625
FXUS61 KLWX 190835
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
335 AM EST TUE NOV 19 2024
SYNOPSIS
PRECIPITATION CHANCES RETURN LATER THIS AFTERNOON AND INTO TONIGHT
AS A WARM FRONT LIFTS THROUGH THE REGION. A STRONG AREA OF LOW
PRESSURE WILL DEVELOP NEAR THE MID-ATLANTIC AND EASTERN GREAT LAKES
LATE WEDNESDAY INTO THURSDAY BEFORE TRACKING TOWARD NEW ENGLAND
LATER THIS WEEK. A SERIES OF COLD FRONTS WILL ACCOMPANY THE STORM
SYSTEM DURING THIS TIME, PRODUCING A PROLONGED PERIOD OF GUSTY
WINDS, MOUNTAINS SNOW SHOWERS, AND CHILLY CONDITIONS HEADING
INTO THE WEEKEND AHEAD.
NEAR TERM /THROUGH TONIGHT/
A BACKDOOR COLD FRONT HAS CONTINUED TO TRAVERSE THE AREA
TOWARDS THE SOUTH EARLY THIS MORNING, WITH VERY LIGHT SPRINKLES
OBSERVED IN A VARIETY OF LOCATIONS FOR A FEW MINUTES OVERNIGHT
LAST NIGHT. CLOUDS WILL CONTINUE TO BUILD FROM THE WEST AHEAD OF
A COMPLEX SYSTEM EXPECTED TO IMPACT THE AREA BY MIDWEEK INTO
THE LATER PORTION OF THE WORKWEEK. WARM ADVECTION SHOWERS WILL
MOVE FURTHER EAST LATER TODAY, LEADING TO LIGHT RAIN
ACCUMULATIONS ACROSS THE AREA. RAIN TOTALS ARE EXPECTED TO BE AT
OR BELOW A QUARTER OF AN INCH AREAWIDE, WITH THE HIGHEST TOTALS
FURTHER WEST. HIGHS WILL BE IN THE MID TO UPPER 50S FOR THE
HIGHER TERRAIN WITH LOW 60S ACROSS THE LOWER ELEVATIONS.
SOUTHEAST WINDS SHOULD REMAIN FAIRLY TAME THROUGHOUT THE DAY.
WARM AIR ADVECTION WILL CONTINUE TO KEEP OVERNIGHT LOWS ABOVE
NORMAL FOR THIS TIME OF YEAR WITH UPPER 40S TO LOW 50S EXPECTED
ACROSS THE AREA HEADING INTO WEDNESDAY.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
WARM AIR AHEAD OF A FRONTAL SYSTEM WILL KEEP CONDITIONS ABOVE
NORMAL WEDNESDAY WITH HIGHS IN THE MID TO UPPER 50S FOR THE
MOUNTAINS AND MID TO UPPER 60S TO NEAR 70 FOR SOME OF THE LOWER
ELEVATIONS. SOME RAIN SHOWERS ARE EXPECTED ALONG AND JUST AHEAD
OF THE FRONTAL PASSAGE WITH THE WARM-AIR ADVECTION INDUCED
COMPONENT DURING THE DAY ON WEDNESDAY. CONDITIONS WILL CHANGE
FAIRLY QUICKLY ALONG A FRONTAL PASSAGE OVERNIGHT WEDNESDAY. THE
TWO BIG SHIFTS WILL BE THE TEMPERATURES AS WELL AS THE ENHANCED
WIND FIELD. GUSTY W-WNW WINDS WILL BEGIN TO PICK UP WEDNESDAY
AFTERNOON BEFORE AMPLIFYING OVERNIGHT. SOME GUIDANCE CONTINUES
TO HINT AT 35 TO 45 MPH GUSTS ACROSS THE HIGHEST ELEVATIONS WITH
LOCALIZED HIGHER GUSTS POSSIBLE. THIS WOULD LIKELY BE THE BEST
TIMEFRAME FOR THE MOST GUSTY ELEVATED WINDS TO BE ABLE TO MIX
DOWN ALONG THE HIGHER TERRAIN. CANNOT RULE OUT THE POTENTIAL FOR
WIND ADVISORIES IN THE AFOREMENTIONED ZONES. GUSTS WILL
CONTINUE TO ELEVATE AND MOVE FURTHER EAST WITH THE FRONTAL
PASSAGE TOWARDS THE WATERS. SHOWER CHANCES WILL DIMINISH HEADING
INTO SUNRISE ON THURSDAY FURTHER EAST. WITH THE CONTINUED
FALLING TEMPERATURES OUT WEST ACROSS THE ALLEGHENY FRONT,
PRECIPITATION TYPES WILL LIKELY SWITCH OVER TO SNOW HEADING INTO
EARLY THURSDAY MORNING. OVERNIGHT LOWS WILL FALL INTO THE MID
20S TO LOW 30S ALONG THE ALLEGHENY FRONT WITH SLIGHTLY WARMER
ABOVE FREEZING TEMPERATURES FURTHER EAST.
