336
FXUS61 KLWX 151935
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
335 PM EDT SAT AUG 15 2026
WHAT HAS CHANGED
A FLOOD WATCH WAS ISSUED FOR GARRETT COUNTY FROM 6 AM SUNDAY TO
12 AM MONDAY. ELSEWHERE, WE CONTINUE TO MONITOR THE POTENTIAL
FOR BOTH SEVERE THUNDERSTORMS AND ISOLATED INSTANCES OF FLASH FLOODING
ON SUNDAY.
KEY MESSAGES
- 1) SEVERE THUNDERSTORMS AND SOME INSTANCES OF FLASH FLOODING
ARE POSSIBLE ON SUNDAY.
- 2) SEASONABLE CONDITIONS CONTINUE THROUGH THE WEEK WITH
A BREAK IN THUNDERSTORM CHANCES TUESDAY AND WEDNESDAY.
DISCUSSION
KEY MESSAGE 1...SEVERE THUNDERSTORMS AND SOME INSTANCES OF
FLASH FLOODING ARE POSSIBLE ON SUNDAY.
SUNDAY IS SHAPING UP TO BE AN ACTIVE WEATHER DAY ACROSS THE REGION.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM LATER THIS AFTERNOON
ACROSS EASTERN INDIANA/WESTERN OHIO AHEAD OF A REMNANT MCV. THESE
THUNDERSTORMS ARE THEN FORECAST TO PERSIST OVERNIGHT AS THEY TRACK
EASTWARD ACROSS EASTERN OHIO, NORTHERN WEST VIRGINIA, AND WESTERN
PENNSYLVANIA. MUCH FURTHER TO THE NORTH, A MORE POTENT SHORTWAVE AND
ASSOCIATED SURFACE LOW WILL TRACK TOWARD HUDSON BAY. RETURN FLOW
AHEAD OF THAT DISTURBANCE ALONG WITH HIGH PRESSURE SHIFTING EASTWARD
OFF THE NEW ENGLAND COAST WILL CAUSE A WARM FRONT TO SIMULTANEOUSLY
LIFT NORTHEASTWARD THROUGH OUR FORECAST LATE TONIGHT INTO THE DAY
TOMORROW. GUIDANCE IS IN GOOD AGREEMENT THAT THE FRONT WILL CLEAR
LOCATIONS TO THE WEST OF THE BLUE RIDGE TOMORROW MORNING, BUT IT MAY
SLOW OR HALT ITS NORTHEASTWARD PROGRESS SOMEWHERE BETWEEN US-15 AND
I-95 AS SHOWERS LINGER THROUGH MUCH OF THE DAY. SOUTHERLY FLOW
BEHIND THE FRONT WILL ADVECT AN INCREASINGLY MOIST AND UNSTABLE
AIRMASS NORTHWARD INTO THE FORECAST AREA, SETTING THE STAGE FOR
SHOWERS AND THUNDERSTORMS TO OCCUR, ESPECIALLY ACROSS SOUTHWESTERN
PORTIONS OF THE FORECAST AREA.
THE ARRIVAL OF THE OVERNIGHT STORMS FROM THE OHIO VALLEY WILL
ROUGHLY COINCIDE WITH THE NORTHEASTWARD MOVEMENT OF THE WARM FRONT,
WITH JUST LIMITED INSTABILITY AVAILABLE TO THESE SHOWERS AND
THUNDERSTORMS AS THEY TRACK EASTWARD ACROSS THE FORECAST AREA.
THESE SHOWERS AND STORMS ARE FORECAST TO REACH THE ALLEGHENY
FRONT AROUND 3-6 AM BEFORE GRADUALLY SHIFTING EASTWARD THROUGH
THE MORNING. ON AND OFF SHOWERS WITH A FEW EMBEDDED
THUNDERSTORMS ARE EXPECTED FOR MOST LOCATIONS THROUGH THE
MORNING. THE SHOWERS MAY EVEN LINGER INTO THE AFTERNOON
NEAR/EAST OF I-95, WHICH WILL LIMIT DAYTIME HEATING AND
RESULTANT DESTABILIZATION IN THOSE LOCATIONS.
