400
FXUS61 KLWX 141936
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
336 PM EDT FRI AUG 14 2026
WHAT HAS CHANGED
HAVE CONTINUED TO UPDATE THE PROBABILITY OF PRECIPITATION
FORECAST FOR TODAY AS THE GUIDANCE HAS STRUGGLED WITH ONGOING
ACTIVITY. OTHERWISE, MODELS HAVE TRENDED UP FOR A REMNANT MCS
POSSIBLY CROSSING THROUGH PORTIONS OF THE AREA LATE SATURDAY
NIGHT. FOR MID/LATE NEXT WEEK, THURSDAY IS STARTING TO PRESENT
ITSELF AS A MORE ACTIVE WEATHER DAY, BUT THAT IS STILL 6 TO 7
DAYS OUT.
KEY MESSAGES
- 1) SEVERE THUNDERSTORMS AND SOME INSTANCES OF FLASH FLOODING ARE
POSSIBLE ON SUNDAY.
- 2) SEASONABLY WARM CONDITIONS AND DAILY SHOWER AND
THUNDERSTORM CHANCES ARE EXPECTED THROUGH MONDAY, BEFORE
ANOTHER ROUND OF STORMS ARE POSSIBLE ON THURSDAY.
DISCUSSION
KEY MESSAGE 1...SEVERE THUNDERSTORMS AND SOME INSTANCES OF FLASH
FLOODING ARE POSSIBLE ON SUNDAY.
SOME RESIDUAL CONVECTIVE ACTIVITY MAY BE ONGOING ON SUNDAY
MORNING. THIS REMAINS TO BE SEEN AND WILL BE GUIDED BY THE
DEGREE OF OVERNIGHT INSTABILITY AND BOUNDARY PLACEMENT. HOW THE
ATMOSPHERE RECOVERS THROUGH THE DAY SHOULD ULTIMATELY DICTATE
THE DEGREE OF SEVERE THUNDERSTORM THREAT DURING THE CORE DIURNAL
HEATING HOURS. THE INGREDIENTS ARE CERTAINLY PRESENT FOR A MORE
IMPACTFUL EVENT IF METEOROLOGICAL PARAMETERS ALL COME TOGETHER.
LOOKING A BIT MORE CLOSELY AT THIS EVENT, A BROAD MID/UPPER
RIDGE PERSIST ACROSS THE FOUR CORNERS EASTWARD TO THE
SOUTHWESTERN ATLANTIC. AMPLIFIED FLOW NORTH OF THIS EXPANSIVE
ANTICYCLONE WILL CONTINUE TO BE A CONDUIT TO ACTIVE CONVECTION,
MANY IN THE FORM OF MESOSCALE CONVECTIVE SYSTEMS (MCS). AS
MENTIONED ABOVE, A REMNANT MCS MIGHT STILL BE ONGOING EARLY
SUNDAY ACROSS THE REGION. WHILE ABOVE AVERAGE HEIGHTS PERSIST,
EXPECT SOME NON-ZERO HEIGHT FALLS TO CROSS THE AREA IN RESPONSE
TO AN APPROACHING SHORTWAVE. WITHIN THIS NORTHWESTERLY FLOW
ALOFT, VERTICAL SHEAR IS AMPLE FOR THE TIME OF YEAR, GENERALLY
AROUND 30 TO 35 KNOTS. DEPENDING ON MODEL CHOICE, MIXED-LAYER
CAPE VALUES APPROACH 1,500 TO 2,500 J/KG. THE COMBINATION OF
THESE TWO WILL EASILY SUPPORT A RISK OF SEVERE WEATHER. WHILE
DAMAGING WIND GUSTS ARE THE MOST LIKELY THREAT, OTHER SEVERE
TYPES LOOM IF STORMS CAN REMAIN DISCRETE IN NATURE.
ADDITIONALLY, A SLIGHT RISK FOR EXCESSIVE RAINFALL CONTINUES
ALONG MUCH OF THE ALLEGHENIES EASTWARD ALONG/NORTH OF I-66/U.S.
