361
FXUS61 KLWX 161541
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1041 AM EST SUN FEB 16 2025
SYNOPSIS
A WARM FRONT WILL LIFTING NORTH OF THE AREA BY THIS AFTERNOON
WILL QUICKLY BE FOLLOWED BY A COLD FRONT AS LOW PRESSURE TRACKS
INTO THE NORTHEAST. AN EXPANSIVE ARCTIC HIGH PRESSURE WILL BUILD
INTO THE NORTH-CENTRAL U.S. THIS WEEK. MEANWHILE, AN AREA OF LOW
PRESSURE WILL TAKE SHAPE OVER THE MISSISSIPPI RIVER VALLEY BY
MID WEEK, THEN TRACK TO THE CAROLINAS AND UP OFF THE EAST COAST
WEDNESDAY INTO THURSDAY. HIGH PRESSURE WILL TAKE OVER LATE IN
THE WEEK.
NEAR TERM /THROUGH TONIGHT/
THE 12Z IAD SOUNDING SHOWS A SHARP LOW LEVEL INVERSION THAT THE
INCREASING WIND FIELDS AND WARM RAIN HAVE BEEN UNABLE TO FULLY
ERODE WITH THE EXCEPTION OF THE CENTRAL SHENANDOAH VALLEY AND
SOUTHERN MARYLAND. TEMPERATURE ADJUSTMENTS ARE LIKELY, WITH ANY
BRIEF SPIKE LIKELY OCCURRING RIGHT ALONG FRONTAL PASSAGE BEFORE
TEMPERATURES CRASH AGAIN.
REMNANT CONVECTION IS MOVING ACROSS THE AREA AT THIS TIME. THE
INITIAL LINE GUSTED OUT, BUT A NEW LINE IS FORMING AS THE
FORCING OVERSPREADS GREATER INSTABILITY CLOSER TO THE CHESAPEAKE
BAY (EAST OF THE WARM FRONT). MOST OF THE FORECAST AREA SHOULD
BE TOO STABLE TO SEE ANY SEVERE WEATHER WITH THIS LINE EXCEPT
PERHAPS FAR SOUTHERN MARYLAND. SEVERE WEATHER IS ALSO OCCURRING
ALONG THE COLD FRONT IN EASTERN KENTUCKY. WILL HAVE TO MONITOR
WHAT CAN SURVIVE THE MOUNTAINS. CAMS HAVE MIXED SIGNALS OF
DECAYING CONVECTION MOVING EASTWARD THIS AFTERNOON.
WITH THE STRONGER INVERSION, WINDS HAVE ALSO BEEN SLOW TO
INCREASE. THIS COULD LEAD TO A SUDDEN ONSET OF STRONG WINDS WITH
FRONTAL PASSAGE THIS AFTERNOON FOR SOME AREAS.
PREVIOUS DISCUSSION:
AS THE PARENT LOW PRESSURE TRACKS THROUGH PA EN ROUTE TO NEW
ENGLAND, THE SYSTEM'S POWERFUL COLD FRONT WILL MARCH STEADILY
EASTWARD THROUGH THE MID-ATLANTIC THIS AFTERNOON.
THE COLD FRONT ITSELF WILL BE ACCOMPANIED BY A WIND SHIFT FROM
THE SOUTHWEST TO WEST, AS WELL AS SHARP PRESSURE RISES AND THE
ONSET OF COLD ADVECTION. THESE FACTORS SHOULD EFFECTIVELY BREAK
THE LOW-LEVEL STABILITY, PERHAPS AIDED BY A BROKEN LINE OF
SHALLOW SHOWERS, RESULTING IN A RAPID INCREASE IN WIND GUSTS TO
50 TO 60 MPH THIS AFTERNOON. UNCERTAINTY IN HOW WELL WINDS MIX
AND THE STRENGTH/SPEED OF DECAY OF THE LOW-LEVEL STABILITY RAISE
SOME UNCERTAINTIES TO EXACT WIND MAGNITUDE AND EXTENT, BUT VERY
GUSTY WINDS WILL BE REALIZED HEADING INTO THE EVENING AS LOW-
LEVEL LAPSE RATES STEEPEN AMID COLD ADVECTION REGARDLESS.
