015
FXUS61 KLWX 271453
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1053 AM EDT THU AUG 27 2026
WHAT HAS CHANGED
ADJUSTED PRECIPITATION CHANCES THIS MORNING FOR ONGOING SPOTTY
SHOWERS AND T-STORMS. CURRENT GUIDANCE SUGGESTING A LATER TIMING
WINDOW FOR POTENTIAL SEVERE WEATHER THIS AFTERNOON BETWEEN 3-9PM.
OTHERWISE CURRENT FORECAST REMAINS ON TRACK.
KEY MESSAGES
- 1) WARM AND HUMID CONDITIONS COMBINED WITH A COLD FRONT WILL LEAD
TO SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE AREA LATER TODAY.
- 2) TURNING DRIER THIS WEEKEND, WITH INCREASINGLY HOT AND HUMID
CONDITIONS FOR EARLY/MID NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...SEVERE THUNDERSTORMS ARE POSSIBLE THURSDAY AMIDST
INCREASINGLY WARM AND HUMID CONDITIONS.
STILL DEALING WITH A FEW SPOTTY SHOWERS AND THUNDERSTORMS THIS
MORNING AS A RESULT OF A SUBTLE JET STREAK WITHIN THE MEAN UPPER
LEVEL TROUGH AXIS. THE BULK OF THIS ACTIVITY HAS BEEN CONFINED TO
CENTRAL AND NORTHEAST MD WITH EVEN A FEW BLIPS EAST OF
CHARLOTTESVILLE, VA. EXPECT THIS SPOTTY SHOWER AND THUNDERSTORM
ACTIVITY TO CONTINUE OVER THE NEXT 2-3 HRS ACROSS THESE AREAS WITH A
LULL INTO THE EARLY AFTERNOON PERIOD BEFORE BETTER FORCING ARRIVES.
ANY OF THESE THUNDERSTORMS WILL CONTAIN 20-30 MPH OF WIND, SMALL,
HAIL, LIGHTNING, AND LOCALLY HEAVY RAINFALL. BEHIND THIS JETLET/JET
STREAK, SKIES HAVE ALREADY STARTED TO CLEAR. THE WARM FRONT IS NOW
UP TOWARD THE RICHMOND, VA AREA WITH COLD FRONT EXTENDING FROM THE
OH/PA BORDER SOUTH TO AREAS JUST WEST OF THE OHIO RIVER.
WITH THIS CLEARING, EXPECT THE ATMOSPHERE TO RELOAD AHEAD OF THE
INCUMBENT COLD FRONTAL BOUNDARY. AS IT STANDS NOW, GUIDANCE HAS
BACKED UP THE TIMING A BIT HEADING INTO THE LATE AFTERNOON AND
PERIOD. THIS IS DUE LARGELY IN PART TO THE ACTUAL COLD FRONT BEING
DISJOINTED FROM THE UPPER LEVEL TROUGH AND ANY KEY MESSAGE 2...
ADDITIONAL PIECES OF SHORTWAVE ENERGY AHEAD OF THE MAIN BOUNDARY.
COVERAGE AS A RESULT WILL BE FAIRLY TRICKY WITH A MASHUP OF SPOTTY
TO SCATTERED STORMS DURING THE AFTERNOON TRANSITIONING INTO SOME
ORGANIZATION INTO THE EVENING HOURS AS THE FRONT DROPS IN. LATEST
HRRR, NAMNEST, ARW, AND EVEN THE HREF SHOW A SCATTERING OF STORMS
INITIATING WEST OF BLUE RIDGE AND ALONG THE WESTERN SHORE OF THE BAY
BETWEEN 2-5PM BEFORE ADVANCING EAST BETWEEN 5-10PM. DAMAGING WINDS
WILL BE THE MAIN THREAT WITH STORMS TODAY GIVEN 25-35 KTS OF DEEP
LAYER SHEAR AND MODEST INSTABILITY VALUES UP OF 1000 J/KG. MODERATE
MID LEVEL LAPSE RATES (6.5-8 C/KM), STRONG WINDS IN THE UPPER
ATMOSPHERE, AND RELATIVELY LIGHT LOW LEVEL WINDS COULD ALSO RESULT
IN SOME SEVERE LEVEL HAIL. AS MENTIONED IN PREVIOUS FORECASTS, HI-
RES MODEL GUIDANCE IS STILL DEPICTING SOME DECENT LOW-LEVEL
CURVATURE TO HODOGRAPHS, ESPECIALLY ALONG THE MD/PA BORDER IN
NORTHEAST MD (DUE TO PERHAPS A BAY BREEZE AHEAD OF THE FRONT AND
SHEAR BOUNDARY IN THE AREA) THE STORM PREDICTION CENTER CONTINUES TO
MENTION TWO-PERCENT TORNADO THREAT TODAY SHOULD THINGS COME
TOGETHER.
