED TO THE MOUNTAINS. HRRR AND FV3
MODELS SHOW ABOUT A SIX HOUR PERIOD OF MODERATE SNOW FRIDAY
AFTERNOON AND EVENING BEFORE THE PRECIPITATION BECOMES PRIMARILY
UPSLOPE DRIVEN OVERNIGHT. PROBABILISTIC GUIDANCE MAINTAINS UP
TO 40 PERCENT PROBABILITY OF 2 INCHES OF SNOW BY FRIDAY EVENING,
WITH THE HIGHEST POTENTIAL FROM TAZEWELL COUNTY THROUGH WESTERN
GREENBRIER COUNTY.
THE SURFACE COLD FRONT CROSSES THROUGH THE AREA ON FRIDAY WITH THE
WIND BECOMING NORTHWEST AND THE COLD AIR ADVECTION BECOMING STRONGER
BY FRIDAY AFTERNOON. SIMILAR TO CONDITIONS THURSDAY MORNING,
TEMPERATURES WILL ONLY SEE MINIMAL WARMING ON FRIDAY DUE TO ALL
THE CLOUDS. NOT MUCH DEVIATION FROM GUIDANCE NEEDED FOR LOWS
TONIGHT.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
AS OF 500 AM EST THURSDAY...
KEY MESSAGES:
1). EXTENDED PERIOD OF BELOW NORMAL/SUB FREEZING TEMPERATURES
EXPECTED ALONG AND WEST OF THE BLUE RIDGE.
2). CLIPPER SYSTEM TO BRING MINOR SNOW ACCUMULATIONS TO AREAS
WEST OF THE BLUE RIDGE FRIDAY-SATURDAY, ESPECIALLY AREAS
ALONG/WEST OF INTERSTATE 77.
A DEEPENING FULL LATITUDE TROUGH WILL EVOLVE ACROSS THE EASTERN
U.S. THROUGH THE WEEKEND AS A STRONG SHORT WAVE TRACKS
SOUTHEAST OUT OF CENTRAL CANADA INTO THE MIDWEST. COLD ADVECTION
INITIATING FRIDAY BEHIND THE INITIAL COLD FRONTAL PASSAGE WILL
INTENSIFY FRIDAY AFTERNOON AS A SECONDARY SURGE OF ARCTIC AIR
MOVES SOUTHEAST INTO THE REGION. 850MB TEMPERATURES WILL DROP
BELOW FREEZING FRIDAY AND CONTINUE TO HEAD DOWNWARD THROUGH
SATURDAY BEFORE SLOWLY MODERATING SUNDAY. BY FRIDAY NIGHT INTO
SATURDAY, 850MB TEMPERATURES WILL AVERAGE AROUND -10C ACROSS THE
CWA.
A STRONG SHORT WAVE WILL USHER IN THE COLDER ARCTIC AIR WHILE
THE UPSLOPE WINDS AND SHORT WAVE DYNAMICS COMBINE TO BRING A
PERIOD OF LIGHT SNOW TO AREAS ALONG/WEST OF THE BLUE RIDGE
MAINLY FRIDAY NIGHT AND EARLY SATURDAY. SNOW ACCUMULATIONS LOOK
TO BE IN THE 1-2 INCH RANGE FOR WESTERN GREENBRIER COUNTY WV AND
MOSTLY AROUND AN INCH ELSEWHERE MAINLY ALONG/WEST OF I-77. AN
ISOLATED REPORT OF 3 INCHES WILL ALSO BE POSSIBLE. FLURRIES AND
A DUSTING OF SNOW WILL BE POSSIBLE AS FAR EAST AS THE BLUE
RIDGE.
ONCE 850MB TEMPERATURES DROP BELOW FREEZING THURSDAY EVENING,
THEY WILL REMAIN BELOW 0C THROUGH THE WEEKEND, RISING ABOVE 0C
SOMETIME MONDAY MORNING. THIS WILL EQUATE TO A VERY COLD WEEKEND
WITH TEMPERATURES AROUND 10F DEGREES BELOW NORMAL. HIGH
TEMPERATURES WILL RANGES OF 100 PM EST THURSDAY...E FROM THE
20S/30S WEST TO THE 40S EAST WITH OVERNIGHT LOW TEMPERATURES IN
THE TEENS AND 20S. FOR THE HIGHER TERRAIN WEST OF THE BLUE
RIDGE, MUCH OF THE PERIOD FRIDAY EVENING THROUGH MONDAY WILL
REMAIN AT OR BELOW FREEZING EVEN DURING THE DAYTIME.
/CONFIDENCE LEVELS IN FORECAST PARAMETERS/
- MODERATE TO HIGH CONFIDENCE IN TEMPERATURES,
- MODERATE CONFIDENCE IN PRECIPITATION PROBABILITIES,
- MODERATE CONFIDENCE IN WIND DIRECTION AND SPEED.
LONG TERM /MONDAY THROUGH WEDNESDAY/
AS OF 530 AM EST THURSDAY...