TEMPERATURES WILL FALL THROUGH THE NIGHT, DROPPING INTO THE
TEENS FOR THE HIGHER ELEVATIONS, THE 20S OVER NORTHERN MD AND
NEAR AND WEST OF US-15, AND AROUND FREEZING NEAR/EAST OF I-95.
AS COLDER AIR RUSHES INTO THE REGION, LINGERING MOISTURE BEHIND
THE DEPARTING LOW WILL INTERSECT THE MOUNTAINS RESULTING IN A
PERIOD OF UPSLOPE SNOW. FROUDE NUMBERS ARE RATHER HIGH,
INDICATING HIGH INVERSION LEVELS AND A HIGH LIKELIHOOD FOR
SPILLOVER EAST OF THE APPALACHIAN CREST. BLIZZARD WARNINGS AND
WINTER WEATHER ADVISORIES REMAIN IN EFFECT NEAR AND WEST OF THE
ALLEGHENY FRONT FOR THIS REASON, WITH NO APPRECIABLE CHANGE IN
EXPECTATION FROM THE PREVIOUS THINKING. THE HIGH FROUDE NUMBERS
MAY ALLOW FLURRIES OR A SNOW SHOWER OR TWO TO DRIFT EAST TOWARD
THE BLUE RIDGE BY DAYBREAK.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
UPSLOPE SNOW WILL LINGER INTO MONDAY MORNING ALONG AND WEST OF
THE ALLEGHENY FRONT. FURTHER EAST, FLURRIES MAY CROSS AS FAR
EAST AS THE BLUE RIDGE TO PERHAPS US-15 BEFORE DRY AIR TAKES
OVER AND CONDITIONS DRY OUT.
MONDAY AND TUESDAY WILL BE NOTABLY COLDER IN THE WAKE OF THE
STRONG COLD FRONT. THIS WILL SET THE STAGE FOR POTENTIAL WINTRY
PRECIP (SNOW) HEADING INTO MID WEEK.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
LOOMING WEDNESDAY-THURSDAY WINTER STORM THREAT YET TO BE
FULLY RESOLVED...
THE FOCUS OF THE LONG TERM PERIOD CONTINUES TO BE ON AN EAST
COAST WINTER STORM THREAT AND ITS POTENTIAL IMPACTS TO THE MID-
ATLANTIC REGION. FOR THE BETTER PART OF THE LAST WEEK, ENSEMBLES
HAVE BEEN HINTING AT THE POTENTIAL OF SIGNIFICANT SNOW AROUND
FEBRUARY 20, THOUGH THERE ARE SOME TRENDS IN THE LAST 48 TO 72
HOURS WORTH NOTING.
