712
FXUS61 KLWX 130744
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
244 AM EST SAT DEC 13 2025
SYNOPSIS
A WEAK AREA OF HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT. AN
UPPER LEVEL DISTURBANCE WILL MOVE THROUGH TOMORROW NIGHT,
PUSHING AN ARCTIC FRONT THROUGH THE AREA AT THE SURFACE. HIGH
PRESSURE WILL BUILD IN FOR THE FIRST HALF OF NEXT WEEK.
NEAR TERM /THROUGH TODAY/
CURRENT CONDITIONS ACROSS THE REGION CAN BE CHARACTERIZED BY
INCREASED CLOUDCOVER AND VERY COLD TEMPERATURES IN THE 20S
AREA-WIDE. LOOKING AT SATELLITE, CAN SEE SEVERAL FEATURES AT
PLAY, WHICH WILL INFLUENCE THE WEATHER PATTERN IN THE NEXT 24-36
HOURS.
FIRST OFF, A WEAK UPPER RIDGE IS MOVING OVERHEAD TODAY. THIS
WILL ACTUALLY BUMP TEMPERATURES BACK INTO THE 40S FOR MOST, AND
ALSO LEAD TO DRY CONDITIONS THROUGHOUT THE DAY. HOWEVER, THERE
IS STILL ENOUGH UPPER-LEVEL MOISTURE STREAMING IN FROM THE WEST,
WHICH WILL LEAD TO ABUNDANT CLOUDCOVER THROUGHOUT THE DAY.
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 LATE SATURDAY AFTERNOON INTO SATURDAY
NIGHT. SNOW NOW APPEARS AS THOUGH IT WILL START DURING THE MID
TO LATE AFTERNOON HOURS IN THE ALLEGHENIES.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/
SNOW REALLY PICKS UP IN INTENSITY ACROSS THE ALLEGHENIES THIS
EVENING INTO TONIGHT, BECOMING MODERATE TO HEAVY AT TIMES. WINTER
STORM WARNINGS REMAIN IN EFFECT FOR WESTERN GARRETT AND WESTERN
GRANT COUNTIES, WHERE 4-8 INCHES OF SNOW IS EXPECTED. WINTER
WEATHER ADVISORIES REMAIN IN EFFECT FOR EASTERN GARRETT,
WESTERN ALLEGANY, AND WESTERN PENDLETON COUNTIES, WHERE 2-4
INCHES OF SNOW IS EXPECTED.
WITH WESTERLY LOW-LEVEL FLOW DOWNSLOPING OFF OF THE
APPALACHIANS, PRECIPITATION WILL STRUGGLE TO MAKE PROGRESS TO
THE EAST OF THE ALLEGHENY FRONT FOR SEVERAL HOURS. AS THE WAVE
AMPLIFIES AND APPROACHES FROM THE WEST, MOST MODELS SHOW A JET
STEAK DEVELOPING DOWNSTREAM, WITH FORCING FOR ASCENT INCREASING
WITHIN THE EQUATORWARD ENTRANCE OF THE JET STREAK. MOST
SOLUTIONS SHOW THE JET ENTRANCE REGION LINING UP RIGHT ALONG
I-95. ASCENT WITHIN THE JET ENTRANCE REGION MAY CAUSE
PRECIPITATION TO JUMP EASTWARD AND DEVELOP IN-SITU ALONG THE
I-95 CORRIDOR, LARGELY SKIPPING LOCATIONS BETWEEN THE ALLEGHENY
FRONT AND BLUE RIDGE.
