373
FXUS61 KRNK 170235
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
935 PM EST THU JAN 16 2025
SYNOPSIS
FRONT PUSHES EAST TO THE COAST THIS EVENING WITH SNOW SHOWERS
OVER THE MOUNTAINS AND GUSTY WINDS ACROSS MOST OF THE AREA
THROUGH EARLY OVERNIGHT. HIGH PRESSURE WILL EXPAND TO COVER THE
MID- ATLANTIC FRIDAY. A LARGE STORM SYSTEM WILL BRING
WIDESPREAD PRECIPITATION FRIDAY NIGHT INTO SATURDAY IN ADVANCE
OF AN ARCTIC AIRMASS THAT WILL ARRIVE ON SUNDAY.
NEAR TERM /THROUGH FRIDAY/
AS OF 920 PM EST THURSDAY...
KEY MESSAGES:
1) WINTER STORM WARNING DOWNGRADED TO ADVISORY FOR R WESTERN
GREENBRIER TONIGHT FOR UP TO 2 INCHES OF ADDITIONAL SNOW.
2) WINTER WEATHER ADVISORY CANCELLED FOR MERCER AND SUMMER
COUNTIES.
3) A WIND ADVISORY IS IN EFFECT FOR MUCH OF THE BLUE RIDGE
TONIGHT.
HAVE DROPPED THE WINTER STORM WARNING TO AN ADVISORY FOR WESTERN
GREENBRIER AS CALLS MADE UP THAT WAY SHOW ONLY A DUSTING TO NO
MORE THAN AN INCH HAVE FALLEN SO FAR FOR THIS EVENING, WHICH WE
WERE EXPECTING MORE WITH THE WARM FRONT, AND NOW ONLY SNOW
SHOWERS WILL BRING MAYBE 2 INCHES OVER THE NORTHWEST PARTS OF
GREENBRIER AS THE UPPER SHORTWAVE IS ALREADY PUSHING AWAY AND
THERE IS NO GOOD LAKE CONNECTION TO BE HAD, WITH WINDS TURNING
MORE WEST AS THE NIGHT PROGRESSES. FURTHER SOUTH, NO MORE THAN A
DUSTING EXPECTED SO DROPPED THE ADVISORY FOR MERCER AND SUMMERS.
WINDS WILL BE STRONGEST FROM NOW UNTIL MIDNIGHT, THEN SHOULD SEE
A DIMINISHING TREND OVERNIGHT. NO CHANGES TO THE WIND ADVISORY.
PREVIOUS DISCUSSION...
THE SNOW EXPECTED WITH THE WARM FRONT AHEAD OF THE CLIPPER
SYSTEM WAS A NO-SHOW FOR OUR AREA THROUGH THE AFTERNOON, AS MAIN
AXIS OF MOISTURE STAYED FURTHER NORTH. WILL BE RELYING MORE ON
UPPER DISTURBANCE THIS EVENING AND UPSLOPE, WHICH FOR NOW DOES
NOT SEEM IT WILL BE ENOUGH FOR WARNING CRITERIA. HOWEVER, SOME
LOW LEVEL INSTABILITY MAY ALLOW FOR HEAVIER SNOW SHOWERS, SO FOR
NOW, WILL LEAVE HEADLINE AS IS.
BEST LOW LEVEL JET ARRIVES BY 11PM, THEN LETTING UP TOWARD 4AM,
SO NO CHANGES TO THE WIND ADVISORY.
PREVIOUS DISCUSSION...
SATELLITE IMAGERY INDICATES SUNSHINE FOR MUCH OF THE LOWER MID-
ATLANTIC, WITH SOUTHWESTERLY WINDS IN PLACE AHEAD OF AN
APPROACHING UPPER LEVEL DISTURBANCE. THE DISTURBANCE WILL MOVE
ACROSS THE MOUNTAINS THIS EVENING SHORTLY AFTER SUNSET,
RESULTING IN UPSLOPE SNOW SHOWERS AFFECTING MAINLY PORTIONS OF
SOUTHEAST WEST VIRGINIA INTO THE ALLEGHANY HIGHLANDS AND THE NEW
RIVER VALLEY. STILL RUNNING WITH A WINTER STORM WARNING FOR
WESTERN GREENBRIER COUNTY, WHERE 4 TO 6 INCHES OF SNOW IS
FORECAST, WITH LOCALLY HIGHER AMOUNTS. UP TO 3 INCHES REMAIN IN
THE FORECAST FOR MERCER AND SUMMERS COUNTIES, WHERE A WINTER
WEATHER ADVISORY REMAINS IN PLACE.
