221  
FXUS61 KLWX 210759  
AFDLWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC  
359 AM EDT SUN JUL 21 2024  
   
SYNOPSIS
 
 
HIGH PRESSURE BRIEFLY RETURNS TODAY, KEEPING A BOUNDARY STALLED TO  
OUR SOUTH BEFORE IT LIFTS AS A WARM FRONT INTO THE REGION ON MONDAY  
AND STALLS OUT AGAIN HEADING INTO MIDWEEK. THIS WILL RESULT IN DAILY  
SHOWER AND THUNDERSTORM CHANCES ALONG WITH INCREASED HUMIDITY AND  
WARMING TEMPERATURES THROUGHOUT MUCH OF NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
SOME LOW CLOUDS/FOG HAVE DEVELOPED EARLY THIS MORNING, PRIMARILY  
IN LOCATIONS THAT RECEIVED RAINFALL YESTERDAY. AS A RESULT, REDUCED  
VISIBLITIES ARE FAIRLY LOCALIZED, AND WIDESPREAD DENSE FOG IS NOT  
CURRENTLY EXPECTED. THAT SAID, THE GREATEST REDUCTIONS IN VISIBILITY  
ARE LIKELY IN PORTIONS OF THE CENTRAL SHENANDOAH, POTOMAC HIGHLANDS,  
AND CENTRAL PIEDMONT. WE'LL CONTINUE TO MONITOR. FOG SHOULD BURN  
OFF SHORTLY AFTER SUNRISE.  
 
THE FRONT IS EXPECTED TO REMAIN STALLED TO OUR SOUTH TODAY,  
RESTRICTING POPS TO OUR SOUTHERN ZONES THIS AFTERNOON AND INTO  
THE EVENING. COVERAGE OF SHOWER ACTIVITY WILL BE SUPPRESSED AS  
HIGH PRESSURE BUILDS IN FROM THE NORTH. REDUCED CLOUD COVER AND  
SOUTHERLY FLOW BRINGS HIGHS BACK TO THE UPPER 80S TO LOW 90S.  
CLOUDS BUILD IN OVERNIGHT RESULTING IN MILDER LOWS, HOVERING IN  
THE 70S EAST OF US-15, WITH MID-UPPER 60S EXPECTED ELSEWHERE.  
FOG AND LOW CLOUDS COULD DEVELOP AGAIN TONIGHT IN AREAS THAT  
RECEIVE RAINFALL.  
 

 
   
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
 
 
ON MONDAY, THE BOUNDARY IS EXPECTED TO LIFT NORTHWARD AND STALL  
ACROSS THE AREA. A BLOCKING SYNOPTIC PATTERN WITH THE STRONG  
BERMUDA RIDGE WILL KEEP THE AREA EAST OF AN UPPER TROUGH, IN  
ASCENT AND SW FLOW ALOFT. THE RESULT WILL BE INCREASING MOISTURE  
AND CHANCES FOR SHOWERS AND THUNDERSTORMS, ESPECIALLY IN THE  
AFTERNOON AND EARLY EVENING.  
 
MOST OF THE RAIN WILL BE BENEFICIAL, WITH OVER HALF OF THE AREA  
IN SEVERE DROUGHT, AND OVER A THIRD OF THE AREA IN EXTREME  
DROUGHT. HOWEVER, WPC DOES HAVE MOST OF THE AREA HIGHLIGHTED  
WITH A MARGINAL RISK OF EXCESSIVE RAINFALL ON MONDAY, WITH QPF  
AROUND 0.50-1.50" ACROSS THE AREA. WHICH AREAS RECEIVE THE BULK  
OF THIS WILL LARGELY BE DETERMINED BY THE LOCATION OF THE FRONT,  
BUT LOCALLY HEAVY AMOUNTS FALLING IN A SHORT PERIOD OF TIME  
COULD CAUSE ISOLATED FLASH FLOODING IN URBAN AND OTHER POOR  
DRAINING AREAS. WE'LL CONTINUE TO MONITOR THE FLOOD THREAT.  
 
A SIMILAR STORY FOR TUESDAY, WITH THE FRONT HANGING AROUND AND  
CONTINUED SHOWER AND THUNDERSTORM CHANCES.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
THE WET WEATHER PATTERN CONTINUES THROUGH THE END OF THE WEEK AS  
WIDESPREAD SHOWERS AND THUNDERSTORMS DEVELOP EACH AFTERNOON TO EARLY  
EVENING. SOME SHOWER ACTIVITY IS LIKELY TO LINGER INTO THE OVERNIGHT  
GIVEN THE UNSTABLE AND MOIST ATMOSPHERE. AT THIS TIME, STORMS ARE  
LIKELY TO REMAIN BELOW SEVERE LIMITS AND BRING MOSTLY BENEFICIAL  
RAINFALL TO THE REGION. ANY FLOOD CONCERN WILL BE OVER THE URBAN  
AREAS IF MULTIPLE STORMS MOVE OVER THE SAME AREA IN A SHORT PERIOD  
OF TIME. A WEAK FRONT IS FORECAST TO CROSS THE AREA SOMETIME FRIDAY,  
WITH DRIER CONDITIONS BEHIND THE FRONT FRIDAY LATE AFTERNOON THROUGH  
AT LEAST THE FIRST HALF OF THE WEEKEND. THERE IS SOME MODEL  
UNCERTAINTY REGARDING THE TIMING OF THIS FRONTAL PASSAGE, WITH A  
DELAYED ARRIVAL LEADING TO HIGHER RAIN CHANCES FRIDAY AFTERNOON.  
 
