340
FXUS61 KLWX 240019
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
819 PM EDT THU APR 23 2026
WHAT HAS CHANGED
A SPOTTY SHOWER OR T-STORM CANNOT BE RULED OUT OVER THE ALLEGHENIES
THIS EVENING AS A WEAK DISTURBANCE PASSES THROUGH. ADDITIONAL
SCATTERED SHOWERS AND T-STORMS, ESPECIALLY NEAR THE POTOMAC
RIVER FRIDAY. MORE SHOWER CHANCES THIS WEEKEND.
KEY MESSAGES
1) A FRONTAL BOUNDARY WILL LINGER NEARBY THROUGH SATURDAY, LEADING
TO CHANCES FOR SHOWERS AND THUNDERSTORMS AT TIMES.
2) HIGH PRESSURE BUILDS IN EARLY NEXT WEEK, BEFORE THE NEXT SYSTEM
APPROACHES FROM THE WEST ON TUESDAY.
DISCUSSION
KEY MESSAGE 1...A FRONTAL BOUNDARY WILL LINGER NEARBY THROUGH
SATURDAY, LEADING TO CHANCES FOR SHOWERS AND THUNDERSTORMS AT TIMES.
STILL MONITORING A WEAK PIECE OF ENERGY ALOFT KICKING OFF A FEW
SPOTTY SHOWERS AND ISOLATED T-STORMS FROM EASTERN OHIO/WESTERN PA
SOUTHEAST INTO CENTRAL VA. OVERALL THIS ACTIVITY REMAINS LIGHT IN
NATURE WITH A BETTER FOCUS ALONG AND WEST OF ALLEGHENIES WHERE THE
INSTABILITY GRADIENT/SURFACE CONVERGENCE IS A BIT STRONGER. ANY
ACTIVITY WILL WANE WELL BEFORE MIDNIGHT WITH THE LOSS OF DAYTIME
HEATING. OUTSIDE THE SPOTTY SHOWER AND T-STORM THREAT EXPECT DRY
CONDITIONS OVERNIGHT WITH LOWS REMAINING MILD IN THE MID TO UPPER
50S. A FEW LOW 50S ARE POSSIBLE OVER NORTHEAST MD AND THE DEEPER
SHELTERED VALLEYS OF THE ALLEGHENIES WHERE SLIGHTLY DRIER AIR WORKS
IN.
EXPECT MORE COVERAGE WHEN IT COMES TO SHOWERS AND T-STORMS FRIDAY,
ESPECIALLY IN THE VICINITY OF THE POTOMAC RIVER. THIS IS LARGELY DUE
IN PART TO A BACKDOOR FRONT DROPPING SOUTHEASTWARD AND STALLING OUT
OVER THE REGION. 12Z AND 18Z CAM GUIDANCE CONTINUE TO STRUGGLE ON
THE PLACEMENT OF THIS BOUNDARY ALONG WITH THE CHAOTIC WIND FIELD THAT
SURROUNDS IT. WHAT WE DO KNOW IS THAT THE COVERAGE OF SHOWERS AND
THUNDERSTORMS WILL LIKELY INCREASE DURING THE PEAK HEATING PERIOD IN
THE VICINITY OF THE FRONT (I.E CENTRAL MD, DC, AND NORTHERN VA).
MODEL SOUNDINGS SHOW DEEP MIXING, WITH RELATIVELY WEAK INSTABILITY
(AROUND 500 J/KG) AND MODEST AMOUNTS OF SHEAR (AROUND 30 KNOTS).
STORMS AREN'T EXPECTED TO BE SEVERE, BUT COULD PRODUCE SOME
LOCALIZED GUSTY WINDS AND MUCH NEEDED HEAVY RAINFALL. ANY STORMS
SHOULD DIMINISH WITH LOSS OF DAYTIME HEATING FRIDAY EVENING.
TEMPERATURES FRIDAY WILL REACH INTO THE 80S TO THE SOUTHWEST OF THE
FRONT, WITH 70S FURTHER NORTHEAST.
