084
FXUS61 KLWX 160210
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
910 PM EST SUN DEC 15 2024
SYNOPSIS
OFF AND ON RAIN WILL CONTINUE OVERNIGHT WITH LIGHT FREEZING RAIN
POSSIBLE AT HIGHER ELEVATIONS. PRECIPITATION CHANCES DECREASE
BRIEFLY MONDAY AFTERNOON BEFORE RETURNING AS A COLD FRONT
PASSES THROUGH THE FORECAST AREA MONDAY NIGHT AND INTO TUESDAY.
ANOTHER FRONTAL SYSTEM IS FORECAST TO IMPACT THE AREA MIDWEEK
AHEAD OF HIGH PRESSURE BRIEFLY BUILDING OVERHEAD THURSDAY. LOW
PRESSURE MOVING OVER THE GREAT LAKES BRINGS PRECIPITATION
CHANCES BACK TO THE AREA FOR THE END OF THE WEEK.
NEAR TERM /UNTIL 7 AM MONDAY MORNING/
RADAR LOOP AS OF 8:45PM SHOWS ON AND OFF PRECIPITATION MOVING
ACROSS THE FORECAST AREA WITH SURFACE OBSERVATIONS INDICATING LOW
CEILINGS AND REDUCED VISIBILITIES. HAVE STARTED CANCELING THE
WINTER WEATHER ADVISORIES FOR THE SOUTHERN PORTIONS OF THE AREA
(EXCEPTION BEING THE BLUE RIDGE ZONES AT HIGHER ELEVATIONS) AS
TEMPERATURES HAVE WARMED AND PRECIPITATION HAS TRANSITIONED TO
RAIN. FREEZING RAIN IS CONTINUING TO BE OBSERVED FURTHER NORTH
AND AT HIGHER ELEVATIONS SO WILL CONTINUE WITH REMAINING WINTER
WEATHER HEADLINES FOR NOW. ADDITIONALLY, TEMPERATURES ALOFT HAVE
WARMED LEADING TO SNOW BEING REMOVED FROM THE FORECAST.
PREVIOUS DISCUSSION: SURFACE TEMPERATURES ALONG THE RIDGES TO
THE SOUTH OF OUR AREAS HAVE RISEN ABOVE FREEZING AS THE CAD
WEDGE SLOWLY ERODES FROM SOUTH TO NORTH. THE HIGHER RIDGES OF
THE BLUE RIDGE IN OUR AREA LIKELY REMAIN NEAR OR BELOW FREEZING
FOR AT LEAST A FEW MORE HOURS, IF NOT UNTIL AFTER SUNSET. HIGHER
ELEVATIONS TO THE WEST (OUTSIDE OF THE COLD POCKET AROUND
FROSTBURG/CUMBERLAND) WILL GRADUALLY WARM ABOVE FREEZING THROUGH
THE NIGHT.
AFTER THE BULK OF PRECIP CURRENTLY MOVING THROUGH, LIGHTER
PRECIP IS EXPECTED LATER THIS AFTERNOON AND INTO TONIGHT. PRECIP
TYPE WILL TRANSITION TO PURE RAIN FROM SOUTH TO NORTH AS WAA
WINS OUT, THOUGH FREEZING RAIN COULD LINGER A BIT LONGER FOR THE
HIGHEST RIDGES. PRECIP CHANCES WILL BE TAPERING OFF LATE
TONIGHT. WITH WAA, TEMPERATURES WILL WARM THROUGH THE NIGHT
NON-DIURNALLY, TO MID 30S AND LOW 40S IN THE LOWLANDS AND LOW
30S AT HIGHER ELEVATIONS. FOG BECOMES A CONCERN AS PRECIP
TERMINATES, AND COULD BECOME LOCALLY DENSE, ESPECIALLY IN AREAS
EAST OF THE MOUNTAINS THAT CLEAR SOME CLOUDS WITH DOWNSLOPING.
SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/
AS THE SHORTWAVE MOVES NORTHEAST, PRECIP FROM THE FIRST SYSTEM
IS EXPECTED TO END BY MONDAY AFTERNOON. HIGHER ELEVATIONS AND A
COLD POCKET NEAR CUMBERLAND COULD STILL SEE FREEZING
RAIN/DRIZZLE EARLY MONDAY MORNING.
