Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 261942 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 242 PM EST Sun Feb 26 2017 .SYNOPSIS... High pressure will return to the area tonight and Monday. A warm front will then lift north into the area Tuesday into Wednesday followed by another cold front Wednesday night. && .NEAR TERM /THROUGH TONIGHT/... The center of high pressure can be found across the southern Appalachians this afternoon. This ridge axis will translate east of the mountains tonight, with return flow commencing during the overnight hours. Since the area will be under high pressure, skies will be clear (visible satellite suggests we`re already almost there as of 230 pm) and winds will decouple. That would suggest that radiational cooling would be favorable. However, mid and high level moisture will be rebounding overnight in return flow, and these clouds will ultimately impede cooling. Will be keeping the cities (DC and Baltimore) and Bayshore communities above freezing, and everyone else will be below. The early evening hours will provide a good gauge on the eventual overnight low. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The forecast area will be in a prolonged period of south/southwest flow Monday-Tuesday, with intervals of enhanced isentropic lift. Above that, flow 500 mb and above will be rather fast westerlies. There will be sufficient upglide to support more clouds than sun by Monday...and it may end up mostly cloudy. Moisture return will be better Tuesday/Tuesday night, and that`s when PoPs will be higher. Temperatures will get progressive warmer once again, into the range of well above normal. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... A cold front will push across our region Wednesday, before moving offshore Wednesday night. Scattered to numerous showers and a couple of thunderstorms will develop ahead of and along the cold front, mainly during the afternoon and evening hours. The main threat will be damaging wind gusts. Once the front passes and the winds shift to the west-northwest, some upslope snow showers could develop Wednesday night and linger into early Thursday. Temperatures ahead of the cold front will also be very mild in the 70s in most places except along the shores of the Chesapeake Bay and over the Appalachian Mountains. Temperatures should quickly fall through the 60s into the 50s behind frontal passage. Upslope snow showers should end around midday in the Appalachians on Thursday. About the same time, an upper level disturbance is expected to approach the region from the Great Lakes and bring a chance for a mix of rain or snow Thursday afternoon into Thursday night. The exact track of the disturbance will determine the precipitation type. An associated surface cold front will bring a re-inforcing shot of colder air into the region on Friday, along with a chance for rain showers in the eastern zones and more upslope snow showers in the Appalachian Mountains. A strong ridge of high pressure should build in behind Friday`s front on Saturday and linger right on into Sunday. Dry conditions and seasonably chilly temperatures are expected both days. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... VFR conditions tonight into Monday under high pressure. Mid and high level clouds increase Monday/Monday night, but there will be no operational impact. Moisture continues to build Tuesday, which may lead to some showers. Any restrictions likely would be no worse than MVFR, and that may be limited. Will also need to monitor increasing wind aloft Monday night and Tuesday night in case LLWS thresholds may be met. Ifr to lifr conditions expected Wednesday afternoon and evening within rain showers and thunderstorms. Mvfr conditions Wednesday overnight and Thursday with a lingering shower. Vfr conditions Thursday night. Winds southwest 10 knots Wednesday. Winds becoming west-northwest 10 to 15 knots gusts 20 knots Wednesday night. Winds west-northwest 15 knots gusts 25 to 30 knots Thursday. Winds becoming west and diminishing 5 to 10 knots Thursday night. && .MARINE... Winds decreasing this afternoon as high pressure builds. Have a staggered end to the Small Craft Advisory. Winds will be light tonight under the ridge. Return (south) flow will begin Monday morning. Mixing on Monday afternoon likely will support gusts in the mid teens, ie: just under Small Craft Advisory conditions. On Tuesday, however, thresholds likely will be met. SCA looks likely on southerly winds as warm front lifts north of the region Wednesday, then gales possible Wednesday night and Thursday behind the cold front. A chance of thunderstorms also exists late Wednesday and Wednesday night as the cold front comes through. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ530>533-538>541. Small Craft Advisory until 4 PM EST this afternoon for ANZ534- 537-542-543. && $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...KLW AVIATION...HTS/KLW MARINE...HTS/KLW/RCM is the U.S. government's official web portal to all federal, state and local government web resources and services.