166
FXUS61 KLWX 311409
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1009 AM EDT MON MAR 31 2025
SYNOPSIS
A STRONG COLD FRONT WILL CROSS THE AREA TONIGHT. HIGH PRESSURE WILL
BUILD TO THE NORTH NEAR NEW ENGLAND TUESDAY INTO WEDNESDAY AS DEEP
LOW PRESSURE DEVELOPS OVER THE PLAINS AND MOVES INTO CANADA. A WARM
FRONT AHEAD OF THE LOW WILL LIFT THROUGH THE AREA WEDNESDAY NIGHT.
THE COLD FRONT WILL MOVE INTO THE AREA THURSDAY, THEN MEANDER NEARBY
THROUGH SATURDAY BEFORE ANOTHER AREA OF LOW PRESSURE LIFTS BY SUNDAY.
NEAR TERM /THROUGH TONIGHT/
THE MORNING ROUND OF ACTIVITY ASSOCIATED WITH WHAT WAS AN MCS
OVER THE OHIO VALLEY HAS MOVED EASTWARD OFF INTO THE ATLANTIC.
IN IT'S WAKE, WIDESPREAD CLEARING HAS DEVELOPED OVER THE AREA
ASIDE FROM THE ALLEGHENIES WHERE MID TO HIGH LEVEL CLOUDS ARE
APPROACHING FROM THE WEST. SURFACE TEMPS HAVE INCREASED INTO THE
UPPER 60S TO LOW 70S FOR MOST - WITH DEW POINTS HOVERING AROUND
60. WITH THE WINDS FORECAST TO TURN MORE WESTERLY IN THE LOW-
LEVELS THROUGH EARLY AFTERNOON, THIS WILL PROMOTE DOWNSLOPING
BUT ALSO LOWER TDS A FEW DEGREES. ONCE THE WINDS BECOME MORE
SOUTHWESTERLY THROUGH THE AFTERNOON, SURFACE TDS SHOULD
INCREASE. ULTIMATELY, THIS SHOULD RESULT IN 400-800 J/KG
MLCAPE, WITH LOCALIZED VALUES OF 900-1400 J/KG POSSIBLE IN AREAS
OF MORE APPRECIABLE HEATING (OR BENEATH POCKETS OF SLIGHTLY
STEEPER LAPSE RATES ALOFT). THE HIGHEST INSTABILITY WILL BE NEAR
AND EAST OF I-81 AND ESPECIALLY EAST OF THE BLUE RIDGE
MOUNTAINS WHERE SLIGHTLY BETTER HEATING AND MOISTURE IS
ANTICIPATED.
LOW-LEVEL SHEAR WILL BE STRONGEST THIS MORNING, ATTENDANT TO A
LLJ SOUTHEAST OF A STRENGTHENING SURFACE LOW MOVING UP THE ST.
LAWRENCE VALLEY. AS THIS SURFACE LOW LIFTS AWAY, WINDS IN THE
925-700 HPA LAYER ACTUALLY WEAKEN, WITH THE LATEST GUIDANCE
INDICATING 30-40 KTS IN THAT LAYER JUST AHEAD OF THE COLD FRONT
LATER THIS AFTERNOON. MEANWHILE, FLOW IN THE 500-250 HPA LAYER
WILL STRENGTHEN HEADING INTO THIS EVENING. THIS WILL BOLSTER
DEEP LAYER SHEAR AND LIFT VIA UPPER DIFFLUENCE IN THE RRQ OF THE
BUCKLING UPPER JET. ENHANCEMENTS TO THE LOW-LEVEL FLOW ARE
POSSIBLE AS WELL, AS ARE ANY BACKED NEAR-SURFACE WINDS. THESE
ENHANCEMENTS WILL LIKELY BE TIED TO (1) SUBTLE PRESSURE AND
VORTICITY PERTURBATIONS, AND (2) IN THE VICINITY OF BAY/RIVER
BREEZES. IT IS IN THESE ZONES (WITH INHERENT LOW PREDICTABILITY)
WHERE MORE VIGOROUS UPDRAFTS AND POSSIBLE DISCRETE/SUPERCELL
ACTIVITY IS POSSIBLE, WITH AN ACCOMPANYING HAIL/TORNADO RISK.
OVERALL, THOUGH, THE RISK FOR TORNADOES OR HAIL EXCEEDING 1"
DIAMETER APPEARS TO BE ON THE MORE MARGINAL/ISOLATED SIDE. THE
PRIMARY RISK APPEARS TO BE DAMAGING WIND GUSTS ASSOCIATED WITH
BANDS/LINES OF STORMS. SEVERE WIND GUSTS OF 58+ MPH MAY ALSO
TEND TO BE SOMEWHAT MORE LOCALIZED/WIDELY SCATTERED GIVEN
QUESTIONS ON HEATING AND LOW-LEVEL LAPSE RATES, DESPITE THE
ANTICIPATION OF WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY LATE
THIS AFTERNOON THROUGH THIS EVENING. SPC HAS MAINTAINED A
MARGINAL RISK (LEVEL 1 OUT OF 5) GENERALLY ALONG/WEST OF I-81
WITH A SLIGHT RISK (LEVEL 2 OUT OF 5) TO THE EAST.
