206
FXUS61 KLWX 120822
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
322 AM EST FRI DEC 12 2025
SYNOPSIS
A FAST-MOVING LOW PRESSURE SYSTEM WILL CROSS SOUTH OF THE
REGION TODAY, BRINGING SNOW TO PORTIONS OF CENTRAL VIRGINIA. A
STRENGTHENING WAVE OF LOW PRESSURE MAY IMPACT THE AREA SATURDAY
NIGHT INTO SUNDAY BEFORE ARCTIC HIGH PRESSURE MOVES IN BY EARLY
NEXT WEEK. THIS RIDGE EXITS OFFSHORE BY THE MIDDLE OF THE WEEK
AHEAD OF THE NEXT FRONTAL SYSTEM, WHICH WILL BRING TEMPERATURES
CLOSER TO NORMAL AGAIN.
NEAR TERM /THROUGH TONIGHT/
AN UPPER-LEVEL LOW IS CENTERED OVER NORTHERN NEW ENGLAND THIS
MORNING. A PIECE OF SHORTWAVE ENERGY CAN CLEARLY BE SEEN IN THE
00Z UPPER AIR ANALYSES, AS WELL AS THE CURRENT WATER VAPOR
IMAGERY, LOCATED OVER WISCONSIN. AT THE SURFACE, A STATIONARY
BOUNDARY IS IN PLACE GENERALLY ACROSS THE CENTRAL CONUS, WHICH
WILL ACT AS THE FOCAL POINT FOR THE DEVELOPMENT OF A WEAK LOW
PRESSURE SYSTEM LATER TODAY, AIDED BY THE AFOREMENTIONED
SHORTWAVE.
THIS WEAK ARE OF LOW PRESSURE WILL MOVE INTO THE REGION FROM THE
WEST THROUGHOUT THE DAY TODAY. THIS SYSTEM IS EXPECTED TO
PRODUCE A PERIOD OF LIGHT SNOW ACROSS PORTIONS OF THE POTOMAC
HIGHLANDS, CENTRAL SHENANDOAH VALLEY AND CENTRAL VIRGINIA DURING
THE DAY TOMORROW. GUIDANCE REMAINS PRETTY CONSISTENT WITH THE
DEVELOPMENT, TRACK, AND STRENGTH OF THIS SYSTEM. WHEN IT COMES
TO LOCAL IMPACTS, THIS MEANS MAYBE AN INCH OR TWO OF
ACCUMULATING SNOWFALL ACROSS CENTRAL VA, MAINLY ALONG/SOUTH OF
THE I-64 CORRIDOR. SOME LOCALLY HIGHER AMOUNTS ARE POSSIBLE
ALONG THE BLUE RIDGE, BUT OVERALL THE MOST LIKELY SCENARIO IS A
LIGHT SNOWFALL EVENT, AS THE SYSTEM REALLY STRUGGLES TO MAINTAIN
MUCH STRENGTH AS IT CROSSES THE APPALACHIANS.
HOWEVER, IT SHOULD BE NOTED THAT THERE IS BOTH BOOM AND BUST
POTENTIAL STILL ON THE TABLE STILL DEPENDING ON HOW MUCH QPF IS
ULTIMATELY OBSERVED. MODEL SOUNDINGS SHOW VERY COLD PROFILES
ALOFT, WITH NEARLY ALL OF THE LIFT OCCURRING THROUGH THE DGZ. IF
LIFT IS STRONG ENOUGH, THIS WOULD PRODUCE LARGE DENDRITES.
MODEL SOUNDINGS ALSO SHOW ALMOST NO WIND IN THE BOUNDARY LAYER.
IN A HIGHER QPF SCENARIO, ALBEIT BECOMING LESS LIKELY WITH EACH
MODEL RUN, YOU WOULD HAVE LARGE DENDRITES GENTLY FALLING AND
THEN STACKING UP WITH LITTLE FRACTURE OR COMPACTION, WHICH WOULD
BE A NEAR IDEAL SCENARIO FOR VERY HIGH SLRS. THIS SCENARIO COULD
YIELD SNOW TOTALS UP TO 4 INCHES ON THE CENTRAL VA BLUE RIDGE,
AND WOULD BE THE WORST CASE SCENARIO FOR IMPACTS. ON THE OTHER
HAND, IF THERE ISN'T MUCH LIFT AND RESULTANT QPF, YOU'D LIKELY
GET MUCH SMALLER CRYSTALS THAT WON'T STACK UP AS EFFECTIVELY. SO
HIGHER QPF WILL LIKELY BEGET HIGHER SLRS AND VICE VERSA, WHICH
HAS A MULTIPLICATIVE EFFECT ON SNOW TOTALS. IN THIS LOW-END
SCENARIO, MOST PLACES WOULD STRUGGLE TO SEE AN INCH.