PRECIPITATION WITHIN THE JET ENTRANCE REGION TO THE EAST OF THE
BLUE RIDGE IS EXPECTED TO BLOSSOM DURING THE MID-LATE EVENING
HOURS, AND THEN SLOWLY DRIFT SOUTHEASTWARD THROUGH THE REMAINDER
OF THE NIGHT. THE PRECIPITATION MAY BEGIN AS A BRIEF PERIOD OF
RAIN OR MIXED RAIN AND SNOW, ESPECIALLY ALONG AND SOUTHEAST OF THE
I-95 CORRIDOR. THIS MIX SHOULD BE SHORT-LIVED HOWEVER, AS MUCH
COLDER AIR RUSHES IN BEHIND AN ARCTIC FRONT THAT WILL MOVE
THROUGH OVER THE COURSE OF THE NIGHT. IN TERMS OF TIMING, SOME
LIGHT PRECIPITATION COULD BEGIN AS EARLY AS THE MID-LATE EVENING
HOURS, BUT THE BULK OF THE PRECIPITATION ALONG THE I-95
CORRIDOR IS EXPECTED TO OCCUR BETWEEN ROUGHLY 11 PM AND 7 AM.
THE BAND THAT WILL DEVELOP WILL BE A RELATIVELY NARROW FEATURE,
AND WILL FEATURE MODERATE TO HEAVY SNOW AT TIMES. SNOWFALL RATES
WITHIN THE BAND COULD NEAR OR POTENTIALLY BRIEFLY EXCEED ONE
INCH PER HOUR AT TIMES LATE SATURDAY NIGHT. WITH A NARROW
FEATURE PRODUCING HEAVY PRECIPITATION, SNOW TOTALS WILL BE
HEAVILY DEPENDENT ON THE ULTIMATE PLACEMENT OF THIS BAND. THIS,
COMBINED WITH THE POTENTIAL FOR A BIT OF MIXING WITH RAIN AT
ONSET MAKES FOR A CHALLENGING SNOWFALL FORECAST.
THE OVERNIGHT MODEL GUIDANCE CONTINUED TO FAVOR THE I-95
CORRIDOR, GENERALLY FROM DC THROUGH NORTHEAST MD, AND ESPECIALLY
EVEN INTO NJ. SO, DECIDED TO HOIST WINTER WEATHER ADVISORIES
DURING THE OVERNIGHT FORECAST CYCLE AS A RESULT. EXPECTING 1-3
INCHES FOR MOST IN THE ADVISORY, WITH SOME HIGHER TOTALS CLOSER
TO 4 INCHES IN FAR NORTHEAST MD. THERE IS STILL THAT POTENTIAL
FOR A BOOM SCENARIO, PARTICULARLY NORTHEAST OF THE DC METRO
INTO NORTHEAST MD, WHERE IN A WORST CASE SCENARIO UP TO 6 INCHES
COULD BE POSSIBLE. EVERYTHING WOULD NEED TO LINE UP PERFECTLY
FOR THIS TO HAPPEN, BUT IT IS STILL NOT OUT OF THE REALM OF
POSSIBILITY.
SNOW WILL END FROM NORTHWEST TO SOUTHEAST A FEW HOURS EITHER
SIDE OF DAYBREAK, WITH THE BACK EDGE OF THE SNOW CLEARING
SOUTHERN MARYLAND BY AROUND MID- MORNING.
STRONG COLD AIR ADVECTION IS EXPECTED BEHIND THE ARCTIC FRONT
THROUGH THE DAY SUNDAY, WITH 850 HPA TEMPERATURES CRASHING TO
AROUND -15 TO -20 C BY PEAK HEATING. THIS WILL CAUSE
TEMPERATURES TO DROP THROUGH THE 20S OVER THE COURSE OF THE DAY.
NORTHWESTERLY WIND GUSTS TO AROUND 35 MPH WILL MAKE IT FEEL EVEN
COLDER, PUSHING WIND CHILLS INTO THE SINGLE DIGITS AND TEENS.
AFTER THE SNOW MOVES OUT, DRY CONDITIONS ARE EXPECTED TO THE
EAST OF THE MOUNTAINS. UPSLOPE SNOW SHOWERS WILL LINGER IN THE
ALLEGHENIES OVER THE COURSE OF THE DAY. COLD AND WINDY
CONDITIONS WILL CONTINUE THROUGH SUNDAY NIGHT, WITH COLD WEATHER
HEADLINES LIKELY BEING NEEDED FOR PORTIONS OF THE AREA.