A TROUGH SWIFTLY APPROACHES FROM THE WEST TO BRING ANOTHER
ROUND FOR MONDAY AFTERNOON INTO MONDAY NIGHT. THIS ROUND IS
EXPECTED TO BE PURE RAIN WITH TEMPERATURES REBOUNDING TO THE 40S
AND 50S. THOUGH HIGH PRESSURE TO OUR NORTHEAST WILL HAVE BEGUN
TO MOVE OFF, THE CAD WEDGE LIKELY STILL LINGERS TO SOME DEGREE
WITHOUT A FRONT TO SWEEP OUT THE MODIFIED COLD AIR MASS, SO
TEMPS COULD RUN COOLER. THERE REMAINS SOME UNCERTAINTY WITH HOW
FAR SOUTH THE SHOWERS WILL GET, WITH GUIDANCE DIFFERING ON THE
AMPLITUDE OF THE UPPER TROUGH. CURRENTLY THE ALLEGHENIES AND
NORTH-CENTRAL MARYLAND SEEM TO HAVE THE BEST SHOT AT PRECIP,
WITH ABOUT 0.25-0.50 INCH QPF BETWEEN MONDAY AFTERNOON AND
TUESDAY MORNING. SOUTHERLY WINDS PICK UP THROUGH THE DAY MONDAY
AHEAD OF AN APPROACHING FRONT, RESULTING IN 15-20 MPH GUSTS AT
THE HIGHER ELEVATIONS BY THE EVENING. OVERNIGHT, WINDS GUST
15-20 MPH FOR MOST OF THE AREA, AND UP TO 40 MPH AT THE HIGHEST
RIDGES.
A WEAK FRONT MOVES THROUGH TUESDAY, BUT WITH STRONG ENOUGH W/NW
FLOW TO HOPEFULLY FORCE OUT THE REMNANTS OF THE CAD WEDGE. AS A
RESULT, TEMPERATURES ARE EXPECTED TO RAMP UP INTO THE 50S AND
60S FOR MOST OF THE AREA, AND THE THE 40S IN THE MOUNTAINS.
BRIEF HIGH PRESSURE WILL ALLOW OVERNIGHT TEMPS TO DROP INTO THE
30S AND 40S BEFORE CLOUDS BEGIN TO INCREASE LATE IN THE NIGHT
AHEAD OF THE NEXT SYSTEM.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
SURFACE HIGH PRESSURE WILL REMAIN ACROSS THE NORTHERN MID-ATLANTIC
AS ANOTHER TROUGH OF LOW PRESSURE AND COLD FRONT MOVE THROUGH THE
REGION MIDWEEK. WARMER CONDITIONS ARE EXPECTED IN ADVANCE OF THIS
STORM SYSTEM LEADING TO A PREDOMINANTLY RAIN EVENT. SURFACE LOW
PRESSURE LOOKS TO TRACK NORTH AND EAST FROM THE MID-SOUTH WEDNESDAY
MORNING SENDING A WARM FRONT NORTHWARD INTO THE AREA. THE SURFACE
LOW PER THE LATEST 12Z GUIDANCE LOOKS TO WORK ACROSS THE CENTRAL
APPALACHIANS AND OFF THE NEW ENGLAND COAST LATE WEDNESDAY INTO
THURSDAY. AS THE LOW TRACKS NORTH AND EAST, IT'S ASSOCIATED COLD
FRONT WILL SWING THROUGH THE AREA LATE WEDNESDAY INTO THURSDAY. HIGH
TEMPERATURES AHEAD OF THIS BOUNDARY WILL PUSH INTO THE MID TO UPPER
50S AND LOW 60S WITH UPPER 40S OVER THE MOUNTAINS. TEMPERATURES WILL
FALL INTO THE UPPER 20S AND LOW TO MID 30S WEDNESDAY NIGHT AS POST
FRONTAL NORTHWEST FLOW ENSUE.
12Z DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUE TO SUGGESTS SOME
SNOW MIXING IN AT THE TAIL END OF THE EVENT ACROSS THE NORTHWESTERN
HALF OF THE FORECAST AREA. CONFIDENCE IN THIS IS LOW GIVEN HOW MUCH
MOISTURE MAY LINGER. HIGHEST CONFIDENCE FOR ANY WINTRY PRECIPITATION
LOOKS TO REMAIN WEST OF THE ALLEGHENIES MIDWEEK GIVEN THE POST
FRONTAL NORTHWEST FLOW ALOFT AND SEVERAL PIECES OF WEAK SHORTWAVE
INGER PIVOTING THROUGH IN THE WAKE OF THE DEPARTING TROUGH. A BRIEF
LULL IS EXPECTED IN THE WAKE OF THE TROUGH THURSDAY AFTERNOON AND
NIGHT BEFORE ANOTHER FRONT APPROACHES FRIDAY INTO THE START OF THE
WEEKEND.
THIS STORM SYSTEM LOOKS MORE LIKE A CLIPPER WITH LOW PRESSURE
ANCHORED OVER THE EASTERN GREAT LAKES ADVANCING EASTWARD THROUGH
SOUTHERN CANADA AND THE INTERIOR NORTHEAST REGION. MEANWHILE, LOW
PRESSURE WILL SIT OFFSHORE WITH A SHORTWAVE TROUGH HUGGING THE COAST.
