250
FXUS61 KLWX 151329
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
929 AM EDT TUE SEP 15 2026
WHAT HAS CHANGED
NO CHANGES HAVE BEEN MADE TO THE FORECAST THIS MORNING.
KEY MESSAGES
- 1) REMAINING COOL TODAY, WITH SHOWER AND THUNDERSTORM CHANCES
RETURNING LATE IN THE WEEK AND INTO THE WEEKEND.
DISCUSSION
KEY MESSAGE 1...REMAINING COOL TODAY, WITH SHOWER AND
THUNDERSTORM CHANCES RETURNING LATE IN THE WEEK AND INTO THE
WEEKEND.
WITH A BROAD 1026-MB SURFACE ANTICYCLONE ANCHORED OVER THE
NORTHEASTERN U.S., EXPECT CONDITIONS TO BE FAIRLY SIMILAR TO
YESTERDAY/MONDAY. THE ONE MAJOR DIFFERENCE WILL BE THE MARKED
REDUCTION IN TEMPERATURES AND HUMIDITY, AS WELL AS WINDS GIVEN
WEAK GRADIENTS WITHIN THE INFLUENCE OF THIS DOME OF HIGH
PRESSURE. TODAY'S HIGH TEMPERATURES ARE FORECAST TO REACH THE
MID 70S TO LOW 80S (UPPER 60S TO LOW 70S IN THE MOUNTAINS). THIS
COMES WITH CONTINUED LOW HUMIDITY WITH DEW POINTS MAINLY IN THE
UPPER 40S TO LOW 50S. ASIDE FROM SOME PASSING HIGH CIRRUS,
ABUNDANT SUNSHINE IS EXPECTED THROUGHOUT THE DAY. LIGHT
SOUTHEASTERLY GRADIENTS WILL FAVOR AN UPTICK IN OVERNIGHT
TEMPERATURES. WHILE STILL COOLER THAN RECENT DAYS, MOST CAN
ANTICIPATE LOWS IN THE MID 50S TO LOW 60S (MILDEST ALONG THE
I-95 URBAN AREAS AS WELL AS NEAR THE POTOMAC RIVER AND
CHESAPEAKE BAY SHORELINES).
BEHIND AN EXITING LONGWAVE TROUGH THAT PUSHES INTO THE CANADIAN
MARITIMES, MID/UPPER HEIGHTS BEGIN TO BUILD IN EARNEST. AN
EXPANSIVE NEAR 600-DM MID-LEVEL RIDGE INITIALLY OVER THE
SOUTHERN U.S. WILL FLEX NORTHWARD IN TIME. THESE ABOVE AVERAGE
HEIGHTS REMAIN A FIXTURE IN THE FORECAST THROUGH THURSDAY. THIS
SUPPORTS A RETURN OF WARMER TEMPERATURES ALONG WITH BUILDING
HUMIDITY LEVELS. DAILY HIGHS PUSH BACK INTO THE MID/UPPER 80S,
LOCALLY REACHING THE LOW 90S IN THE WARM SPOTS. THE RETURN OF
THE HUMIDITY ALSO FAVORS MILDER NIGHTS WITH WIDESPREAD LOWS IN
THE 60S. ANY SHOWER AND THUNDERSTORM CHANCES SHOULD HOLD OFF
UNTIL THURSDAY GIVEN THE STOUT RIDGE ALOFT QUELLING MOST
PRECIPITATION CHANCES. MOST MODELS KEEP SUCH A THREAT MAINLY
WEST OF THE SHENANDOAH VALLEY, ESPECIALLY CLOSER TO THE
ALLEGHENIES.