HEAVY RAINFALL WILL REMAIN A CONCERN GIVEN MULTIPLE ROUNDS OF
CONVECTION, ESPECIALLY OVER CENTRAL AND NORTHEAST MD. GIVEN
RELATIVELY UNIDIRECTIONAL FLOW RELATIVE TO THE SURFACE TROUGH COULD
RESULT IN SOME TRAINING (HINTED AT BY SPLOTCHES OF HIGHER QPF IN
SOME CAMS FROM BALTIMORE, MD POINTS NORTHEAST). NO FLOOD WATCHES ARE
PLANNED AT THIS TIME, BUT WILL BE SOMETHING TO MONITOR GIVEN HOW
THINGS EVOLVE THIS AFTERNOON. WHILE SOME SHOWERS AND STORMS MAY
LINGER INTO THE NIGHT, THE SEVERE WEATHER THREAT SHOULD BE WINDING
DOWN AFTER 9-10PM.
THE SLOW MOVING COLD FRONT WILL BISECT THE AREA FRIDAY MORNING WHILE
THE MID/UPPER LEVEL TROUGH LAGS TO THE WEST. AS A RESULT, EXPECT
ADDITIONAL SHOWERS AND THUNDERSTORMS DURING THE PEAK HEATING PERIOD,
ESPECIALLY ALONG AND SOUTH OF THE FRONT. HIGHEST PROBABILITIES FOR
SEVERE WEATHER APPEAR TO BE SOUTH OF I-66/US-50 ACROSS SOUTHERN MD,
THE VA PIEDMONT, AND NORTHERN NECK OF VA. DAMAGING WINDS WILL BE THE
MAIN THREAT ALONG WITH LOCALLY HEAVY RAINFALL. COVERAGE ONCE AGAIN
WILL BE SCATTERED, BUT HIGHLY DEPENDENT ON WHERE THE FRONT RESIDES
AND IF ANY CLOUD COVER LINGERS ACROSS THE REGION.
KEY MESSAGE 2...TURNING DRIER THIS WEEKEND, WITH INCREASINGLY HOT
AND HUMID CONDITIONS FOR EARLY/MID NEXT WEEK.
THE LATE WEEK COLD FRONT IS EXPECTED TO STALL ALONG THE SOUTHEASTERN
U.S. COASTLINE THROUGHOUT THE WEEKEND. AS THIS OCCURS, BROAD SURFACE
HIGH PRESSURE IS LIKELY TO EXTEND FROM THE SOUTHERN MID-ATLANTIC UP
TO NEW ENGLAND. THIS CONFIGURATION WILL SUPPORT TRANQUIL WEATHER
THIS WEEKEND WITH SEASONABLE TEMPERATURES. MID-LEVEL HEIGHTS (585 TO
589 DM) REMAIN SLIGHTLY ABOVE AVERAGE WHICH DOES KEEP TEMPERATURES
ON THE WARMER SIDE. HUMIDITY LEVELS DROP A BIT TO START THE WEEKEND,
BUT DO BEGIN TO COME UP SOME AS WINDS SHIFT TO SOUTHERLY ON THE BACK
SIDE OF THE EXITING SURFACE RIDGE. THIS EVENTUALLY SETS UP FOR A HOT
AND HUMID PERIOD INTO NEXT WEEK WHICH ALSO MARKS THE CONCLUSION OF
METEOROLOGICAL SUMMER (JUNE 1-AUGUST 31).