AFTERNOON HIGHS WEDNESDAY THROUGH FRIDAY REACH THE MID TO UPPER 80S,  
WITH OVERNIGHT LOWS IN THE UPPER 60S TO MID 70S. A BIT WARMER ON  
SATURDAY BEHIND THE FRONT AS HIGHS REACH THE UPPER 80S TO LOW  
90S.  
 

 
   
AVIATION /07Z SUNDAY THROUGH THURSDAY/
 
 
SOME LOW CLOUDS/FOG HAVE DEVELOPED OVER PORTIONS OF THE AREA  
EARLY THIS MORNING, FOCUSED OVER AREAS THAT RECEIVED RAIN  
YESTERDAY. GUIDANCE HAS HAD A POOR HANDLE ON THE DEVELOPMENT  
THUS FAR, GIVEN THE LOCALIZED NATURE OF IT, BUT CHO AND MRB SEEM  
MOST LIKELY TO SEE RESTRICTIONS THIS MORNING, AND POSSIBLY IAD.  
EARLIER OVERNIGHT, SOME FOG HAD DEVELOPED ALONG THE WESTERN  
SHORE OF THE CHESAPEAKE BAY, JUST SOUTH OF BWI. IT HAS SINCE  
DISSIPATED, BUT A FEW NEARBY OBS STILL HAVE REDUCED VSBY. WILL  
MONITOR FOR POSSIBLE REDEVELOPMENT MAKING IT INTO BWI, AND  
HINTED AT THE POSSIBILITY IN THE TAF. OTHERWISE, AFTER FOG BURNS  
OFF THIS MORNING MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH THE  
DAY. CHO COULD SEE BRIEF RESTRICTIONS FROM SHOWERS/TSTORMS  
TODAY, AND POSSIBLE LOW CLOUDS/FOG AGAIN TONIGHT.  
 
AS A FRONT LIFTS BACK INTO THE AREA EARLY IN THE WEEK, SUB-VFR  
CIGS WILL BE POSSIBLE FOR MOST OF THE AREA BY MONDAY MORNING,  
WITH SOME IMPROVEMENT IN THE AFTERNOON. SHOWER AND THUNDERSTORMS  
WILL BRING ADDITIONAL REDUCTIONS. DEPENDING ON THE FRONT'S  
POSITION, RESTRICTIONS COULD CONTINUE INTO TUESDAY.  
 
WHILE OVERALL VFR CONDITIONS PREVAIL THROUGH THE END OF THE WEEK,  
THE EXPECTED WET WEATHER PATTERN COULD PRODUCE PERIODS OF SUB-VFR  
CONDITIONS EACH DAY. THIS IS MOST LIKELY IN THE AFTERNOON TO EARLY  
EVENING WHEN WIDESPREAD SHOWERS AND THUNDERSTORMS DEVELOP. IN  
ADDITION TO HEAVY RAINFALL, SOME GUSTY WINDS AND FREQUENT LIGHTNING  
STRIKES ARE POSSIBLE WITH THE STRONGEST STORMS.  
 

 
   
MARINE
 
 
LIGHT S/SE WINDS OVER THE WATERS TODAY INCREASE HEADING INTO THE  
EARLY PART OF THE WORK WEEK, VARYING BETWEEN SE AND SW AS A  
FRONT MEANDERS OVER THE WATERS. SHOWERS AND THUNDERSTORMS  
ASSOCIATED WITH THIS BOUNDARY COULD BRING STRONGER GUSTS TO  
WATERS ON MONDAY AND TUESDAY.  
 
SOUTHWEST WINDS AROUND 10 KNOTS PREVAIL ACROSS THE LOCAL WATERS  
WEDNESDAY AND THURSDAY. THERE COULD BE SOME ENHANCEMENT TO THE WINDS  
OVER THE OPEN WATERS OF THE MIDDLE CHESAPEAKE BAY WEDNESDAY NIGHT  
AND THURSDAY NIGHT THAT COULD RESULT IN SHORT PERIODS OF MARGINAL  
SCA WINDS. OTHERWISE, THE MAIN THREAT TO MARINERS WILL BE THE  
WIDESPREAD SHOWERS AND THUNDERSTORMS EACH AFTERNOON TO EARLY  
EVENING. SOME OF THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING  
WIND GUSTS TO AROUND 30-35 KNOTS, IN ADDITION TO LIGHTNING  
STRIKES.  
 

 
   
TIDES/COASTAL FLOODING
 
 
LIGHTER WINDS EARLY THIS MORNING HAVE ALLOWED WATER ANOMALIES TO  
DROP, AND THUS PREVENTING MINOR FLOODING AT VULNERABLE SHORELINES  
(NAMELY ANNAPOLIS). WINDS ARE FORECAST TO INCREASE SLIGHTLY TONIGHT  
INTO MONDAY, WHICH COULD PUSH WATER LEVELS TO NEAR MINOR FLOOD AT  
SENSITIVE LOCATIONS DURING THE MONDAY AND TUESDAY MORNING HIGH TIDE  
CYCLES. WATER LEVELS ARE LIKELY TO REMAIN ELEVATED WITH SOUTH TO  
SOUTHWEST WINDS PERSISTING THROUGH MUCH OF THE UPCOMING WEEK.  
 

 
   
LWX WATCHES/WARNINGS/ADVISORIES
 
 
DC...NONE.  
MD...NONE.  
VA...NONE.  
WV...NONE.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...LWX  
NEAR TERM...CAS  
SHORT TERM...CAS  
LONG TERM...KRR  
AVIATION...CAS/KRR  
MARINE...CAS/KRR  
TIDES/COASTAL FLOODING...KRR  
 
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