GUIDANCE IS SPLIT ON WHETHER THUNDERSTORMS WILL FORM IMMEDIATELY
BEHIND THE MORNING SHOWERS, BUT IT LIKELY WON'T TAKE MUCH HEATING
FOR STORMS TO REFIRE GIVEN THE UNCAPPED AND VERY MOIST AIRMASS THAT
WILL BE IN PLACE. IF THE STORMS DON'T IMMEDIATELY REFORM ON THE BACK
EDGE OF THE PRECIPITATION SHIELD, THERE COULD BE A BRIEF LULL FOR A
FEW HOURS IN THE SUBSIDENCE BEHIND THE DEPARTING MCV, BEFORE
THE NEXT DISTURBANCE APPROACHES FROM THE OHIO VALLEY. INITIAL
ACTIVITY ASSOCIATED WITH THIS DISTURBANCE WILL LIKELY FORM OFF
TO OUR NORTH AND WEST IN THE OHIO VALLEY DURING THE AFTERNOON
AND THEN MOVE IN FROM THE WEST DURING THE EVENING HOURS. THESE
STORMS WILL THEN TRACK EASTWARD ACROSS THE AREA THROUGH THE
FIRST HALF OF THE OVERNIGHT, WITH CONDITIONS FINALLY DRYING OUT
LATER SUNDAY NIGHT.
STORMS ON SUNDAY WILL POSE A THREAT FOR BOTH FLASH FLOODING AND
SEVERE WEATHER. PRECIPITABLE WATER VALUES ARE FORECAST TO CLIMB TO
WELL IN EXCESS OF 2 INCHES, WHICH WHEN WHEN COMBINED WITH INCREASING
INSTABILITY AND DEEP WARM CLOUD LAYERS WILL MAKE ANY STORMS CAPABLE
OF PRODUCING VERY HEAVY RAINFALL. FLOW WILL BE INCREASING ALOFT,
WHICH WILL KEEP STORMS PROGRESSIVE. HOWEVER, WITH THE POTENTIAL FOR
MULTIPLE ROUNDS AND HIGH INSTANTANEOUS RATES, ISOLATED INSTANCES OF
FLASH FLOODING COULD BE POSSIBLE ANYWHERE IN THE FORECAST AREA. A
FLOOD WATCH WAS ISSUED FOR GARRETT COUNTY FROM 6 AM TO MIDNIGHT,
WHERE FLOODING WAS OBSERVED A FEW NIGHTS AGO AND SOILS REMAIN
SATURATED. FURTHER EAST, CONFIDENCE IN THE PLACEMENT OF HEAVIER
STORMS WAS TOO LOW FOR A WATCH TO BE ISSUED AT THIS TIME.
STORMS MAY ALSO BE CAPABLE OF PRODUCING DAMAGING WINDS, AND
POTENTIALLY EVEN A TORNADO OR TWO. THE SEVERE THUNDERSTORM THREAT
APPEARS TO BE GREATEST TO THE WEST OF THE BLUE RIDGE/TO THE SOUTH OF
I-66 EAST OF THE BLUE RIDGE, WHERE THEY'LL HAVE A BETTER CHANCE
TO DESTABILIZE BEHIND THE MORNING CONVECTION. THIS SAME AREA IS
OUTLOOKED WITH A SLIGHT RISK FOR SEVERE THUNDERSTORMS FROM SPC.
FURTHER NORTHEAST, INSTABILITY WILL BE MORE LIMITED, WITH A
MARGINAL RISK FROM SPC. AS IT STANDS NOW, THE HIGHEST POTENTIAL
FOR SEVERE STORMS MAY BE WITH THE LATER THUNDERSTORMS AS THEY
MOVE TOWARD THE ALLEGHENIES FROM THE OHIO VALLEY IN THE EVENING.