50. PRECIPITABLE WATER VALUES RISE MARKEDLY, POSSIBLY INTO THE 2
TO 2.25 INCH RANGE. WHILE A SINGLE THUNDERSTORM WILL BE CAPABLE
OF TORRENTIAL DOWNPOURS, THE BIGGER THREAT WOULD BE FOR REPEAT
AND/OR TRAINING CONVECTION. THE LATTER POTENTIAL EXISTS WHICH
SUPPORTS THE FLASH FLOOD RISK. ALTHOUGH DROUGHT CONTINUES OVER
MUCH OF THE REGION, MANY AREAS HAVE SEEN A ONE CATEGORY
IMPROVEMENT OVER THE PAST WEEK. CONVECTION WILL LIKELY BE
ONGOING INTO SUNDAY NIGHT WITH THE COLD FRONT NOT PASSING
THROUGH UNTIL EARLY MONDAY.
KEY MESSAGE 2...SEASONABLY WARM CONDITIONS AND DAILY SHOWER AND
THUNDERSTORM CHANCES ARE EXPECTED THROUGH MONDAY, BEFORE ANOTHER
ROUND OF STORMS ARE POSSIBLE ON THURSDAY.
THE LOCAL AREA HAS LARGELY REMAINED JUST NORTH OF A WEST-EAST
ORIENTED SEMI-STALLED FRONTAL ZONE. AS OF THE EARLY AFTERNOON,
THE BOUNDARY CURRENTLY STRETCHES FROM THE DELMARVA PENINSULA
BACK ACROSS THE RICHMOND METRO AREA INTO CENTRAL WEST VIRGINIA.
ON THE LOCAL WSR-88D RADAR IMAGERY, WHAT REMAINS OF AN OVERNIGHT
CONVECTIVE COMPLEX ACROSS THE OHIO VALLEY IS CROSSING THE AREA.
ALTHOUGH MOST OF IT HAS DISSIPATED, THE REMNANT MESOSCALE
CONVECTIVE VORTEX (MCV) IS CURRENTLY TREKKING ACROSS THE CENTRAL
VIRGINIA PIEDMONT. WHILE THERE ARE NO CURRENT THREATS WITH THIS
FEATURE, THESE CAN NOTORIOUSLY BE TRIGGERS TOWARD MORE INTENSE
CONVECTION. THIS CYCLONIC SWIRL IS LIKELY TO CROSS THE I-95
CORRIDOR IN CENTRAL VIRGINIA BY AROUND 4 PM BEFORE MOVING INTO
THE NORTHERN NECK OF VIRGINIA. OFF TO THE NORTH, SPOTTY SHOWERS
REMAIN BUT THESE ARE PRODUCING MINIMAL PRECIPITATION AT BEST.
WITH EARLIER OVERCAST SKIES YIELDING MANY CLOUD BREAKS, SUCH
AREAS OF CLEARING WILL NEED TO MONITORED FOR FURTHER CONVECTIVE
INITATION. AS OF THE WRITING OF THIS DISCUSSION, NOTHING IS
IMMINENT AT THIS POINT.
FOR THE REMAINDER OF THE DAY, WILL MAINTAIN SHOWER AND
THUNDERSTORM CHANCES ACROSS MUCH OF THE AREA, ESPECIALLY SOUTH
OF I-66/U.S. 50. THIS GENERALLY FOLLOWS THE MARGINAL RISK AREA
MAINTAINED BY THE STORM PREDICTION CENTER. ANY TALLER UPDRAFT
WOULD BE CAPABLE OF PRODUCING POCKETS OF DAMAGING WIND GUSTS.
ALL CONVECTIVE THREATS SHOULD WANE BY SUNDOWN WITH THE LOSS OF
DAYTIME HEATING. TODAY'S HIGHS WILL TOP OUT IN THE 80S (70S FOR
THE MOUNTAINS) GIVEN IMMENSE CLOUD COVER AND NORTH TO
NORTHEASTERLY COMPONENT OF THE WINDS. TONIGHT REMAINS DRY WITH
SOME PATCHY FOG FOR THOSE ALONG/WEST OF U.S. 15. OVERNIGHT LOW
TEMPERATURES FALL INTO THE 60S TO LOW 70S, MILDEST ACROSS THE
CITY METROS.
