084
FXUS61 KLWX 200240
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
940 PM EST THU DEC 19 2024
SYNOPSIS
AN AREA OF LOW PRESSURE AND COLD FRONT WILL IMPACT THE AREA
FRIDAY INTO EARLY SATURDAY BRINGING AN INCREASED CHANCE FOR
LIGHT RAIN AND SNOW. HIGH PRESSURE RETURNS LATE SATURDAY THROUGH
MONDAY WITH DRY AND COLD CONDITIONS. PRECIPITATION CHANCES
INCREASE WITH ANOTHER FRONT TUESDAY INTO THE MIDDLE OF NEXT
WEEK.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
CLOUDS WILL BE ON THE INCREASE FROM WEST TO EAST AS A LOW
PRESSURE SYSTEM APPROACHES FROM THE WEST. LIGHT WINDS WILL
SHIFT MORE OUT OF THE NORTHEAST TONIGHT AS THE LOW APPROACHES.
OVERNIGHT LOWS WILL BE IN THE MID TO UPPER 20S OUT WEST AND
UPPER 20S TO LOW 30S FURTHER EAST OF THE BLUE RIDGE MOUNTAINS
WITH DRY CONDITIONS CONTINUING.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/
TWO MAIN FEATURES ON FRIDAY WILL BRING PRECIPITATION ACROSS THE
MID-ATLANTIC. THE FIRST BEING A LOW OFF THE VA/NC COAST,
USHERING IN RAIN EARLY FRIDAY MORNING ALONG PORTIONS OF THE I-95
CORRIDOR AND AREAS JUST WEST. A CLIPPER SYSTEM WILL BE THE
OTHER FEATURE OF INTEREST THAT WILL BUILD IN FROM THE NORTHWEST
EARLY FRIDAY. WITH PRECIPITATION OVERLAPPING WITH COLDER
TEMPERATURES, THERE IS AN INCREASING CHANCE FOR SNOW SHOWERS,
ESPECIALLY ACROSS THE NORTHWESTERN PORTIONS OF THE AREA.
NOTABLY, 12Z GUIDANCE HAS BEGUN TO HINT AT A LOCAL MAXIMUM 12Z
TO 18Z FRIDAY FOR PORTIONS OF THE EASTERN WV PANHANDLE AND
WESTERN MD ESPECIALLY. MOST LIKELY TOTALS DURING THAT PERIOD FOR
THERE WOULD BE UP TO 1.5". THERE IS STILL SOME SPREAD IN THE
GUIDANCE REGARDING THIS FEATURE. FURTHER EAST, THERE WILL LIKELY
BE AN OPPORTUNITY EARLY IN THE MORNING AND AGAIN LATER THAT
NIGHT FOR A RAIN-SNOW MIX DEPENDING ON TEMPERATURES BUT RAIN
WILL BE THE MOST COMMON P-TYPE. THERE WILL LIKELY BE A LULL IN
PRECIPITATION DURING THE DAY BEFORE RETURNING FRIDAY NIGHT,
ESPECIALLY IN THE ALLEGHENY FRONT.
AS THESE SNOW SHOWERS CONTINUE INTO EARLY SATURDAY MORNING, THE
ALLEGHENIES ARE EXPECTED AT THIS TIME TO END UP WITH ANYWHERE
FROM 2 TO 5 INCHES OF SNOW. HEADLINES MAY BE NEEDED ACROSS THE
ALLEGHENY FRONT AND AREAS JUST EAST OF THERE BUT CONFIDENCE WAS
LOWER FOR THE MORNING COMMUTE TOTALS TO BE NEAR ADVISORY-LEVEL.
WILL REASSESS DURING THE SUBSEQUENT SHIFTS.
SURFACE HIGH BUILDS IN DURING THE DAY ON SATURDAY, LEADING TO
MOSTLY DRY CONDITIONS WITH HIGHS RANGING FROM THE LOW 20S ALONG
THE ALLEGHENY FRONT TO MID TO UPPER 30S CLOSER TO THE WATERS.
WITH THE HIGH PLACEMENT SATURDAY NIGHT, OVERNIGHT LOWS WILL FALL
INTO THE TEENS ACROSS MOST AREAS WITH EVEN SINGLE DIGITS ALONG
THE ALLEGHENY FRONT. WIND CHILLS WILL BE SEVERAL DEGREES COOLER
WITH SOME OF THE ALLEGHENIES GETTING INTO THE NEGATIVE SINGLE
DIGITS.
LONG TERM /SUNDAY THROUGH THURSDAY/
COLD AND DRY CONDITIONS LOOK TO CONTINUE THROUGH MONDAY AS STRONG
CANADIAN HIGH PRESSURE MAINTAINS ITS PRESENCE OVER THE REGION. HIGH
PRESSURE WILL PUSH OFFSHORE LATE MONDAY INTO TUESDAY AS A NORTHERN
STREAM LOW PRESSURE SYSTEM RACES EAST FROM THE CENTRAL GREAT LAKES
AND NORTHERN OHIO RIVER VALLEY. THIS LOW PRESSURE SYSTEM COULD BRING
RENEWED SNOW SHOWER CHANCES TO THE ALLEGHENIES AS EARLY AS MONDAY
NIGHT. ANY WIDESPREAD PRECIPITATION LOOKS TO HOLD OFF UNTIL TUESDAY
AND WEDNESDAY AS THE LOW PRESSURE SYSTEM TRACKS NORTH OF THE AREA.