A MULTITUDE OF COMPLEXITIES ASSOCIATED WITH THE FORECAST BEGINS
EARLY THURSDAY AND CONTINUES THROUGH THE REMAINDER OF THE PERIOD
AND BEYOND AS A SERIES OF LOWS AND CYCLOGENESIS IMPACTS THE
MID-ATLANTIC AND NORTHEAST. THE HIGHER ELEVATIONS OF THE
ALLEGHENY FRONT APPEAR TO BE THE LOCATION OF THE HIGHEST IMPACTS
LOCALLY DURING THIS PERIOD WITH RESPECT TO SNOW TOTALS COUPLED
WITH GUSTY WINDS. THERE ARE A NUMBER OF FACTORS IN THE POSSIBLE
ACCUMULATION TOTALS, ONE BEING THE STRENGTH OF A LOW EXPECTED
TO FORM AT OR JUST SOUTH OF THE GREAT LAKES THURSDAY
AFTERNOON/NIGHT. A SUB 1000 MB LOW WOULD BRING HIGHER TOTALS
LOCALLY COMPARED TO A HIGHER PRESSURE OBSERVED. COLDER 850 MB
TEMPERATURES OUT WEST WOULD FAVOR HIGHER TOTALS AS WELL. THERE
STILL REMAINS A GREAT RANGE OF POSSIBILITIES WITH THIS SYSTEM.
FOR NOW, ACCUMULATING SNOW WILL LIKELY START LATE WEDNESDAY
NIGHT AND CONTINUE THROUGH THE WORK WEEK. GIVEN THE INCREASING
LIKELIHOOD IN AT LEAST 6 INCHES OF SNOW BEING OBSERVED ACROSS
THE ALLEGHENY FRONT, A WINTER STORM WATCH HAS BEEN ISSUED
THURSDAY THROUGH SATURDAY WITH THE THREAT FOR SIGNIFICANT
ACCUMULATING SNOW AS WELL AS BLOWING SNOW AS A RESULT OF GUSTY
WINDS. THE FORECAST WILL CONTINUE TO BE FLUID APPROACHING THE
EVENT AS GUIDANCE CONTINUES TO COME INTO AGREEMENT AND SYNOPTIC
FEATURES BECOME MORE WELL DEFINED AND OBSERVED ACROSS THE
CONUS. CONTINUE TO VISIT WEATHER.GOV/LWX/WINTER FOR THE LATEST
ON THE WINTER WEATHER THREAT.
LONG TERM /FRIDAY THROUGH MONDAY/
SYNOPTICALLY, WE CONTINUE TO SEE BLOCKING LOW PRESSURE/TROUGHING
OVER THE WESTERN ATLANTIC AND STRONG RIDGING IN THE WESTERN U.S.