HIGH PRESSURE BUILDING ACROSS SOUTHERN QUEBEC DOWN INTO NEW
ENGLAND WILL FAVOR A MOSTLY QUIET DAY FOR THE AREA ON SATURDAY.
AN ONSHORE COMPONENT TO THE WINDS SHOULD FAVOR A MIX OF CLOUDS
AND SUN THROUGH THE DAY. HIGHS WILL RISE INTO THE MID/UPPER 80S
WITH ANY SHOWER/THUNDERSTORM CHANCES CONFINED TO THE POTOMAC
HIGHLANDS ACROSS THE CENTRAL SHENANDOAH VALLEY TOWARD I-64.
RECENT HIGH-RESOLUTION MODELS ARE SHOWING AN MCS RACING ACROSS
THE OHIO VALLEY LATE SATURDAY. SOME OF THIS COULD LEAK ACROSS
THE ALLEGHENIES, BUT CONFIDENCE IS LOW GIVEN A FAIRLY MIXED
MODEL SIGNAL.
AS SUNDAY'S COLD FRONT TRACKS OFFSHORE, UPPER-LEVEL ZONAL FLOW
BRINGING DRIER AIR FROM THE GREAT LAKES PERSISTS OVER THE MID-
ATLANTIC THROUGH MIDWEEK, CREATING A BREAK IN THE RAIN AND
THUNDERSTORMS. WHILE TEMPERATURES & DEWPOINTS DROP A FEW DEGREES BY
TUESDAY IN THE WAKE OF THE FRONT, TEMPERATURES SHOULD GRADUALLY
INCREASE AGAIN IN THE LATTER HALF OF THE WEEK AS HIGH PRESSURE
BUILDS OVERHEAD.
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 MOVING THROUGH THE MID-
ATLANTIC BETWEEN THURSDAY AND FRIDAY. MEDIUM-RANGE ALGORITHMS ARE
ALREADY HIGHLIGHTING A POTENTIAL FOR SEVERE THUNDERSTORMS WITH THIS
SYSTEM. HOWEVER, SEVERE PROBABILITIES CURRENTLY VARY WIDELY ACROSS
MODELS, WITH CSU ML PROBABILITIES HIGHLIGHTING ONLY A MARGINAL 5%-
15% PROBABILITY AS OF THE 12Z MODEL RUNS WHILE THE WXNEXT2 MEAN AI
OUTLOOK IS ALREADY SHOWING A 30%-45% PROBABILITY. DETERMINISTICALLY,
THE GFS/EDMWF ALSO HAVE NOT QUITE ALIGNED ON THE TIMING AND
PLACEMENT OF THE TROUGH 7 DAYS OUT. SHOULD THIS SETUP MATERALIZE,
STORMS CAPABLE OF HEAVY DOWNPOURS AND DAMAGING WINDS WOULD BE
POSSIBLE. AS DROUGHT CONDITIONS CONTINUE TO IMPROVE AREA-WIDE,
LOCALIZED FLOODING BECOMES MORE OF A CONCERN WITH ANY THUNDERSTORMS
THAT FORM IN THE REGION. FOR NOW, THIS WILL BE A FEATURE TO CONTINUE
TO MONITOR AS THE SYNOPTIC SETUP BECOMES MORE DEFINED.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
WHAT HAD INITIALLY APPEARED TO BE A MORE ACTIVE DAY OF
CONVECTION HAS BEEN MORE LACKLUSTER IN NATURE. HOWEVER, THERE
ARE A NUMBER OF CLOUD BREAKS OCCURRING WHICH COULD LEAD TO SOME
DESTABILIZATION THIS AFTERNOON, PARTICULARLY AROUND KCHO GIVEN
CLOSER PROXIMITY TO THE FRONT. WILL MAINTAIN A PROB30 GROUP FROM
4-8 PM FOR THIS TERMINAL GIVEN THE THREAT OF THUNDERSTORMS.
OTHERWISE, EXPECT VFR CONDITIONS WITH LIGHT WINDS TURNING MORE
NORTHEAST TO EASTERLY INTO SATURDAY.