THE DISTURBANCE WILL ALSO BRING A BRIEF PERIOD OF STRONG WINDS
ACROSS THE CENTRAL APPALACHIANS, BRINGING 45 TO 50 MPH GUSTS
ACROSS THE HIGHER RIDGES FROM WATAUGA COUNTY THROUGH THE
SOUTHERN SHENANDOAH VALLEY. THE WINDOW FOR THESE WINDS ARE
SHORT HOWEVER AS THE DISTURBANCE MOVES QUICKLY AWAY TO THE EAST
OVERNIGHT, AND HAVE THEREFORE ISSUED A WIND ADVISORY IN EFFECT
FROM 7 PM THIS EVENING THROUGH 4 AM FRIDAY.
ONCE THE DISTURBANCE BEGINS TO EXIT TO THE EAST OVERNIGHT, HIGH
PRESSURE WILL QUICKLY FILL IN FROM THE WEST. THIS WILL RESULT
IN DECREASING WIND SPEEDS, IN ADDITION TO DIMINISHING MOUNTAIN
SNOW SHOWER ACTIVITY AND DECREASING CLOUDS AS DAWN APPROACHES.
UPPER LEVEL RIDGING PASSING ACROSS THE REGION ON FRIDAY,
COMBINED WITH SUNSHINE AND WINDS SHIFTING FROM THE SOUTH WILL
MAKE FOR NEAR-NORMAL AFTERNOON TEMPERATURES. HIGHS WILL RANGE
FROM THE MID 30S ALONG THE INTERSTATE 64 CORRIDOR WEST OF
LEXINGTON, TO THE MID/UPPER 40S ACROSS THE PIEDMONT.
KEEPING AN EYE ON AN APPROACHING DISTURBANCE
SHORT WAVE CROSSING THROUGH THE LONG WAVE EASTERN UNITED STATES
TROUGH WILL MOVE THROUGH THE MID ATLANTIC AREA TODAY AND TONIGHT.
THE BEST SYNOPTIC SCALE LIFT WITH THE UPPER JET AND POSITIVE
VORTICITY ADVECTION, FOLLOWED BY UPSLOPE LIFT WILL BE IN THE 10AM-
10PM TIME FRAME. ENOUGH LIQUID EQUIVALENT PRECIPITATION, AROUND 0.5
INCHES AND LARGE ENOUGH SNOW RATIOS, ROUGHLY 15:1 TO GET SNOW
ACCUMULATIONS IN SOUTHEAST WEST VIRGINIA OF 2 TO 8 INCHES. SOME
LOCALLY HIGHER AMOUNTS ARE POSSIBLE IN WESTERN GREENBRIER COUNTY.
ALSO MODELS ARE SUGGESTING SOME RELATIVE INSTABILITY THIS AFTERNOON
THAT MAY BE ENOUGH FOR SNOW SQUALLS OR AT LEAST NARROW BANDS OF
HEAVIER SNOWFALL RATES. COLDER AIR ALOFT DOES ARRIVE IN THE AREA
AROUND THAT TIME. BIGGEST QUESTION IS THE AMOUNT OF MOISTURE. THE
AIR MASS IS STARTING THE DAY WELL BELOW 0.25 INCHES OF PRECIPITABLE
WATER AND SOME OF THE EARLY SNOWFALL MAY GO INTO SATURATING THE AIR
MASS INSTEAD OF ACCUMULATING. BUT, EVENTUALLY THE PRECIPITABLE WATER
VALUES ARE BACK UP AROUND 0.25 INCHES. LATEST HRRR HAS THE SNOW
REACHING MOST OF SOUTHEAST WEST VIRGINIA BETWEEN 7AM AND 10AM.
THIS FEATURE GOES BY WITH THE 500MB TROUGH AXIS TO THE EAST BY
FRIDAY MORNING. WINDS TURN TO THE WEST AND NORTHWEST TONIGHT. THE
LOW LEVEL JET INCREASES THIS EVENING WITH THE STRONGEST 850MB WIND
FROM 00Z/7PM TO 06Z/1AM WITH GOOD PRESSURE RISES, 5-8MB IN 6 HOURS
AT THE SAME TIME. WILL ASSESS AGAIN TODAY TO DETERMINE IF A WIND
ADVISORY IS NEEDED ALONG THE SOUTHERN BLUE RIDGE. WIND SPEEDS DROP
OFF QUICKLY BY FRIDAY MORNING. BY THEN SURFACE HIGH PRESSURE
DIRECTLY OVER THE CENTRAL AND SOUTHERN APPALACHIANS.