LONG TERM /TUESDAY THROUGH FRIDAY/
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. WAA WILL ENSUE AT THE SURFACE LATE TUESDAY
INTO WEDNESDAY AS A WARM FRONT LIFTS TOWARD THE REGION. THIS WILL
BRING RAIN SHOWERS WEDNESDAY THAT LINGER INTO THURSDAY. 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. HIGH PRESSURE BUILDS AGAIN OVER THE AREA TO END
THE WEEK.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS AND LIGHT SOUTHWESTERLY WINDS ARE EXPECTED AT
ALL TERMINALS DURING THE DAY TODAY.
LOWER CEILINGS AND SNOW ARE EXPECTED TO DEVELOP ACROSS MUCH OF
THE FORECAST AREA, STARTING AS EARLY AS THIS EVENING. BWI, MTN,
DCA, AND IAD ARE MOST LIKELY TO EXPERIENCE THE GREATEST IMPACTS
FROM SNOW, WITH A COUPLE INCHES OF ACCUMULATION POSSIBLE DURING
THE SECOND HALF OF THE NIGHT. THE PRECIPITATION COULD ALSO
BRIEFLY MIX WITH RAIN AT ONSET. CHANCES FOR SNOWFALL ARE A BIT
LESSER AT MRB, BUT WOULD BE ON THE EARLIER SIDE OF THINGS,
STARTING AS EARLY AS 01Z TONIGHT. BUT ACCUMULATIONS LOOK TO BE
VERY MINIMAL IF THEY OCCUR AT ALL AT MRB. SNOW APPEARS AS
THOUGH IT WILL LIKELY AVOID CHO ALTOGETHER, THOUGH CAN'T RULE
OUT A FEW FLURRIES OVERNIGHT INTO EARLY SUNDAY.
CONDITIONS ARE EXPECTED TO IMPROVE BACK TO VFR BY MID-MORNING
SUNDAY AT ALL TERMINALS AS THE BAND OF SNOW QUICKLY RETREATS
TOWARDS THE EAST. NORTHWESTERLY GUSTS OF UP TO 35 KNOTS ARE
POSSIBLE THROUGHOUT THE AFTERNOON IN THE WAKE OF THIS STRONG
FRONT.
WHILE VFR CONDITIONS ARE FORECAST FOR MONDAY, WINDS REMAIN GUSTY
IN THE WAKE OF THE AFOREMENTIONED ARCTIC FRONT. EXPECT GUSTS UP
TO 25 KNOTS DURING THE FIRST HALF OF THE DAY. THESE TAPER OFF
DURING THE AFTERNOON, GOING NEARLY CALM MONDAY NIGHT.
VFR CONDITIONS TUESDAY AND WEDNESDAY AS HIGH PRESSURE MOVES
OVERHEAD AND EVENTUALLY OFFSHORE. WINDS LIGHT AND VARIABLE
TUESDAY AS THE HIGH IS OVERHEAD, BUT WILL TURN OUT OF THE
SOUTHWEST TUESDAY NIGHT INTO WEDNESDAY, ALBEIT REMAINING LIGHT.
MARINE
DUE TO SOME SOUTHERLY CHANNELING UP THE CHESAPEAKE BAY EARLY
THIS MORNING, A BRIEF PERIOD OF NEAR-SCA WINDS IS POSSIBLE
AROUND DAYBREAK. CONFIDENCE WAS TOO LOW FOR AN SCA THOUGH, BUT
SHOULD THIS OCCUR, AN MWS MAY SUFFICE TO COVER THIS THREAT. WILL
CONTINUE TO MONITOR OVER THE NEXT COUPLE OF HOURS.
