066
FXUS61 KLWX 061422
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1022 AM EDT TUE MAY 6 2025
SYNOPSIS
A COLD FRONT WILL SLOWLY PROGRESS EASTWARD ACROSS THE REGION
TODAY BEFORE AN UPPER-LEVEL DISTURBANCE PASSES THROUGH TONIGHT.
HIGH PRESSURE WILL FOLLOW BRIEFLY FOR WEDNESDAY. A STRONGER COLD
FRONT WILL APPROACH THURSDAY BEFORE PASSING THROUGH THURSDAY
NIGHT INTO FRIDAY WHILE LOW PRESSURE DEVELOPS ALONG THE
BOUNDARY. HIGH PRESSURE WILL LIKELY FOLLOW FOR THE UPCOMING
WEEKEND.
NEAR TERM /THROUGH TONIGHT/
THE 12Z KIAD SOUNDING SHOWS PLENTY OF DRY AIR IN THE ATMOSPHERE
WITH A MID LEVEL RH OF 31 PERCENT AND A LOW LEVEL RH OF 86
PERCENT. THIS DRY AIR ALOFT WILL HINDER ANY CONVECTION LATER
THIS AFTERNOON FROM STRENGTHENING AS OUTLINED IN THE FORECAST
DISCUSSION BELOW. NO CHANGES WERE MADE FROM THE PREVIOUS
FORECAST WITH THE PREVIOUS FORECAST DISCUSSION BELOW.
CUTOFF UPPER-LEVEL LOW PRESSURE REMAINS TO OUR WEST EARLY THIS
MORNING, AND DRIER AIR ALOFT HAS ROTATED AROUND THE LOW, CAUSING
SKIES TO CLEAR OUT AND PRECIPITATION TO DIMINISH. WITH LIGHT
WINDS AND PLENTY OF LOW-LEVEL MOISTURE, THIS WILL RESULT IN
AREAS OF FOG EARLY THIS MORNING. SOME FOG MAY BE LOCALLY DENSE,
ESPECIALLY IN THE VALLEYS OF THE POTOMAC HIGHLANDS TO THE
SHENANDOAH VALLEY AND VIRGINIA PIEDMONT. WILL MONITOR CLOSELY TO
SEE IF A DENSE FOG ADVISORY IS NEEDED.
THE UPPER-LEVEL LOW WILL SLOWLY MOVE NORTHEAST INTO PENNSYLVANIA
TODAY WHILE A COLD FRONT SLOWLY PASSES THROUGH THE AREA FROM
SOUTHWEST TO NORTHEAST (OCCLUDED BOUNDARY). ANOTHER POTENT
SHORTWAVE ASSOCIATED WITH THE UPPER-LEVEL LOW WILL PASS THROUGH
THE AREA LATER THIS MORNING THROUGH THIS AFTERNOON. THIS WILL
COINCIDE WITH PEAK HEATING. MORE SHOWERS ARE LIKELY ALONG WITH
SCATTERED THUNDERSTORMS, ESPECIALLY NORTH OF INTERSTATE 66 AND
US 48 WHERE INSTABILITY WILL BE HIGHEST CLOSER TO THE TRACK OF
THE POTENT SHORTWAVE. DRIER AIR ALOFT AND SUBSIDENCE WILL ALLOW
FOR A CAPPING INVERSION TO LIMIT THE STRENGTH OF CONVECTION FOR
MOST AREAS. THEREFORE, THE SEVERE THREAT SEEMS LOW. HOWEVER,
WITH PLENTY OF COLD AIR ALOFT AND STEEP LOW-LEVEL LAPSE RATES,
HAIL AND GUSTY WINDS MAY ACCOMPANY THE STRONGER STORMS
(ESPECIALLY ACROSS NORTHERN MD, THE EASTERN WV PANHANDLE, AND
EXTREME NORTHERN VIRGINIA).
LOW-LEVEL DRY AIR SHOULD MIX DOWN BEHIND THE COLD FRONT ACROSS
CENTRAL VIRGINIA INTO SOUTHERN MD, ALLOWING FOR MOST AREAS TO BE
DRY TODAY.
