015
FXUS61 KLWX 210032
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
832 PM EDT SUN JUL 20 2025
SYNOPSIS
ANY RESIDUAL SHOWER AND THUNDERSTORM ACTIVITY WILL DIMINISH LATER
THIS EVENING AS A COLD FRONT PASSES THROUGH. LESS HUMIDITY AND DRIER
CONDITIONS MONDAY AND TUESDAY AS CANADIAN HIGH PRESSURE BUILDS NORTH
OF THE REGION. HIGH PRESSURE SHIFTS OFF THE NEW ENGLAND COAST
WEDNESDAY ALLOWING HEAT, HUMIDITY AND THUNDERSTORM CHANCES TO RETURN
LATE WEEK INTO THE UPCOMING WEEKEND.
NEAR TERM /THROUGH MONDAY NIGHT/
A COMPLEX OF DECAYING SHOWERS AND ISOLATED T-STORMS CONTINUES
TO DIVE SOUTH AND EAST ACROSS THE ALLEGHENY HIGHLANDS INTO THE
SOUTHERN SHENANDOAH VALLEY AND CENTRAL VIRGINIA PIEDMONT REGION.
THESE SHOWERS AND THUNDERSTORMS ARE IN ASSOCIATION WITH A COLD
FRONTAL BOUNDARY THAT LOOKS TO CROSS THE AREA TONIGHT INTO EARLY
MONDAY MORNING. MOST LOCATIONS WILL REMAIN DRY AS THE FRONTAL
BOUNDARY CROSSES THROUGH WITH PARTLY TO MOSTLY CLOUDY SKIES
EXPECTED. HIGHEST CHANCES FOR SHOWERS AND THUNDERSTORMS LOOK TO
BE SOUTH OF US-48 AND WEST OF I-81. EVEN WITH THAT SAID, AN
ISOLATED SHOWER CANNOT BE RULED OUT OVER THE REST OF THE AREA,
BUT WITH DEEP WESTERLY DOWNSLOPE FLOW AHEAD OF THE FRONT
CONFIDENCE IS LOW. WINDS WILL TURN BACK TO THE NORTH LATE
TONIGHT INTO EARLY MONDAY MORNING DELIVERING DRIER AIR AND
LOWERING HUMIDITY. LOWS TONIGHT WILL FALL INTO THE UPPER 60S AND
LOW 70S WITH DEWPOINTS FALLING INTO THE MID TO UPPER 60S MONDAY
MORNING. SOME PATCHY FOG IS POSSIBLE IN THE SHELTERED RIVER
VALLEYS.
THE COLD FRONT CONTINUES SOUTH AND EAST OF THE AREA MONDAY AS
CANADIAN HIGH PRESSURE SLIDES EAST FROM THE GREAT LAKES REGION.
MOSTLY SUNNY TO PARTLY CLOUDY SKIES WILL PREVAIL FOR MOST OF THE
REGION ESPECIALLY NORTH OF I-66/US-50 WHERE THE DRIER AIR PUSHES IN
THE FASTEST. AREAS FURTHER SOUTH TOWARD THE I-64 CORRIDOR MAY HAVE
ENOUGH MOISTURE AND INSTABILITY LEFTOVER FOR AN ISOLATED
SHOWER/T- STORM. HAVE CAPPED CHANCES LESS THAN 25 PERCENT FROM
MONTEREY, VA OVER TO CHARLOTTESVILLE/RICHMOND, VA. CONVECTION
SHOULD BE FAIRLY SHORT-LIVED BETWEEN (12-5PM MONDAY) WITH
SUFFICIENT DRY AIR WORKING IN ALOFT. THE BIGGER STORY MONDAY
WILL BE THE NOTABLE DROP IN HUMIDITY ON LIGHT NORTH-
NORTHWESTERLY FLOW. DEWPOINTS WILL FALL FROM THE MID TO UPPER
60S DOWN INTO THE UPPER 50S AND LOW 60S MONDAY
AFTERNOON/EVENING. HIGHS MONDAY WILL PUSH INTO THE UPPER 70S AND
LOW TO MID 80S. LOWS MONDAY NIGHT WILL FALL INTO THE UPPER 50S
AND LOW 60S.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
THE BRIEF REPRIEVE FROM THE HIGH HEAT AND HUMIDITY CONTINUES
TUESDAY AS CANADIAN HIGH PRESSURE DRIFTS ACROSS INTERIOR NEW
ENGLAND AND TOWARD THE COAST. HIGH TEMPERATURES WILL ONCE AGAIN
TOP OUT IN THE UPPER 70S AND LOW TO MID 80S WITH DEWPOINTS IN
THE UPPER 50S AND MID 60S. OVERNIGHT LOWS WILL RANGE FROM THE
UPPER 50S WEST OF THE BLUE RIDGE TO LOW AND MID 60S FURTHER
EAST. A FEW PASSING SHOWERS ARE POSSIBLE OVER THE POTOMAC
HIGHLANDS AND CENTRAL SHENANDAOH VALLEY TUESDAY AFTERNOON AND
EVENING AS A WEAK PIECE OF SHORTWAVE ENERGY RIPPLES THROUGH.