A PERSISTENT MID/UPPER RIDGE ACROSS THE SOUTHERN TIER OF THE COUNTRY
IS FORECAST TO FLEX NORTHWARD IN TIME. GLOBAL ENSEMBLES GENERALLY
AGREE ON THIS EVOLUTION, BUT VARY WITH DETAILS ALONG THE NORTHERN
EDGE OF THIS RIDGE. THE NET RESULT WILL BE ANOTHER ROUND OF HOT
TEMPERATURES ALONG WITH INCREASING HUMIDITY. DURING THE EARLY TO MID-
WEEK PERIOD, FORECAST HIGHS RISE INTO THE LOW/MID 90S, WITH HEAT
INDICES BETWEEN 98 AND 103 DEGREES. THIS COULD INCH CLOSER TO THE
105 DEGREE HEAT INDEX MARK BY TUESDAY AND WEDNESDAY WHICH IS HEAT
ADVISORY CRITERIA FOR LOCATIONS EAST OF THE BLUE RIDGE. DESPITE ALL
OF THE HEAT AND HUMIDITY, DAILY THUNDERSTORM CHANCES COULD BE MORE
LIMITED IF THE AREA IS UNDERNEATH THE UPPER RIDGE. HOWEVER, THESE
DETAILS WILL LIKELY BECOME BETTER RESOLVED IN A FEW DAYS.
LOOKING A BIT FURTHER AHEAD, THE DAY 6 TO 10 OUTLOOK FROM THE
CLIMATE PREDICTION CENTER FAVORS ABOVE AVERAGE CHANCES FOR CONTINUED
HEAT TO LINGER INTO SUBSEQUENT DAYS.
AVIATION /14Z THURSDAY THROUGH MONDAY/
VFR CONDITIONS WILL CONTINUE TO PREVAIL THROUGH THIS EVENING OUTSIDE
OF THUNDERSTORMS. SOME PATCHES OF MVFR HAVE BEEN NOTED NORTH AND
EAST OF BWI/MTN TOWARD LNS/PHL GIVEN SCATTERED SHOWERS AND
THUNDERSTORMS. BIGGEST THREAT WITH THE SPOTTY ACTIVITY THIS MORNING
WILL BE ERRATIC WINDS, SMALL HAIL, LIGHTNING, AND LOCALLY HEAVY
RAINFALL. EXPECT THESE VICINITY STORMS/SHOWERS TO CONTINUE TO PULL
NORTH AND EAST OF BWI/MTN OVER THE NEXT 2-3 HRS.
A COLD FRONT WILL APPROACH THE REGION LATER THIS AFTERNOON AND
EVENING BEFORE PUSHING SOUTH OF THE AREA FRIDAY EVENING. A FEW
STRONG TO SEVERE STORMS ARE POSSIBLE DURING THE AFTERNOON/EVENING,
WITH GUSTY WINDS BEING THE PRIMARY THREAT. THE TIMING OF STORMS
REMAINS A BIT UNCERTAIN GIVEN ONGOING CONVECTION OVER NORTHEAST MD
AND THE PLACEMENT OF SURFACE FEATURES THAT WILL PROVIDE THE MAIN
LIFT FOR STORMS TO GET GOING THIS AFTERNOON. AREAS WITH THE HIGHEST
CONFIDENCE FOR STORMS INCLUDE BWI, IAD, MTN, AND MRB WITH LOWER
CONFIDENCE TOWARD DCA AND CHO. WENT WITH PREVAILING
THUNDERSTORMS OVER THESE LOCATIONS GIVEN THE POTENTIAL FOR
MULTIPLE ROUNDS AND PROB30S AT DCA/CHO. RIGHT NOW, HAVE STORMS
INITIATING ALONG AND WEST OF A LINE FROM MRB/HGR TO SHD BETWEEN
18-21Z/2-5PM AND ALONG THE WESTERN SHORE OF THE BAY DURING THIS
SAME TIME. EVENTUALLY ACTIVITY WILL SHIFT EAST LIKELY IN A
BROKEN LINE BETWEEN 21-02Z/5-10PM. STORMS COULD BE SLOW TO PUSH
THROUGH, SO THERE MAY BE SOME PROLONGED PERIOD OF RESTRICTIONS
FOR THOSE THAT DO GET STORMS TODAY.