HIGH PRESSURE OVER NEW ENGLAND WILL STRENGTHEN SATURDAY WHILE AN
UPPER LEVEL DISTURBANCE SIMULTANEOUSLY TRACKS OVERHEAD.
AS THE HIGH STRENGTHENS TO OUR NORTHEAST, A STRONGER SURGE OF
EASTERLY (MARITIME) FLOW WILL MOVE IN, CAUSING THE BACKDOOR FRONT TO
PUSH FURTHER SOUTHWEST, AND LOW CLOUDS AND COOLER AIR TO MOVE IN
FROM THE NORTHEAST. AS A RESULT, A SHARP TEMPERATURE GRADIENT MAY
SET UP ACROSS THE AREA ON SATURDAY. TEMPERATURES TO THE NORTHEAST OF
THE FRONT WILL LIKELY HOLD IN THE 50S (NORTHEAST MD/CENTRAL MD),
WHILE FURTHER SOUTHWEST (SOUTHWEST OF THE POTOMAC RIVER) HIGHS WILL
REACH INTO THE 70S. SATURDAY WILL LIKELY FEATURE ON AND OFF SHOWERS
ACROSS THE ENTIRE AREA, WITH MORE IN THE WAY OF CLOUD COVER FURTHER
TO THE NORTHEAST.
RAINFALL AMOUNTS THROUGH SATURDAY NIGHT WILL RANGE BETWEEN A TENTH
TO A QUARTER OF AN INCH ACROSS THE REGION. LOCALLY HIGHER TOTALS ARE
POSSIBLE IN HEAVIER THUNDERSTORMS. ANY RAIN WILL BE WELCOMED GIVEN
SEVERE DROUGHT EXPANSION ACROSS MUCH OF THE FORECAST AREA.
KEY MESSAGE 2...HIGH PRESSURE BUILDS IN EARLY NEXT WEEK, BEFORE THE
NEXT SYSTEM APPROACHES FROM THE WEST ON TUESDAY.
THE AFOREMENTIONED UPPER LEVEL DISTURBANCE WILL PROGRESS OFF TO OUR
EAST ON SUNDAY, CAUSING SHOWERS TO WIND DOWN FROM WEST TO EAST
DURING THE MORNING HOURS. UPPER RIDGING WILL BUILD IN ITS WAKE, AND
HOLD STRONG OVERHEAD THROUGH MUCH OF MONDAY AND TUESDAY. HOWEVER,
HIGH PRESSURE WILL REMAIN IN PLACE TO OUR NORTHEAST. AS A RESULT,
PERSISTENT ONSHORE FLOW IS EXPECTED. THIS SHOULD LEAD TO BELOW
NORMAL TEMPERATURES AND MORE IN THE WAY OF CLOUDS THAN SUN.
TEMPERATURES ON SUNDAY, MONDAY, AND TUESDAY SHOULD REACH UP INTO THE
60S DURING THE DAY, AND THEN DROP BACK INTO THE 40S AT NIGHT.
AN UPPER TROUGH AND ASSOCIATED SURFACE LOW WILL TRACK INTO THE GREAT
LAKES ON TUESDAY. AS OF NOW, IT LOOKS LIKE WE'LL STAY STABLE, SO
JUST SHOWERS ARE EXPECTED TUESDAY AFTERNOON INTO TUESDAY NIGHT AS
LARGE SCALE ASCENT AHEAD OF THAT SYSTEM OVERSPREADS THE AREA.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
OVERALL VFR CONDITIONS WILL PREVAIL AMONGST THE TERMINALS THROUGH
FRIDAY EVENING. THERE MAY BE A PERIOD OF TEMPORARY SUB-VFR
REDUCTIONS FRIDAY AFTERNOON AND EVENING DUE TO SCATTERED SHOWERS AND
THUNDERSTORMS ALONG A BACKDOOR FRONT THAT LOOKS TO STALL OVER THE
CORRIDOR. WENT AHEAD AND ADDED PROB30S AT ALL TAF SITES FOR THE 00Z
CYCLE. WINDS WILL REMAIN LIGHT OUT OF THE NORTHWEST THIS EVENING
BEFORE BECOMING CALM TONIGHT. WINDS BECOME A BIT MORE CHAOTIC FRIDAY
PENDING THE PLACEMENT OF A STALLED BACKDOOR FRONTAL BOUNDARY. WINDS
WILL LIKELY TURN TO THE EAST AND NORTHEAST; EAST OF THE STALLED
FROM WITH WEST TO NORTHWEST WINDS; WEST OF THE BOUNDARY. RIGHT
NOW, 12- 18Z HI-RES GUIDANCE HAS THE FRONT STALLING NEAR
IAD/DCA DIRECTLY IN THE VICINITY OF THE POTOMAC RIVER FRIDAY
AFTERNOON. SHOWERS AND THUNDERSTORMS ALONG THE BOUNDARY WILL
QUICKLY DIMINISH AFTER 00Z/8PM FRIDAY EVENING WITH THE LOSS OF
DAYTIME HEATING.