CONVECTION SHOULD DIMINISH FOR NORTHERN AREAS LATE THIS
AFTERNOON INTO EARLY THIS EVENING AS DRIER AIR MOVES IN BEHIND
THE COLD FRONT. HOWEVER, ANOTHER SHORTWAVE AND JETMAX ASSOCIATED
WITH THE UPPER-LEVEL LOW WILL BE FAST ON ITS HEELS, PASSING
THROUGH THE AREA TONIGHT. MORE SHOWERS ARE LIKELY ACROSS
NORTHERN MD, THE EASTERN PANHANDLE OF WV, AND THE ALLEGHENY
HIGHLANDS (ESPECIALLY NORTH OF I-66 AND US 48). A RUMBLE OF
THUNDER CANNOT BE RULED OUT, BUT LITTLE CAPE IS PROGGED TO BE
ABOVE THE -10C LEVEL IN FORECAST SOUNDINGS. FARTHER SOUTH, DRY
CONDITIONS ARE MOST LIKELY FARTHER AWAY FROM THE SHORTWAVE
(CENTRAL VIRGINIA INTO SOUTHERN MD). LOWS TONIGHT WILL RANGE
FROM THE 40S IN THE ALLEGHENY HIGHLANDS TO THE 50S FOR MOST
OTHER AREAS.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
THE UPPER-LEVEL LOW WILL FINALLY MOVE AWAY FROM THE AREA
WEDNESDAY, AND THE COMBINATION OF RISING HEIGHTS, WESTERLY FLOW,
AND WEAK HIGH PRESSURE WILL ALLOW FOR DRY CONDITIONS FOR MOST
AREAS ALONG WITH SOME SUNSHINE. HIGHS WILL RANGE FROM THE 60S IN
THE MOUNTAINS TO THE 70S/NEAR 80 FOR MOST OTHER LOCATIONS. DRY
CONDITIONS WILL MOST LIKELY PERSIST FOR WEDNESDAY NIGHT AS WELL.
A STRONGER COLD FRONT WILL APPROACH FROM THE NORTHWEST THURSDAY
BEFORE PASSING TROUGH THURSDAY NIGHT INTO FRIDAY. THERE IS STILL
SOME UNCERTAINTY TO THE TIMING OF THIS SYSTEM AND STRENGTH.
GUIDANCE SHOWS ANOTHER CUTOFF UPPER-LEVEL LOW DEVELOPING, AND
THIS WILL LIKELY CAUSE SURFACE LOW PRESSURE TO DEVELOP ALONG THE
COLD FRONT. THE EXACT POSITION OF WHERE THIS UPPER-LEVEL LOW
DEVELOPS WILL DICTATE HOW STRONG THE SURFACE LOW IS ALONG THE
FRONT, AND CONSEQUENTLY HOW QUICKLY THE DRY AIR BEHIND THE FRONT
CAN MOVE INTO THE AREA. AS OF NOW, IT LOOKS LIKE SHOWERS ARE
LIKELY WITH POSSIBLE THUNDERSTORMS LATER THURSDAY INTO THURSDAY
EVENING. ADDITIONAL SHOWERS ARE POSSIBLE OVERNIGHT THURSDAY,
DEPENDING ON THE SPEED OF THE COLD FRONT.
LONG TERM /FRIDAY THROUGH MONDAY/
A BLOCKY PATTERN REMAINS IN PLACE INTO THE EARLY PART OF NEXT WEEK,
MEANING THAT THERE COULD BE SOME PREDICTABILITY ISSUES. ON FRIDAY, A
COLD FRONT WILL BE NEAR OR SOUTHEAST OF THE AREA. A NORTHERN STREAM
TROUGH WILL BE CLOSING OFF INTO AN UPPER LOW. ALTHOUGH THERE IS A
TREND TOWARD A LOW DEVELOPING ALONG OR OFF THE COAST IN RESPONSE TO
THE TROUGH, THERE IS STILL CONSIDERABLE UNCERTAINTY IN ITS
PLACEMENT. THIS WILL DETERMINE WHETHER THERE ARE ANY LINGERING RAIN
CHANCES ON FRIDAY. HOWEVER, CONFIDENCE IS HIGHER THAT TEMPERATURES
WILL FALL BELOW NORMAL FOR FRIDAY AND FRIDAY NIGHT.
AS LONG AS THE CLOSED LOW REMAINS TO THE EAST, HIGH PRESSURE WILL
LIKELY PROVIDE DRY WEATHER AND A WARMING TREND FOR THE WEEKEND. A
DECAYING COLD FRONT MAY DROP TOWARD THE AREA SUNDAY BUT WOULD HAVE
NEGLIGIBLE EFFECTS ON SENSIBLE WEATHER. HIGH PRESSURE MAY STICK
AROUND INTO MONDAY, BUT MOISTURE ORIGINATING FROM A DIFFERENT CLOSED
LOW OVER THE DEEP SOUTH MAY START TO WORK NORTHWARD AT SOME POINT
NEXT WEEK.
