Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250729 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 329 AM EDT Sat Jun 25 2016 .SYNOPSIS...
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High pressure will overhead this morning and it will remain in place through Sunday. High pressure will move off the coast Sunday night through Monday and a cold front will move into the region late Tuesday into Tuesday night. The boundary will remain nearby during the middle and latter portions of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A weak boundary continues to drop to the south while high pressure approaches from the north and east early this morning. Drier air is slowly working its way in from the north and east...but plenty of moisture still remains trapped underneath the subsidence and nocturnal inversions. This means that low clouds and patchy fog will persist for most areas through 12z this morning. There may be some breaks across northeastern Maryland during this time. Drier air will continue to work its way into the region later this morning through this afternoon...and clouds will give way to sunshine from northeast to southwest during this time. Most areas will be dry this afternoon with plenty of sunshine. However...it may take til around mid-afternoon for sunshine to increase across portions of central Virginia into the Potomac Highlands. An isolated shower cannot be ruled across the ridge tops of Highland and Pendleton County where moisture will hang around for most of the day...but even across these areas most of the time will be dry. Max temps will range from the lower 70s in the mountains to the lower and middle 80s across most other locations. High pressure will remain overhead tonight. More dry conditions are expected along with mainly clear skies.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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The high will continue to dominate the weather pattern Sunday allowing for plenty of sunshine along with seasonably warm conditions and low humidity. Dewpoints will be in the 50s to lower 60s. The high will weaken and move out to sea Sunday night into Monday. A return southerly flow will develop during this time. An upper- level disturbance will also approach the area Sunday night before passing through Monday. Sunday night should turn out dry and comfortable...but moisture will increase Monday due to the southerly flow and the upper-level disturbance may trigger a few showers and thunderstorms...especially during the afternoon and evening hours. Monday and Monday night will be warm and noticeably more humid with dewpoints rising into the upper 60s and lower 70s for most areas.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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00Z model suite in decent agreement with a cold front progressing through the Mid-Atlantic. However, the exact timing and progression of the front looks to have diverging answers amongst the models, with a split on the front completely clearing the region to the south as surface high pressure builds in from the west to lingering just south of the forecast area. Nothing is really noted in the mid and upper levels to aid in completely clearing the front, especially with the upper level ridge holding in place over the western US, resulting in continual troughing over the eastern half. As such, will maintain at least slight chance PoPs in the forecast to account for the uncertainty of the surface boundary. Temps currently look to be right around to slightly be low normal, but this could change depending on extent of precipitation coverage as well as placement of the front and trough axis aloft.
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&& .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
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High pressure will build over the terminals today. However...low clouds remain trapped underneath the subsidence inversion early this morning. Low clouds should remain around through 12z for most areas...but there may be some breaks near KMTN and KBWI. Low clouds will clear out from northeast to southwest between 12 and 18z. Low end MVFR conditions are expected early this morning before lifting to VFR levels later this morning into early this afternoon. However...hires guidance continues to show cigs dropping to IFR levels. Therefore...a period of IFR levels is in the forecast but confidence is low at this time. VFR conditions are expected later today through Sunday with high pressure overhead. High pressure will move off the coast Sunday night and a return southerly flow will increase moisture for Monday into Monday night...possibly triggering some showers and thunderstorms. Generally VFR conditions Tues-Fri with possible sub-VFR with any shower or thunderstorm each day.
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&& .MARINE...
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High pressure will build along the Mid-Atlantic coast this morning and it will remain nearby through Sunday. A northeast flow this morning will turn to the east and southeast this afternoon into tonight. The east to southeast flow will persist through Sunday before turning to the south Monday ahead of an approaching cold front. Winds should remain below SCA criteria through Sunday night...but the gradient will increase a bit for Monday into Monday night so SCA conditions are possible across portions of the waters. A few showers and thunderstorms may impact the waters later Monday afternoon into Monday night. Locally gusty winds are possible in any thunderstorms that develop. Generally sub-SCA conditions on all waters the middle of next week.
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&& .TIDES/COASTAL FLOODING...
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Tidal anomalies remain around one-quarter to one-half foot above normal. An onshore flow will persist through the weekend...but it should remain light. Therefore...the anomalies should not change too much. This would keep water levels below minor flooding thresholds...but anomalies will have to be watched throughout this period for sensitive areas.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...Sears AVIATION...BJL/Sears MARINE...BJL/Sears TIDES/COASTAL FLOODING...BJL

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