Area Forecast Discussion
Issued by NWS Sterling, VA

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259 FXUS61 KLWX 230800 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 400 AM EDT Wed May 23 2018 .SYNOPSIS... A cold front will push south through the area today. High pressure will build eastward from the Great Lakes tonight, eventually moving offshore by Friday. Moisture will increase ahead of a low pressure system over the weekend into early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A cold front stretches across Pennsylvania this morning. Convection in northeast Pennsylvania is moving to the east, and the convective complex in West Virginia is rapidly weakening, with radar returns east of the Appalachian crest dissipating. Thus, am largely expecting the day to start dry. There could be some patchy fog, but development will be hindered by convective debris clouds. Expect some clearing as the day progresses and the cold front pushes south into the area. Moisture and forcing will be weak along the front, although it will still be near our southern CWA border as peak heating is reached. 00Z HREF suggests showers and thunderstorms will begin developing near or south of Charlottesville around midday, then quickly move southeast by late afternoon. Have introduced 30-40 PoPs to this area, though it`s possible convective initiation occurs south of our CWA. High temperatures will be in the lower to mid 80s for most locations. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... The center of surface high pressure will be located over the Great Lakes tonight, moving overhead by Thursday evening, then off the Mid-Atlantic coast Friday. With ridging building aloft as well, a respite from the recent unsettled weather will extend through the end of the work week. Temperatures will be a little above normal, with highs in the lower to mid 80s, and low temperatures in the 50s to lower 60s. Some moisture will begin to advance northward in the return flow on the back side of the high by late Friday and Friday night. Most of this advection will be focused on the Ohio Valley, and while it`s not impossible a few showers could develop over the Appalachians, have kept the forecast dry through Friday night for now. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Southerly flow will continue advecting moist and warm air over our region on Saturday as a Bermuda High is settled over the North Atlantic. Temperatures will be between the low and the mid 80s on Saturday with possible showers and thunderstorms in the afternoon due to diurnal heating. A low pressure system will be moving north from the Gulf coast and along the southeastern states Sunday into Monday as Bermuda high continues settled east of us. Winds will be turning more easterly as moist air continues to be advected Sunday and Monday with additional showers and thunderstorms. A boundary will approach the area on Tuesday and settle over us into Wednesday. This may trigger more showers and thunderstorms both days. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... A challenging aviation forecast to start the morning. IFR ceilings had developed over the Baltimore and Washington metro areas and were forecast to remain in place through sunrise. However, these clouds have dissipated as thicker mid level clouds moved in. These clouds also seem to be thwarting any fog development, although there may be some clearing right around daybreak. Amendments to the TAFs are likely through the period. Otherwise a cold front will push south today, turning winds to the northwest shortly after sunrise. It will be a dry frontal passage for the most part, although a stray shower or storm could develop near CHO around 17-20Z. High pressure will then build across the area through Friday. VFR conditions and light winds are expected through the period. VFR conditions likely Saturday with possible afternoon showers and thunderstorms which may decrease the CIGS. Sunday and Monday looks wetter with additional moisture over us, therefore more showers and thunderstorms possible. && .MARINE... A surge of southwest winds accompanying a disturbance has been affecting the southern Maryland waters. Given the HRRR had picked up on this trend, issued a Small Craft Advisory through 6 AM. Winds seem to be on a downward trend now though, and the advisory may be cancelled early. A cold front will push south through the area this morning, with winds becoming northwesterly. It looks like peak winds will be around 15 kt through the day, with a low probability for a few higher gusts. High pressure will build across the waters tonight and Thursday before moving offshore on Friday with light winds. Some of the wider waters of the Bay may come close to SCA criteria Friday night as southerly flow increases on the back side of the high. Winds are expected to remain below SCA criteria from Saturday into Monday, not anticipating an advisory for this period. && .TIDES/COASTAL FLOODING... Tidal anomalies should decrease today as northwesterly winds develop behind a cold front. However, water levels remain more elevated around DC given some freshwater input, with the current high tide barely coming in below flood stage. This situation may repeat itself during the morning high tides the next couple days. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 AM EDT early this morning for ANZ534-537-543. && $$ SYNOPSIS...ADS NEAR TERM...ADS SHORT TERM...ADS LONG TERM...IMR AVIATION...ADS/IMR MARINE...ADS/IMR TIDES/COASTAL FLOODING...ADS

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