WITH MORNING CONVECTION MOVING THROUGH, FORECAST CONFIDENCE IN
THE DETAILS IS LOW, SO WE'LL NEED TO MONITOR SHORT TERM TRENDS
AND ADJUST THE FORECAST ACCORDINGLY.
KEY MESSAGE 2...SEASONABLE CONDITIONS CONTINUE THROUGH THE WEEK WITH
A BREAK IN THUNDERSTORM CHANCES TUESDAY AND WEDNESDAY.
WINDS WILL SHIFT WEST OR NORTHWEST BY MONDAY, BUT THE ACTUAL COLD
FRONT/MOISTURE GRADIENT WILL BE LAGGING IN THE OHIO VALLEY. IT'S
POSSIBLE A FEW SHOWERS AND THUNDERSTORMS FORM MONDAY AS THE FRONT
MOVES THROUGH, ALTHOUGH THE DOWNSLOPING FLOW AND MODEST MID LEVEL
LAPSE RATES WILL LIKELY LIMIT COVERAGE. ABOVE NORMAL TEMPERATURES
AND HUMID CONDITIONS WILL CONTINUE UNTIL THE FRONT CLEARS THE AREA
MONDAY NIGHT.
UPPER-LEVEL ZONAL FLOW BRINGING DRIER AIR FROM THE GREAT LAKES WILL
BE IN PLACE TUESDAY AND WEDNESDAY, CREATING A BREAK IN THE RAIN AND
THUNDERSTORMS. TEMPERATURES AND HUMIDITY LEVELS WILL DROP A BIT BUT
REMAIN NEAR SEASONABLE AVERAGES.
MEANWHILE, AN UPPER-LEVEL TROUGH WILL BEGIN TO FORM OVER THE
NORTHERN PLAINS AND THEN TRACK ACROSS THE GREAT LAKES LATE IN THE
WEEK, WITH A STRONG COLD FRONT POTENTIALLY APPROACHING THE MID-
ATLANTIC BETWEEN THURSDAY AND FRIDAY. THIS FRONT COULD EVEN STALL
ACROSS THE AREA INTO NEXT WEEKEND, BRINGING PERSISTENT CHANCES FOR
SHOWERS AND THUNDERSTORMS. AT THIS TIME, IT'S UNCLEAR IF THE
POSITION OF SYNOPTIC FEATURES AND INSTABILITY WILL BE SUFFICIENT FOR
A THREAT OF SEVERE WEATHER OR FLOODING. FOR NOW, THIS WILL BE A
FEATURE TO CONTINUE TO MONITOR AS THE SYNOPTIC SETUP BECOMES MORE
DEFINED. TEMPERATURES MAY FLUCTUATE A LITTLE DEPENDING ON WHAT SIDE
OF THE FRONT WE'RE ON, BUT LIKELY FALL SOME BY NEXT WEEKEND ASSUMING
THE FRONT PUSHES TO THE SOUTHEAST.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
VFR CONDITIONS ARE EXPECTED TODAY, WITH POTENTIALLY A PASSING
SHOWER OR STORM NEAR CHO. ELSEWHERE, DRY CONDITIONS ARE
EXPECTED. MVFR CEILINGS AND SHOWERS MOVE IN TOMORROW MORNING
FROM WEST TO EAST, ALONG WITH POTENTIALLY A FEW EMBEDDED
THUNDERSTORMS. PROB30 GROUPS HAVE BEEN ADDED FOR NOW TO ACCOUNT
FOR THIS ACTIVITY. THERE MAY BE A BRIEF LULL BEFORE ANOTHER
ROUND OF SHOWERS AND THUNDERSTORMS MOVES IN FROM THE WEST
TOMORROW EVENING. THESE SHOWERS AND STORMS MAY LINGER THROUGH
THE FIRST HALF OF THE NIGHT, ESPECIALLY FURTHER EAST.