SHOWER AND THUNDERSTORM ACTIVITY MAY LINGER INTO THE FRONT HALF
OF THE OVERNIGHT PERIOD PRIOR TO 6Z/2AM AS THE FRONT STALLS
NEARBY. SOME MVFR AND IFR CIGS AND VSBYS MAY DEVELOP AS A
RESULT. CURRENT GUIDANCE SEEMS TO BE FAVOR FOG, ESPECIALLY WEST
OF THE METRO AREAS. SHOWERS AND STORMS COULD EVEN REDEVELOP
FRIDAY, BUT UNSURE IF THIS WOULD IMPACT ANY OF THE TERMINALS
(CHO AND PERHAPS DCA WOULD HAVE THE HIGHEST CHANCES).
VFR CONDITIONS ARE EXPECTED SATURDAY THROUGH TUESDAY, WHICH COMES
WITH A MOSTLY DRY FORECAST. INITIAL WINDS WILL BE OUT OF THE SOUTH
BEFORE AN EVENTUAL SHIFT TO THE WEST BY EARLY NEXT WEEK. RELATIVELY
WEAK GRADIENTS SHOULD SUPPORT PEAK GUSTS AROUND 5 TO 15 KNOTS.
MARINE
SMALL CRAFT ADVISORIES REMAIN IN EFFECT THROUGH 9PM THIS
EVENING FOR THE MIDDLE AND LOWER BAY AS WELL AS LOWER TIDAL
POTOMAC DUE TO SOUTHERLY CHANNELING.
A COLD FRONT WILL APPROACH FROM THE NORTH AND WEST LATER THIS
AFTERNOON AND EVENING BRINGING THE RISK OF STRONG
THUNDERSTORMS. SPECIAL MARINE WARNINGS WILL ACCOMPANY THIS
THREAT, ESPECIALLY LATER THIS AFTERNOON AND EVENING. THE SEVERE
THREAT WILL GRADUALLY DIMINISH LATER THIS EVENING AND INTO THE
OVERNIGHT HOURS.
SUB-SMALL CRAFT ADVISORY LEVEL WINDS ARE EXPECTED ON FRIDAY AS A
COLD FRONT MOVES IN FROM THE NORTHWEST. WHILE SOME ADDITIONAL
THUNDERSTORMS ARE POSSIBLE, THE GREATER RISK MAY BE SOUTH OF
MARYLAND. SUB-SCA LEVEL NORTH TO NORTHEASTERLY WINDS ARE FORECAST
FOR SATURDAY, BECOMING SOUTHERLY SUNDAY AS HIGH PRESSURE PUSHES TO
THE EAST.
WHILE DEVOID OF ANY DISCERNIBLE CONVECTIVE ACTIVITY, SOUTHERLY
CHANNELING EFFECTS COULD BRING AREAS NEAR SMALL CRAFT ADVISORY
CRITERIA ON SUNDAY EVENING INTO THE EARLY OVERNIGHT PERIOD. WINDS
SHIFT TO WESTERLY BY MONDAY WITH A GRADUAL REDUCTION IN WIND GUSTS.
TIDES/COASTAL FLOODING
INCREASING SOUTHERLY FLOW CONTINUES THROUGH TONIGHT, LEADING TO
RISING WATER LEVELS. MOST LOCATIONS WILL ONLY SEE ACTION
STAGES, BUT ANNAPOLIS COULD APPROACH MINOR FLOOD STAGE EARLY
THURSDAY MORNING. WITH THE LATEST FORECAST ONLY BARELY REACHING
FLOOD STAGE, WILL HOLD OFF ON AN ADVISORY UNTIL CONFIDENCE IN
THE WATER LEVEL TRENDS INCREASES.
LWX WATCHES/WARNINGS/ADVISORIES
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 PM EDT THIS EVENING FOR
ANZ531>534-537-539>541-543.
DISCUSSION...CJL/EST
AVIATION...CJL/EST
MARINE...CJL/EST
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