748
FXUS61 KLWX 311812
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
212 PM 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/
NOT MUCH HAS CHANGED REGARDING THE EXPECTATIONS FOR THIS
AFTERNOON INTO THIS EVENING. SKIES DID CLEAR RATHER QUICKLY
AFTER THE MORNING WAVE MOVED EAST OF THE AREA, MUCH FASTER THAN
ANY GUIDANCE SUGGESTED. SURFACE TEMPS HAVE INCREASED INTO THE
UPPER 70S TO LOW 80S FOR MOST - WITH DEW POINTS FALLING INTO THE
MID 50S THANKS TO DOWNSLOPING IN WESTERLY FLOW. THIS WILL
CONTINUE UNTIL THE WINDS BECOME MORE SOUTHWESTERLY THROUGH THE
AFTERNOON AHEAD OF THE SURFACE TROUGH, WHICH SHOULD PROMPT
SURFACE TDS TO INCREASE. OF NOTE ON CURRENT MESONALYSIS, THE
DCAPE IS MODEST (NEAR 700-1000 J/KG) WITH STEEP LOW- LEVEL LAPSE
RATES APPROACHING (8 C/KM). THE COMBINATION OF THIS WITH A
MODEST WIND FIELD SHOULD RESULT IN SOME SPORADIC DAMAGING WINDS.
STILL EXPECTING 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.
LATEST GUIDANCE CONTINUES TO SHOW 30-40 KTS OF LOW LEVEL SHEAR
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 (GENERALLY 4-5 PM). 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 TONIGHT, STRONG HIGH
PRESSURE WILL BUILD TO THE NORTH IN THE VICINITY OF NEW ENGLAND
TUESDAY INTO WEDNESDAY. NW'LY 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/
UPPER RIDGE WILL HOLD THROUGH THE END OF THE WEEK. A COLD FRONT
DROPPING INTO THE AREA THU NIGHT - FRI WILL BRING THE LIKELIHOOD OF
SHOWERS AND THUNDERSTORMS. THE FRONT WILL STALL OVER NORTH CAROLINA
SATURDAY BEFORE RETURNING NORTH AS A WARM FRONT SUNDAY AFTERNOON.
EXPECT GENERALLY CLOUDY AND COOL CONDITIONS FRI AND SAT WITH THE
CHANCE OF SHOWERS. ANOTHER COLD FRONT WILL CROSS THE AREA SUNDAY
AFTERNOON WITH THE THREAT FOR MORE SHOWERS AND THUNDERSTORMS.
AVIATION /18Z MONDAY THROUGH SATURDAY/
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 AFTERNOON AS CONVECTION INITIATES.
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.
GUSTS TO 20 KT FRI AND SAT AND SHIFTING WINDS AS BACKDOOR FRONT
DROPS IN. SHOWERS LIKELY ON FRI AND POSSIBLE SATURDAY.
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. THIS WILL REQUIRE SMWS. 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.
SCA CONDITIONS ARE POSSIBLE FRI INTO SATURDAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY UNTIL NOON EDT TUESDAY FOR MDZ008.
COASTAL FLOOD ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR
MDZ508.
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/CPB
LONG TERM...LFR
AVIATION...LFR/CPB
MARINE...LFR/CPB
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