457
FXUS61 KLWX 180120
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
920 PM EDT FRI APR 17 2026
WHAT HAS CHANGED
SMALL CRAFT ADVISORIES WERE ALLOWED TO EXPIRE EARLIER THIS
EVENING AS NORTHWEST WINDS DIMINISHED QUICKLY.
KEY MESSAGES
- (1) ABOVE AVERAGE TEMPERATURES CONTINUE THROUGH SATURDAY
BEFORE A COLD FRONT CROSSES OVERNIGHT.
- (2) FIRE WEATHER CONCERNS RETURN NEXT WEEK WITH DRY AND
BREEZY CONDITIONS EXPECTED.
DISCUSSION
KEY MESSAGE 1...ABOVE AVERAGE TEMPERATURES CONTINUE THROUGH
SATURDAY BEFORE A COLD FRONT CROSSES OVERNIGHT.
A DRY AIR MASS CONTINUES AS SHOWN BY THE 00Z IAD SOUNDING. THE
PROFILE WAS PARTICULARLY DRY IN THE MID-LEVELS WITH AVERAGE
RELATIVE HUMIDITIES AROUND 25 PERCENT. THE REPORTED PRECIPITABLE
WATER WAS 0.71 INCHES WITH STEEP LOW-LEVEL LAPSE RATES CLOSE TO
DRY ADIABATIC. AS THE BOUNDARY LAYER BEGINS TO DECOUPLE LATER
THIS EVENING, EXPECT COOLING AND LESS MIXING WHICH RESULTS IN
LIGHT WINDS OVERNIGHT. WHILE MILD, TEMPERATURES WILL BE COOLER
THAN LAST NIGHT WITH LOWS IN THE 50S TO LOW 60S. THIS COMES WITH
A FEW PASSING HIGH CLOUDS.
DRY CONDITIONS ARE EXPECTED THROUGH AT LEAST MIDDAY SATURDAY. A
STRONG UPPER TROUGH AND COLD FRONT WILL APPROACH FROM THE WEST
SATURDAY, THEN CROSS THE MID-ATLANTIC SATURDAY NIGHT INTO SUNDAY
MORNING. THE UPPER TROUGH AND SURFACE COLD FRONT WILL BECOME A
BIT DISJOINTED AS THEY APPROACH, BUT INCREASING LOW-LEVEL WINDS
AND FORCING FOR ASCENT ARE EXPECTED TO GENERATE AT LEAST BRIEF
SHOWERS OVER MOST OF THE AREA FROM LATE SATURDAY AFTERNOON (WEST
OF I-81) THROUGH SUNDAY AFTERNOON (EAST OF I-95). A FEW
THUNDERSTORMS CAN'T BE RULED OUT, AND A SUBSET OF THE LATEST
CAMS ARE SUSPICIOUSLY CONSISTENT IN A COUPLE BANDS OF STORMS (1)
NEAR WESTERN MD LATE SATURDAY AFTERNOON, AND (2) APPROACHING
AND CROSSING THE SHENANDOAH VALLEY SATURDAY EVENING. GIVEN STEEP
LOW-LEVEL LAPSE RATES, THESE COULD PRODUCE GUSTY WINDS. FURTHER
EAST, MORE STABLE ONSHORE FLOW AND LESS OF A CHANCE FOR THUNDER
IS ANTICIPATED. THERE COULD BE SOME ELEVATED INSTABILITY ALOFT
AS THE FRONT CROSSES OVERNIGHT INTO EARLY SUNDAY MORNING, BUT
THE WEAKER INSTABILITY AND INCREASINGLY UNFAVORABLE ENVIRONMENT
MAY KEEP THUNDER CHANCES TO A MINIMUM. STILL, A GUSTY LINE OF
SHOWERS WILL LIKELY ACCOMPANY THE FRONT HEADING INTO SUNDAY
MORNING GIVEN A MODERATE STRONG PRESSURE FALL/RISE COUPLET AND
WIND SHIFT FROM S/SE TO W/NW.
BREEZY CONDITIONS AMID COOL/DRY ADVECTION WILL ENSUE SUNDAY WITH
OCCASIONAL SHOWER ACTIVITY AS THE FRONT PUSHES OFFSHORE. HIGH
TEMPERATURES ON SUNDAY MAY BE REACHED EARLY IN THE DAY, AND ARE
EXPECTED TO BE 15 TO 25 DEGREES COOLER THAN SATURDAY - A STARK
CONTRAST TO THE RECENT SPELL OF RECORD HEAT.
DEPENDING ON HOW MUCH RAIN FALLS AND HOW QUICKLY HUMIDITY DROPS,
A FIRE WEATHER THREAT COULD DEVELOP MAINLY WEST OF THE BLUE
RIDGE AND CATOCTIN MOUNTAINS BY LATE SUNDAY AFTERNOON. SEE THE
FIRE WEATHER SECTION BELOW FOR MORE DETAILS.