FOR MID WEEK, UPPER-LEVEL PATTERN/ENSEMBLE MEAN 500 HPA HEIGHT
TRENDS THE LAST COUPLE OF DAYS HAVE BEEN FOR (1) A SOMEWHAT
WEAKER NORTHERN STREAM UPPER LOW DESCENDING INTO THE NORTHERN
PLAINS, AND (2) A WEAKER WEST COAST/ROCKIES RIDGE LIKELY DUE AT
LEAST IN PART TO A STRONGER AND FASTER SHORTWAVE PROGGED TO BE
APPROACHING THE PACIFIC NORTHWEST. IT APPEARS THESE TRENDS
REACHED A CRITICAL THRESHOLD IN THE 15/12Z GUIDANCE SUITE, WITH
A BIMODAL DISTRIBUTION AMONG VARYING ENSEMBLES SLIGHTLY FAVORING
LESS MERIDIONAL FLOW AND A MORE OFFSHORE SURFACE LOW TRACK. THIS
PATTERN SHIFT, IF IT VERIFIES, WOULD ALLOW THE SOUTHERN STREAM
SHORTWAVE TO NOT BE FULLY CAUGHT AS QUICKLY BY THE SLIGHTLY LESS
AMPLIFIED NORTHERN STREAM UPPER LOW, WITH LESS PHASING RESULTING
IN THE FURTHER SOUTHEAST/OFFSHORE TRACK. THE TREND WAS MOST
OBVIOUS IN THE EPS (ECMWF ENSEMBLE) AND MOGREPS-G (UKMET
ENSEMBLE), WHICH SHOWED A SOUTHEASTWARD SHIFT IN THE AXIS OF
HIGHEST SNOWFALL PROBABILITIES. THE TREND PERSISTED THROUGH THE
15/18Z CYCLE, AND APPEARS TO HAVE STABILIZED A BIT IN THE 16/00Z
CYCLE (THOUGH WITH SOME -INCREASING- SPREAD).
INTERESTINGLY, SOME MACHINE LEARNING GUIDANCE (I.E. THE
GRAPHCAST GFS AND ECMWF-AIFS) HAD BEEN SHOWING THIS OFFSHORE
TRACK POTENTIAL FOR SEVERAL DAYS NOW. HOWEVER, THEIR LATEST RUNS
HAVE TRENDED A BIT TO THE NORTHWEST (CLOSER TO THE COAST),
PERHAPS INDICATIVE OF A STABILIZING OR EVEN REVERSAL IN TRENDS.
ALSO OF NOTE, ALTHOUGH THE HIGHEST PROBABILITIES FOR 6- AND
12-INCH PLUS SNOWS HAVE SHIFTED SOUTHEASTWARD FOR THE TIME
BEING, PROBABILITIES FOR 2 INCHES OF SNOW REMAIN ELEVATED. THIS
SUGGESTS THAT AT LEAST SOME SNOW IS HIGHLY LIKELY (PROBABLY WITH
THE PASSING NORTHERN STREAM UPPER TROUGH/LOW EVEN IN A LESS
AMPLIFIED SCENARIO).
IT IS IMPORTANT TO NOTE THIS TREND, BUT ALSO THE CONTINUED
VARIABILITY AND LIKELY FUTURE SHIFTS IN THE TRACK. DESPITE THE
SHIFT IN ENSEMBLE MEANS AND THE RATHER LOW AMOUNTS OF SNOW
LOCALLY IN THE 16/00Z CMC AND UKMET DETERMINISTIC, THE ECMWF
DETERMINISTIC REMAINS STEADFAST IN SOLID WARNING LEVEL SNOW FOR
MUCH OF THE REGION. THE RECENT GFS AND ICON DETERMINISTIC ALSO
INDICATE A HIGH LIKELIHOOD OF WARNING LEVEL SNOW FOR AT LEAST
ROUGHLY THE SOUTHEASTERN HALF OF THE CWA.
GIVEN THE AMOUNT OF COLD AIR, MOISTURE, AND ENERGY PRESENT, THE
POTENTIAL FOR A SIGNIFICANT WINTER STORM STILL EXISTS AND NEEDS
TO BE CLOSELY MONITORED. BUT, THE EXACT DETAILS OF HOW THIS ALL
UNFOLDS REMAIN UNCLEAR THIS FAR IN ADVANCE.
LATE WEEK WEATHER WILL BE DICTATED BY THE EVOLUTION OF THE
WEDNESDAY-THURSDAY SYSTEM, AS A STRONGER SYSTEM WOULD RESULT IN
MORE SNOW, AND COLDER TEMPERATURES AND MORE WIND IN ITS WAKE.