IN TERMS OF TIMING, SNOW IS EXPECTED TO MOVE INTO CENTRAL
VIRGINIA AROUND 6 AM AND END BY AROUND 6 PM. TEMPERATURES WILL
BE COLD, SO THERE COULD BE POTENTIAL IMPACTS TO BOTH THE MORNING
AND EVENING COMMUTES.
FURTHER NORTH, JUST CLOUDY CONDITIONS ARE EXPECTED TODAY ACROSS
THE DC AND BALTIMORE METROS. HIGH TEMPERATURES ARE EXPECTED TO
BE IN THE 30S ACROSS THE LOWER ELEVATIONS, WITH 20S IN THE
MOUNTAINS.
AS WE MOVE INTO TONIGHT, A STRAY FLURRY OR A BIT OF FREEZING
FOG COULD BE POSSIBLE ANYWHERE ACROSS THE FORECAST AREA. THE
BEST CHANCE FOR SNOW TOMORROW NIGHT WILL BE IN THE ALLEGHENIES
WITHIN A BRIEF SURGE OF UPSLOPE FLOW. A COATING TO AN INCH OF
SNOW APPEARS LIKELY IN THE ALLEGHENIES.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
A WEAK RIDGE OF HIGH PRESSURE WILL BECOME CENTERED OVER THE
REGION ON SATURDAY. MOSTLY CLOUDY SKIES AND DRY CONDITIONS ARE
EXPECTED, WITH HIGHS IN THE UPPER 30S TO MID 40S FOR MOST (20S
MOUNTAINS). MEANWHILE, MUCH FURTHER TO THE WEST, THE WAVEGUIDE
ACROSS NORTH AMERICA WILL START TO AMPLIFY AS A SYSTEM TRACKS
TOWARD THE BRITISH COLUMBIA COAST. A RIDGE BUILDING EVENT WILL
ENSUE DOWNSTREAM OVER WESTERN CANADA, WHICH WILL CAUSE A PRE-
EXISTING UPPER LOW OVER THE UPPER GREAT LAKES TO DROP
SOUTHEASTWARD TOWARD THE MID- ATLANTIC AND AMPLIFY INTO A
SHORTER WAVELENGTH OPEN WAVE. AS THIS OCCURS, LARGE SCALE
FORCING FOR ASCENT WILL INCREASE ACROSS THE AREA SATURDAY NIGHT.
PRECIPITATION COULD START AS EARLY AS THE EVENING IN THE
ALLEGHENIES, BEFORE SPREADING EASTWARD DURING THE OVERNIGHT
HOURS.
AS THE WAVE AMPLIFIES, MOST MODELS SHOW A JET STEAK DEVELOPING
DOWNSTREAM, WITH AN ENHANCED BAND OF PRECIPITATION DEVELOPING
IN THE EQUATORWARD ENTRANCE REGION OF THE JET STREAK. WHILE
THERE'S STILL SOME UNCERTAINTY WITH RESPECT TO EXACTLY WHERE
THIS BAND WINDS UP, MOST SOLUTIONS HAVE THIS ENHANCED BAND OF
PRECIPITATION DEVELOPING ALONG THE I-95 CORRIDOR SATURDAY
NIGHT. THIS COULD RESULT IN A RELATIVE MINIMUM IN PRECIPITATION
BETWEEN THE BLUE RIDGE AND THE ALLEGHENIES, WITH HIGHER TOTALS
ALONG THE I-95 CORRIDOR (WHERE THE BEST SYNOPTIC FORCING WILL
BE) AND IN THE ALLEGHENIES (WHERE THERE WILL BE SOME ADDITIONAL
UPSLOPE SNOW AS THE SYSTEM DEPARTS).
WITH SUCH A NARROW BANDED FEATURE, THERE'S STILL A FAIR AMOUNT
OF UNCERTAINTY WITH RESPECT TO HOW MUCH PRECIPITATION WILL
ULTIMATELY FALL. PRECIPITATION COULD ALSO POTENTIALLY START AS A
BRIEF PERIOD OF RAIN ALONG THE I-95 CORRIDOR BEFORE MUCH COLDER
AIR RUSHES IN LATER DURING THE NIGHT BEHIND AN ARCTIC FRONT. FOR
THESE REASONS, A WIDE VARIETY OF POTENTIAL SOLUTIONS EXISTS,
ESPECIALLY ALONG THE I-95 CORRIDOR. FURTHER WEST, A HIGH END-
ADVISORY OR LOW-END WARNING LEVEL SNOWFALL APPEARS LIKELY.
