411
FXUS61 KLWX 280121
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
921 PM EDT FRI JUN 27 2025
SYNOPSIS
A FRONT WILL WILL REMAIN STALLED ACROSS THE AREA THROUGH TONIGHT,
BEFORE LIFTING BACK TO THE NORTH INTO NEW ENGLAND THIS WEEKEND. A
SECOND FRONT MAY BRIEFLY DIP INTO THE AREA SUNDAY. SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE EACH DAY UNTIL A STRONGER COLD
FRONT CROSSES THE AREA TUESDAY.
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
SHOWERS AND THUNDERSTORMS CONTINUE TO TRACK NORTHWARD ALONG THE
ALLEGHENY RIDGE WITH THE FLASH FLOOD WATCH CONTINUING IN
PENDLETON AND HIGHLAND COUNTIES UNTIL 10 PM. PATCHY FOG WILL
LEAD TO REDUCED VISIBILITIES ALONG THE EASTERN SLOPES. OTHERWISE
NO CHANGES WERE MADE TO THE FORECAST WITH THE PREVIOUS FORECAST
DISCUSSION BELOW.
THE BACKDOOR FRONT HAS PUSHED WELL INTO SOUTHERN VIRGINIA,
CURLING NORTHWARD UP THE APPALACHIAN SPINE. HOWEVER, THERE IS A
ZONE BETWEEN THE WIND SHIFT AND LOWER DEW POINTS AND MARINE-
INFLUENCED STRATUS, WHICH WILL BE THE FOCUS FOR CONVECTION THIS
AFTERNOON. CONVERGENT UPSLOPE FLOW ALONG THE APPALACHIAN SPINE
IS ALREADY RESULTING IN NUMEROUS THUNDERSTORMS IN THIS AREA,
WHICH ARE SLOW MOVING. THE AREA OF PREVIOUS CONVECTION ALONG THE
850 MB BOUNDARY HAS STRATIFIED, BUT STILL LURKING IN NORTHERN
VIRGINIA. EXPECT THIS RAIN TO DISSIPATE AS THE AFTERNOON
PROGRESSES.
THE MAIN HAZARD THROUGH THIS EVENING IS FLASH FLOODING POTENTIAL
FROM CENTRAL VIRGINIA INTO THE APPALACHIANS. CONFIDENCE IN HEAVY
RAIN IS GREATEST OVER THE POTOMAC HIGHLANDS, ALONG THE BOUNDARY,
WITH GOOD AGREEMENT IN MOST GUIDANCE. HIGH END POTENTIAL OF 5
INCHES OF RAIN COULD RESULT IN A MORE SIGNIFICANT INSTANCE OF
FLASH FLOODING. A FLOOD WATCH FOR FLASH FLOODING REMAINS IN
EFFECT UNTIL 10 PM. THERE'S MUCH MORE UNCERTAINTY HOW FAR
EASTWARD THE HEAVY RAIN REACHES, AS AIR QUICKLY STABILIZES IN
THE COOL AIR WEDGE. MLCAPE UP TO 2000 J/KG SOUTHWEST OF THE
BOUNDARY COULD RESULT IN AN ISOLATED SEVERE THUNDERSTORM WITH
DAMAGING DOWNBURST WINDS, BUT WEAK SHEAR AND LOWER DCAPE SHOULD
LIMIT THIS THREAT.
CONVECTION SHOULD WANE THIS EVENING AS IS DRIFTS INTO MORE
STABLE AIR IN THE CAD WEDGE. CLOSER TO THE METRO AREAS, ANY
SHOWERS (BESIDES DRIZZLE) MAY OCCUR DURING THE SECOND HALF OF
THE NIGHT WITH ISENTROPIC LIFT AS THE BOUNDARY ALOFT LIFTS BACK
NORTHWARD. EXPECT THE STRATUS TO LOWER FURTHER OVERNIGHT, WHICH
COULD REDUCE THE VISIBILITY IN FOG IS SOME LOCATIONS, ESPECIALLY
ALONG THE HIGHER ELEVATIONS. LOWS WILL RANGE FROM THE MID 60S TO
LOWER 70S.
SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/
THE FRONT WILL LIFT BACK NORTHWARD SATURDAY, WITH GOOD AGREEMENT
ON CLEARING BY MIDDAY. THIS WILL RESULT IN TEMPERATURES WARMING
BACK INTO THE UPPER 80S AND LOWER 90S. A RELATIVELY MOIST
AIRMASS REMAINS IN PLACE THOUGH, SO DEW POINTS WILL BE FAIRLY
HIGH IN THE 70S. THIS MAY RESULT IN HEAT INDEX VALUES IN THE
LOWER 100S IN SOME LOCATIONS. A HEAT ADVISORY CAN'T BE RULED
OUT, BUT CURRENT THINKING IS VALUES WILL GENERALLY REMAIN BELOW
THE THRESHOLD. A SUBTLE TROUGH IN THE FLOW ALOFT ALONG WITH
TERRAIN CIRCULATIONS WILL LIKELY INITIATE CONVECTION IN THE
AFTERNOON IN THE HOT AND HUMID AIRMASS. COVERAGE IS A BIT
UNCERTAIN GIVEN LACK OF A STRONG FOCUS AND A WESTERLY COMPONENT
TO THE WINDS ALOFT. HOWEVER, MODERATE TO HIGH INSTABILITY COULD
RESULT IN SOME PULSE SEVERE STORMS WITH DAMAGING WINDS. GREATER
COVERAGE OF STORMS MAY BE FOUND TO THE NORTHWEST ALONG A
SOUTHWARD MOVING COLD FRONT. THE REMNANTS OF THESE COULD MOVE
INTO THE AREA DURING THE EVENING BEFORE DIMINISHING.
THE AFOREMENTIONED FRONT WILL BRIEFLY SETTLE SOUTH INTO THE AREA
ON SUNDAY. UNLIKE THE PREVIOUS FRONT, DRIER AIR WILL BE LOCATED
NORTH OF THIS BOUNDARY, AND TEMPERATURES WILL REMAIN ABOVE
NORMAL WITH LITTLE COLD ADVECTION. IT APPEARS THE BEST
CONVECTIVE CHANCES WILL BE ACROSS THE SOUTHERN HALF OF THE AREA,
AND EVEN THEN COVERAGE MAY BE SOMEWHAT LIMITED. DIURNAL
DIMINISHING WILL CONTINUE TO BE THE THEME.
LONG TERM /MONDAY THROUGH FRIDAY/
THE FRONT WILL LIFT BACK NORTH MONDAY. HOWEVER, FALLING HEIGHTS,
A PREFRONTAL TROUGH, AND TERRAIN CIRCULATIONS IN A HOT AND HUMID
AIRMASS WILL LIKELY RESULT IN SCATTERED TO NUMEROUS
THUNDERSTORMS DURING THE AFTERNOON AND EVENING.
POTENT SHORTWAVE-TROUGH AND ACCOMPANYING SFC COLD FRONT WILL CROSS
THE AREA TUE AFTERNOON AND BRING A THREAT OF SEVERE THUNDERSTORMS
TUE AFTERNOON INTO THE EVENING. THE MAIN THREAT WILL BE DAMAGING
WINDS GIVEN EXPECTED FAST STORM MOTIONS AND STRONG INSTABILITY.
AFTER TROUGH AXIS PASSES TUE NIGHT, HEIGHT RISES AND BUILDING HIGH
PRESSURE WILL RESULT IN SEASONABLE WARM AND DRY/TRANQUIL CONDITIONS
THROUGH THE FOURTH OF JULY HOLIDAY WEEKEND.
