895
FXUS61 KLWX 011400
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
900 AM EST MON DEC 1 2025
SYNOPSIS
HIGH PRESSURE WILL RETURN TODAY. THE NEXT STORM SYSTEM WILL
MOVE ACROSS THE REGION EARLY TUESDAY MORNING, AND THIS WILL
BRING A WINTRY MIX TO MUCH OF THE REGION. ANOTHER DISTURBANCE
MAY MOVE THROUGH THE REGION LATER IN THE WEEK.
KEY MESSAGES:
- FIRST WIDESPREAD WINTER SYSTEM EXPECTED TO IMPACT THE AREA
TONIGHT INTO TUESDAY MORNING. THE TUESDAY MORNING COMMUTE
COULD BE IMPACTED.
- WINTER WEATHER ADVISORIES HAVE BEEN ISSUED FOR AREAS
ALONG/WEST OF US-15 AND NORTH OF I-70 IN MARYLAND WHERE
CONFIDENCE IN ACCUMULATING SNOW AND ICE IS GREATEST.
- WINTER WEATHER ADVISORIES MAY NEED TO BE EXPANDED SLIGHTLY
SOUTHEASTWARD OVER PORTIONS OF INTERIOR CENTRAL MARYLAND TO
THE NORTH-CENTRAL VIRGINIA PIEDMONT WEST OF I-95
9 AM EST UPDATE /THROUGH 6 PM THIS EVENING/
AS SOME HI-RES GUIDANCE HAD HINTED AT OVER THE LAST 24 HOURS, A
FEW FLURRIES HAVE DRIFTED INTO WESTERN MD AND THE HIGHER ELEVS
OF EASTERN WV MAINLY ALONG/WEST OF THE ALLEGHENY FRONT. NO
ACCUMULATION IS EXPECTED, THOUGH VISIBILITY MAY BRIEFLY BE
REDUCED TO 3 TO 5 MILES THROUGH LATE MORNING.
OTHERWISE, THE FORECAST FOR TODAY IS ON TRACK WITH NO CHANGES
PLANNED. WILL EXAMINE 12Z GUIDANCE FOR UPCOMING WINTRY PRECIP.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
SFC HIGH PRESSURE WILL BRIEFLY BUILD OVER THE MID-ATLANTIC
TODAY BEFORE LIFTING INTO NEW ENGLAND TONIGHT. ALTHOUGH BRIEFLY
IN A FAVORABLE POSITION, THE HIGH WILL BE STEADILY RETREATING
HEADING INTO TUESDAY'S WINTER EVENT. IN TURN, THE LOW-LEVEL COLD
AIR WILL NOT BE ENTRENCHED AND THE UL TROUGH WILL NOT BE SLOWED
DOWN BY A STALLED HIGH RESULTING IN A MORE PROGRESSIVE SYSTEM.
AN AREA OF SFC LOW PRESSURE WILL MOVE FROM THE SE-US OFF THE
CAROLINAS AND TOWARDS NEW ENGLAND TUESDAY INTO WEDNESDAY. A
STRENGTHENING JET COUPLED WITH ISENTROPIC ASCENT DUE TO WAA WILL
BE THE MAIN PRECIP DRIVERS. 700MB FGEN LOOKS TO BE TO THE NW OF
THE FA, BUT THE 850MB FGEN LOOKS TO BE OVER THE FA. IF TEMPS
ARE MARGINAL, RATES UNDER THIS BAND BAY BRIEFLY SUPPORT MORE
WINTRY PRECIP THAN CURRENTLY FORECAST DUE TO DYNAMICAL COOLING.