THERE IS A HIGHER LIKELIHOOD OF SUB-VFR CONDITIONS SATURDAY GIVEN
EASTERLY ONSHORE MARITIME FLOW. THIS IS DUE IN PART TO A
STRENGTHENING AREA OF HIGH PRESSURE OVER EASTERN NEW ENGLAND THAT
WILL BRING A STRONGER PUSH OF EAST TO NORTHEASTERLY WINDS INTO THE
REGION. THE SURFACE HIGH WILL WEDGE SOUTHWARD SHUNTING THE COLD
FRONTAL BOUNDARY DOWN TOWARD CENTRAL VA. THIS WILL ALLOW LOWER CIGS
(POTENTIALLY IFR (LOW CLOUDS)) TO MOVE IN FROM NORTHEAST TO
SOUTHWEST ACROSS THE REGION. SUB-VFR CEILINGS AND SHOWERS APPEAR
LIKELY AT MOST TERMINALS ON SATURDAY, ALTHOUGH CHO MAY REMAIN ON THE
WARM SIDE OF THE BOUNDARY AND ESCAPE THE LOWER CLOUDS. CONDITIONS
SHOULD IMPROVE BACK TO VFR FOR ALL ON SUNDAY AS WINDS TURN
NORTHERLY. VFR CONDITIONS AND LIGHT EASTERLY WINDS ARE FORECAST FOR
MONDAY.
MARINE
WINDS TURN TO THE SOUTH TONIGHT, AND COULD NEAR LOW- END SCA LEVELS
BRIEFLY WITHIN CHANNELED FLOW. A BACKDOOR COLD FRONT WILL DROP
SOUTHWESTWARD OVER THE WATERS OVER THE COURSE OF FRIDAY. THIS WILL
CAUSE WINDS OVER THE BAY TO TURN NORTH TO NORTHEASTERLY. EVENTUALLY
THE FRONT WILL STALL OUT OVER THE MIDDLE OF THE FORECAST AREA.
DEPENDING ON THE ULTIMATE POSITIONING OF THE FRONT, WINDS MAY STAY
NORTHWESTERLY ON THE TIDAL POTOMAC. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP IN THE VICINITY OF THE FRONT FRIDAY AFTERNOON.
SOME OF THE STRONGER STORMS MAY LEAD TO SMWS BEING ISSUED FOR GUSTY
WINDS.
WINDS WILL TURN EASTERLY FRIDAY NIGHT AND REMAIN EASTERLY THOUGH THE
DAY SATURDAY. WINDS MAY POTENTIALLY REACH LOW-END SCA STRENGTH IN
EASTERLY FLOW SATURDAY INTO SATURDAY NIGHT. SCA GUSTS ALSO APPEAR
POSSIBLE ON SUNDAY AS WINDS SHIFT TO OUT OF THE NORTH. SUB-SCA
EASTERLY WINDS ARE FORECAST FOR MONDAY.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...KJP/EST
AVIATION...KJP/EST
MARINE...KJP/EST
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