IN TERMS OF TIMING, CONVECTIVE INITIATION LOOKS TO TAKE PLACE
MID TO LATE AFTERNOON NEAR THE BLUE RIDGE ALONG A PRESSURE OR
PRE-FRONTAL TROUGH. ACTIVITY SHOULD QUICKLY GROW UPSCALE AS THE
PRESSURE TROUGH IS OVERTAKEN BY THE SYNOPTIC COLD FRONT THIS
EVENING. SHOWERS AND THUNDERSTORMS IN ONE OR MORE BANDS SHOULD
TREK EAST ACROSS THE I-95 CORRIDOR/DC AND BALTIMORE METROS THIS
EVENING, BEFORE EXITING THE CHESAPEAKE BAY AROUND MIDNIGHT.
SOME HIGH RESOLUTION GUIDANCE INDICATES THE POTENTIAL FOR
LOCALIZED RAINFALL AMOUNTS OF 2-3", BUT THE FACT THAT IT HAS
BEEN SO DRY RECENTLY AND THESE TOTALS WOULD LIKELY FALL IN A 3-4
HOUR WINDOW PRECLUDES A MORE APPRECIABLE FLOOD/FLASH FLOOD RISK.
STRONG PRESSURE RISES IN THE WAKE OF THE COLD FRONT WILL RESULT
IN BREEZY NORTHWEST WINDS LATER TONIGHT, USHERING IN MUCH COOLER
AIR (WITH TEMPERATURE DROPS OF 25-35 DEGREES BY TUESDAY MORNING).
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
FOLLOWING THE PASSAGE OF A COLD FRONT MONDAY NIGHT, STRONG HIGH
PRESSURE WILL BUILD TO THE NORTH IN THE VICINITY OF NEW ENGLAND
TUESDAY INTO WEDNESDAY. INITIAL NORTHWESTERLY BREEZES TUESDAY
WILL TURN EAST TO SOUTHEAST TUESDAY NIGHT INTO WEDNESDAY AS A
COOL AIR WEDGE DEVELOPS IN THE LEE OF THE APPALACHIANS. BREEZY
CONDITIONS MAY DEVELOP OVER THE HIGHER ELEVATIONS AS ANOTHER
AREA OF STRONG LOW PRESSURE DEVELOPS OVER THE MIDDLE OF THE
COUNTRY. A WARM/WEDGE FRONT DEVELOPING EAST OF THIS LOW SHOULD
LIFT NORTHWARD LATE WEDNESDAY INTO WEDNESDAY NIGHT, LIFTING
TEMPERATURES FROM JUST BELOW NORMAL TO SEVERAL DEGREES ABOVE
NORMAL HEADING INTO THE SECOND HALF OF THE WEEK. SOME RAIN
SHOWERS MAY DEVELOP ALONG AND AHEAD OF THE LIFTING FRONT DURING
THE MIDDLE OF THE WEEK, BUT THE LOCAL AREA WILL BE PRETTY FAR
REMOVED FROM FORCING OTHER THAN ISENTROPIC LIFT OVER THE FRONT.
LONG TERM /THURSDAY THROUGH SUNDAY/
THE LONG TERM PERIOD WILL START OUT WARM AS A WARM FRONT DEPARTS TO
OUR NORTH AND SOUTHERLY FLOW USHERS IN PLENTY OF WARM AIR.
TEMPERATURES ON THURSDAY AND FRIDAY WILL BE IN THE 70S TO 80S WITH
THOSE IN THE MOUNTAINS STAYING IN THE 60S. A COLD FRONT APPROACHES
FROM THE WEST ON THURSDAY BEFORE STALLING OVER THE FORECAST AREA
THROUGHOUT THE WEEKEND. MULTIPLE WAVES OF LOW PRESSURE DEVELOPING
ALONG THE FRONTAL BOUNDARY WILL BRING DAILY PRECIPITATION CHANCES
AREAWIDE.
WITH THE FRONTAL BOUNDARY OVER THE AREA, TEMPERATURES WILL BE COOLER
FOR THE WEEKEND. HIGH TEMPERATURES ON SATURDAY AND SUNDAY WILL BE IN
THE 60S AND 70S WITH THOSE ALONG THE PA/MD BORDER STAYING IN THE
50S. OVERNIGHT LOW TEMPERATURES ON SATURDAY WILL BE IN THE 40S AND
50S. THE AFOREMENTIONED COLD FRONT EXITS THE FORECAST AREA SUNDAY
NIGHT, WITH OVERNIGHT LOW TEMPERATURES EXPECTED TO BE IN THE 40S
(30S IN THE MOUNTAINS) FOR MOST.