RESIDUAL LOW-LEVEL COLD AIR WILL RESULT IN PRECIPITATION
BEGINNING AS A WINTRY MIX ESPECIALLY WEST OF US-15 LATE TONIGHT
INTO EARLY TUESDAY MORNING. THE LATEST GUIDANCE CONTINUES TO
TREND TOWARD A QUICKER ONSET TIME OF PRECIPITATION DUE TO A
FASTER AND MORE PROGRESSIVE/SOMEWHAT FLATTER LOW TRACK. THE
SOUTHEAST EXTENT OF WINTRY PRECIPITATION AS WELL AS SPECIFIC
TIMING OF CHANGEOVER AND AMOUNTS REMAIN UNCERTAIN GIVEN THE
TRANSIENT COLD AIR AND RESIDUAL SPREAD IN THE TRACK OF THE LOW.
AREAS IN THE VICINITY OF NORTHERN AND WESTERN MARYLAND HAVE THE
GREATEST POTENTIAL TO STAY ALL SNOW THROUGH THE EVENT WITH WITH
THOSE IN EASTERN WEST VIRGINIA INTO THE SHENANDOAH VALLEY AND
VIRGINIA PIEDMONT MOST AT RISK FOR ICE GIVEN THE EARLIER ONSET
IN THOSE AREAS.
GIVEN THAT THIS WILL LIKELY BE THE FIRST WINTRY PRECIPITATION
EVENT OF THE SEASON FOR MUCH OF THE AREA, AND COMING OFF THE
HEELS OF ONE OF THE BUSIEST TRAVEL WEEKENDS OF THE YEAR, IT IS
PRUDENT TO CHECK BACK FOR THE LATEST AT WEATHER.GOV/LWX/WINTER.
SHOULD THE FORECAST TREND SLIGHTLY COLDER, AN EASTWARD EXPANSION
OF THE WINTER WEATHER ADVISORY MAY BE NEEDED.
BEHIND THE SYSTEM TUESDAY AFTERNOON AND EVENING, UPSLOPE SNOW
SHOWERS ARE EXPECTED AMIDST NW FLOW. AN ADDITIONAL COATING TO AN
INCH OR SO IS EXPECTED ALONG THE ALLEGHENY FRONT.
FOR WEDNESDAY, HIGH PRESSURE WILL BUILD OVER THE CENTRAL
APPALACHIANS BRINGING DRY AND COLD CONDITIONS. HIGHS IN THE
UPPER 30S TO LOW 40S WITH OVERNIGHT LOWS IN THE 20S.
LONG TERM /THURSDAY THROUGH SUNDAY/
AN ACTIVE WINTER PATTERN PERSISTS WITHIN A HIGHLY AMPLIFIED SPLIT
FLOW REGIME. THE KEY PLAYERS IN THIS SETUP ARE A DEEP UPPER TROUGH
ACROSS MUCH OF EASTERN NORTH AMERICA, A PROGRESSIVE WAVE EJECTING
OUT OF THE FOUR CORNERS, AND A STRONG RIDGE OVER THE EASTERN
PACIFIC. OF MOST INTEREST IS THAT SHORTWAVE COMING FROM AROUND NEW
MEXICO AND THE OKLAHOMA/TEXAS PANHANDLES. THERE CONTINUES TO BE A
HALF DECENT SIGNAL OF LOW PRESSURE DEVELOPMENT NEAR THE SOUTHEASTERN
U.S. COAST ON FRIDAY NIGHT. THE POSITION AND INTENSITY OF THIS WAVE
AS IT LIFTS NORTHEASTWARD ALONG THE GULF STREAM WILL DICTATE THE
LOCAL IMPACTS.
OVERALL, BELOW AVERAGE TEMPERATURES RULE THE EXTENDED FORECAST
PERIOD. AMPLIFICATION IN THE NORTHERN STREAM DRIVES A COLD FRONTAL
PASSAGE THROUGH THE REGION ON THURSDAY. ASIDE FROM A FEW UPSLOPE
SNOW SHOWERS IN THE WAKE, THIS SHOULD LARGELY PROVE TO BE A DRY
FRONT WITH INCREASING NORTHWESTERLY WINDS. CANADIAN HIGH PRESSURE
BUILDS IN FOR FRIDAY MORNING WHICH MAKES FOR A VERY CHILLY NIGHT.
