Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 170740 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 340 AM EDT Tue Oct 17 2017 .SYNOPSIS...
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High pressure will remain across the Mid Atlantic through the rest of the week and this weekend. A low pressure system may affect the region early next week.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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The elongated center of high pressure is located from the central Appalachians to Mid-Mississippi Valley this morning. This position has allowed enough gradient that winds have been slow to calm, especially east of the Blue Ridge. Will give temperatures another hour or two to fall, but some headlines may be able to be cancelled. The high will continue to overspread the area today, with full sunshine expected. The thermal trough will exiting slowly, so highs should only reach the lower to mid 60s once again.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
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The center of high pressure will remain over the Mid-Atlantic through the middle of the week, then being pushed back to the southwest a little by late Thursday as a shortwave trough swings across the area. Some cirrus could be associated with this feature as well but otherwise skies will be clear. Tonight will offer another opportunity for frost, with perhaps a better chance for most outlying areas across the CWA given calm winds and dew points in the mid 30s. Think the freeze potential is fairly low, but it could be close in the colder valleys. With deeper low level ridging, temperatures will moderate Wednesday and Thursday, with highs edging into the 70s. Some of the typical colder locales could be close to frost potential Wednesday night, but lows will be back into the 40s for most (50s for the cities) by Thursday night.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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High pressure will cross the region Friday and pass off the Atlantic coast Saturday. It will remain in control off the coast Sunday, but then an approaching cold front and low pressure wave will begin to increase clouds Sunday night, with an increasing chance of rain on Monday. Southerly flow will allow temperatures to remain mild even Monday despite the increased cloud cover and increasing risk of rain... with highs in the 70s through the long term. Lows will be moderating, with 40s to start and 50s likely by Sunday night. In fact, if clouds and southerly flow dominate enough, its not impossible that it stays in the 60s in many locales Sunday night. Guidance is pretty impressive with the wave of low pressure Monday night into Tuesday, with a signal for heavy rain and possibly thunderstorms, but given that it is still a week out, a lot can still change.
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&& .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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High pressure will provide mostly clear skies and light winds through Saturday.
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&& .MARINE...
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There`s still enough gradient to allow Small Craft Advisory conditions on the wider waterways this morning. Based on forecast winds aloft, don`t think winds will really start calming until mid- morning from north to south. Have thus made extensions to some segments of the advisory, although it still looks like winds will fall below criteria by noontime. High pressure moves in from the west later today and will remain nearby through Saturday. Winds will be 10 kt or less through the period.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Frost Advisory until 9 AM EDT this morning for MDZ003>006- 501>503-505-507. VA...Frost Advisory until 9 AM EDT this morning for VAZ025>031-039- 040-050-051-501-502-505-506. Freeze Warning until 9 AM EDT this morning for VAZ503-504. WV...Frost Advisory until 9 AM EDT this morning for WVZ050>053-055- 503-504. Freeze Warning until 9 AM EDT this morning for WVZ501-502-505- 506. MARINE...Small Craft Advisory until noon EDT today for ANZ531>534-537- 539>543. Small Craft Advisory until 6 AM EDT early this morning for ANZ536.
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&& $$ SYNOPSIS...RCM NEAR TERM...ADS SHORT TERM...ADS LONG TERM...RCM AVIATION...ADS/RCM MARINE...ADS/RCM

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