218
FXUS61 KRNK 201042
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
542 AM EST FRI DEC 20 2024
SYNOPSIS
LOW PRESSURE OVER THE UPPER MISSISSIPPI VALLEY WILL MOVE ACROSS
THE OHIO VALLEY TODAY THEN OFF THE NEW ENGLAND COAST BY
SATURDAY BRINGING SNOW TO THE MOUNTAINS. COLDER TEMPERATURES
WITH HIGH PRESSURE FOLLOW FOR THE WEEKEND. TEMPERATURES WARM ON
MONDAY AND TUESDAY AHEAD OF A LOW PRESSURE PRESSURE SYSTEM OVER
THE SOUTHERN PLAINS.
NEAR TERM /THROUGH TONIGHT/
AS OF 145 AM EST FRIDAY...
KEY MESSAGES:
1) SNOW ARRIVES FOR THE MOUNTAINS THIS AFTERNOON AND LINGERS
OVERNIGHT.
2) COLDER TEMPERATURES AND GUSTY WINDS TONIGHT.
A POTENT CLIPPER SYSTEM WILL CROSS THE REGION THIS AFTERNOON AND
EVENING BRINGING PERIODS OF MODERATE SNOW ACROSS THE MOUNTAINS.
CURRENT WATER VAPOR SHOWS A DEEPENING TROUGH ACROSS THE MIDDLE
MISSISSIPPI VALLEY THIS MORNING. INITIAL LEADING SHORTWAVE WILL
CROSS THE AREA AROUND DAYBREAK, POSSIBLY RESULTING IN LIGHT
PRECIPITATION ACROSS SOUTHEAST WEST VIRGINIA AND INTO SOUTHWEST
VIRGINIA. THIS MAY PRODUCE SOME LIGHT DRIZZLE/RAIN AND/OR SNOW
SHOWERS, EVENTUALLY DEPARTING NORTHEAST BY LATE MORNING.
MORE WIDESPREAD RAIN/SNOW ARRIVES LATER THIS AFTERNOON AND
EVENING ASSOCIATED WITH A QUICK MOVING AND RATHER POTENT
VORTMAX. SHOULD SEE PRECIPITATION REACH THE WESTERN MOUNTAINS
AROUND 3PM, THEN SPREAD EAST INTO THE 81 CORRIDOR AROUND EVENING
RUSH HOUR. COVERAGE WILL GRADUALLY DECREASE AFTER 8PM, CONFINED
AGAIN TO MAINLY JUST THE WESTERN SLOPES.
TAKING A LOOK AT THERMAL PROFILES OFF OF RECENT HI-RES GUIDANCE,
PRECIPITATION MAY START AS RAIN WITH ABOVE FREEZING
TEMPERATURES IN THE LOWEST FEW THOUSAND FEET IN THE UPPER 30S TO
LOWER 40S, BUT SHOULD QUICKLY TRANSITION TO SNOW IN THE HIGHER
ELEVATIONS ABOVE 2500FT. STRONG LIFT ASSOCIATED WITH THE
PASSAGE UP THE UPPER VORT COULD RESULT IN SOME HEAVIER SNOW
SQUALLS BETWEEN 4PM AND 6PM. THESE COULD QUICKLY REDUCE
VISIBILITY AND COAT ROADWAYS, MAKING TRAVEL TREACHEROUS WITHIN A
VERY SHORT WINDOW OF TIME.
SINCE TEMPERATURES WILL BE MARGINAL, THE HIGHEST CONFIDENCE FOR
ACCUMULATING SNOW WILL BE ELEVATIONS 2500FT OR HIGHER IN THE
FAVORED WESTERN MOUNTAINS FROM THE NORTH CAROLINA MOUNTAINS UP
INTO SOUTHEAST WEST VIRGINIA. GENERALLY EXPECTING 1 TO 2 INCHES
WITH HIGHER AMOUNTS INTO THE 2 TO 4 INCHES RANGE IN WESTERN
GREENBRIER. NO CHANGES TO THE CURRENT WINTER HEADLINES ARE
ANTICIPATED.
LOWS TONIGHT FALL INTO THE 20S AND LOW 30S WITH GUSTY NORTHWEST
WINDS 20 TO 30MPH IN THE HIGHER ELEVATIONS. THIS COULD RESULT IN
WIND CHILLS IN THE LOW 20S AND TEENS.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
AS OF 500 AM EST FRIDAY...
KEY MESSAGES:
1). A FRESH ARCTIC SURGE TO BRING MUCH BELOW NORMAL TEMPERATURES
BACK TO THE AREA FOR THE WEEKEND CONTINUING INTO EARLY NEXT
WEEK.
2). CLIPPER-LIKE NORTHWEST FLOW SYSTEM TO BRING ACCUMULATING
SNOW TO THE WESTERN MOUNTAINS.