OVERALL CONFIDENCE AMONGST CURRENT SYNOPTIC AND ENSEMBLE
GUIDANCE REMAINS LOW SO CAPPED POPS LESS THAN 15 PERCENT WITH A
FOCUS SOUTH OF A LINE EXTENDING FROM MONTEREY, VA DOWN TOWARD
LOVINGSTON , VA. MOST WILL SEE ANOTHER DRY DAY WITH PARTLY
CLOUDY TO MOSTLY SUNNY SKIES EXPECTED.
BY WEDNESDAY, HIGH PRESSURE SHIFTS OFF THE NEW ENGLAND COAST.
HUMIDITY WILL GRADUALLY RETURN UNDER LIGHT SOUTHEASTERLY FLOW.
DEWPOINTS WILL CLIMB BACK INTO THE UPPER 60S AND LOW 70S WITH HIGH
TEMPERATURES PUSHING BACK TOWARD 90 DEGREES.
LONG TERM /THURSDAY THROUGH SUNDAY/
A LARGE UPPER RIDGE INITIALLY ACROSS THE GULF COAST UP TO THE
TENNESSEE/OHIO VALLEY IS EXPECTED TO BUILD NORTH AND EAST ON
WEDNESDAY AND THURSDAY. AS THIS OCCURS, STRONG SUBSIDENCE UNDERNEATH
THIS ANTICYCLONE CENTER WILL KEEP CONDITIONS DRY OVER THE REGION.
MOISTURE RETURN IS EXPECTED TO SLOWLY INCREASE THROUGH THE WEEK AS
HIGH PRESSURE ALONG THE EASTERN SEABOARD WEAKENS. BY THURSDAY, THIS
HELPS USHERS DEW POINTS BACK INTO THE LOW 70S. WHILE SOME EROSION OF
THE NORTHERN EXTENT OF THIS RIDGE OCCURS, EXPECT ABOVE AVERAGE
TEMPERATURES TO RETURN TO THE PICTURE FOR FRIDAY ONWARD. THE GLOBAL
MODEL CONSENSUS SUPPORTS MID/UPPER 90S TEMPERATURES ON FRIDAY, WHILE
LIKELY CONTINUING INTO SATURDAY. ADDING THE INCREASE IN HUMIDITY
LEVELS SHOULD ALLOW HEAT INDICES TO PUSH BACK INTO THE 100 TO 105
DEGREE RANGE. THUS, SOME SPOTS COULD NEAR OR REACH ADVISORY LEVEL
HEAT BOTH DAYS. GIVEN THIS IS STILL 5 TO 6 DAYS AWAY, DETAILS LIKE
CLOUD COVER, WIND SPEED/DIRECTION, AND INFLUENCE OF SHOWERS COULD
LEAD TO MORE PREDICTABILITY THAN GLOBAL ENSEMBLES SUGGEST.
THE GUIDANCE FURTHER INCREASE CONVECTIVE CHANCES NEXT WEEKEND AS A
SLOW MOVING FRONTAL BOUNDARY APPROACHES FROM THE WEST. GIVEN NEAR
NEUTRAL HEIGHT CHANGES, THERE IS SOME POTENTIAL FOR THIS BOUNDARY TO
STALL NEARBY. ENSEMBLE SPREAD INCREASES FURTHER GIVEN UNKNOWNS ABOUT
THE POSITION OF THIS FRONTAL SYSTEM.
