Area Forecast Discussion
Issued by NWS Sterling, VA

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638 FXUS61 KLWX 311815 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 215 PM EDT Fri May 31 2024 .SYNOPSIS... High pressure will build across the area today through Saturday before sliding offshore Sunday. Dry conditions and below normal temperatures will continue as a result into the start of the weekend. Temperatures start to warm with increasing shower and thunderstorm chances Sunday into the middle part of next week. && .NEAR TERM /THROUGH TONIGHT/...
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Warm afternoons and cool mornings/evenings look to continue into the start of the weekend. Upper level troughing will continue push further offshore while large Canadian high pressure builds into the region. This will lead to abundant sunshine across the region along with comfortable humidity values thanks to north to northwesterly flow. Light north to northwest breezes will continue to blow through mid- afternoon as the center of the high swings overhead. Gusts of 15-20 mph can be expected mainly east of the Blue Ridge before the gradient relaxes late afternoon into the early evening hours. Even with the breeze, high temperatures will recover nicely into the low mid 70s for most with mid to upper 60s over the mountains. Another chilly night is expected with mid to upper 40s mainly along and west of the Blue Ridge and low to mid 50s further east. Some high sheltered valley locations could fall back into the upper 30s depending on how quickly things decouple with clear skies and light winds in place as high pressure sits overhead.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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Low humidity and dry conditions will continue into the start of the weekend as high pressure pushes toward the Mid-Atlantic coast. The high eventually heads offshore Saturday night into Sunday as a weak area of low pressure approaches from the Ohio River Valley. This will allow for increasing clouds across the area along with renewed chances for scattered showers and thunderstorms mainly west of the Blue Ridge Sunday late morning and into the evening hours. High temperatures Saturday will be a touch warmer in the upper 70s and lower 80s. Winds will turn to the south while remaining light as high pressure pushes towards the coast. Skies will remain mostly sunny with just some high cirrus floating through. Low level moisture increases Saturday night into Sunday morning leading to added cloud cover and perhaps a few showers west of the Allegheny Front as weak low pressure pushes east from the Ohio River Valley. Lows Saturday night will fall back into the mid 50s to low 60s for most of the area outside the mountains. By Sunday, upper level ridging begins to flatten with high pressure just offshore. Zonal flow will develop aloft allowing for the progression of several shortwave disturbances eastward into the region. This will lead to isolated to scattered showers and thunderstorms mainly west of the Blue Ridge early in the day before spreading east toward the metros late in the afternoon. Storms should be sub-severe although some gusty winds and hail cannot be ruled out. Winds will will switch to the southwest with gusts up to 20 mph ushering in warmer temperatures in the upper 70s and low to mid 80s. Humidity will also increase as well. Any convection will wane after sunset Sunday with quieter conditions expected due to upper level ridging nearby. Lows Sunday night will fall back into the upper 50s and low to mid 60s.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/...
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A closed upper low will be exiting the area Monday afternoon with upper ridging forecast to build in during the middle portion of next week. Dry conditions are expected Monday and Tuesday. A large cyclonic circulation over south central Canada will dive southeastward toward the Great Lakes during the second half of next week pushing a cold front into the area during the Thu-Thu night frame. Expect an increase in shower and thunderstorms Wednesday into Thursday. Shear and instability do not look particularly strong enough at this time to support a significant severe wx threat.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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VFR conditions are expected at all terminals through Saturday. Winds will be out of the north and northwest today with gusts between 15- 20 kts. Winds will gradually decrease later this afternoon and evening as high pressure builds overhead. Winds will remain light and variable Saturday morning before switching to the south Saturday afternoon and night as high pressure gradually pushes offshore. Skies will remain mostly sunny to clear with high cirrus likely returning to western terminals Saturday afternoon. More widespread mid and high level cloud cover returns late Saturday night into Sunday morning. Even with that said, VFR conditions should prevail. VFR conditions are expected Sunday with high pressure just offshore. A slight chance for a few thunderstorms is possible mainly at terminals along and west of a line from KMRB down to KCHO. Some restrictions are possible in and around any thunderstorm activity that may form. Prevailing VFR conditions are expected on both Monday and Tuesday. Winds will be light out of the north to northwest on Monday, and light out of the southeast on Tuesday. Higher chances for more widespread restrictions from shower and thunderstorm activity are possible during the afternoon and evening hours Wednesday through Thursday as multiple pieces of shortwave energy push through. Highest chances for thunderstorms will be at terminals west of a line from KHGR/KMRB/KIAD/KDCA south toward KCHO and KLYH.
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&& .MARINE...
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SCA level north to northwesterly winds (gusts up to 20kts) are expected especially over southern waters (bay and lower tidal Potomac)through this afternoon before decreasing this evening and into tonight. Sub-SCA level winds are expected through early Sunday morning as high pressure remains nearby. Winds will become light and variable tonight before switching to the south Saturday afternoon. Sub-SCA level winds are expected Sunday into Monday. South to southeasterly winds return Sunday as high pressure pushes off the southeast U.S coast. An isolated shower or thunderstorm cannot be ruled out due to the bay breeze Sunday afternoon/evening. Better chances for showers and thunderstorms exists Monday through Wednesday as multiple disturbances pass through. Cannot completely rule out the need for a Special Marine Warning for any strong storms that cross the waters during that period.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ533- 534-537-541>543.
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&& $$ SYNOPSIS...EST NEAR TERM...EST SHORT TERM...EST LONG TERM...LFR AVIATION...LFR/EST MARINE...LFR/EST