GENERALLY SPEAKING, HIGH PRESSURE WILL BUILD INTO THE REGION
FRIDAY INTO SATURDAY. A NORTHWEST BREEZE COULD GUST UP TO 25 MPH
IN MOST PLACES IN THE MOUNTAINS, ALONG THE MASON-DIXON REGION,
AND OVER MUCH OF THE EASTERN HALF OF REGION ON FRIDAY. LESSER
GUSTS ARE EXPECTED IN THE CENTRAL SHENANDOAH VALLEY. THIS
NORTHWEST WIND WILL BE A DOWNSLOPING FLOW TO THE EAST OF THE
MOUNTAINS, SO LITTLE TO NO PRECIPITATION IS EXPECTED IN THESE
AREAS. THIS WIND WILL BE AN UPSLOPE INTO THE MOUNTAINS, BUT
LITTLE TO NO MOISTURE AVAILABLE WILL LEAD TO VERY LITTLE
UPSLOPE SNOW IN THE MOUNTAINS. MOST WOULD OCCUR THURSDAY, THE
DAY BEFORE, AS THE POWERFUL LOW PRESSURE SYSTEM PULLS AWAY FROM
THE MID-ATLANTIC. HIGH TEMPERATURES FRIDAY AND LOW TEMPERATURES
FRIDAY NIGHT WILL BE CHILLY WITH HIGHS IN THE 30S AND LOWS IN
THE TEENS AND 20S. THROUGH THE DAY SATURDAY, SOME SUN AND CLOUDS
ARE EXPECTED WITH THE SAME HIGH PRESSURE CENTER OVERHEAD. HIGH
TEMPERATURES WILL REMAIN CHILLY, BUT COULD BE A FEW DEGREES
HIGHER THAN FRIDAY.
AVIATION /16Z SUNDAY THROUGH THURSDAY/
IFR TO LIFR CEILINGS, LOWER VISIBILITIES, AND LIGHTER WINDS
(WITH SOME LLWS PRESENT) WILL BE PERISTING LONGER INTO THE
MIDDAY HOURS DUE TO A STRONG STABLE LAYER. THE DENSEST FOG IS
GENERALY IMPROVING AS A MODERATE RAIN HAS OVERSPREAD THE AREA.
AFTER THIS BAND MOVES THROUGH, THERE WILL BE A BREAK IN THE RAIN
BUT THERE STILL COULD BE A FEW SHOWERS OR DRIZZLE.
THIS AFTERNOON, A STRONG COLD FRONT WILL CROSS FROM WEST TO EAST
(ROUGHLY 17Z TO 21Z FROM WEST TO EAST). ALTHOUGH WINDS WILL
LIKELY INCREASE AND TURN FROM S TO SW AS EARLY AS LATE THIS
MORNING, A MORE MARKED INCREASE IN WINDS AS WELL AS A SHIFT TO
WESTERLY CAN BE ANTICIPATED AS THE FRONT CROSSES. A FEW LOW
TOPPED SHOWERS MAY ACCOMPANY THE FRONT, ALONG WITH AN INCREASE
IN WIND GUSTS OF 40 TO 45 KNOTS (50 KNOTS IS QUITE POSSIBLE,
THOUGH TEMPERED CONFIDENCE OF VALUES THAT HIGH AND THE EXACT
TIMING AT ANY ONE SPOT PRECLUDE AN EXPLICIT INCLUSION IN THE
TAFS AS OF THIS WRITING). AFTER FROPA, VFR QUICKLY RETURNS.
VFR IS THEN EXPECTED THROUGH TUESDAY NIGHT WITH W/NW WINDS ONLY
GRADUALLY DIMINISHING. WINDS TURN N BY WED/THU. SNOW POTENTIAL
INCREASES AS LOW PRESSURE APPROACHES FROM THE SW DURING THIS
TIME, THOUGH DETAILS IN EXTENT OF SNOW AND RESTRICTIONS REMAINS
UNCERTAIN AT THIS TIME.