AVIATION /01Z MONDAY THROUGH FRIDAY/
AN ISOLATED SHOWER REMAINS POSSIBLE WEST OF THE CORRIDOR PRIOR TO
04Z/MIDNIGHT. ANY SHOWER ACTIVITY WILL BE LIGHT AND SHORT LIVED
GIVEN DRIER ALOFT. SHOWER ACTIVITY IS IN ASSOCIATION WITH A COLD
FRONT THAT IS SET TO PASS THROUGH THE AREA TONIGHT INTO MONDAY
MORNING. THE FRONT WILL SAG SOUTH AND EAST OF THE CORRIDOR MONDAY.
VFR CONDITIONS WILL PREVAIL FOR MOST WITH AN ISOLATED SHOWER OR
THUNDERSTORM REMAINING POSSIBLE BETWEEN 16-21Z/12-5PM DOWN TOWARD
KCHO/KRIC/KLYH. CONFIDENCE IN THIS IS FAIRLY LOW SO WENT WITH A
PROB30 GIVEN THE DRIER AIR ALOFT. WINDS SHIFT FROM THE WEST, TO
NORTH AND NORTHWEST LATE TONIGHT INTO MONDAY. GUSTS UP TO 15 KTS ARE
POSSIBLE LATE MORNING INTO MID-AFTERNOON AT ALL TERMINALS OUTSIDE OF
KCHO AS HEIGHTS RISE WITH HIGH PRESSURE BUILDING NORTH OF THE AREA.
PREVAILING VFR CONDITIONS ARE EXPECTED TUESDAY THROUGH FRIDAY. SUB-
VFR REDUCTIONS REMAIN POSSIBLE DURING THE AFTERNOON AND EVENING
HOURS FRIDAY AS A RESULT OF SHOWERS AND THUNDERSTORMS. WINDS WILL
REMAIN LIGHT OUT OF THE EAST AND SOUTHEAST TUESDAY BEFORE TURNING
SOUTH/SOUTHWESTERLY MID TO LATE NEXT WEEK AS HIGH PRESSURE PUSHES
OFF THE NEW ENGLAND COAST.
MARINE
SUB-SCA LEVEL WINDS CONTINUE OUT OF THE WEST THIS EVENING. SCA
LEVEL WINDS RETURN LATE TONIGHT INTO MONDAY AS A COLD FRONT
PASSES THROUGH. WINDS TURN TO THE NORTH AND NORTHWEST LATE
TONIGHT INTO MONDAY FOR THE CHESAPEAKE BAY AND LOWER TIDAL
POTOMAC. THIS IS DUE IN PART TO NORTHERLY CHANNELING WITH GUSTS
UP TO 25 KTS.
GRADIENTS REMAIN ON THE WEAKER SIDE WHICH SHOULD KEEP WINDS BELOW
ADVISORY THRESHOLDS. AS WINDS SHIFT TO SOUTHERLY ON THURSDAY, SOME
CHANNELING EFFECTS ARE POSSIBLE DURING THE EVENING INTO THE
OVERNIGHT HOURS. ANY CONVECTIVE CHANCES ARE VERY LOW UNTIL
CONDITIONS TURN MORE ACTIVE INTO NEXT WEEKEND.
TIDES/COASTAL FLOODING
WATER LEVELS ARE EXPECTED TO DROP THROUGH MONDAY AS NW TO N
WINDS STRENGTHEN WITH A FRONTAL PASSAGE. BY THE MIDDLE OF THE
WEEK, WATER LEVELS ARE EXPECTED TO RISE AGAIN ON STRENGTHENING
SSE WINDS. FOLLOWED ESTOFS GUIDANCE WHICH HAS PERFORMED THE BEST
ON SOUTHERLY FLOW REGIMES THIS SUMMER.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY UNTIL NOON EDT MONDAY FOR MDZ008.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT MONDAY FOR ANZ530>534-537-
539>541-543.
SYNOPSIS...EST
NEAR TERM...EST
SHORT TERM...LFR/KRR/EST
LONG TERM...BRO
AVIATION...LFR/BRO/EST
MARINE...LFR/BRO/EST
TIDES/COASTAL FLOODING...BRO
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