Area Forecast Discussion
Issued by NWS Sterling, VA

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913 FXUS61 KLWX 251428 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1028 AM EDT Sun Jun 25 2017 .SYNOPSIS...
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High pressure will build west of the area through the rest of the weekend and into next week as a series of weak cold fronts cross the region. The high will then cross the region Wednesday and settle over the western Atlantic Ocean late in the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A mix of sun and clouds expected today as a low pressure system pushes from the eastern Great Lakes and into New England. High clouds will depart by the afternoon, but expecting fair weather cumulus to continue to develop and spread across the area. Westerly winds will pick back up with gusts up to about 20-25 mph. Temperatures will be within a couple degrees of normals, with highs from the upper 70s to upper 80s. Partly to mostly clear skies expected overnight with lows in the 50s/60s.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Another reinforcing shot of cooler air pushes south across the area late Monday into Monday night. Forcing remains weak and moisture remains limited so think precip will be hard to come by. Clouds may be a bit more common though. Highs will slip down a bit more with upper 70s to low 80s common. Dew points will slip into the upper 40s during part of the day. Lows Monday night will drop back into the 50s most spots, but still 60s in the warmest locales. Strong upper trough will cross the region Tuesday with another surface boundary. This trough is probably the most interesting weather through the forecast period, with increased instability associated with it. Some guidance is still dry with it (the Canadian suite), but others, including the NAM and ECMWF, are rather convective, so we could definitely see some scattered showers and thunderstorms given the cold pool aloft and decent PVA. For now have kept POPS rather low east of the mountains, but may need to be bumped if guidance comes into better agreement. Highs Tuesday will be quite cool, with most places failing to reach 80. Dew points will be slightly higher, with most places staying in the 50s. Clearing Tuesday night behind the trough, with lows into the 50s in most places, except near 60 in the cities and bay shore and 40s in the mountains. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... The upper level trough axis shifts east of the Mid-Atlantic Tuesday night per global guidance consensus. The trailing surface low will then be overhead Wednesday before shifting offshore later that day. The streak of below normal temperatures end Thursday with the return southerly flow that begins Wednesday night. The high becomes centered over Bermuda with a return to summer- like conditions (max temps around 90F) Thursday into the weekend. The jet stream and associated low pressure looks to stay north of the central Mid-Atlantic/over the Great Lakes through the weekend with continued low chance probabilities for precipitation. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/...
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VFR through the period with sustained winds generally around 10 knots or less, gusting to around 20 knots each afternoon. Main concern will be an isolated showers/thunderstorms on Tuesday. Otherwise, no significant winds, precipitation, visibility or ceiling limitations expected.
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&& .MARINE...
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Winds below SCA criteria currently, but with deeper mixing and a weak system passing near/north of the region, expect some gusts to reach up to around 20 knots later today and into this evening. Thus SCA remains in effect from Noon-10 PM. There is concern again for marginal SCA on Monday with another weak boundary and good mixing, but given marginal event expected, did not raise headlines yet. On Tuesday, a passing trough may cause spotty showers and thunderstorms, and given dry environment overall, some gusty winds could accompany them. Tranquil and cool weather Wednesday under surface high pressure. Return southerly flow begins Wednesday night as the high shifts to Bermuda.
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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 10 PM EDT this evening for ANZ530>532-535-538>540.
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&& $$ SYNOPSIS...MM/RCM NEAR TERM...MM/RCM SHORT TERM...RCM LONG TERM...BAJ AVIATION...BAJ/MM/RCM MARINE...BAJ/MM/RCM

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