865
FXUS61 KLWX 040708
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
308 AM EDT SUN MAY 4 2025
SYNOPSIS
A SLOW-MOVING COLD FRONT WILL GRADUALLY CROSS THE MID-ATLANTIC FROM
WEST TO EAST THROUGH TUESDAY. HIGH PRESSURE MAY FOLLOW BRIEFLY FOR
WEDNESDAY, THEN ANOTHER AREA OF LOW PRESSURE MAY APPROACH LATE
IN THE WEEK.
NEAR TERM /THROUGH TONIGHT/
AN UPPER LOW AND ASSOCIATED SURFACE COLD FRONT REMAIN JUST WEST
OF THE APPALACHIANS AS OF EARLY THIS MORNING, AND WILL MAKE
LITTLE EASTWARD PROGRESS OVER THE NEXT 24 HOURS. WAVES OF PVA
AND MOISTURE ADVECTION AROUND THE LOW IS RESULTING IN A WAVE OF
SHOWERS AND A FEW THUNDERSTORMS THIS MORNING LIFTING NORTH FROM
SOUTHERN VA UP THE I-95 CORRIDOR MAINLY EAST OF THE BLUE RIDGE
TOWARD CENTRAL AND EASTERN MD.
ONCE THIS MORNING'S ACTIVITY CLEARS, MUTED SURFACE HEATING
BENEATH LINGERING MID AND HIGH CLOUDS (ESPECIALLY EAST) AS WELL
AS MID-LEVEL LAPSE RATES NEAR 6.5 C/KM WILL LIKELY RESULT IN
ABOUT 1000 J/KG MLCAPE, MAINLY WEST OF I-95. GIVEN LOWERING
FREEZING LEVELS, ANY DEEPER CELLS COULD PRODUCE SOME SMALL HAIL.
GUSTY WINDS ARE POSSIBLE GIVEN MODEST FLOW IN THE MID LEVELS,
BUT CLOUD COVER MAY HINDER HEATING/GREATER DCAPE. ALSO, THE
STORM COVERAGE IS IN QUESTION LATER TODAY GIVEN NEBULOUS FORCING
BETWEEN WAVES FOR MOST OF THE DAY. THE MOST CONCENTRATED
ACTIVITY AFTER THIS MORNING APPEARS MOST LIKELY WHERE BETTER
HEATING TAKES PLACE TOWARD THE POTOMAC AND ALLEGHENY HIGHLANDS,
AND THIS EVENING ACROSS CENTRAL TO NORTHEAST MD AND THE DC AND
BALTIMORE METROS AS ANOTHER RIPPLE MOVES BY.
LOW CLOUDS ARE EXPECTED TO DEVELOP TONIGHT WITH PATCHY FOG
POSSIBLE AS LOW-LEVEL MOISTURE LINGERS. SHOWER COVERAGE SHOULD
BE WIDELY SCATTERED OVERNIGHT, AND LIMITED TO EASTERN AREAS.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
THE UPPER LOW AND SURFACE COLD FRONT WILL ONLY SLOWLY DRIFT EAST
THROUGH TUESDAY. ENHANCED FLOW IN THE 850-500 HPA LAYER AS WELL
AS INCREASING JET DYNAMICS FROM A WAVE AND JET STREAK ROUNDING
THE UPPER LOW WILL PROBABLY LEAD TO GREATER STORM COVERAGE ON
MONDAY AFTERNOON AND EVENING. LAPSE RATES ALOFT STEEPEN A BIT
AND FREEZING LEVELS LOWER FURTHER, BOLSTERING THE HAIL/WIND RISK
WITH ANY DEEPER STORM CORES. SHOULD GREATER HEATING AND
INSTABILITY DEVELOP, STRONG TO SEVERE STORM COVERAGE COULD BE A
LITTLE HIGHER.
ONE LAST STRONG WAVE ROUNDS THE UPPER LOW AND CROSSES THE REGION
TUESDAY, BEFORE THE UPPER LOW ITSELF PIVOTS NEARBY OR JUST TO
THE NORTH TUESDAY NIGHT. ANOTHER ROUND OF SHOWERS AND POSSIBLE
STORMS CAN BE EXPECTED AS THE UPPER LOW CROSSES.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
A BLOCKY PATTERN REMAINS IN PLACE FOR THE MIDDLE AND LATTER PART OF
THE WEEK, MEANING THAT THERE COULD BE SOME PREDICTABILITY ISSUES. AT
THIS TIME, THE UPPER LOW APPEARS IT WILL BE PULLING EAST OF THE AREA
WEDNESDAY, WHICH SHOULD RESULT IN A LOWER CHANCE OF RAIN COMPARED TO
THE PRECEDING DAYS. TEMPERATURES MAY REBOUND SLIGHTLY BUT REMAIN
NEAR NORMAL.