MARINE
THE WARM FRONT HAS BEEN SLOW TO LIFT NORTHWARD, SO WINDS HAVE
BEEN RATHER TAME EXCEPT ACROSS SOUTHERN MARYLAND. STRONGER GUSTS
ARE POSSIBLE IN ASSOCIATION WITH A REMNANT BAND OF CONVECTION
THAT IS CURRENTLY APPROACHING THE WATERS, ESPECIALLY ACROSS
SOUTHERN MARYLAND. THIS ACTIVITY MAY HELP TO START MIXING OUT
THE LOW- LEVEL INVERSION, BUT WARMER AIR OVER COOLER WATER COULD
KEEP HIGHER GUSTS LIMITED TO THE NEAR SHORE WATERS UNTIL A COLD
FRONT CROSSES THIS AFTERNOON, POSSIBLY ACCOMPANIED BY MORE
GUSTY SHOWERS. A WIND SHIFT TO THE WEST AND A SHARP INCREASE IN
WINDS TO STORM FORCE ARE LIKELY AS THE FRONT CROSSES MID TO LATE
AFTERNOON.
AS THE COLD FRONT MOVES OFFSHORE, A LARGE AREA OF HIGH PRESSURE
WILL DESCEND INTO THE NORTH-CENTRAL U.S. THE GRADIENT BETWEEN
THESE TWO SYSTEMS WILL LEAD TO ONLY GRADUALLY DIMINISHING WINDS
THROUGH TUESDAY (GALES LIKELY LINGER INTO MONDAY, SCAS INTO
TUESDAY). WINDS TURN NORTH WEDNESDAY INTO THURSDAY AS LOW
PRESSURE DEVELOPS TO THE SOUTH. UNCERTAINTY LOOMS WITH THIS MID
WEEK LOW, SO THE WIND FORECAST IS A BIT UNCERTAIN AS WELL.
LWX WATCHES/WARNINGS/ADVISORIES
DC...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR DCZ001.
MD...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR MDZ004>006-
008-011-013-014-016>018-503>508.
STORM WARNING UNTIL 10 PM EST THIS EVENING FOR MDZ008.
GALE WARNING FROM 10 PM THIS EVENING TO 4 PM EST MONDAY FOR
MDZ008.
FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR MDZ001-501.
BLIZZARD WARNING UNTIL 3 PM EST MONDAY FOR MDZ001.
HIGH WIND WARNING UNTIL 1 AM EST MONDAY FOR MDZ003.
HIGH WIND WARNING UNTIL NOON EST MONDAY FOR MDZ501-502.
WINTER WEATHER ADVISORY UNTIL 3 PM EST MONDAY FOR MDZ501.
VA...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR VAZ040-053-
054-501-505-506-526-527.
FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR VAZ025-503-504.
HIGH WIND WARNING UNTIL 1 AM EST MONDAY FOR VAZ025>031.
HIGH WIND WARNING UNTIL NOON EST MONDAY FOR VAZ503-504-507-508.
WINTER WEATHER ADVISORY UNTIL 3 PM EST MONDAY FOR VAZ503.
WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR VAZ036>039-050-
051-055>057-502.
WV...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR WVZ501>503-505-506.
BLIZZARD WARNING UNTIL 3 PM EST MONDAY FOR WVZ501-505.
HIGH WIND WARNING UNTIL 1 AM EST MONDAY FOR WVZ050>053-055.
HIGH WIND WARNING UNTIL NOON EST MONDAY FOR WVZ502>504-506.
WINTER WEATHER ADVISORY UNTIL 3 PM EST MONDAY FOR WVZ503.
MARINE...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ530.
STORM WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ530>543.
GALE WARNING FROM 10 PM THIS EVENING TO 4 PM EST MONDAY FOR
ANZ530>543.
SYNOPSIS...DHOF
NEAR TERM...ADS/DHOF
SHORT TERM...DHOF
LONG TERM...DHOF
AVIATION...ADS/DHOF
MARINE...ADS/DHOF
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