THE TRAILING COLD FRONT WILL KEEP THE TROUGH OFFSHORE WHILE LENDING
TO THE CONTINUATION OF UPSLOPE SNOW SHOWERS OVER THE MOUNTAINS. EVEN
WITH THAT SAID, THE COMBINATION OF THE COASTAL TROUGH AND INCOMING
COLD FRONT MAY LEAD TO A BRIEF PERIOD OF RAIN/SNOW SHOWERS OVER
NORTHWESTERN PORTIONS OF THE FORECAST AREA FRIDAY. CONFIDENCE ONCE
AGAIN IS LOW DUE TO SUBTLE MODEL DIFFERENCES.
THE BIGGER STORY WITH THE LATE WEEK FRONT WILL BE THE COLD WITH WELL
BELOW NORMAL TEMPERATURES EXPECTED THIS WEEKEND. HIGHS SUNDAY MAY
BE THE COLDEST OF THE SEASON THUS FAR. SINGLE DIGIT TO TEENS WIND
CHILLS POSSIBLE FRIDAY THROUGH SUNDAY, ESPECIALLY OVERNIGHT AND
EARLY IN THE MORNING.
AVIATION /02Z MONDAY THROUGH FRIDAY/
ON AND OFF PRECIPITATION WILL CONTINUE OVERNIGHT AT ALL
TERMINALS, RESULTING IN FLIGHT RESTRICTIONS. EASTERN TERMINALS
CAN EXPECT LOSSES IN VSBY, BUT MAYBE NOT QUITE AS LOW WITH RAIN
RATHER THAN SNOW. WINTRY PRECIP IS MOST LIKELY FOR MRB OVER THE
NEXT FEW HOURS, AND COULD BE OBSERVED AT CHO OFF AND ON BEFORE
THE CAD WEDGE IS FORCED NORTH.
ONCE SOCKED IN TONIGHT, IFR CONDITIONS LIKELY CONTINUE THROUGH
SUNDAY NIGHT AND WELL INTO MONDAY AS COLD AIR DAMMING CONTINUES.
SOUTHERLY FLOW INCREASES AHEAD OF AN APPROACHING FRONT MONDAY
NIGHT, WITH GUSTS TO AROUND 20 KTS. THE FRONT MOVES THROUGH
TUESDAY MORNING, FINALLY PUSHING OUT THE CAD WEDGE AND HOPEFULLY
IMPROVING CONDITIONS. LIGHT W/NW FLOW FOLLOWS AS HIGH PRESSURE
BRIEFLY BUILDS IN.
SUB-VFR RESTRICTIONS ARE POSSIBLE WEDNESDAY AFTERNOON THROUGH
THURSDAY MORNING AS ANOTHER LOW PRESSURE SYSTEM BRINGS RAIN TO THE
REGION. VFR CONDITIONS ARE EXPECTED THURSDAY AFTERNOON THROUGH
FRIDAY BEFORE ANOTHER PERIOD OF SUB-VFR CONDITIONS RETURN WITH A
COLD FRONT LATER IN THE WEEK.
MARINE
EAST/NORTHEAST WINDS REMAIN LIGHT THROUGH TONIGHT. WINDS
INCREASE OUT OF THE SOUTH ON MONDAY AHEAD OF AN APPROACHING COLD
FRONT WHICH LIKELY NECESSITATE SCAS MONDAY NIGHT. BEHIND THE
COLD FRONT, WINDS DIMINISH AND TURN W/SW ON TUESDAY.
NO MARINE WIND HAZARDS ARE EXPECTED WEDNESDAY WITH SOUTHEASTERLY
WINDS GUSTING LESS THAN 15 KNOTS. SCAS ARE POSSIBLE OVER THE WATERS
THURSDAY IN POST-FRONTAL NORTHWEST FLOW. THE TIGHTENED GRADIENT BETWEEN
THE DEPARTING LOW AND INCOMING FRONTAL BOUNDARY LATER THIS WEEK WILL
LEAD TO A CONTINUATION OF SCAS FOR PORTIONS OF THE WATERS THROUGH
THE START OF THE WEEKEND.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR MDZ001-501.
WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR MDZ003-502.
VA...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR VAZ027-028-
031-503-507-508.
WV...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR WVZ501-503-505.
WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR WVZ050>053-
055-502-504.
MARINE...NONE.
SYNOPSIS...AVS
NEAR TERM...AVS/CAS
SHORT TERM...CAS
LONG TERM...EST
AVIATION...AVS/CAS/EST
MARINE...CAS/EST
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