CLOSED UPPER LEVEL LOW PRESSURE IS STALLED IN-BETWEEN WITH
SEVERAL PIECES OF SHORTWAVE ENERGY PIVOTING THROUGH. SOME
UNCERTAINTY REMAINS IN REGARDS TO THE TIMING, PLACEMENT,
INTENSITY, AND PROGRESSION OF THE STALLED UPPER LEVEL
LOW/RESULTANT SHORTWAVE TROUGHS. CURRENT 00Z/06Z GUIDANCE SHOWS
THE UPPER LEVEL LOW JUST NORTH OF THE MID-ATLANTIC REGION FRIDAY
BEFORE PUSHING IT OFF THE NEW ENGLAND COAST LATE SATURDAY INTO
SUNDAY. AS A RESULT, EXPECT A PROLONGED PERIOD OF GUSTY WINDS,
MOUNTAIN UPSLOPE SNOW SHOWERS, AND CHILLY CONDITIONS.
THE STEADIEST AND HEAVIEST UPSLOPE MOUNTAIN SNOW SHOWER ACTIVITY
LOOKS TO OCCUR FRIDAY INTO SATURDAY MORNING. THIS IS WHEN THE
STRONGEST PIECE OF SHORTWAVE ENERGY PIVOTS THROUGH AS THE
CUTOFF UPPER LOW PROGRESSES NORTH AND EAST TOWARD NEW ENGLAND.
00Z AND 06Z DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUES TO
FOLLOW THIS NOTION WITH INCREASED WEST TO NORTHWEST LOW LEVEL
FLOW IN THE WAKE OF THE DEPARTING SHORTWAVE SATURDAY MORNING.
SNOW SHOWER ACTIVITY WILL LIKELY LINGER THROUGH MUCH OF SATURDAY
AND PERHAPS INTO SUNDAY MORNING AS NORTHWEST FLOW CONTINUES.
OVERALL THE COVERAGE AND INTENSITY WILL SLOWLY DECREASE WITH
TIME AS DRIER AIR FILTERS IN.
AS FOR ACCUMULATION (THURSDAY 11/21/24 THROUGH SATURDAY EVENING
11/23/24), WE ARE LIKELY LOOKING AT THE FIRST SIGNIFICANT MOUNTAIN
EVENT OF THE SEASON WITH 6+ INCHES OF SNOW ALONG AND WEST OF THE
ALLEGHENY FRONT. HIGHEST SNOW TOTALS WILL BE CONFINED TO ELEVATIONS
ABOVE 2500 FEET WITH LOWER TOTALS DOWN IN THE HIGHER VALLEY
LOCATIONS ALONG WEST OF A LINE FROM BIG SAVAGE MOUNTAIN IN MD SOUTH
TOWARD MOUNT STORM, WV AND SPRUCE KNOB, WV. SNOW RATIOS WILL FAVOR
CLIMATOLOGY WITH LOWER RATIOS IN THE 10:1 RANGE DURING THE DAYLIGHT
HOURS INCREASING TO 13:1 TO 16:1 DURING THE EARLY MORNING AND
OVERNIGHT PERIODS. THIS WILL LEAD TO PERIODS OF COMPACTION,
ALTHOUGH MOST OF THE SNOW FRIDAY SHOULD BE OF FLUFFIER
CONSISTENCY GIVEN THE COLDER AIRMASS IN PLACE. OUTSIDE OF THE
SIGNIFICANT SNOW ACCUMULATION, BLOWING AND DRIFTING WILL BECOME
A PROBLEM. THIS IS DUE LARGELY IN PART TO INCREASING WINDS
FRIDAY AFTERNOON INTO SATURDAY AS THE SHORTWAVE DISTURBANCE LIFT
OUT OF THE REGION. GUSTS WILL BE CLOSE TO WIND ADVISORY
CRITERIA (UP TO 50 MPH) ALONG THE HIGHER RIDGES WITH 30-40 MPH
GUSTS DOWN BELOW. THIS WILL YIELD WIND CHILLS IN THE TEENS AND
20S FRIDAY INTO SATURDAY. WINTER STORM WATCHES CONTINUE THROUGH
SATURDAY EVENING FOR ALL LOCATIONS WEST OF THE ALLEGHENY FRONT.