ON THURSDAY, A NORTHERN STREAM TROUGH WILL ROUND THE RIDGE AND DROP
TOWARD NEW ENGLAND. THIS WILL SEND A COLD FRONT SOUTH ACROSS THE
AREA. THE UPPER TROUGH WILL THEN CLOSE OFF INTO ANOTHER LOW TO OUR
EAST OR NORTHEAST THROUGH THE END OF THE WEEK. THE HIGHEST CHANCE OF
RAIN IS THURSDAY, BUT WITH LIMITED MOISTURE RETURN, BOTH RAINFALL
AMOUNTS AND CHANCES FOR THUNDERSTORMS WILL BE ON THE LOWER END OF
THE SPECTRUM.
AS LONG AS THE CLOSED LOW REMAINS TO THE EAST, THE DRIER POST-
FRONTAL AIR WILL RESULT IN LOWER RAIN CHANCES FOR FRIDAY AND
SATURDAY. TEMPERATURES MAY DROP A LITTLE BELOW NORMAL FRIDAY AND
FRIDAY NIGHT BEFORE RISING SLIGHTLY SATURDAY.
AVIATION /07Z SUNDAY THROUGH THURSDAY/
LOWER CIGS WERE DEVELOPING A FEW HOURS PRIOR TO DAYBREAK, WITH A
PERIOD OF IFR CIGS LIKELY IN BETWEEN STEADIER SHOWERS THROUGH
ABOUT MIDDAY (A BIT EARLY AT CHO, LATER AT MRB/MTN). SHOWERS AND
A FEW LIGHTNING STRIKES ARE ANTICIPATED ROUGHLY 10-15Z FROM SW
TO NE, BUT COULD LINGER NEAR BWI/MTN INTO EARLY AFTERNOON (OR
PERHAPS REDEVELOP BACK TOWARD DCA AS INDICATED BY THE HRRR).
LIGHT AND VARIABLE/NORTH TO EAST FLOW EARLY THIS MORNING SHOULD
GIVE WAY TO SOUTH FLOW BY MID TO LATE MORNING THROUGH THIS
AFTERNOON AND EVENING. ADDITIONAL THUNDERSTORMS ARE POSSIBLE
LATE THIS AFTERNOON INTO THIS EVENING, BUT COVERAGE MAY BE MORE
WIDELY SCATTERED. ACTIVITY SHOULD DIMINISH BY LATE EVENING.
LOW CIGS (IFR TO LIFR) ARE ANTICIPATED LATER TONIGHT INTO MONDAY
MORNING. CONDITIONS SHOULD IMPROVE BY MIDDAY MONDAY, THEN MORE
SCATTERED THUNDERSTORM ACTIVITY COULD DEVELOP. SIMILAR WEATHER
IS EXPECTED MONDAY NIGHT THROUGH TUESDAY BEFORE IMPROVING
TUESDAY NIGHT. WITH LOWERING FREEZING LEVELS, EVEN SHALLOW
CONVECTION COULD PRODUCE SMALL HAIL/GUSTY WINDS AT TIMES.
DECREASING SHOWER CHANCES AND FEWER CLOUDS ARE FORECAST BY
WEDNESDAY AS AN UPPER-LEVEL LOW DEPARTS. AN APPROACHING COLD
FRONT COULD BRING A HIGHER CHANCE OF SHOWERS AND A FEW
THUNDERSTORMS THURSDAY. OTHERWISE, VFR CONDITIONS ARE LIKELY.
MARINE
SOUTHERLY FLOW IS EXPECTED TO INCREASE A BIT TODAY IN THE WAKE
OF MORNING SHOWERS AND A FEW THUNDERSTORMS, WITH A 3-6 HOUR
WINDOW OF SCA CONDITIONS LIKELY OVER THE NORTHERN BAY, MID TO
UPPER TIDAL POTOMAC, AND SMALLER TRIBUTARIES. WINDS LIKELY
REMAIN ELEVATED OVER THE WIDER WATERS THROUGH THIS EVENING.
ADDITIONAL SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE THIS
EVENING, AS WELL AS MONDAY AND TUESDAY AFTERNOON/EVENING. SE
FLOW COULD APPROACH SCA LEVELS MONDAY INTO MONDAY NIGHT,
OTHERWISE SUB-SCA CONDITIONS ARE EXPECTED THROUGH TUESDAY NIGHT
AS WINDS SHIFT TO WEST.
LIGHT WEST WINDS ARE FORECAST FOR WEDNESDAY. A COLD FRONT WILL DROP
THROUGH THURSDAY AND SHIFT WINDS TO THE NORTH. SCAS MAY BE NEEDED BY
THURSDAY NIGHT, ESPECIALLY ALONG THE BAY WHERE THE NORTHERLY WINDS
COULD CHANNEL.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 5 PM EDT THIS
AFTERNOON FOR ANZ530-531-538>540-542.
SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 10 PM EDT THIS
EVENING FOR ANZ532.
SMALL CRAFT ADVISORY UNTIL 1 AM EDT MONDAY FOR ANZ533-534-537-
541-543.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 3 PM EDT THIS
AFTERNOON FOR ANZ535-536.
SYNOPSIS...DHOF
NEAR TERM...DHOF
SHORT TERM...DHOF
LONG TERM...ADS
AVIATION...ADS/DHOF
MARINE...ADS/DHOF
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