BETWEEN THE ALLEGHENY FRONT AND BLUE RIDGE LESSER QPF AMOUNTS
ARE LIKELY WITH ALL PRECIPITATION LIKELY FALLING AS SNOW. MOST
SOLUTIONS SHOW A COATING TO TWO INCHES OF SNOW IN THIS AREA, BUT
AS MUCH AS 4 INCHES COULD BE POSSIBLE IN A HIGH END SCENARIO IN
THE SHENADOAH VALLEY. FURTHER EAST, AROUND THE I-95 CORRIDOR,
THE WIDEST RANGE OF POTENTIAL SOLUTIONS EXISTS. IF MOST OF THE
PRECIPITATION WERE TO FALL AS RAIN, OR THE BAND OF HIGHER QPF
WERE TO SHIFT NORTHWARD OUT OF THE AREA, AS LITTLE AS A COATING
TO AN INCH OF SNOW COULD OCCUR. CURRENTLY, WE HAVE 1-4 INCHES OF
SNOW FORECAST AS THE MOST LIKELY SCENARIO TO THE EAST OF THE
BLUE RIDGE. IN A HIGH END SCENARIO, AS MUCH AS 6 INCHES OF SNOW
COULD OCCUR UNDER THE HEAVIEST PART OF THE BAND IF THE
PRECIPITATION STAYS ALL SNOW.
ASIDE FROM THE THREAT FOR SNOW EARLY IN THE DAY, WINDS WILL PICK
UP SUBSTANTIALLY BEHIND THIS ARCTIC FRONT BY SUNDAY AFTERNOON.
EXPECT WIND GUSTS OUT OF THE NORTHWEST UP TO 30 MPH, WITH GUSTS
CLOSER TO 45 MPH ON THE RIDGETOPS OUT WEST. WIND HEADLINES
CANNOT BE RULED OUT FOR THE RIDGES DURING THIS TIMEFRAME AS A
RESULT.
WHILE WINDS WILL TAPER OFF INTO LATE SUNDAY NIGHT AND INTO THE
PRE-DAWN HOURS ON MONDAY, THERE WILL STILL BE ENOUGH OF A BREEZE
TO SIGNIFICANTLY DROP WIND CHILLS. THE ARCTIC HIGH LIKELY BRINGS
SOME OF THE COLDEST AIR OF THE SEASON THUS FAR. EXPECT LOWS TO
BE IN THE TEENS FOR MOST (SINGLE DIGITS IN TYPICALLY WELL-
RADIATED SPOTS, ESPECIALLY THOSE WITH A SNOWPACK. MOUNTAIN
LOCATIONS CAN EXPECT LOWS IN THE SINGLE DIGITS, WITH SOME OF THE
HIGHER SPOTS LIKELY STRUGGLING TO GO ABOVE ZERO. COMBINE THIS
WITH CONTINUE GUSTY WINDS, AND THERE IS THE POTENTIAL FOR OUR
FIRST COLD WEATHER HEADLINES OF THE SEASON OUT OVER THE
ALLEGHENIES.
LONG TERM /MONDAY THROUGH THURSDAY/
CANADIAN HIGH PRESSURE SETTLES OVERHEAD MONDAY INTO MONDAY NIGHT
ALLOWING THE WINDS TO GRADUALLY SETTLE DOWN. GUSTS OF 15 TO 25 MPH
CAN BE EXPECTED THROUGH THE AFTERNOON WITH HIGHS FOR MOST STRUGGLING
TO MAKE FREEZING. MOUNTAIN LOCATIONS WILL REMAIN IN THE MID TO UPPER
TEENS THROUGHOUT THE DAY. THE ADDED WIND WILL KEEP WIND CHILLS IN
THE SINGLE DIGITS OVER THE MOUNTAINS WITH LOW TO MID 20S ELSEWHERE
ACROSS THE REGION. LOWS MONDAY NIGHT WILL FALL INTO THE MID TO UPPER
TEENS AND LOW 20S UNDER CLEAR SKIES.
THE COLD WEATHER PATTERN WILL BE REPLACED WITH A WARMER ONE TUESDAY
INTO WEDNESDAY. THE DEEP UPPER LEVEL TROUGH THAT DOMINATED THE
WEATHER PATTERN OVER THE LAST SEVERAL DAYS SHIFTS OFFSHORE WITH
RIDGING BUILDING ALOFT. THIS WILL ALLOW FOR MORE OF A ZONAL FLOW
PATTERN INTO THE REGION. WARM AIR ADVECTION WILL ENSUE AT THE
SURFACE LATE TUESDAY INTO WEDNESDAY AS A WARM FRONT LIFTS TOWARD THE
REGION. THE WARM FRONT WILL BE ASSOCIATED WITH AN AREA OF LOW
PRESSURE ACROSS THE WESTERN GREAT LAKES WHICH WILL DRAG A COLD FRONT
TOWARD THE REGION NEXT WEEKEND INTO EARLY NEXT WEEK. UNTIL THEN
EXPECT A CHANCES FOR A FEW SHOWERS WEDNESDAY AND THURSDAY ALONG WITH
TEMPERATURES THAT LOOK TO WARM BACK TO NORMAL AND ABOVE NORMAL
LEVELS. HIGHS WEDNESDAY LOOK TO PUSH BACK INTO THE MID 40S AND LOW
50S WITH MID TO UPPER 50S THURSDAY. MOUNTAIN LOCATIONS WILL REMAIN A
TOUCH COOLER IN THE LOW TO MID 40S.