UPPER RIDGING ON FRIDAY AND MORE SUNSHINE WILL RESULT IN
TEMPERATURES AROUND NORMAL. STAYED CLOSE TO A NBM/LAV GUIDANCE BLEND
FOR HIGHS AND LOWS THROUGH THIS PERIOD.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
AS OF 220 PM EST THURSDAY...
KEY MESSAGES:
1) WINTRY MIX OF SNOW, SLEET, AND FREEZING RAIN EXPECTED
SATURDAY MORNING BECOMING MOSTLY RAIN BY AFTERNOON.
2) WINDY, BECOMING BITTERLY COLD, WITH MOUNTAIN SNOW SHOWERS
MONDAY INTO TUESDAY.
A VIGOROUS SOUTHERN STREAM SHORTWAVE AHEAD OF A DEEPENING
EASTERN U.S. TROUGH WILL MOVE THROUGH THE REGION SATURDAY
MORNING, BRINGING PRECIPITATION TO THE REGION. AT THE ONSET TIME
OF THIS PRECIPITATION AROUND DAYBREAK SATURDAY, TEMPERATURES
WILL BE IN THE MID 20S TO LOWER 30S ACROSS THE CWA. A WEAK WARM
NOSE IS EVIDENT IN THE MODEL SOUNDINGS SUGGESTING THAT
PRECIPITATION WILL TRANSITION FROM SNOW, TO SLEET, TO
POTENTIALLY FREEZING RAIN IN THE SOUTHERN PARTS OF THE CWA.
TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING BY LATE MORNING
INTO THE EARLY AFTERNOON ALLOWING ALL PRECIPITATION TO CHANGE
OVER TO RAIN. THE LIMITED DURATION OF FROZEN/FREEZING
PRECIPITATION AND THE LIMITED QPF OVERALL FROM HAVING TO
OVERCOME AN ANTECEDENT DRY AIR MASS, WILL LIMIT ICE/SNOW
ACCUMULATIONS. NONETHELESS, COULD CERTAINLY SEE A SCENARIO WHERE
A WINTER WEATHER ADVISORY WILL BE WARRANTED WITH LATER
FORECASTS FOR MUCH OF THE CWA DURING THE LATE FRIDAY
NIGHT/SATURDAY MORNING TIME FRAME. TEMPERATURES SHOULD TOP OUT
IN THE UPPER 30S TO LOWER 40S BY AFTERNOON WITH JUST WEAK
WEDGING. QPF LOOKS TO BE IN THE 1/4 TO 1/3 INCH RANGE, THUS AN
INCH OR SO OF SNOW/SLEET/FREEZING RAIN MIXTURE WILL BE POSSIBLE
DURING THE MORNING HOURS.
THE PASSAGE OF THIS INITIAL SHORT WAVE WILL QUICKLY RESULT IN
FURTHER DEEPENING OF THE UPPER TROUGH ACROSS THE EASTERN U.S.
AND ALSO BRING THE FIRST SURGE OF WHAT WILL PROVE TO BE THE
COLDEST ARCTIC AIR TO VISIT THIS REGION IN SEVERAL YEARS.
PRECIPITATION ALONG/EAST OF THE BLUE RIDGE WILL MOSTLY END BY
SATURDAY EVENING AND TRANSITION TO TYPICAL UPSLOPE SNOW SHOWERS.
ON MONDAY, THE FIRST OF TWO BRUTALLY COLD SURGES OF ARCTIC AIR
WILL SETTLE OVER THE AREA IN THE FORM OF A 1044MB ARCTIC HIGH.
THIS FIRST SURGE WILL PALE IN COMPARISON TO THE NEXT MIDWEEK
SURGE. LOOK FOR A NON-DIURNAL TEMPERATURE TREND ON MONDAY WITH
STRONG COLD ADVECTION ALL DAY AS 850MB TEMPERATURES PLUMMET FROM
-4C EARLY IN THE DAY TO NEARLY -20C BY THE END OF THE DAY.
/CONFIDENCE LEVELS IN FORECAST PARAMETERS/
- MODERATE TO HIGH CONFIDENCE IN TEMPERATURES,
- MODERATE CONFIDENCE IN PRECIPITATION PROBABILITIES,
- MODERATE CONFIDENCE IN WIND SPEED, HIGH CONFIDENCE IN WIND
DIRECTION.