SUB-SCA LEVEL SOUTHWESTERLY WINDS ARE EXPECTED DURING THE DAY
TODAY. WINDS WILL THEN TURN OUT OF THE NORTHWEST AND PICK UP
FAIRLY RAPIDLY IN MAGNITUDE DURING THE SECOND HALF OF THE NIGHT
AS AN ARCTIC FRONT MOVES OVER THE WATERS. GALE WARNINGS HAVE
BEEN HOISTED WITH THE OVERNIGHT FORECAST PACKAGE TO COVER THIS
THREAT. HOWEVER, THE PEAK WINDS MAY NOT OCCUR UNTIL MID-LATE
MORNING. STILL, CONDITIONS WILL DETERIORATE QUICKLY AROUND
DAYBREAK. FREEZING SPRAY MAY ALSO BE POSSIBLE AT TIMES DURING
THE DAY SUNDAY AND INTO SUNDAY NIGHT, ESPECIALLY OVER THE WIDER
WATERS OF THE CHESAPEAKE BAY, WHERE WAVES MAY BE UP TO 5 FEET
AT TIMES AND WINDS REMAIN GALE-FORCE.
GALE CONDITIONS GRADUALLY TAPER OFF OVERNIGHT FROM NORTHWEST TO
SOUTHEAST, BUT WILL LINGER OVER THE LOWER TIDAL POTOMAC AND
MIDDLE BAY UNTIL EARLY MONDAY MORNING.
SCA CONDITIONS EXPECTED TO CONTINUE MONDAY WITH GUSTS UP TO 25
KT, DIMINISHING GRADUALLY THROUGH THE DAY AND NIGHT, AND
DROPPING BELOW SCA THRESHOLD BY DAYBREAK TUESDAY.
LIGHTER WINDS EXPECTED ON TUESDAY AND WEDNESDAY, WITH NO MARINE
HAZARDS EXPECTED.
TIDES/COASTAL FLOODING
FOLLOWING THE PASSAGE OF A STRONG ARCTIC COLD FRONT SUNDAY,
GUSTY NORTHWEST WINDS WILL PUSH WATER SOUTH AND TOWARDS THE
SOUTHERN PORTIONS OF THE CHESAPEAKE BAY FAIRLY RAPIDLY. BLOWOUT
TIDES SEEM LIKELY FOR MANY AREAS ALONG THE WESTERN SHORELINE OF
THE CHESAPEAKE BAY BY THE SUNDAY EVENING LOW TIDE CYCLE AND
CONTINUING INTO MONDAY AS WELL.
LWX WATCHES/WARNINGS/ADVISORIES
DC...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 7 AM EST
SUNDAY FOR DCZ001.
MD...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 7 AM EST
SUNDAY FOR MDZ005-006-008-011-013-014-503>508.
GALE WARNING FROM 6 AM TO 6 PM EST SUNDAY FOR MDZ008.
SMALL CRAFT ADVISORY FROM 6 PM SUNDAY TO 6 AM EST MONDAY FOR
MDZ008.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST
SUNDAY FOR MDZ016-018.
WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
SUNDAY FOR MDZ501-510.
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 4 PM EST
SUNDAY FOR MDZ509.
VA...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 7 AM EST
SUNDAY FOR VAZ053-054.
WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST
SUNDAY FOR WVZ503-505.
WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 4 PM EST
SUNDAY FOR WVZ501.
MARINE...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 7 AM EST
SUNDAY FOR ANZ530.
GALE WARNING FROM 6 AM TO 6 PM EST SUNDAY FOR ANZ530-531-535-
536-538-539.
SMALL CRAFT ADVISORY FROM 6 PM SUNDAY TO 6 AM EST MONDAY FOR
ANZ530-531-535-536-538-539.
GALE WARNING FROM 6 AM SUNDAY TO 6 AM EST MONDAY FOR
ANZ532>534-537-540>543.
SYNOPSIS...CJL
NEAR TERM...CJL
SHORT TERM...CJL/KJP
LONG TERM...CPB
AVIATION...ADS/CJL/CPB
MARINE...CJL/CPB
TIDES/COASTAL FLOODING...CJL
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