WIDESPREAD LOWS IN THE TEENS ARE LIKELY, WITH POCKETS OF LOW/MID 20S
ALONG AND EAST OF I-95. THIS SETS THE STAGES FOR A CHILLY FRIDAY
WITH HIGHS HOLDING STEADY IN THE UPPER 20S TO 30S. ADDITIONALLY, THE
MODIFIED CANADIAN AIR MASS SHOULD HOLD DEW POINTS DOWN IN THE TEENS.
IF ANY PRECIPITATION ARRIVES, WET-BULBING EFFECTS WOULD EASILY HELP
KEEP TEMPERATURES BELOW FREEZING. DEPENDING ON HOW THE MENTIONED
SOUTHERN STREAM WAVE EVOLVES, SOME WINTRY PRECIPITATION COULD AFFECT
THE MID-ATLANTIC REGION BY LATE FRIDAY. HOWEVER, UNCERTAINTY IS
STILL VERY HIGH BASED ON ALL OF THE RUN-TO-RUN INCONSISTENCIES.
HIGH PRESSURE EVENTUALLY RETURNS OVER THE WEEKEND. ASIDE FROM A FEW
ALLEGHENY SNOW SHOWERS, THE PATTERN IS CURRENTLY LOOKING DRY BEHIND
THAT COASTAL STORM.
AVIATION /12Z MONDAY THROUGH FRIDAY/
WINDS LESSEN TODAY AND BECOME MORE NORTHERLY WITH JUST A FEW
MID/HIGH CLOUDS. OVC040 AT KMRB SHOULD GRADUALLY SCATTERED AND
LIFT THROUGH ROUGHLY 18Z. WINDS WILL GENERALLY BE AOB 10 KTS.
NOT MUCH HAS CHANGED IN TERMS OF THE POSSIBLE WINTRY MIX ACROSS
THE TAF SITES. PRECIPITATION IS EXPECTED TO MOVE IN AFTER
MIDNIGHT TONIGHT. A WINTRY MIX IS MOST LIKELY NEAR KMRB (SN/PL)
AND KCHO (PL/ZR), THOUGH A BRIEF MIX IS POSSIBLE INTO THE
METROS (ESPECIALLY KIAD) EARLY TUESDAY MORNING. THE TEMPERATURES
SHOULD WARM QUICKLY TO SUPPORT PLAIN RAIN IN THE METROS TUESDAY
MORNING, AND KCHO TOWARD LATE MORNING. KMRB MAY HOLD ONTO
WINTRY PRECIP WELL INTO TUESDAY DEPENDING ON LOW TRACK.
PRECIPITATION WILL EXIT QUICKLY HEADING INTO TUESDAY EVENING.
GIVEN THE PATTERN, A PERIOD OF IFR IS LIKELY EARLY TUESDAY
MORNING THROUGH TUESDAY AFTERNOON. SOUTHEAST WINDS LATE MONDAY
NIGHT INTO TUESDAY WILL BECOME NORTHWEST LATE TUESDAY AFTERNOON
THROUGH TUESDAY NIGHT WITH GUSTS OF 15 TO 25 KNOTS POSSIBLE.
HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST ON WEDNESDAY,
THEN MOVES OVERHEAD WEDNESDAY NIGHT INTO THURSDAY. ONGOING SCA
CONDITIONS WEDNESDAY MORNING WILL QUICKLY DIMINISH BY EARLY
AFTERNOON.
VFR CONDITIONS ARE EXPECTED ON THURSDAY INTO MUCH OF FRIDAY. A DRY
COLD FRONT RACES ACROSS THE REGION ON THURSDAY LEADING TO AN UPTICK
IN NORTHWESTERLY WINDS. GUSTS UP TO 15 TO 20 KNOTS ARE POSSIBLE
DURING THIS NORTHWESTERLY SURGE. HIGH PRESSURE BUILDS IN FOR
THURSDAY NIGHT THROUGH THE FIRST HALF OF FRIDAY. THIS ANTICYCLONE
EXITS OFFSHORE YIELDING A SHIFT TO SOUTHERLIES BY FRIDAY AFTERNOON.