A DEEP TROUGH WILL PROGRESS SLOWLY ACROSS THE EASTERN U.S.
DURING THE WEEKEND. WITHIN THIS TROUGH, A VIGOROUS UPPER-LEVEL
DISTURBANCE WILL TRACK THROUGH THE BASE OF THE TROUGH AND THEN
NORTHEAST TOWARD THE MID-ATLANTIC. WITH TIME, LOW PRESSURE WILL
DEVELOP OFF THE DELMARVA AND RACE NORTHEAST INTO NEW ENGLAND.
THIS WILL HELP TO PULL THE SNOW SHOWER ACTIVITY NORTHEAST AWAY
FROM OUR REGION FAIRLY QUICKLY DURING SATURDAY MORNING.
OTHERWISE, AS 850MB TEMPERATURES PLUNGE FROM AROUND 0C TO -12C
THROUGH SATURDAY ON THE HEELS OF GUSTY NORTHWEST WINDS, LOOK FOR
A VERY COLD WEEKEND WITH MANY AREAS WEST OF THE BLUE RIDGE
REMAINING AT OR BELOW FREEZING THROUGH THE WEEKEND WITH LOW
TEMPERATURES IN THE TEENS AT NIGHT. TEMPERATURES THROUGH THE
WEEKEND WILL AVERAGE AROUND 10 DEGREES BELOW NORMAL FOR MAXIMUM
LEVELS AND ABOUT 5 DEGREES BELOW NORMAL FOR MINIMUM LEVELS. WIND
CHILL READINGS APPROACH ZERO ACROSS THE HIGHER MOUNTAINS TERRAIN
IN THE WEST PART OF THE CWA. GREENBRIER COUNTY WV MAY NEED A
COLD WEATHER ADVISORY.
/CONFIDENCE LEVELS IN FORECAST PARAMETERS/
- MODERATE TO HIGH CONFIDENCE IN TEMPERATURES,
- MODERATE CONFIDENCE IN PRECIPITATION PROBABILITIES,
- MODERATE TO HIGH CONFIDENCE IN WIND SPEED AND DIRECTION.
LONG TERM /MONDAY THROUGH THURSDAY/
AS OF 530 AM EST FRIDAY...
KEY MESSAGES:
1). BACK TO A WET, INCREASINGLY UNSETTLED WEATHER PATTERN FOR
MUCH OF THE NEW WORK WEEK,
2) TEMPERATURES SLOWLY MODERATE TO NEAR NORMAL LEVELS AGAIN BY
THE END OF THE WEEK.
LINGERING ARCTIC AIR WILL SLOWLY RETREAT NORTHEAST AWAY FROM THE
REGION DURING THE CHRISTMAS WEEK. THE UPPER-LEVEL FLOW WILL
BECOME INCREASINGLY ZONAL AS THE SOUTHERN STREAM BECOMES
INCREASINGLY ACTIVE. A SERIES OF VIGOROUS UPPER-LEVEL SHORT
WAVES WILL TRACK THROUGH THE SOUTHERN STREAM ACROSS THE
SOUTHWEST U.S. INTO THE MIDSOUTH AND THEN HEAD NORTHEAST INTO
OUR REGION AS A SUBTROPICAL RIDGE OFF THE SOUTHEAST U.S. COAST
SHUNTS THESE SYSTEMS NORTHWARD. THE FIRST SYSTEM WILL ARRIVE
CHRISTMAS DAY AND LINGER INTO THE 26TH. ANOTHER STRONG SHORT
WAVE WILL ARRIVE ON THE HEELS OF THE FIRST ONE EARLY THE
FOLLOWING WEEK. WIDESPREAD PRECIPITATION, MOSTLY RAIN, IS
EXPECTED WITH BOTH OF THESE SYSTEMS AS 850MB TEMPERATURES RETURN
TO TYPICAL LEVELS. SOME LIGHT FREEZING RAIN/SLEET MAY BE
POSSIBLE AT THE BEGINNING OF THIS LONG DURATION RAIN EVENT IN
THE FORM OF HEAVY RAINFALL IN NORTHWEST NC ESPECIALLY.
TEMPERATURES WILL TREND TOWARD NORMAL READINGS BUT REMAIN ON THE
CHILLY SIDE WITH HIGHS MOSTLY IN THE 30S AND 40S AND LOWS IN THE
20S AND 30S.
/CONFIDENCE LEVELS IN FORECAST PARAMETERS/
- MODERATE CONFIDENCE IN TEMPERATURES,
- MODERATE TO HIGH CONFIDENCE IN PRECIPITATION PROBABILITIES,
- MODERATE CONFIDENCE IN WIND DIRECTION AND SPEED.
SYNOPSIS...BMG
NEAR TERM...BMG
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...BMG
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