AVIATION /14Z TUESDAY THROUGH SATURDAY/
AREAS OF FOG AND LOW CLOUDS WILL CAUSE IFR/SUBIFR CONDITIONS
THROUGH 12-13Z. VFR CONDITIONS WILL RETURN AFTERWARDS. THE BEST
CHANCE FOR DENSE FOG WILL BE AROUND KMRB AND KCHO, WITH MORE IN
THE WAY OF LOW CLOUDS ACROSS THE EASTERN TERMINALS.
MORE POPUP SHOWERS ARE LIKELY WITH POSSIBLE THUNDERSTORMS THIS
AFTERNOON, ESPECIALLY BETWEEN 17Z AND 23Z FROM WEST TO EAST.
THE BEST CHANCE FOR THUNDERSTORMS WILL BE ACROSS KMRB, BUT
POSSIBLE TO THE SOUTH AROUND THE DC AND BALTIMORE METRO AREAS AS
WELL.
CONVECTION WILL DISSIPATE BY EARLY THIS EVENING, AND VFR
CONDITIONS ARE EXPECTED FOR MOST AREAS TONIGHT. HOWEVER,
ADDITIONAL SHOWERS ARE LIKELY LATER THIS EVENING AND OVERNIGHT,
ESPECIALLY AROUND KMRB, BUT POSSIBLY INTO THE DC AND BALTIMORE
METRO AREAS AS WELL. MVFR CONDITIONS ARE POSSIBLE IN SHOWERS.
HIGH PRESSURE WILL BRING VFR CONDITIONS FOR WEDNESDAY THROUGH
THURSDAY MORNING, BUT ADDITIONAL SHOWERS ARE LIKELY WITH
POSSIBLE THUNDERSTORMS THURSDAY AFTERNOON INTO THURSDAY NIGHT
WITH POSSIBLE SUB-VFR CONDITIONS.
SUB-VFR CEILINGS AND SHOWERS MAY PERSIST INTO FRIDAY DEPENDING ON
THE POSITION OF DEVELOPING LOW PRESSURE OFF THE COAST. VFR
CONDITIONS WILL FOLLOW AS HIGH PRESSURE BUILDS TOWARD THE AREA
SATURDAY.
MARINE
PATCHY FOG MAY IMPACT THE WATERS EARLY THIS MORNING, ESPECIALLY
NEAR THE INLETS, BUT CONFIDENCE FOR WIDESPREAD DENSE FOG IS LOW.
AN UPPER-LEVEL DISTURBANCE MAY BRING A FEW SHOWERS AND PERHAPS
A THUNDERSTORM THIS AFTERNOON INTO EARLY THIS EVENING (BEST
CHANCE BETWEEN 18Z AND 23Z ACROSS THE NORTHERN CHESAPEAKE BAY
AND UPPER TIDAL POTOMAC RIVER. GUSTY WINDS AND HAIL ARE
POSSIBLE DUE TO STEEP LOW-LEVEL LAPSE RATES AND COLD AIR ALOFT.
THE GRADIENT WIND WILL ALSO PICK UP LATE THIS AFTERNOON/EARLY
EVENING BEHIND THE COLD FRONT. AN SCA IS IN EFFECT FOR THE UPPER
TIDAL POTOMAC RIVER AND NORTHERN CHESAPEAKE BAY FOR SOUTHWEST
WINDS GUSTING AROUND 20 KNOTS. WINDS WILL DIMINISH LATER THIS
EVENING.
WEAK HIGH PRESSURE WILL BUILD OVERHEAD FOR WEDNESDAY INTO EARLY
THURSDAY. HOWEVER, MORE SHOWERS ARE LIKELY WITH POSSIBLE
THUNDERSTORMS THURSDAY AFTERNOON INTO THURSDAY NIGHT.
AS LOW PRESSURE MOVES OFF THE COAST, WINDS WILL BE NORTH TO
NORTHWEST FRIDAY INTO SATURDAY. SCAS MAY BE NEEDED FRIDAY INTO
FRIDAY NIGHT, ESPECIALLY ALONG THE BAY WHERE THE NORTHERLY WINDS
COULD CHANNEL.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 PM EDT THIS
EVENING FOR MDZ008.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 PM EDT THIS
EVENING FOR ANZ530>532-535-538>540.
SYNOPSIS...BJL
NEAR TERM...BJL/AVS
SHORT TERM...BJL
LONG TERM...ADS
AVIATION...BJL/ADS
MARINE...BJL/ADS
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