Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250800 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 400 AM EDT Mon Sep 25 2017 .SYNOPSIS...
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High pressure will remain in place today, then slowly weaken its grip over the area Tuesday and Wednesday as Hurricane Maria moves northward through the Western Atlantic. A cold front will move through Thursday, bringing more seasonable temperatures for the end of the week. Little if any rain is expected.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Current surface analysis shows high pressure centered just to our north. Aloft, ridge is also centered just to our north. This has brought more mostly clear skies and light winds, with patchy fog early this morning. Fog should break after sunrise, followed by another mostly sunny day. Some high cloudiness may increase as outflow from Hurricane Maria pushes northward over the region. Otherwise, a slight weakening of the ridge aloft should result in a slightly cooler day, but still plenty warm for late September, with high 80s and spotty low 90s expected once again. Tonight, the influence of Maria will increase somewhat as it continues moving north and approaches the Outer Banks. Northeast flow will increase, but remain in the 10-15 mph range overall. This may allow moisture to move in from the Atlantic, so there maybe some more patchy fog or low clouds. Otherwise, another mild night, with lows mostly in the 60s.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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Maria will push northward and then stall just east of the Outer Banks Tuesday and Wednesday before getting kicked out to sea by an approaching trough/cold front during the long term period. It will stay far enough away such that influence on our region will be minimal, with just an increased northeast breeze, perhaps reaching 25 mph in gusts in far S MD, and slightly cooler temps thanks to increased clouds and a chance of a few showers with highest chance near the bay. Highs will cool slightly, but remain well above normal with 80s continued. Lows at night still in the 60s.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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There`s really not much prospect for appreciable precip through the weekend. The region will remain ensconced by high pressure, with a dry cold front Thursday and an upper-level trough Saturday the only exceptions. The guidance has trended quicker and flatter with the Saturday trough, which lowers the chance for widespread precipitation, though an increase in clouds and a few scattered showers are still plausible. Gusty winds are likely both Thursday behind the dry frontal passage and again Saturday with the trough axis. Although it will be noticeably breezy, wind gusts in both periods should remain well below any headline criteria over land.
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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VFR generally expected through Wednesday. Patchy fog possible which could result in reduced vis at MRB, CHO and perhaps even IAD, though odds at the latter are lower. Fog possible again tomorrow night, though odds reduced as surface winds will begin to increase as Maria gets a little closer. Maria unlikely to produce much effect on local weather other than a northeast to north breeze perhaps gusting to 20 knots Tuesday and Wednesday, and perhaps a stray shower. Mainly VFR expected to end the week. Gusty N winds Thu behind frontal passage, becoming lighter Fri.
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&& .MARINE...
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Winds sub SCA today as high pressure lingers. Winds will start to increase tonight into Tuesday as Maria approaches NC from the SE. Wind field will be expanding, so issued SCA for our southernmost Bay zones, but looks marginal to be sure. SCA likely to continue through Wednesday, mainly our southernmost bay zones though. Otherwise, no more than a stray shower expected from Maria. Solid SCA conditions likely in northerly surge behind a cold frontal passage Thursday. Gales possible.
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&& .TIDES/COASTAL FLOODING...
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Anomalies have receded significantly for the time being, but will gradually increase as Maria brushes NC and heads out to sea. The threat for (minor) flooding will likely return by Tuesday afternoon and linger into early Thursday.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 10 AM to 6 PM EDT Tuesday for ANZ534- 543.
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&& $$ SYNOPSIS...RCM NEAR TERM...RCM SHORT TERM...RCM LONG TERM...DFH AVIATION...RCM/DFH MARINE...RCM/DFH TIDES/COASTAL FLOODING...DFH

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