KEY MESSAGE 2...COOLER AIR RETURNS EARLY NEXT WEEK, ALONG WITH
RENEWED FIRE WEATHER CONCERNS.
SURFACE HIGH PRESSURE WILL BUILD OVER THE MID-ATLANTIC EARLY
NEXT WEEK WITH DRY CONDITIONS EXPECTED. A PRESSURE GRADIENT
BETWEEN SURFACE HIGH PRESSURE OVERHEAD AND A DEPARTING COLD
FRONT AND ASSOCIATED WAVES OF LOW PRESSURE WILL LEAD TO GUSTY
NORTHWEST WINDS BLOWING 10 TO 15 MPH WITH GUSTS BETWEEN 20 AND
30 MPH EXPECTED MONDAY. DESPITE SOME RAINFALL EXPECTED OVER THE
WEEKEND, PERSISTENT MODERATE TO SEVERE DROUGHT, GUSTY WINDS,
AND DRY CONDITIONS (LOWER RH) WILL ALLOW FOR FUELS TO DRY OUT
EARLY NEXT WEEK. CONFIDENCE IS HIGHEST ACROSS CENTRAL VIRGINIA
WHERE IT WILL BE THE DRIEST AND ANY RAINFALL THIS WEEKEND WILL
BE LIGHT, BUT VERY DRY AIR COULD MIX DOWN AREAWIDE ON MONDAY
GIVEN VERY STEEP SURFACE-3KM AGL LAPSE RATES APPROACHING 9-10
C/KM IN MANY MODEL SOUNDINGS.
BEHIND THE COLD FRONT, TEMPERATURES WILL COOL DOWN WITH HIGHS ON
MONDAY IN THE 50S TO LOW 60S (40S MOUNTAINS). FROST/FREEZE CONCERNS
RETURN MONDAY NIGHT AS LOW TEMPERATURES DROP INTO THE 20S AND 30S.
AS HIGH PRESSURE SHIFTS OFFSHORE THROUGH THE WEEK, TEMPERATURES
MODERATE WITH HIGHS IN THE 70S FOR MOST BY WEDNESDAY.
AVIATION /01Z SATURDAY THROUGH WEDNESDAY/
NW WINDS WILL BECOME NE TO SE TONIGHT INTO SAT AM AS HIGH
PRESSURE PULLS OFFSHORE.
VFR CONDITIONS ARE FORECAST FOR THE MOST PART THROUGH SAT AFT.
SOME LOWER CIGS MAY DEVELOP AND PRESS ONSHORE LATE TONIGHT INTO
SAT MORNING (ROUGHLY 08Z-16Z), WITH KMTN AND KBWI THE MOST
LIKELY TO BE IMPACTED. SOME GUIDANCE (LIKE THE HRRR) ACTUALLY
HAS BRIEF DENSE FOG AROUND/JUST AFTER DAYBREAK SAT NEAR THE
CHESAPEAKE BAY, SO WILL HAVE TO KEEP AN EYE ON HOW THE LOW-LEVEL
MOISTURE PROFILE EVOLVES TONIGHT. PROBS FOR RAIN INCREASE AFTER
00Z SUN NEAR KMRB, 03Z NEAR KCHO, AND BY 06Z FOR THE METRO TAF
SITES. THUNDER PROBS ARE HIGHEST WEST OF THE METROS SAT EVENING.
SOME LLWS IS ALSO POSSIBLE SAT EVE, MAINLY NEAR THE METROS.
FROPA WILL LIKELY BE ACCOMPANIED BY AN ABRUPT WIND SHIFT AND
WIND GUSTS OF 25-35 KTS 06Z-12Z SUN. SHRA LIKELY LINGERS INTO
SUN AFT. VFR CONDITIONS ARE EXPECTED MON-TUE AS HIGH PRESSURE
BUILDS OVER THE AREA LEADING TO DRY CONDITIONS ACROSS THE
TERMINALS. NORTHWEST WINDS GUST 15 TO 20 KTS MON AFT BEFORE
DIMINISHING OVERNIGHT. WIND SHIFT TO SOUTHERLY ON TUE, BLOWING
5 TO 10 KTS WITH GUSTS UP TO 15 KTS EXPECTED.
MARINE
NORTHWEST WINDS WEAKENED RATHER QUICKLY THIS EVENING, WITH A SHIFT
TO THE NORTHEAST TO SOUTHEAST TONIGHT THROUGH SATURDAY MORNING
AS HIGH PRESSURE DRIFTS INTO THE ATLANTIC.
AN INCREASE IN SOUTH/SOUTHEAST FLOW IS LIKELY SATURDAY, BUT THE
ONSET OF SCA CONDITIONS IS SOMEWHAT UNCLEAR. THERE IS EVIDENCE
OF A STRONG STABLE LAYER JUST ABOVE THE SURFACE, AND THE AIR MAY
BE A BIT WARMER THAN THE WATER. HOWEVER, FAVORABLE CHANNELING
AND AN INCREASING BACKGROUND GRADIENT/WIND FIELD MAY COMPENSATE
RESULTING IN GUSTS DEVELOPING BY MID AFTERNOON, ESPECIALLY FOR
FAVORED AREAS OF THE MID TIDAL POTOMAC RIVER/MID CHESAPEAKE BAY.