SOME UNCERTAINTY REMAINS AMONGST BOTH THE DETERMINISTIC AND ENSEMBLE
GUIDANCE OF WHAT THE MAIN PRECIPITATION TYPE WILL BE DURING THE
TUESDAY AND WEDNESDAY TIMEFRAME. AS IT STANDS NOW, IT LOOKS AS IF
TEMPERATURES APPEAR COLD ENOUGH AT ONSET FOR A LIGHT WINTRY MIX
TUESDAY INTO EARLY WEDNESDAY MORNING (CHRISTMAS EVE/CHRISTMAS DAY)
ESPECIALLY IN LOCATIONS ALONG AND NORTH OF I-66/US-50. THIS IS DUE
LARGELY IN PART TO THE PLACEMENT OF HIGH PRESSURE OVER NEW ENGLAND
WEDGING A SHALLOW POOL OF COLD AIR ALONG THE APPALACHIANS. BEYOND
THIS POINT, UNCERTAINTY REMAINS TO HOW MUCH COLD AIR WILL BE
LEFTOVER CHRISTMAS DAY, AS THE BULK OF THE 12Z GUIDANCE SUGGESTS A
WARMER SOLUTION. ANY RESIDUAL FROZEN PRECIPITATION CHRISTMAS MORNING
WILL LIKELY CHANGE OVER TO PLAIN RAIN OUTSIDE THE MOUNTAINS WHICH
COULD HOLD ONTO THE COLD AIR LONGER. OVERALL THE PROBABILITY FOR A
WHITE CHRISTMAS ACROSS THE AREA REMAINS LOW, BUT NOT ZERO ESPECIALLY
FOR THOSE WEST OF THE ALLEGHENIES.
SOME OF THE COLDEST AIR BY FAR THIS SEASON LOOKS TO IMPACT THE AREA
SUNDAY AS HIGHS STRUGGLE TO REACH FREEZING IN MOST LOCATIONS. WIND
GUSTS OF 15 TO 20 MPH ARE EXPECTED YIELDING WIND CHILLS IN THE MID
TO UPPER TEENS AND LOW 20S THROUGHOUT THE DAY OUTSIDE THE MOUNTAINS.
COLD TEMPERATURES CONTINUE MONDAY WITH HIGHS IN THE LOW TO MID 30S.
BY TUESDAY AND WEDNESDAY, HIGHS PUSH BACK INTO THE UPPER 30S AND LOW
TO MID 40S. OVERNIGHTS LOWS WILL SIT IN THE TEENS SUNDAY NIGHT
BEFORE WARMING INTO THE 20S AND 30S LATER IN THE WEEK.
AVIATION /03Z FRIDAY THROUGH TUESDAY/
WINDS DIMINISH AND SHIFT TO NORTHEASTERLY TONIGHT WITH VFR
CONDITIONS EXPECTED TO CONTINUE.
FLIGHT RESTRICTIONS RETURN FRIDAY AS A COLD FRONT BRINGS LIGHT RAIN
AND POSSIBLY SNOW TO ALL TERMINALS. WINDS SHIFT TO NORTHWESTERLY IN
THE WAKE OF THE FRONT WITH WIND GUSTS BETWEEN 20 AND 30 KNOTS
POSSIBLE ON SATURDAY. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE DAY
ON SATURDAY.
VFR CONDITIONS CONTINUE THROUGH MONDAY AS CANADIAN HIGH PRESSURE
REMAINS NEARBY. THE NEXT CHANCE FOR SUB-VFR CONDITIONS ARRIVES
TUESDAY (CHRISTMAS EVE) AND WEDNESDAY (CHRISTMAS DAY) AS AN AREA OF
LOW PRESSURE AND FRONT CROSS THE REGION.
MARINE
WINDS REMAIN SUB-SCA CRITERIA TONIGHT WHILE SHIFTING TO
NORTHEASTERLY. WINDS STAY BELOW SCA CRITERIA THROUGH FRIDAY
EVENING, WHEN AN APPROACHING COLD FRONT BRINGS GUSTY
NORTHWESTERLY WINDS. SMALL CRAFT ADVISORIES ARE LIKELY FRIDAY
NIGHT THROUGH SATURDAY AS NORTHWESTERLY WINDS GUST UP TO 30
KNOTS.
SCA CONDITIONS LOOK TO CONTINUE THROUGH SUNDAY MID-AFTERNOON WITH
GUSTS UP TO 20 KTS. WINDS WILL DIMINISH SUNDAY AFTERNOON AND REMAIN
BELOW SCA LEVELS THROUGH TUESDAY. SHOWER CHANCES LOOK TO RETURN TO
THE WATERS DURING THIS TIME AND CONTINUE THROUGH THE WEDNESDAY
(CHRISTMAS) HOLIDAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM FRIDAY TO 10 AM EST SUNDAY FOR
ANZ530>532-536-538>540-542.
SMALL CRAFT ADVISORY FROM 4 PM FRIDAY TO 4 PM EST SUNDAY FOR
ANZ533-534-537-541-543.
SMALL CRAFT ADVISORY FROM 7 AM TO 7 PM EST SATURDAY FOR ANZ535.
SYNOPSIS...DHOF/ADM/EST
NEAR TERM...DHOF/ADM
SHORT TERM...ADM
LONG TERM...EST
AVIATION...DHOF/ADM/EST
MARINE...DHOF/ADM/EST
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