AVIATION /14Z MONDAY THROUGH FRIDAY/
SPOTTY INSTANCES OF LLWS ARE POSSIBLE EARLY THIS MORNING IN
AREAS WHERE SURFACE WINDS BECOME LIGHT AS A LLJ LIFTS OVERHEAD;
THIS LLJ WILL WEAKEN AND LIFT AWAY BY LATE MORNING.
A PERIOD OF SHOWERS AND THUNDERSTORMS (PERHAPS MULTIPLE ROUNDS)
IS EXPECTED ROUGHLY 21Z-03Z (PERHAPS 1-2 HOURS EARLIER FOR MRB
AND CHO TERMINALS). GREATLY REDUCED VISIBILITY IN HEAVY RAIN AND
STRONGER WIND GUSTS (POSSIBLY AS HIGH AS AROUND 50 KTS) ARE
POSSIBLE IN/NEAR STRONGER CONVECTION. REFINEMENTS IN THE EXACT
TIMING OF CONVECTION AND SUBSEQUENT GUSTS/RESTRICTIONS WILL BE
NEEDED THROUGH THE DAY AS CONDITIONS EVOLVE. OTHERWISE, S/SW
WINDS GUSTING 20-25 KTS ARE EXPECTED.
VFR AND NW FLOW WILL RETURN IN THE WAKE OF A COLD FRONT LATE
THIS EVENING/OVERNIGHT. SOME BRIEFLY STRONGER GUSTS TO AROUND
25 KTS ARE POSSIBLE IMMEDIATELY BEHIND THE FRONT. VFR AND
LIGHTER NW FLOW WILL PREVAIL TUESDAY. WINDS WILL THEN BECOME E
TO SE THROUGH WEDNESDAY NIGHT WITH LOWER CIGS POSSIBLE AT TIMES
AS A COOL AIR WEDGE DEVELOPS OVERHEAD.
SOUTHWESTERLY WINDS ON THURSDAY SHIFT TO WEST/NORTHWESTERLY FRIDAY
AFTERNOON. FLIGHT RESTRICTIONS ARE POSSIBLE BOTH DAYS DURING
PRECIPITATION.
MARINE
SOUTH TO SOUTHWEST FLOW WILL PREVAIL THROUGH EARLY THIS EVENING
AHEAD OF A STRONG COLD FRONT, WITH FREQUENT GUSTS OF 15 TO 25
KNOTS EXPECTED. STRONG TO SEVERE THUNDERSTORMS ARE ANTICIPATED
THIS EVENING ALONG AND AHEAD OF THE FRONT. WINDS WILL THEN TURN
NORTHWESTERLY BEHIND THE FRONT, WITH GUSTS AS HIGH AS 30 KNOTS
POSSIBLE. WINDS WILL GRADUALLY BECOME LIGHTER TUESDAY, THEN
SHIFT TO THE EAST AND SOUTHEAST TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT. SCA LEVEL GUSTS WILL LIKELY DEVELOP BY LATE WEDNESDAY.
SOUTHWESTERLY WINDS ON THURSDAY SHIFT TO WEST/NORTHWESTERLY FRIDAY
AFTERNOON WITH SCA CRITERIA WINDS EXPECTED ALL DAY THURSDAY. WINDS
DIMINISH EARLY FRIDAY MORNING AND WILL LIKELY STAY BELOW SCA
CRITERIA THROUGHOUT THE DAY.
TIDES/COASTAL FLOODING
SENSITIVE TIDAL LOCATIONS SUCH AS BALTIMORE, ANNAPOLIS, AND HAVRE DE
GRACE WILL REACH ACTION STAGE AND NEAR MINOR FLOOD STAGE AS A
STRONG COLD FRONT APPROACHES THE WATERS. STRONG SOUTHERLY FLOW
WILL LEAD TO INCREASED TIDAL ANOMALIES AHEAD OF THE FRONTAL
PASSAGE, WITH ANOMALIES PEAKING THIS AFTERNOON. IN THE WAKE OF
THE FRONTAL PASSAGE, WINDS SHIFT TO NORTHWESTERLY LEADING TO
TIDAL ANOMALIES FALLING THROUGH MIDWEEK.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY UNTIL NOON EDT TUESDAY FOR MDZ008.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TUESDAY FOR ANZ530>543.
SYNOPSIS...DHOF/CPB
NEAR TERM...DHOF/CPB
SHORT TERM...DHOF
LONG TERM...AVS
AVIATION...AVS/DHOF/CPB
MARINE...AVS/DHOF/CPB
TIDES/COASTAL FLOODING...
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