FROUDE NUMBERS WILL SIT AT OR LESS THAN 1 THROUGH THE BULK OF THE
EVENT BLOCKING ANY SUBSTANTIAL SPILLAGE EASTWARD ACROSS THE
ALLEGHENIES AND TOWARD THE BLUE RIDGE OR METRO AREAS. EVEN WITH THAT
SAID, SOME GRAUPEL OR WET SNOW COULD MIX WITH SOME RAIN EARLY FRIDAY
MORNING ACROSS NORTHERN AND CENTRAL MD, NORTHERN VA, AND THE EASTERN
WV PANHANDLE. OUTSIDE OF SOME MORNING RAIN AND SNOW, DRY CONDITIONS
WILL PREVAIL UNDER WEST TO NORTHWEST DOWNSLOPE FLOW. EXPECT WIND
GUSTS 30-40 MPH WITH GUSTS UP TO 50 MPH ALONG THE CREST OF THE BLUE
RIDGE. THE STRONGEST WINDS EAST OF THE MOUNTAINS WILL OCCUR LATE
FRIDAY NIGHT INTO SATURDAY MORNING BEFORE DECREASING INTO SUNDAY.
HIGH TEMPERATURES WILL RANGE FROM BELOW FREEZING OVER THE MOUNTAINS
TO MID TO UPPER 40S AND LOW 50S FURTHER EAST FRIDAY AND SATURDAY.
MOUNTAIN LOCATIONS GET BACK ABOVE FREEZING SUNDAY WITH MODERATION IN
TEMPERATURES CONTINUING INTO THE FIRST HALF OF NEXT WEEK.
HIGH PRESSURE BRIEFLY BUILDS IN FROM THE SOUTH SUNDAY INTO MONDAY
BEFORE ANOTHER WARM FRONT LIFTS INTO THE REGION. A COLD FRONT WILL
FOLLOW WITH ADDITIONAL PRECIPITATION CHANCES TUESDAY INTO THE MIDDLE
OF NEXT WEEK.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
EAST-SOUTHEASTERLY WINDS WILL BUILD IN THROUGHOUT THE DAY TODAY
WITH MOSTLY VFR CONDITIONS EXPECTED. A FEW SHOWERS MAY APPROACH
THE TERMINALS, ESPECIALLY KMRB/KIAD THIS AFTERNOON AND EVENING.
GUSTY WINDS WILL BEGIN TO BUILD MIDDAY WEDNESDAY AHEAD OF A
FRONTAL PASSAGE EXPECTED TO IMPACT THE TERMINALS. 20 TO 30 KNOT
GUSTS ARE EXPECTED OUT OF THE W-NW WITH SOME SHOWERS MIXED IN.
THESE GUSTY WINDS WILL CONTINUE INTO THURSDAY WITH POCKETS OF
MVFR CEILINGS EXPECTED TO BUILD HEADING INTO THE REMAINDER OF
THE WORKWEEK.
A STRONG AREA OF LOW PRESSURE WILL CONTINUE TO SLOWLY PUSH NORTH AND
EAST OF THE AREA FRIDAY. PREDOMINANTLY VFR CONDITIONS (SOME BRIEF
MVFR PERIODS AT TIMES) ARE EXPECTED ALONG AND EAST OF THE
ALLEGHENIES WITH SUB-VFR CONDITIONS WEST DUE TO CONTINUED UPSLOPE
SNOW SHOWER ACTIVITY. A FEW SHOWERS WITH PERHAPS A FEW WET
SNOWFLAKES OR EVEN A LITTLE GRAUPEL ARE POSSIBLE AT KMRB, KHGR,
KOKV, AND KFDK FRIDAY MORNING ALTHOUGH CONFIDENCE IS LOW. WINDS WILL
BE THE BIGGER STORY FOR AVIATION IN THE EXTENDED WITH WEST TO
NORTHWEST GUSTS RUNNING 20 TO 30 KNOTS ON BOTH FRIDAY AND SATURDAY
AFTERNOONS. LOCALLY HIGHER GUSTS ARE POSSIBLE AT TERMINALS NEAR THE
WATERS AND RIDGES. WINDS DECREASE SUNDAY AS HIGH PRESSURE BUILDS
IN.