A HIGH LATITUDE TROUGH DIGGING ACROSS SOUTHEASTERN CANADA SHOULD
BE ENOUGH TO NUDGE THE UPPER RIDGE BACK TOWARD THE SOUTH-CENTRAL
U.S. THIS ALLOWS A COLD FRONT TO PUSH THROUGH EARLY FRIDAY
WHICH AGAIN BRINGS A GRADUAL COOL DOWN WITH DECREASING HUMIDITY
INTO SATURDAY. HOWEVER, THIS REPRIEVE IS SOMEWHAT BRIEF AS
ADDITIONAL DISTURBANCES IN THE ATMOSPHERE TRACK TOWARD THE AREA
LATE IN THE WEEKEND. THE OVERALL JET PATTERN TURNS A BIT MORE
COMPLEX AS AN ARRAY OF FEATURES ENTER THE PICTURE. A BROAD
UPPER LOW RETROGRADES ACROSS THE GULF. AT THE SAME TIME, A
MYRIAD OF SHORTWAVES WILL EJECT ACROSS THE CENTRAL U.S. TOWARD
THE MISSISSIPPI VALLEY. HOW THESE IMPULSES BEHAVE ALONG WITH
WHERE SURFACE FEATURES RESIDE WILL DICTATE ANY LOCAL WEATHER
IMPACTS. HOWEVER, ALL SIGNS POINT TOWARD A MORE ACTIVE PATTERN
ON SUNDAY INTO EARLY NEXT WEEK.
AVIATION /13Z TUESDAY THROUGH SATURDAY/
CANADIAN HIGH PRESSURE WILL SUPPORT VFR CONDITIONS THROUGH MID-
WEEK. WEAK GRADIENTS KEEP LIGHTER WINDS THAN YESTERDAY/MONDAY,
WITH WINDS GRADUALLY SHIFTING FROM EAST TO SOUTHEASTERLY TODAY.
THIS RIDGE EVENTUALLY EDGES TOWARD THE ATLANTIC COASTLINE WHICH
WILL SUPPORT MAINLY SOUTHERLY WINDS ON WEDNESDAY INTO THURSDAY.
SOME STORM CHANCES EMERGE BY THURSDAY, BUT THESE ARE CURRENTLY
EXPECTED TO STAY WEST OF THE AREA TAF SITES.
A COLD FRONT MOVES THROUGH EARLY FRIDAY WHICH RESULTS IN SOME
UPTICK IN SHOWER CHANCES. THIS MAY COME WITH A FEW RESTRICTIONS
IF CONVECTION BECOMES MORE PRONOUNCED. IN THE WAKE OF THIS
FRONTAL PASSAGE, WINDS TURN MORE NORTHERLY WITH AFTERNOON GUSTS
TO AROUND 15 KNOTS OR SO. HIGH PRESSURE BUILDING TO THE NORTH
RESULTS IN AN EAST TO SOUTHEASTERLY WIND FOR SATURDAY. THIS
COMES WITH LIKELY VFR CONDITIONS.
MARINE
GRADIENTS WILL CONTINUE TO WEAKEN THROUGH THE DAY WITH WINDS
AROUND 5 TO 10 KNOTS.
HIGH PRESSURE SLOWLY PUSHES AWAY TOWARD THE COAST WHICH RESULTS
IN A SOUTH TO SOUTHEASTERLY WIND FOR WEDNESDAY AND THURSDAY.
SOME SOUTHERLY CHANNELING EFFECTS MAY NECESSITATE SMALL CRAFT
ADVISORIES FOR PARTS OF THURSDAY, ESPECIALLY ACROSS SOUTHERN
SECTIONS OF THE CHESAPEAKE BAY. A COLD FRONT TRACKS ACROSS THE
WATERS ON FRIDAY MORNING WHICH FAVORS A SHIFT TO NORTH TO
NORTHEASTERLY WINDS. THESE COULD NEAR ADVISORY CRITERIA, BUT
CONFIDENCE IS LOW. HIGH PRESSURE PASSING BY TO THE NORTH WILL
RESULT IN A SHIFT TO EAST-SOUTHEASTERLIES FOR SATURDAY. GUSTS UP
TO 15 TO PERHAPS 20 KNOTS ARE POSSIBLE.
TIDES/COASTAL FLOODING
CURRENT TIDAL ANOMALIES REMAIN AROUND ZERO FEET. HOWEVER, EXPECT
A GRADUAL RISE IN WATER LEVELS LATER TODAY AS HIGH PRESSURE
PULLS AWAY FROM THE EASTERN SEABOARD. THIS AGAIN PUSHES A NUMBER
OF SITES INTO ACTION STAGE DURING THE HIGHER OF THE TWO
ASTRONOMICAL HIGH TIDES, PARTICULARLY TONIGHT AND AGAIN LATE
WEDNESDAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...BRO/DHOF
AVIATION...BRO/DHOF
MARINE...BRO/DHOF
TIDES/COASTAL FLOODING...BRO
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