KEY MESSAGES:
1) REMAINING COLD WITH BELOW NORMAL TEMPERATURES, BUT A BIT
LESS FRIGID THAN THE WEEKEND.
2) UNSETTLED, PROGRESSIVE WEATHER PATTERN WILL BRING ANOTHER
WIDESPREAD RAIN, POTENTIALLY BRIEF WINTER WEATHER EVENT, TO THE
AREA JUST IN TIME FOR CHRISTMAS EVE/CHRISTMAS.
AN ACTIVE/PROGRESSIVE PATTERN WILL REMAIN IN PLACE AS BOTH THE
NORTHERN AND SOUTHERN STREAM REMAIN FAIRLY ACTIVE. FOR OUR
REGION, THE NORTHERN STREAM WILL GENERALLY DOMINATE THROUGH THE
PERIOD. HOWEVER, A STRONG SOUTHERN STREAM SYSTEM PROMISES TO
BRING ANOTHER WIDESPREAD RAIN EVENT TO THE AREA JUST IN TIME FOR
CHRISTMAS. TEMPERATURES MAY BE COLD ENOUGH AT THE ONSET FOR SOME
LIGHT FREEZING RAIN, BUT FOR THE MOST PART THIS APPEARS TO BE
ANOTHER RAIN EVENT. NO WHITE CHRISTMAS EXPECTED THIS YEAR.
THE COLD AIR MASS WILL BE FIRMLY ENTRENCHED ACROSS THE REGION
EARLY MONDAY AND LINGER THROUGH THE FIRST HALF OF THE NEXT WEEK
BEFORE FINALLY LIFTING OUT OF THE AREA MIDWEEK, LOW
TEMPERATURES WILL REMAIN BELOW NORMAL DURING THE DAYTIME AND
NEAR NORMAL AT NIGHT THROUGH THE WEEKEND WITH MAXIMUM
TEMPERATURES IN THE 30S AND 40S AND POINTS WEST TO THE 40S
PIEDMONT. LOW TEMPERATURES WILL AVERAGE IN THE 20S TO MID 30S.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
AS OF 120 PM EST THURSDAY...
ROBUST SHORT WAVE AND SURFACE LOW PRESSURE SYSTEM OVER THE UPPER
MISSISSIPPI VALLEY WILL REACH THE MID ATLANTIC REGION ON FRIDAY.
CLOUD COVER FILLS IN THIS EVENING AND OVERNIGHT. MAINLY MVFR
WEST OF THE BLUE RIDGE AND 3-5KFT IN THE VIRGINIA AND NORTH
CAROLINA PIEDMONT. KLYH WAS ON THE EDGE OF THE CLOUD SHIELD AND
STRATOCUMULUS HAD CLEARED OUT OF KBCB THIS AFTERNOON.
ISOLATED TO SCATTERED VFR LIGHT RAIN AND SNOW SHOWERS ARE
EXPECTED TO CROSS THE AREA FRIDAY MORNING. CEILINGS WILL LOWER
TO MVFR TONIGHT AND REMAIN IN THE MVFR TO IFR CATEGORIES FRIDAY
MORNING.
PROBABILISTIC GUIDANCE MAINTAINS UP TO 40 PERCENT PROBABILITY
OF 2 INCHES OF SNOW BY FRIDAY EVENING, WITH THE HIGHEST
POTENTIAL FROM TAZEWELL COUNTY THROUGH WESTERN GREENBRIER
COUNTY.
THE SURFACE COLD FRONT CROSSES THROUGH THE AREA ON FRIDAY WITH THE
WIND BECOMING NORTHWEST AND THE COLD AIR ADVECTION BECOMING STRONGER
BY FRIDAY AFTERNOON.
EXTENDED AVIATION OUTLOOK...
THE MORE ORGANIZED AREA OF MVFR VISIBILITY SNOW WILL REMAIN
CONFINED TO THE MOUNTAINS, HRRR AND FV3 MODELS SHOW ABOUT A SIX
HOUR PERIOD OF MODERATE SNOW FRIDAY AFTERNOON AND EVENING BEFORE
THE PRECIPITATION BECOMES PRIMARILY UPSLOPE DRIVEN OVERNIGHT.
THIS INCLUDES KBLF. GUSTS IN THE 20 TO 30 KNOT RANGE ARE LIKELY
FRIDAY NIGHT.
SNOW SHOWERS IN THE MOUNTAINS FRIDAY INTO FRIDAY NIGHT COULD
DROP VSBYS TO MVFR TO IFR. THESE SUB- VFR CIGS COULD LINGER INTO
LATE SATURDAY OVER THE MOUNTAINS BEFORE VFR RETURNS FOR SUNDAY
MORNING.
DRY AND WARMER VFR CONDITIONS ARE EXPECTED MONDAY AND TUESDAY.
RNK WATCHES/WARNINGS/ADVISORIES
VA...NONE.
NC...NONE.
WV...NONE.
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...AMS/BMG
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