072
FXUS61 KLWX 182032
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
332 PM EST WED DEC 18 2024
SYNOPSIS
LOW PRESSURE WILL TRACK THROUGH THIS EVENING WITH A COLD FRONT
MOVING THROUGH OVERNIGHT. HIGH PRESSURE WILL BUILD TO OUR NORTH
TOMORROW, BEFORE A CLIPPER SYSTEM MOVES THROUGH ON FRIDAY. HIGH
PRESSURE WILL BUILD IN FROM THE GREAT LAKES THIS WEEKEND.
NEAR TERM /THROUGH TONIGHT/
UPPER TROUGHING AND A WEAK AREA OF LOW PRESSURE AT THE SURFACE
WILL APPROACH FROM THE WEST LATER THIS AFTERNOON INTO THIS
EVENING. A FEW SHOWERS ARE ONGOING ACROSS THE WEST VIRGINIA
PANHANDLE AND NORTHERN MARYLAND WITHIN LOW-LEVEL WARM ADVECTION.
FURTHER WEST, A STEADIER AREA OF RAIN ASSOCIATED WITH
FRONTOGENETICAL FORCING IS LOCATED ALONG THE SPINE OF THE
APPALACHIANS. THIS AREA OF RAIN WILL TRANSLATE EASTWARD ACROSS
THE AREA THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING.
MOST LOCATIONS SHOULD EXPERIENCE A 3-6 HOUR WINDOW WITH ON AND
OFF RAIN DURING THAT TIME. THE RAIN WILL MOVE OUT OF THE
MOUNTAINS BY THIS EVENING, AND WILL CLEAR THE ENTIRE AREA BY
SHORTLY AFTER MIDNIGHT. WINDS WILL TURN NORTHWESTERLY AS A COLD
FRONT MOVES THROUGH THE AREA. COLD ADVECTION BEHIND THE FRONT
WILL USHER COOLER AIR INTO THE REGION BY MORNING. MOST
LOCATIONS SHOULD SEE LOW TEMPERATURES IN THE 30S, WITH THE
MOUNTAINS DROPPING INTO THE UPPER 20S.
WHILE LOCATIONS TO THE EAST OF THE ALLEGHENIES WILL DRY OUT FOR
THE SECOND HALF OF THE NIGHT, UPSLOPE FLOW WILL PROLONG LIGHT
PRECIPITATION THROUGH THE NIGHT IN THE MOUNTAINS. AS COLDER AIR
FILTERS IN, PRECIPITATION WILL CHANGE OVER TO A MIXTURE OF
LIGHT SNOW AND/OR FREEZING DRIZZLE (DEPENDING ON WHETHER ICE
CRYSTALS ARE LOST). VERY MINOR SNOW ACCUMULATIONS (LESS THAN AN
INCH) ARE EXPECTED, ALONG WITH THE POTENTIAL FOR A GLAZE OF ICE
(ESPECIALLY ON WEST FACING RIDGETOPS). A SPECIAL WEATHER
STATEMENT WAS ISSUED TO ACCOUNT FOR THIS POTENTIAL OF A GLAZE OF
ICE. IF CONFIDENCE IN THIS OCCURRING INCREASES, A WINTER
WEATHER ADVISORY MAY POTENTIALLY BE NEEDED FOR THOSE LOCATIONS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
A WEAK AREA OF HIGH PRESSURE WILL BUILD INTO THE AREA TOMORROW,
LEADING TO DRY CONDITIONS. DAYTIME HIGH TEMPERATURES WILL
REACH INTO THE LOW TO MID 40S FOR MOST (30S MOUNTAINS) BENEATH
A MIXTURE OF CLOUDS AND SUN. WINDS WILL BE OUT OF THE NORTHWEST,
AND WILL GRADUALLY DECREASE THROUGH THE DAY. DRY CONDITIONS
WILL CONTINUE THROUGH TOMORROW NIGHT. WINDS WILL GO LIGHT TO
CALM, WITH OVERNIGHT LOWS IN THE 20S.
