600
FXUS61 KLWX 110039
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
839 PM EDT SAT MAY 10 2025
SYNOPSIS
LOW PRESSURE WILL DEPART OFF THE NEW ENGLAND COASTLINE TODAY,
ENABLING HIGH PRESSURE TO BUILD TO OUR NORTH DURING THE DAY
TOMORROW. HIGH PRESSURE WILL MOVE OFFSHORE ON MONDAY AS AN UPPER LOW
SLOWLY STARTS TO APPROACH FROM THE SOUTHWEST. THIS UPPER LOW WILL
GRADUALLY DRIFT NORTHEASTWARD, BEFORE SHEARING OUT INTO AN OPEN
WAVE AND DEPARTING OFF TOWARD OUR NORTHEAST ON THURSDAY.
NEAR TERM /THROUGH SUNDAY/
LOW PRESSURE CONTINUES TO TRACK AWAY FROM THE NEW ENGLAND COAST
THIS EVENING, WHILE HIGH PRESSURE BUILDS TO OUR NORTH OVER THE
GREAT LAKES. WINDS ARE DECREASING THIS EVENING AS DAYTIME MIXING
SHUTS OFF AND THE PRESSURE GRADIENT STARTS TO RELAX. HIGH CLOUDS
ARE INCREASING WELL IN ADVANCE OF AN UPPER LOW CENTERED OVER
THE LOWER MISSISSIPPI VALLEY, BUT NO PRECIPITATION IS EXPECTED
OVERNIGHT. LOW TEMPERATURES WILL BE IN THE UPPER 40S TO MID 50S
FOR MOST.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
HIGH PRESSURE WILL BUILD TO OUR NORTH ON SUNDAY, WHILE AN UPPER
LOW CIRCULATES OVER THE SOUTHEAST. HIGH CLOUDS WILL CONTINUE TO
SPREAD NORTHWARD INTO THE AREA, BUT CONDITIONS WILL REMAIN DRY.
WINDS WILL STAY LIGHT, WITH HIGHS IN THE UPPER 70S AND LOWER
80S FOR MOST.
CLOUDS WILL BEGIN TO THICKEN TOMORROW NIGHT AS THE
AFOREMENTIONED UPPER LOW CONTINUES TO SLOWLY DRIFT NORTHEASTWARD
THROUGH THE LOWER MISSISSIPPI VALLEY. CONDITIONS SHOULD REMAIN
DRY THROUGH THE NIGHT FOR MOST, BUT SOME SHOWERS MAY BEGIN TO
WORK INTO THE CENTRAL SHENANDOAH VALLEY OR CENTRAL VIRGINIA JUST
PRIOR TO DAYBREAK. OVERNIGHT LOWS WILL BE IN THE 50S TO LOWER
60S.
THE UPPER LOW WILL CONTINUE TO SLOWLY DRIFT NORTHEASTWARD FROM
THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY MONDAY
INTO MONDAY NIGHT. AS THIS OCCURS, SHOWERS WILL GRADUALLY
OVERSPREAD THE AREA FROM SOUTHWEST TO NORTHEAST. AS IT STANDS
NOW, MOST GUIDANCE HOLDS PRECIPITATION OFF IN THE DC METRO
UNTIL THE LATE AFTERNOON OR EARLY EVENING HOURS, WITH
PRECIPITATION NOT STARTING UNTIL AFTER DARK MONDAY NIGHT AROUND
BALTIMORE. THE RAIN MAY START TO BECOME STEADIER AND MODERATE
TO LOCALLY HEAVY AT TIMES BY LATE MONDAY NIGHT, ESPECIALLY
ACROSS CENTRAL VIRGINIA. BY MONDAY NIGHT, MODEL SOUNDINGS SHOW
DEEP, SATURATED PROFILES, WITH VERY LIMITED INSTABILITY AND
PRECIPITABLE WATER VALUES CLOSING IN ON 1.5 INCHES. THE LACK OF
INSTABILITY SHOULD LIMIT RAINFALL RATES SOMEWHAT, WITH MOST OF
THE RAIN FALLING AS A STEADY, SOAKING RAIN AS OPPOSED TO VERY
HEAVY DOWNPOURS THAT YOU'D TYPICALLY SEE WITH A SUMMER
THUNDERSTORM. STILL, MODEL GUIDANCE HINTS THAT RAINFALL TOTALS
MAY REACH AROUND 1-2 INCHES ACROSS CENTRAL VIRGINIA BY DAYBREAK
TUESDAY, WITH MORE RAIN EXPECTED TO FALL TUESDAY INTO AT LEAST
WEDNESDAY (SEE LONG TERM DISCUSSION BELOW).
