Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 302353 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 753 PM EDT Thu Jun 30 2016 .SYNOPSIS... A warm front will lift through the area tonight into early Friday. A cold front will pass through the region Friday night and high pressure will return for Saturday into Sunday. Low pressure will pass through the region Monday into Tuesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... High pressure will continue to move off the coast this evening and a southerly flow will usher more moisture into the area. Increased dewpoints have led to some more instability...but instability is limited since the deepest moisture remains to our south. A few popup showers are expected this evening...but coverage will remain isolated to widely scattered due to the lack of a strong lifting mechanism. Moisture will continue to advect into the area overnight...resulting in noticeably more humid conditions. A few popup showers and perhaps a rumble of thunder are possible...but coverage will remain isolated to widely scattered due to the lack of a strong lifting mechanism...with weak isentropic lift combined with a jet streak being the primary mechanism. Min temps will be in the 60s for most locations. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... A cold front will pass through the Ohio Valley Friday and a southwest flow ahead of the boundary will continue to usher in more moisture across the area. It will turn out warm and humid with highs in the mid to upper 80s across most locations. Some areas may crack 90. Aloft...an upper-level low will track across eastern Canada into New England...causing mid and upper-level winds to strengthen. This will cause shear profiles to strengthen with 0-6KM shear values most likely between 30 and 40 knots. The southwest flow will usher in more instability across the area...and with higher dewpoints in the upper 60s MLCAPE values are expected to reach 1000-2000J/KG. Showers and thunderstorms are likely especially from Washington DC on north and east...with lower coverage expected further south and west. Development of storms is expected to occur primarily within a pressure trough which will likely set up near the Catoctin and Blue Ridge Mountains. From there, the storms will probably expand in coverage as they head east late in the day. The moderate CAPE and moderate shear profiles suggest that a few of the thunderstorms may become severe...with damaging winds and large hail being the primary threats. The best chance for severe storms will be east of the pressure trough across the Washington and Baltimore Metropolitan areas into southern Maryland. The cold front will pass through late Friday evening into the overnight and drier air will gradually move in from the north and west. High pressure will build over the region Saturday into Saturday night...resulting in sunshine along with noticeably less humid conditions. There may be some high clouds moving through in the zonal flow aloft. && .LONG TERM /SUNDAY THROUGH THURSDAY/... A slight chance of showers or a thunderstorm across the southern half of our region Sunday and Sunday night with a stalled front along the Virginia and North Carolina state line. As a storm system develops along the western end of the front and across portions of the Midwest U.S. Monday into Monday night, the stalled front will propagate northward as a warm front. This warm front will usher in more humid and warm air northward to help fuel showers and a few thunderstorm farther north into northern Virginia, Maryland and eastern West Virginia Monday into Monday night. The next storm system will move across the eastern Ohio Valley and portions of the mid-Atlantic Tuesday. The chance for showers and thunderstorms will accompany the storm system Tuesday. The storm is expected to exit east and move offshore the East Coast Tuesday night. High pressure will usher in cooler and drier air into the region Wednesday. A small wave of upper level disturbances will slide across the region Thursday to bring back the chance of showers and thunderstorms. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... VFR conditions are expected through the rest of this evening. An isolated shower cannot be ruled out...but most areas will be dry. Patchy fog and low clouds are expected late tonight into Friday morning. MVFR conditions are likely west of I-95...and IFR conditions are possible. Near I-95...clouds and a few more showers overnight are likely to disrupt fog formation and keep cigs and vis in the VFR range. Cigs will improve later Friday...but showers and thunderstorms are expected to develop in the afternoon near the I-95 corridor. Thunderstorms will be most numerous across the eastern terminals later Friday afternoon into Friday evening. A cold front will pass through Friday night. Saturday/Saturday night will be dry with VFR conditions. A warm front will approach Sunday before stalling out over the area Monday into Tuesday. Low pressure will track along the boundary...bringing unsettled conditions. Uncertainty remains in the timing && .MARINE... South to southeast winds are expected through Friday...but gradient winds should remain below SCA criteria. Popup showers are possible through The most widespread coverage will be late Friday afternoon and evening. tonight. More numerous showers and thunderstorms are expected Friday afternoon into Friday evening. A few of those thunderstorms may produce gusty winds and hail. A cold front will pass through the waters Friday night and high pressure will return for Saturday and Saturday night. A small craft advisory may be needed for portions of the waters Friday night and Saturday. No marine hazards expected Sunday and Sunday night. Winds northwest around 10 knots Sunday and Sunday night. Low pressure may bring unsettled conditions Monday into Tuesday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...BJL/RCM NEAR TERM...BJL/RCM SHORT TERM...BJL/RCM LONG TERM...KLW/RCM AVIATION...BJL/KLW/RCM MARINE...BJL/KLW/RCM

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