THEREAFTER, PREVAILING VFR CONDITIONS ARE EXPECTED THROUGH
MONDAY. THERE MAY ALSO BE A CHANCE FOR A PASSING SHOWER OR STORM
ON MONDAY AFTERNOON, BUT COVERAGE IS EXPECTED TO BE MUCH LOWER
COMPARED TO SUNDAY.
LIGHT AND SOMEWHAT VARIABLE WINDS ARE FORECAST AT THE TERMINALS
TODAY. WINDS TURN LIGHT OUT OF THE SOUTH TO SOUTHEAST TONIGHT,
BEFORE PICKING UP AND GUSTING TO AROUND 15-20 KNOTS OUT OF THE
SOUTH TOMORROW AFTERNOON. WINDS THEN SHIFT TO OUT OF THE
NORTHWEST ON MONDAY.
PREVAILING VFR CONDITIONS ARE ANTICIPATED TUESDAY THROUGH WEDNESDAY
WITH HIGH PRESSURE. POTENTIAL SHOWERS AND THUNDERSTORMS RE-ENTER THE
FORECAST THURSDAY.
MARINE
LIGHT AND VARIABLE WINDS ARE EXPECTED OVER THE WATERS THROUGH
THIS AFTERNOON. WINDS TURN SOUTHERLY LATER TONIGHT INTO
TOMORROW. THOSE SOUTHERLY WINDS SHOULD REACH SCA LEVELS OVER ALL
WATERS TOMORROW AFTERNOON. THE SCA LEVEL WINDS SHOULD END OVER
THE NARROWER WATERS OF THE MIDDLE AND UPPER TIDAL POTOMAC AFTER
SUNSET, BUT CONTINUE ACROSS THE LOWER TIDAL POTOMAC AND BAY
THROUGH MUCH OF NIGHT. SCAS HAVE BEEN ISSUED FOR ALL WATERS.
SUB-SCA LEVEL NORTHWESTERLY WINDS ARE EXPECTED ON MONDAY. SMWS
MAY POTENTIALLY BE NEEDED AS THUNDERSTORMS MOVE OVER THE WATERS
ON BOTH SUNDAY AND MONDAY, ALTHOUGH COVERAGE OF STORMS IS
FORECAST TO BE MUCH GREATER ON SUNDAY.
NORTH TO NORTHWEST WINDS CONTINUE FOR TUESDAY BUT LIKELY REMAIN
BELOW SCA LEVELS. AS HIGH PRESSURE DEPARTS, WINDS TURN SOUTHERLY ON
WEDNESDAY, AND CHANNELING MAY BRING MARGINAL SCA CONDITIONS ALONG
THE BAY DURING THE EVENING/OVERNIGHT. A COLD FRONT MAY BRING SOME
THUNDERSTORMS ON THURSDAY.
TIDES/COASTAL FLOODING
WATER LEVELS MAY REACH INTO ACTION STAGE AT ANNAPOLIS TODAY.
WATER LEVELS INCREASE EVERYWHERE TOMORROW AS SOUTHERLY WINDS
PICK UP. MINOR FLOODING MAY BE POSSIBLE WITH TOMORROW EVENING'S
HIGH TIDE AT ANNAPOLIS. ELSEWHERE, MANY LOCATIONS WILL RISE INTO
ACTION STAGE. WATER LEVELS ARE FORECAST TO DECREASE FOR MONDAY
INTO TUESDAY AS WINDS TURN OUT OF THE WEST AND THEN NORTHWEST.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EDT MONDAY FOR
MDZ008.
FLOOD WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
MDZ509-510.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON SUNDAY TO 6 AM EDT MONDAY FOR
ANZ530>534-537>543.
SMALL CRAFT ADVISORY FROM NOON TO 8 PM EDT SUNDAY FOR ANZ535-
536.
DISCUSSION...ADS/KJP
AVIATION...ADS/KJP
MARINE...ADS/KJP
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