A CLIPPER SYSTEM WILL APPROACH THE AREA WITHIN NORTHWESTERLY
FLOW ON FRIDAY. AS THE UPPER TROUGH ASSOCIATED WITH THIS SYSTEM
PASSES OVERHEAD, A FEW RAIN OR SNOW SHOWERS MAY BE POSSIBLE,
ESPECIALLY FRIDAY AFTERNOON OR EVENING. HIGH TEMPERATURES SHOULD
BE IN THE UPPER 30S TO LOW 40S FOR MOST, WITH LOWER 30S IN THE
MOUNTAINS. A REINFORCING SHOT OF COLD AIR WILL MOVE IN BEHIND
THE SYSTEM'S COLD FRONT FRIDAY NIGHT. THIS WILL LEAD TO UPSLOPE
SNOW SHOWERS IN THE MOUNTAINS. AS COLDER AIR FILTERS IN, SNOW IN
THE MOUNTAINS WILL TRANSITION FROM MORE OF A WET (LOWER SLR)
SNOW FRIDAY AFTERNOON TO A DRY, FLUFFY (HIGHER SLR) SNOW FRIDAY
NIGHT. BY DAYBREAK SATURDAY, A GENERAL 2-5 INCHES OF SNOW IS
EXPECTED IN THE ALLEGHENIES.
WHILE PRECIPITATION SHOULD BE LIGHT, SHOWERY, AND MOSTLY
INCONSEQUENTIAL TO THE EAST OF THE MOUNTAINS, ONE AREA TO WATCH
IS FAR NORTHEASTERN MARYLAND. SOME GUIDANCE IS HINTING AT THE
DEVELOPMENT OF A NORLUN TROUGH BETWEEN THE PRIMARY CLIPPER LOW
AND A DEVELOPING COASTAL LOW. THE MAJORITY OF GUIDANCE HAS THIS
NORLUN TROUGH AND ASSOCIATED PRECIPITATION SETTING UP ACROSS NJ
AND SOUTHEASTERN PA, BUT IT BEARS WATCHING IN NORTHEAST
MARYLAND. CURRENTLY THE FORECAST CALLS FOR A COATING TO AN INCH
OF SNOW FRIDAY NIGHT IN FAR NORTHEAST MARYLAND (CECIL COUNTY),
BUT IF THE FEATURE WERE TO TREND SOUTHWESTWARD, A FEW INCHES OF
SNOW COULD BE POSSIBLE.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
UPSLOPE SNOW ALONG THE ALLEGHENIES LIKELY CONTINUES INTO SATURDAY
MORNING. PRECIP COULD MAKE IT EAST OF THE MOUNTAINS AS WELL, BUT
UNCERTAINTY REMAINS. IF AREAS OUTSIDE OF THE MOUNTAINS WERE TO
RECEIVE SNOW, HIGHER PROBABILITIES ARE CURRENTLY RESTRICTED TO WEST
OF THE BLUE RIDGE AND FAR NORTHERN MARYLAND.
REGARDLESS, AFTER THE SHORTWAVE MOVES OUT, STRONG HIGH PRESSURE
BUILDS IN BEHIND IT WITH THE BITTER COLD AIR MASS. DRY CONDITIONS
ARE EXPECTED TO FOLLOW FOR THE REMAINDER OF THE WEEKEND INTO MONDAY.
HIGH TEMPERATURES ON SATURDAY THROUGH MONDAY ARE EXPECTED TO BE IN
THE 30S FOR MOST OF THE AREA, AND THE TEENS AND 20S IN THE
MOUNTAINS. LOW TEMPERATURES PLUMMET TO THE TEENS AND UPPER 20S
ACROSS THE BOARD, AND POSSIBLY SINGLE DIGITS IN THE HIGHER
ELEVATIONS. GUSTY NW WINDS AROUND 20-25 MPH (UP TO 30 MPH IN THE
MOUNTAINS) COULD KNOCK ANOTHER 10 DEGREES OFF THE LOW TEMPERATURES
FOR WIND CHILLS ON SATURDAY.