LONG TERM /MONDAY THROUGH THURSDAY/
AS OF 245 PM EST THURSDAY...
KEY MESSAGES:
1). BITTERLY COLD WITH DANGEROUSLY LOW WIND CHILLS THROUGH THE
PERIOD.
2). POTENTIAL SNOW EVENT JUST BEHIND THIS PERIOD...NEED TO WATCH
CLOSELY.
TRULY ONE OF THE COLDEST AIR MASSES TO VISIT THE REGION IN MANY
YEARS WILL SPREAD ACROSS MUCH OF THE EASTERN U.S. DURING THE MID
PART OF NEXT WEEK. LOOKING FOR 850 MB TEMPERATURES TO RANGE
ANYWHERE FROM -20C TO -25C FROM THE MIDWEST TO THE MID-
ATLANTIC TO SETTLE OVER THE FORECAST AREA AS A 1050+ MB SURFACE
HIGH DRIFTS SOUTHEAST OUT OF CANADA BY MIDWEEK. A LARGE CORE OF
-30C TEMPERATURES IS NOTED WITHIN THE CENTER OF THIS FRIGID AIR
MASS, LARGER THAN I HAVE SEEN IN SEVERAL YEARS. THIS WILL
EVENTUALLY BE VERY CLOSE TO THE CWA MIDWEEK.
LOOK FOR MULTIPLE DAYS WITH HIGHS WELL BELOW FREEZING AND LOWS
NEAR TO EVEN BELOW ZERO DURING THE LATER HALF OF THE WEEK. PLAN
ACCORDINGLY FOR SOME OF THE COLDEST TEMPERATURES OF LONG
DURATION IN SEVERAL YEARS. THIS WILL BE COLDER THAN THE SPELL
DURING CHRISTMAS 2022. WIND CHILLS WILL BE DANGEROUSLY LOW
MULTIPLE MORNINGS IN A ROW.
FINALLY, KEEPING AN EYE ON A POTENTIAL WINTER STORM FOR NEXT
WEEKEND. WILL LEAVE THAT DISCUSSION FOR LATER.
/CONFIDENCE LEVELS IN FORECAST PARAMETERS/
- HIGH CONFIDENCE IN TEMPERATURES,
- MODERATE CONFIDENCE IN PRECIPITATION PROBABILITIES,
- HIGH CONFIDENCE IN WIND DIRECTION AND SPEED.
AVIATION /03Z FRIDAY THROUGH TUESDAY/
AS OF 635 PM EST THURSDAY...
VFR FOR MOST OF THE AREA THROUGH THE PERIOD. EXCEPTION WILL BE
IFR TO MVFR CIGS AND VSBYS AT BLF WITH SNOW SHOWERS THROUGH 12Z,
WITH MAINLY MVFR AT LWB. MAY SEE MVFR CIGS AT BCB AS WELL
BETWEEN 02-08Z. WEST WINDS WILL PICK UP AND GUST 20-30KTS ACROSS
THE MOUNTAINS BETWEEN 02Z-09Z, WITH LESS WIND IN THE LYH/DAN
AREA.
HIGH PRESSURE BUILDS IN BRINGING VFR BACK TO THE MOUNTAINS AND
LOWERING THE WIND SPEEDS BY MIDDAY FRIDAY.
AVIATION OUTLOOK...
CLOUDS WILL INCREASE AGAIN FRIDAY EVENING AS AN APPROACHING LOW
PRESSURE SYSTEM IS EXPECTED TO BRING WIDESPREAD PRECIPITATION
AND POOR FLYING CONDITIONS FRIDAY NIGHT AND SATURDAY ACROSS THE
REGION. SUB-VFR CONDITIONS WILL PERSIST THROUGH SUNDAY WITH
UPSLOPE SNOW SHOWERS IN THE MOUNTAINS.
MONDAY AND TUESDAY WILL BE UNSEASONABLY COLD, DRY AND VFR.
RNK WATCHES/WARNINGS/ADVISORIES
VA...WIND ADVISORY UNTIL 4 AM EST FRIDAY FOR VAZ007-009>020-022>024-
032>035.
NC...WIND ADVISORY UNTIL 4 AM EST FRIDAY FOR NCZ001-002-018.
WV...WINTER WEATHER ADVISORY UNTIL 7 AM EST FRIDAY FOR WVZ508.
SYNOPSIS...AMS/NF/WP
NEAR TERM...AMS/NF/WP
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...AMS/NF/WP
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