AFTER A BRIEF LULL OVER MOST OF THE WATERS (EXCEPT PERHAPS OFF
SOUTHERN MD) LATE SATURDAY NIGHT, WINDS WILL SHIFT TO THE NW AND
QUICKLY BECOME GUSTY AS A STRONG COLD FRONT CROSSES EARLY
SUNDAY MORNING. GALE-FORCE GUSTS ARE QUITE POSSIBLE WITH 30-40
KTS IN THE MIXED-LAYER AMID COLD ADVECTION AND STRONG PRESSURE
RISES. HOWEVER, THE MOST FAVORABLE WINDOW FOR GUSTS MAY BE BRIEF
(LESS THAN 3 HOURS, I.E. IN THE SMW VS. GALE WARNING REALM).
HAVE THEREFORE HELD OFF ON A GALE WATCH.
IT WILL BE BREEZY NONETHELESS SUNDAY INTO SUNDAY NIGHT, LIKELY
RIGHT ON INTO EARLY NEXT WEEK. SMALL CRAFT ADVISORIES ARE LIKELY
ON MONDAY AS NORTHWEST WINDS GUST UP TO 20 KNOTS IN THE WAKE OF
THE COLD FRONT. WINDS SHIFT TO SOUTHERLY AND DIMINISH TO BELOW
SCA CRITERIA OVERNIGHT THROUGH TUESDAY MORNING. SOUTH WINDS GUST
NEAR 20 KNOTS TUESDAY NIGHT WITH ADDITIONAL SCAS POSSIBLE.
FIRE WEATHER
ELEVATED FIRE WEATHER CONDITIONS MAY PERSIST THROUGH SATURDAY
DUE TO ABOVE NORMAL TEMPERATURES, LOW RHS AND NO WETTING RAIN.
HOWEVER, RH WILL BE MORE MARGINAL WITH MINRH VALUES IN THE 30S
GENERALLY LIMITED IN AREA TO THE SHENANDOAH VALLEY INTO VA
PIEDMONT THROUGH SATURDAY AFTERNOON.
SUNDAY...WHILE SOME RAIN IS EXPECTED LATE SATURDAY EVENING INTO
SUNDAY MORNING, AMOUNTS OF A TENTH TO TWO TENTHS OF AN INCH (ON
AVERAGE) WILL NOT BE SUFFICIENT TO INCREASE 100-HR FUEL
MOISTURE VALUES SIGNIFICANTLY. MORE IMPORTANTLY, THE
PRECIPITATION DURATION IS EXPECTED TO BE SHORT-LIVED, GENERALLY
6 HOURS OR LESS IN ANY ONE SPOT. FURTHERMORE, VERY STRONG GUSTY
WINDS OF 35 MPH WITH POTENTIAL FOR GUSTS AS HIGH AS 45 MPH WILL
CREATE RENEWED FIRE WEATHER CONCERNS DESPITE MARGINAL
HUMIDITIES AND THE LIGHT RAINFALL. THE 10-HR FUEL MOISTURE
VALUES WILL LIKELY DROP RAPIDLY THROUGH THE DAY DUE TO THE
DRYING EFFECTS OF THE STRONG WINDS AND LOWERING HUMIDITY THROUGH
THE DAY.
REST OF NEXT WEEK...MUCH COOLER TEMPERATURE ARE EXPECTED MON AND
TUE WITH A MODERATING TREND IN TEMPERATURES EXPECTED DURING THE
MIDDLE AND SECOND HALF OF THE WEEK. WINDS WILL BE ON THE LIGHT
SIDE THANKS TO HIGH PRESSURE OVERHEAD, BUT HUMIDITIES WILL BE
MARGINALLY LOW TO NEAR CRITICAL LEVELS. A DRY PATTERN SEEMS
LIKELY TO CONTINUE WITH LITTLE TO NO RAINFALL.
TIDES/COASTAL FLOODING
SOUTHEAST FLOW WILL CAUSE TIDES TO RISE TO AROUND OR A LITTLE
OVER ONE FOOT ABOVE NORMAL LATER SATURDAY INTO SATURDAY NIGHT
AHEAD OF A COLD FRONT. MINOR TIDAL FLOODING IS POSSIBLE AT MANY
SITES ESPECIALLY FOR THE WATERS AROUND CENTRAL TO SOUTHERN MD,
WITH NEAR MODERATE FLOODING POSSIBLE IN A HIGH-END SCENARIO AT
ANNAPOLIS.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...LFR/BRO/DHOF/KJP
AVIATION...LFR/BRO/DHOF/KJP
MARINE...LFR/BRO/DHOF/KJP
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