VFR CONDITIONS ARE EXPECTED FOR SATURDAY AS HIGH PRESSURE BUILDS
OVER NEW ENGLAND INTO SOUTHERN QUEBEC. ANY SHOWER CHANCES ARE
LIKELY CONFINED TO THOSE WEST OF THE BLUE RIDGE AND SOUTH OF
I-66. A DECAYING MCS COULD MOVE THROUGH LATE SATURDAY NIGHT, BUT
THERE IS PLENTY OF UNCERTAINTY AT THIS POINT. SUNDAY PRESENTS
ITSELF AS A MUCH MORE ACTIVE WEATHER DAY WHICH WOULD INCLUDE
SOME CONVECTIVE-DRIVEN RESTRICTIONS. AHEAD OF THE APPROACHING
COLD FRONT, SOUTHERLY WINDS PICK UP IN STRENGTH WITH AFTERNOON
GUSTS TO AROUND 15 TO 20 KNOTS. CONVECTION COULD LOOM INTO
SUNDAY NIGHT AND MONDAY MORNING WHICH WOULD SUPPORT ADDITIONAL
SUB-VFR CONDITIONS. CONDITIONS TURN DRIER FOR LATER IN THE DAY
AS THE COLD FRONT MOVES OFF TOWARD THE SOUTHEAST.
PREVAILING VFR CONDITIONS ARE ANTICIPATED AT TERMINALS TUESDAY
THROUGH WEDNESDAY. LIGHT NORTHWEST WINDS SHIFT SOUTHERLY ON
WEDNESDAY.
MARINE
THE MARINE WATERS SHOULD STAY MOSTLY HAZARD FREE, ALTHOUGH THE
MORE SOUTHERN WATERS COULD SEE A THUNDERSTORM OR TWO CAPABLE OF
FREQUENT LIGHTNING. OTHERWISE, BACKGROUND WIND FIELDS REMAIN
BELOW ADVISORY THRESHOLD THROUGH EARLY SUNDAY. AHEAD OF A COLD
FRONT, SOUTHERLY WINDS INCREASE IN EARNEST WHICH WILL CARRY
GUSTS TO AROUND 20 TO 25 KNOTS. THIS LIKELY REQUIRES SMALL CRAFT
ADVISORIES FROM SUNDAY AFTERNOON INTO THE OVERNIGHT HOURS.
ADDITIONALLY, THERE WILL BE AN INCREASING RISK OF STRONG TO
SEVERE THUNDERSTORMS, MANY OF WHICH MAY NEED SPECIAL MARINE
WARNINGS. SUNDAY LIKELY PRESENTS ITSELF AS THE MOST HAZARDOUS
DAY TO BE ON THE WATERS, PARTICULARLY FROM THE AFTERNOON ONWARD.
CONVECTION MAY CONTINUE INTO MONDAY MORNING BEFORE THE STORM
THREAT AND WINDS DROP OFF THROUGH THE DAY.
WINDS STAY BELOW SCA THRESHOLDS ON TUESDAY. BEGINNING WEDNESDAY
AFTERNOON, WIND GUSTS PICK UP TO MARGINAL SCA THRESHOLDS BEFORE
DIMINISHING OVERNIGHT. NORTHWEST WINDS SHIFT SOUTHEAST BY WEDNESDAY
MORNING.
TIDES/COASTAL FLOODING
WATER LEVELS ARE LARGELY EXPECTED TO STAY BELOW ACTION STAGE
THROUGH SATURDAY. THE POTENTIAL EXCEPTION COULD BE ANNAPOLIS,
WHICH COULD REACH ACTION STAGE AT THE HIGHER OF THE DAILY TIDES.
WATER LEVELS WILL START TO INCREASE IN SOUTHERLY FLOW ON
SUNDAY, WITH ANNAPOLIS POTENTIALLY APPROACHING MINOR FLOOD
STAGE.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
DISCUSSION...BRO/SRT
AVIATION...BRO/SRT
MARINE...BRO/SRT
TIDES/COASTAL FLOODING...LWX
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