AVIATION /06Z FRIDAY THROUGH TUESDAY/
VFR CONDITIONS ARE EXPECTED ACROSS MOST TERMINALS TODAY AS HIGH
PRESSURE DOMINATES SLIDES OVERHEAD AND EVENTUALLY OFFSHORE. THE
ONLY EXCEPTION WILL BE ACROSS CENTRAL VA, SPECIFICALLY AT CHO,
WHERE LOW CEILINGS AND LIGHT SNOW ARE EXPECTED.
VFR CONDITIONS AND SOUTHWESTERLY WINDS ARE EXPECTED DURING THE
DAYLIGHT HOURS ON SATURDAY. LOW CEILINGS AND SNOW WILL WILL
LIKELY MOVE IN SATURDAY NIGHT, LEADING TO RESTRICTIONS AT THE
TERMINALS. WINDS WILL TURN OUT OF THE NORTHWEST AND PICK UP IN
MAGNITUDE LATE SATURDAY NIGHT AS AN ARCTIC FRONT MOVES THROUGH
THE AREA.
SOME TEMPORARY SUB-VFR REDUCTIONS ARE EXPECTED TO LINGER EARLY
SUNDAY MORNING AS LOW PRESSURE DEPARTS THE REGION. ANY SNOW
WILL WRAP UP WITHIN THE I-95 CORRIDOR EARLY SUNDAY MORNING WITH
VFR CONDITIONS RETURNING SUNDAY AFTERNOON. WIND WILL BE THE
BIGGER ISSUE FOR AVIATORS WITH GUSTS HOVERING BETWEEN 20 TO 30
KTS. THIS IS ESPECIALLY TRUE AT TERMINALS NEAR THE WATERS AND
RIDGES AS THERE WILL BE A STOUT PRESSURE GRADIENT BETWEEN THE
DEPARTING FRONT AND INCOMING COLD HIGH PRESSURE SYSTEM.
BREEZY CONDITIONS CONTINUE THROUGH MONDAY AFTERNOON WITH WINDS
TRENDING DOWNWARD TUESDAY. VFR CONDITIONS ARE EXPECTED BOTH DAYS
WITH SHOWER CHANCES RETURNING MID WEEK.
MARINE
HIGH PRESSURE SLIDING OVERHEAD AND EVENTUALLY OFFSHORE TODAY
INTO SATURDAY WILL LEAD TO GENERALLY LIGHT WINDS OUT OF THE
SOUTH TODAY. WINDS WILL PICK UP A BIT ON SATURDAY, BUT SHOULD
STAY BELOW SCA CRITERIA.
AN ARCTIC FRONT WILL MOVE OVER THE WATERS LATE SATURDAY NIGHT.
WINDS WILL SHIFT TO NORTHWESTERLY BEHIND THE FRONT, WITH SCA
CONDITIONS LIKELY LATE IN THE NIGHT INTO SUNDAY. ADDITIONALLY,
COULD SEE SOME SNOW SUNDAY MORNING, ESPECIALLY IN THE UPPER
TIDAL POTOMAC AND MUCH OF THE CENTRAL/NORTHERN CHESAPEAKE BAY.
GALE CONDITIONS BECOME POSSIBLE BY SUNDAY AFTERNOON AND CONTINUE
THROUGH MONDAY MORNING IN THE WAKE OF THE ARCTIC FRONT.
GALE CONDITIONS DIMINISH MONDAY MORNING. WINDS FURTHER DROP BELOW
SUB-SCA LEVELS MONDAY EVENING AND REMAIN BELOW ON TUESDAY. SCA
CONDITIONS RETURN WITH A WARM FRONT WEDNESDAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
MDZ008.
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR MDZ509.
VA...WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST
THIS EVENING FOR VAZ036-508.
WV...WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR WVZ501.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
ANZ530>534-537-539>541-543.
SYNOPSIS...CJL
NEAR TERM...CJL/KJP
SHORT TERM...CJL/KJP
LONG TERM...CPB
AVIATION...CJL/KJP/CPB
MARINE...CJL/CPB
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