AVIATION /01Z SATURDAY THROUGH WEDNESDAY/
IFR TO LOW END MVFR CONDITIONS PERSIST THIS AFTERNOON AT ALL
TERMINALS. PREVIOUS SHOWERS AROUND THE DC METRO AREA CONTINUE TO
DISSIPATE, ALTHOUGH SOME PATCHY DRIZZLE/MIST MAY CONTINUE.
ADDITIONAL CONVECTION LOOKS HIGHLY UNLIKELY IN THIS AREA. SOME
THUNDERSTORMS MAY PROPAGATE TOWARD MRB/CHO TOWARD THIS EVENING,
SO LEFT IN THE PROB30 GROUP AS THIS REMAINS UNCERTAIN.
WHILE A FEW SHOWERS MAY MOVE ACROSS THE AREA OVERNIGHT, THE MAIN
CONCERN WILL BE LOWERING CEILINGS, WHICH MAY BE CLOSE TO LIFR BY
DAYBREAK. AT THIS TIME, IT LOOKS LIKE STRATUS WILL PREVAIL OVER
DENSE FOG, BUT VISIBILITIES MAY STILL BE REDUCED. EASTERLY WINDS
WILL TREND TOWARD CALM OVERNIGHT.
CONDITIONS ARE EXPECTED TO IMPROVE BACK TO VFR BY MIDDAY
SATURDAY, WITH THUNDERSTORMS POSSIBLE DURING THE AFTERNOON.
PREVAILING VFR CONDITIONS, WITH LESSER, BUT NON-ZERO CHANCES FOR
THUNDERSTORMS ARE EXPECTED ON SUNDAY. WINDS WILL BE LIGHT OUT
OF THE SOUTHWEST ON SATURDAY, AND LIGHT OUT OF THE NORTHWEST ON
SUNDAY.
SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE MONDAY
AFTERNOON AND EVENING. NMRS SHOWERS AND THUNDERSTORMS EXPECTED
TUE AFTERNOON, SOME POSSIBLY SEVERE WITH DAMAGING WINDS. DRY
CONDITIONS EXPECTED WED.
MARINE
SUB-SCA CONDITIONS SHOULD PREVAIL THROUGH THE WEEKEND. EASTERLY
WINDS CONTINUE THROUGH TONIGHT, THEN BECOME SOUTHWEST ON
SATURDAY, AND NORTHWEST ON SUNDAY. A FEW THUNDERSTORMS MAY NEAR
THE SOUTHERN WATERS TODAY, BUT THERE WILL BE A GREATER CHANCE OF
GUSTY THUNDERSTORMS ON SATURDAY AFTERNOON AND EVENING.
THUNDERSTORMS ARE POSSIBLE AGAIN SUNDAY AFTERNOON AND EVENING,
ESPECIALLY NEAR SOUTHERN MARYLAND, BUT OVERALL COVERAGE SHOULD
BE LOWER.
THUNDERSTORMS WITH GUSTY WINDS ARE POSSIBLE MONDAY AFTERNOON AND
EVENING. POSSIBLE SCA CONDITIONS MON NIGHT-TUE NIGHT. STRONG TO
SEVERE T-STORMS ARE POSSIBLE TUE AFTERNOON, WHICH MAY REQUIRE
SMWS.
TIDES/COASTAL FLOODING
EASTERLY FLOW TODAY AND TONIGHT WILL BECOME MORE SOUTHERLY SATURDAY
AND RESULT IN WATER LEVEL RISES WITH ANNAPOLIS LIKELY TO REACH MINOR
COASTAL FLOODING EARLY SATURDAY MORNING.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR VAZ503-504.
WV...FLOOD WATCH UNTIL 10 PM EDT THIS EVENING FOR WVZ505-506.
MARINE...NONE.
SYNOPSIS...ADS
NEAR TERM...ADS/AVS
SHORT TERM...ADS
LONG TERM...LFR
AVIATION...ADS/LFR
MARINE...ADS/LFR
TIDES/COASTAL FLOODING...
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