LONG TERM /TUESDAY THROUGH SATURDAY/
A HIGHLY AMPLIFIED AND BLOCKY SYNOPTIC PATTERN SETS UP FOR A
MAJORITY OF NEXT WEEK. THE INITIAL FEATURE OF INTEREST IS A SLOW
MOVING CLOSED LOW WHICH IS CURRENTLY SPINNING OVER THE DEEP SOUTH.
THIS DEEP AND ANOMALOUS SYSTEM IS SET TO BECOME MORE NEGATIVELY-
TILTED IN TIME WHILE CROSSING THE TENNESSEE VALLEY ON TUESDAY.
EVENTUALLY THIS TROUGH BEGINS TO EVOLVE INTO MORE OF AN OPEN WAVE AS
IT TREKS TOWARD THE MID-ATLANTIC REGION BY MID-WEEK. THE SLOW
FORWARD MOTION OF THIS PARTICULAR SYSTEM MAY NOT SEE THE TROUGH AXIS
PASS BY UNTIL THURSDAY MORNING. AT THIS POINT, THE ASSOCIATED
SURFACE FRONTS EXIT INTO THE COASTAL ATLANTIC AS HIGH PRESSURE
BRIEFLY RETURNS. MID/UPPER HEIGHTS BEGIN TO BUILD IN EARNEST BY LATE
IN THE WORK WEEK AHEAD OF THE NEXT WEATHER MAKER.
WHAT IS CURRENTLY A STRONG UPPER TROUGH OFF THE WEST COAST WILL
UNDERGO A COMPLEX EVOLUTION ACROSS THE NATION OVER THE NEXT SEVERAL
DAYS. AS EXPECTED, A LARGE ARRAY OF SPREAD IS NOTED ACROSS THE BOARD
WHEN EVALUATING ALL RECENT GUIDANCE. THE OVERALL PATTERN SHIFT DOES
FAVOR UNSETTLED CONDITIONS ON FRIDAY INTO PORTIONS OF NEXT WEEKEND.
LOOKING MORE CLOSELY AT TUESDAY INTO WEDNESDAY, THE MENTIONED CLOSED
LOW WILL TAP INTO ANOMALOUS GULF MOISTURE. CHARACTERIZED BY
ANOMALIES AROUND 1 TO 1.5 STANDARD DEVIATIONS ABOVE NORMAL, THIS
SYSTEM WILL INTERACT WITH STRONG DYNAMICS WITH THE UPPER LOW TO
PRODUCE PERIODS OF MODERATE TO HEAVY RAINFALL. ENSEMBLES SUPPORT
AROUND 2 TO 3 INCHES OF RAIN DURING A 24 TO 48 HOUR PERIOD.
DEPENDING ON HOW MUCH OF THIS FALLS AT ONCE, THERE WILL BE SOME
FLOOD THREAT THAT EMERGES. HOWEVER, THIS WILL DEPEND ON LOCATION AND
INTENSITY OF SUCH SHOWERS.
AFTER A SHORT REPRIEVE, THE SYSTEM LATER IN THE WEEK WILL HAVE A LOT
MORE FUEL TO WORK WITH. AS HIGH TEMPERATURES ON FRIDAY ARE EXPECTED
TO RISE INTO THE MID/UPPER 80S (COUPLED WITH DEW POINTS APPROACHING
70 DEGREES), INSTABILITY SHOULD BE PLENTIFUL. SOME STRONG TO SEVERE
THUNDERSTORMS ARE POSSIBLE AS THIS SYSTEM TRACKS THROUGH ON FRIDAY
INTO EARLY NEXT WEEKEND. DETAILS HOPEFULLY BECOME MORE APPARENT IN
THE NEXT FEW DAYS.