MARINE
WINDS ALONG THE WATERS WILL MOST LIKELY BE BELOW SCA CRITERIA
HEADING THROUGH WEDNESDAY MORNING. A FEW SHOWERS ARE POSSIBLE
LATER THIS AFTERNOON AND EVENING BEFORE TAPERING OFF OVERNIGHT.
SCAS WILL LIKELY BUILD IN LATER WEDNESDAY AHEAD OF A STRONG COLD
FRONT EXPECTED TO IMPACT THE AREA FOR THE REMAINDER OF THE WORK
WEEK. GIVEN THE INCREASING WIND FIELD WITH THIS EVENT, SOME 30
TO 40 KNOTS GUSTS MAY BE POSSIBLE WEDNESDAY NIGHT INTO EARLY
THURSDAY MORNING. THUS, A GALE WATCH HAS BEEN HOISTED. THERE IS
SOME UNCERTAINTY TO THE TIMING AND MAGNITUDE ASPECT. WINDS MAY
NOT MIX COMPLETELY DOWN DURING THIS TIME PERIOD AND COULD KEEP
ONLY HIGH-END SCA GUSTS DOWN AT THE SURFACE. ADDITIONALLY, THE
STRONGEST GUSTS COULD ONLY BE 1 TO 2 HOURS BEHIND THE COLD
FRONT AND MAY WARRANT JUST HAVING SPECIAL MARINE WARNINGS OUT TO
ACCOUNT FOR THE GALE-FORCE WINDS. THIS WILL BE WORTH MONITORING
AS WE APPROACH THE EVENT. GUSTY WESTERLY WINDS ARE EXPECTED
OVER THE WATERS ON BOTH THURSDAY AS LOW PRESSURE TRACKS TO OUR
NORTH.
HIGH END SCAS ARE LIKELY TO CONTINUE THROUGH SATURDAY WITH PERHAPS A
PERIOD OF GALE CONDITIONS OVER THE OPEN WATERS FRIDAY NIGHT INTO
SATURDAY AS LOW PRESSURE LIFTS NORTH AND EAST OF THE REGION. WEST TO
NORTHWEST GUSTS UP TO 30 KTS ARE POSSIBLE ON BOTH FRIDAY AND
SATURDAY AFTERNOON. GALE FORCE GUSTS ARE POSSIBLE OVER THE OPEN
WATERS OF THE BAY AND LOWER TIDAL POTOMAC LATE FRIDAY NIGHT INTO
SATURDAY AS WINDS SURGE BEHIND A DEPARTING SHORTWAVE TROUGH. WINDS
DECREASE TO LOW END SCA LEVEL SUNDAY.
TIDES/COASTAL FLOODING
MINOR COASTAL FLOODING IS POSSIBLE AT THE MORE SENSITIVE TIDAL
SITES LIKE ANNAPOLIS, DC SW WATERFRONT, AND DAHLGREN THROUGH
THE NEXT SEVERAL DAYS DUE TO SNAP BACK AND THEN STRENGTHENING
SOUTHERLY FLOW.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT
FOR MDZ008.
WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH SATURDAY
EVENING FOR MDZ001.
VA...WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH SATURDAY
EVENING FOR VAZ503.
WV...WINTER STORM WATCH FROM THURSDAY AFTERNOON THROUGH SATURDAY
EVENING FOR WVZ501-503-505.
MARINE...GALE WATCH FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT
FOR ANZ530>543.
SYNOPSIS...ADM/EST
NEAR TERM...ADM
SHORT TERM...ADM
LONG TERM...EST
AVIATION...ADM/EST
MARINE...ADM/EST
TIDES/COASTAL FLOODING...ADM
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