Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 260030 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 830 PM EDT Sun Jun 25 2017 .SYNOPSIS... High pressure will build west of the area through Tuesday as a series of weak boundaries cross the region. The high will then cross the region Wednesday and settle over the western Atlantic Ocean late in the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Surface high pressure will remain centered over the Midwest into the Tennessee Valley tonight while an upper-level trough remains overhead. A west to northwest flow will allow for dry and cool conditions for this time of year. Leaned toward the cooler guidance thinking that the atmosphere will decouple...and with mainly clear skies...light winds and low dewpoints this does favor radiational cooling. Min temps are forecast to range from the 40s in the colder valleys of the Potomac Highlands and Shenandoah the 50s across most other the middle 60s in downtown Washington and Baltimore. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Another weak trough/boundary will move near the region Monday. Again, little if any sensible impacts expected. Will once again see an instability-driven cumulus field develop. A very low chance of a shower exists, mainly north. The region will remain in westerly flow with gusts up to about 20 mph. Highs from the mid 70s to low 80s. Quiet weather will continue Monday night, with lows in the 50s to low 60s. The highest chances of any precipitation in this stretch will come on Tuesday as an upper trough and its surface reflection move across the area. With a small amount of instability due to the anomalously cool temperatures aloft, there will likely be some isolated- scattered showers and possible thunderstorms around the area. This will also be the coolest day with highs in the 70s area-wide. High pressure will build in overhead, with lows in the 50s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... High pressure will be in control Wednesday, bringing dry conditions and below normal temperatures, before sliding offshore Thursday. As high pressure moves over the western Atlantic, warmer temperatures and increasing chances of showers and thunderstorms will develop Thursday night through Sunday. The best chance for showers and storms will be Saturday and Sunday. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... VFR expected through at least Tuesday night with a fair weather cumulus deck each day. Main concern will be an isolated showers/thunderstorms on Tuesday. Otherwise, winds generally westerly with gusts to about 20 knots during the daylight hours. VFR conditions Wednesday through Friday. Winds northwest to start will turn south/southwest by late in the week. Chances for showers/thunderstorms are introduced by Friday. && .MARINE... Small Craft Advisory remains in effect until 10 pm for the northern Chesapeake Bay and upper Tidal Potomac River. As cooler air moves over the warm water temperatures overnight, its possible gusts continue past 10 PM across the Chesapeake Bay, but confidence low in this marginal situation, so will not extend at this time. Wind field looks slightly lower on Monday, but gusts may again approach SCA-criteria Monday afternoon. Have kept forecast below at this time. Westerly flow will continue on Tuesday with marginal SCA conditions possible. There will also be an increased chance for some isolated-scattered showers/thunderstorms. No marine hazards expected Wednesday and Wednesday night. Winds south 5 to 10 knots. Small craft advisories may be needed Thursday and Thursday night. Winds southwest 10 to 15 knots gusts 20 knots. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ530>532-535-538>540. && $$ SYNOPSIS...MM NEAR TERM...BJL/MM SHORT TERM...MM LONG TERM...KLW AVIATION...BJL/MM/KLW MARINE...BJL/MM/KLW is the U.S. government's official web portal to all federal, state and local government web resources and services.