SOME THREAT FOR WINTRY PRECIPITATION ARRIVES LATE FRIDAY WHICH WOULD
SUPPORT RESTRICTIONS. HOWEVER, UNCERTAINTY IS RATHER HIGH AT THIS
TIME.
MARINE
WINDS WILL SHIFT TO NORTH, EAST, THEN SOUTHEAST LATER THIS
MORNING THROUGH TONIGHT AT LIGHTER SPEEDS. LIGHT SOUTHEAST WINDS
WILL LINGER THROUGH TUESDAY AFTERNOON BEFORE SHIFTING TO
NORTHWEST AND INCREASING POSSIBLY TO GALE FORCE FOR PORTIONS OF
THE WATERS LATE TUESDAY AFTERNOON THROUGH TUESDAY NIGHT. LIGHT
RAIN THIS EVENING WILL EXIT OVERNIGHT, WITH RAIN OR A WINTRY MIX
POSSIBLE LATE MONDAY NIGHT THROUGH TUESDAY AFTERNOON.
HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST ON WEDNESDAY,
THEN MOVES OVERHEAD WEDNESDAY NIGHT INTO THURSDAY. ONGOING SCA
CONDITIONS WEDNESDAY MORNING WILL QUICKLY DIMINISH BY EARLY
AFTERNOON. SUB-SCA WINDS PREVAIL THROUGH THURSDAY MORNING, THEN SCA
CONDITIONS ARE POSSIBLE AGAIN AS WINDS TURN SOUTH TO SOUTHWEST.
BEHIND A QUICK MOVING COLD FRONT, NORTHWESTERLY WINDS INCREASE IN
EARNEST. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED LATE THURSDAY
AFTERNOON INTO PORTIONS OF THE NIGHT. HIGH PRESSURE BUILDS IN BEFORE
EXITING OFFSHORE BY FRIDAY AFTERNOON AS WINDS DROP BELOW ADVISORY
LEVELS.
TIDES/COASTAL FLOODING
GUSTY NORTHWESTERLY WINDS WILL LEAD TO POSSIBLE BLOW OUT TIDES
STARTING THIS MORNING. LOW WATER LEVELS ARE POSSIBLE AT
CHESAPEAKE CITY, HAVRE DE GRACE, BALTIMORE, ANNAPOLIS, AND
SOLOMONS ISLAND. TIDAL ANOMALIES BEGIN RISING TUESDAY MORNING.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...WINTER WEATHER ADVISORY FROM 3 AM TO 1 PM EST TUESDAY FOR
MDZ003>006-507.
WINTER WEATHER ADVISORY FROM 1 AM TO 1 PM EST TUESDAY FOR
MDZ501-502-509-510.
VA...WINTER WEATHER ADVISORY FROM 1 AM TO NOON EST TUESDAY FOR
VAZ025>031-036>040-050-051-501-503>505-507-508.
WV...WINTER WEATHER ADVISORY FROM 3 AM TO 1 PM EST TUESDAY FOR
WVZ051>053.
WINTER WEATHER ADVISORY FROM 1 AM TO 1 PM EST TUESDAY FOR
WVZ501-503-504.
WINTER WEATHER ADVISORY FROM 1 AM TO NOON EST TUESDAY FOR
WVZ050-055-502-505-506.
MARINE...GALE WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY NIGHT
FOR ANZ533-534-537-541>543.
SYNOPSIS...DHOF/CPB
NEAR TERM...DHOF/CPB
SHORT TERM...DHOF/CPB
LONG TERM...BRO
AVIATION...BRO/DHOF/CPB
MARINE...BRO/DHOF/CPB
TIDES/COASTAL FLOODING...LWX
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