FOR EARLY NEXT WEEK, BROAD WEAK RIDGING ALOFT WILL GIVE WAY TO
ANOTHER UPPER TROUGH. DETERMINISTIC GUIDANCE IS IN GENERAL AGREEMENT
OF A SERIES OF SHORTWAVES TREKKING EAST DURING THIS TIME, WITH
DECENT CONSENSUS OF ONE AROUND THE SOUTHERN PLAINS AND ANOTHER NEAR
THE MIDWEST, BUT OTHERWISE THERE IS WIDE VARIATION ON STRENGTH,
TIMING, ETC. THE NEXT SYSTEM TO BRING PRECIP TO THE AREA LOOKS TO BE
SOMETIME BETWEEN MONDAY AND TUESDAY, OR POSSIBLY AS LATE AS
WEDNESDAY.
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
CEILINGS ARE GRADUALLY DROPPING THIS AFTERNOON AS A SYSTEM MOVES
IN FROM THE WEST. MOST LOCATIONS SHOULD GO MVFR WITHIN THE NEXT
COUPLE HOURS, AND MAY APPROACH HIGH-END IFR FOR A TIME LATER
THIS EVENING. RAIN WILL ALSO OVERSPREAD THE AREA FROM WEST TO
EAST LATER THIS AFTERNOON INTO THIS EVENING. SHOWERS WILL
CONTINUE, ALONG WITH LOW-END MVFR/HIGH-END IFR CEILINGS THROUGH
THE FIRST HALF OF THE NIGHT. WINDS WILL BE LIGHT OUT OF THE
SOUTH TO SOUTHEAST THROUGH THIS EVENING.
A COLD FRONT WILL MOVE THROUGH THE AREA TONIGHT. WINDS WILL TURN
NORTHWESTERLY BEHIND THE FRONT, WITH GUSTS TO AROUND 15-20 KNOTS
POSSIBLE LATER TONIGHT THROUGH TOMORROW MORNING. CONDITIONS WILL
ALSO IMPROVE TO VFR BEHIND THE FRONT. VFR CONDITIONS AND
NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE DAY TOMORROW.
WINDS TURN NORTH TO NORTHEASTERLY TOMORROW NIGHT INTO FRIDAY
MORNING, WITH CONTINUED VFR CEILINGS. SOME LIGHT RAIN OR SNOW
SHOWERS MAY BE POSSIBLE, ALONG WITH SUB-VFR CEILINGS DURING THE
DAY FRIDAY, BUT THE MAJORITY OF THE TIME SHOULD REMAIN DRY.
CONDITIONS WILL RETURN TO VFR AND WINDS WILL INCREASE OUT OF THE
NORTHWEST FRIDAY NIGHT.
VFR CONDITIONS ARE EXPECTED OVER THE WEEKEND. GUSTY NW FLOW ON
SATURDAY COULD GUST 15-20 KTS. WINDS WEAKEN AND TURN NORTHERLY ON
SUNDAY.
MARINE
SUB-SCA LEVEL SOUTH TO SOUTHEASTERLY WINDS ARE EXPECTED TODAY. A
COLD FRONT WILL CROSS OVER THE WATERS THIS EVENING. WINDS WILL
SHIFT TO OUT OF THE NORTHWEST BEHIND THIS FRONT. SCAS ARE IN
EFFECT WITHIN NORTHWESTERLY FLOW FOR ALL WATERS LATER THIS
EVENING THROUGH THE EARLY AFTERNOON HOURS TOMORROW. THEREAFTER,
WINDS DECREASE TO SUB-SCA LEVELS AND BECOME NORTH TO
NORTHEASTERLY TOMORROW NIGHT THROUGH FRIDAY. ANOTHER COLD FRONT
WILL MOVE OVER THE WATERS FRIDAY NIGHT, WITH SCA CONDITIONS
LIKELY IN THE WAKE OF THAT FRONT FRIDAY NIGHT.
GUSTY NW WINDS LIKELY RESULT IN SCA CONDITIONS THROUGH SUNDAY
MORNING, AND POSSIBLY INTO THE AFTERNOON FOR OUR SOUTHERN WATERS.
WINDS BECOME NORTHERLY AND GRADUALLY DIMINISH THROUGH SUNDAY NIGHT.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 3 PM EST
THURSDAY FOR MDZ008.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 3 PM EST
THURSDAY FOR ANZ530>543.
SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...CAS
AVIATION...KJP/CAS
MARINE...KJP/CAS
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