AVIATION /01Z SUNDAY THROUGH THURSDAY/
VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS THROUGH SUNDAY NIGHT.
LOWER CEILINGS AND SHOWERS/THUNDERSTORMS WILL OVERSPREAD THE AREA
FROM SOUTHWEST TO NORTHEAST MONDAY INTO MONDAY NIGHT, ALTHOUGH SOME
UNCERTAINTY REMAINS REGARDING THE EXACT ONSET TIMING OF THE LOWER
CEILINGS AND PRECIPITATION.
WINDS ARE LIGHT OUT OF THE SOUTHWEST THIS EVENING, BUT WILL
BECOME LIGHT AND VARIABLE AS THE NIGHT PROGRESSES. THE WIND
DIRECTION FORECAST IS A TOUGH ONE DURING THE DAYLIGHT HOURS
TOMORROW, ESPECIALLY FOR IAD AND DCA. FOR NOW WILL LEAVE
VARIABLE WINDS FOR THOSE TERMINALS. LOCATIONS FURTHER NORTH
HAVE A BETTER CHANCE OF TURNING LIGHT OUT OF THE NORTH TOMORROW,
WHILE LOCATIONS FURTHER SOUTH (ESPECIALLY CHO) HAVE A BETTER
CHANCE OF DEVELOPING SOUTHERLY WINDS. WINDS WILL SHIFT TO OUT
OF THE SOUTHEAST FOR ALL BY THE DAY ON MONDAY.
LENGTHY RESTRICTIONS ARE LIKELY ON TUESDAY GIVEN THE PROLONGED
PERIOD OF RAIN TRACKING THROUGH THE AREA. THIS WILL COME WITH A
STEADY SOUTHEASTERLY WIND WHICH MAY GUST UP TO 20 KNOTS AT TIMES.
RAIN MAY BECOME HEAVY AT TIMES, PARTICULARLY HEADING INTO TUESDAY
NIGHT. SOME RESIDUAL RESTRICTIONS ARE POSSIBLE FOR PARTS OF
WEDNESDAY AS THE UPPER LOW REMAINS NEARBY. WINDS TURN A BIT MORE
EASTERLY AS LOW PRESSURE PASSES BY TO THE SOUTH. BY THURSDAY, THE
PATTERN SLOWLY BECOMES MORE CONVECTIVE IN NATURE AS HEAT AND
HUMIDITY INCREASE. WHILE MAINLY VFR, SOME RESTRICTIONS ARE POSSIBLE
AS STORMS ROLL THROUGH.
MARINE
SUB- SCA LEVEL WINDS ARE EXPECTED TONIGHT THROUGH SUNDAY, WITH
VARIABLE WIND SPEEDS AND DIRECTIONS DEPENDING ON TIME OF DAY AND
LOCATION. WINDS WILL TURN OUT OF THE SOUTHEAST ON MONDAY, AND
COULD NEAR LOW-END SCA LEVELS DURING THE AFTERNOON HOURS.
A SLOW MOVING UPPER LOW WILL DRIFT NORTHEASTWARD FROM THE TENNESSEE
VALLEY ON TUESDAY. AHEAD OF IT, PERIODS OF MODERATE TO HEAVY RAIN
ARE LIKELY AMIDST A STEADY SOUTHEASTERLY WIND. GUSTS UP TO 20 KNOTS
AT TIMES WILL LIKELY REQUIRE SMALL CRAFT ADVISORIES ACROSS PORTIONS
OF THE WATERS. THE ASSOCIATED FRONTAL SYSTEM PASSES BY LATE
WEDNESDAY WITH SOME RESIDUAL GUSTY WINDS POSSIBLE.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...BRO
AVIATION...BRO/KJP
MARINE...BRO/KJP
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