Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 171833 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 233 PM EDT Sun Mar 17 2024 .SYNOPSIS...
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A couple of cold fronts will cross the area through Monday, then high pressure gradually builds in from the Midwest. A third cold front will cross the region Wednesday. High pressure will build to the north through the end of the week as low pressure takes shape to the south.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Stronger winds have mixed down along the eastern slopes of the Alleghenies into the Shenandoah Valley, where gusts of 40-45mph have been observed in Petersburg, Upper Tract, near Staunton, Afton, Martinsburg, and along I-68 in western MD. This compressional warming has also resulted in higher temps than forecast, with mid to upper 60s. Similar winds are occurring atop and on the eastern slopes of the Blue Ridge, with temps in the upper 60s to 70s east to the Western Shore. Westerly wind gusts of 20-25mph east of the Blue Ridge likely through sunset. Clouds have mostly dissipated, resulting in mostly to partly sunny skies. Colder air filters into the region tonight dropping temperatures to near normal for mid-March. Some cloud cover will build back in tonight. Overnight lows drop to or below freezing west of the Blue Ridge, and in the mid to upper 30s to the east.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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Another cold front crosses the area on Monday, bringing another increase in west-northwest winds Monday afternoon. The FROPA itself will be dry, though mountain snow showers are expected behind the front Monday evening into Tuesday. Recent model trends have increased QPF in the Alleghenies as favorable dynamics support higher snow totals. The forecast has been upped to 1-3 inches of snow, with most of that expected above 2500ft. Cooler temperatures Monday afternoon in the 40s west of US-15, and the low to mid 50s to the east. Winds gust around 20-30mph through late afternoon, with higher gusts possible in the mountains. Temperatures over most of the area drop to or below freezing Monday night. The cooler temps continues into Tuesday, with another burst of mountain snow showers possible Tuesday night. Given several days of dry, breezy conditions, the potential for rapid fire spread may increase as the week progresses (see the Fire Weather section below).
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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The synoptic pattern will be more zonal by Wednesday, but maintains broad troughing over the eastern CONUS and a closed low over the southwest US. A modest wave may bring a burst of snow to the Alleghenies Tuesday night/early Wednesday morning, then high pressure builds in from the southwest. Gusty winds continue into Wednesday with the passage of a dry reinforcing cold front. The strongest winds during this period are expected to gust 25-35 mph and up to around 40-45 mph in the higher elevations along the Allegheny Front. Winds gradually decrease through Thursday afternoon. Temperatures will be mild on Wednesday before dropping behind the cold front Wednesday night. The pattern becomes less certain towards the end of the week. Guidance has come into better agreement on a low passing through the Southeast and developing offshore, but models diverge timing and how far north it tracks towards our area. Regardless, it seems the next shot for precipitation for the area comes Friday or into the weekend.
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&& .AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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VFR conditions are expected through Tuesday night. A series of cold fronts will cross the area in that time. While they won`t bring any precip east of the Alleghenies, expect increasing west to northwest wind gusts each afternoon. Peak gusts around 25-30kt expected, with some occasional higher gusts possible. CIGs remain well above VFR due to high mixing heights each afternoon. VFR conditions are expected Wednesday and Thursday with any possible precipitation early Wednesday morning limited to the Alleghenies and as such not expected to impact the terminals. The main concern will be gusty W/NW winds 25 to 30 kts on Wednesday.
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&& .MARINE...
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A series of cold fronts will cross the waters over the next few days, bringing gusty west to northwest winds to all the waters. Small Craft Advisories are in effect, and likely to be needed Tuesday and Wednesday. The strongest gusts are expected Monday evening into Tuesday morning, where near-gale gusts possible over the open waters of the Chesapeake Bay. Gusty and northwesterly winds are expected on Wednesday as a dry reinforcing cold front passes through and low pressure departs to the northeast. SCA conditions are likely over portions of the waters Wednesday and all waters for the first half of Thursday.
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&& .FIRE WEATHER...
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Gusty conditions along the eastern slopes of most mountains this afternoon, with westerly gusts of 40-45mph due to downsloping winds. To the east of the Blue Ridge and in the Shenandoah Valley, minimum relative humidity values between 20-25pct this afternoon. Gusts to 25-30mph expected in most other areas. This will produce very good to excellent smoke dispersion today. Looking at the week ahead, minimum RH values drop to 20 to 35 percent each afternoon through Thursday. Generally poor relative humidity recovery to 50 to 60 percent is anticipated each night. These dry conditions will be accompanied by westerly to northwesterly winds of 15 to 20 mph with gusts to around 30 mph at times, especially during the afternoon hours each day. Higher gusts around 40 mph are possible over the higher elevations at times. Scattered to broken high clouds and stratocumulus are possible at times. Mixing and smoke dispersion are expected to be good to excellent much of the week. The next chance of wetting rain comes with approaching low pressure on Friday.
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&& .TIDES/COASTAL FLOODING...
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Tidal anomalies reach their peak this afternoon as Annapolis, Straits Point, and SW DC Waterfront all reached Minor Flood stage. Many other sites reached Action Stage. Winds have now shifted to west/northwest behind a weak cold front that crossed the area. This is going to help bring tidal anomalies down over the next few days. No tidal flooding is currently anticipated, though sensitive sites at Annapolis, Straits Point, and DC SW Waterfront could reach Action Stage during high tide this evening.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Coastal Flood Advisory until 5 PM EDT this afternoon for DCZ001. MD...Coastal Flood Advisory until 4 PM EDT this afternoon for MDZ014. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ530>543. Small Craft Advisory from 9 AM to 6 PM EDT Monday for ANZ530- 535-536-538-542. Small Craft Advisory from 10 PM this evening to 6 PM EDT Monday for ANZ531>533-539>541. Small Craft Advisory from 1 AM to 6 PM EDT Monday for ANZ534- 537-543.
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&& $$ SYNOPSIS...KRR NEAR TERM...KRR SHORT TERM...KRR LONG TERM...CAS AVIATION...KRR/CAS MARINE...KRR/CAS FIRE WEATHER...KRR TIDES/COASTAL FLOODING...KRR

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