Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 161338 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 938 AM EDT Sat Mar 16 2024 .SYNOPSIS... High pressure will briefly build over the Mid-Atlantic today. A cold front will deliver cooler and blustery conditions heading into early next week. High pressure will build in from the southwest by mid-week, then low pressure may follow toward the end of next week. && .NEAR TERM /THROUGH TONIGHT/...
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Stratocumulus is likely to persist in the Alleghenies through this afternoon, as some high clouds possibly build in by late in the day. Otherwise, it looks like a sunny Saturday as highs reach the 60s, which is still above normal for mid-March. Scattered showers are possible over the Alleghenies after midnight as a cold front dives in from the Great Lakes. Otherwise, the region is expected to see increasing clouds with mild overnight temperatures.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... The cold front will cross the region Sunday, pushing offshore Sunday night. This will be the leading edge of much cooler temperatures and blustery conditions. Given the dry air in place, precipitation is unlikely east of the mountains. After one more day of above normal high temperatures, things turn much cooler especially heading into Monday as cold air pushes in. There may be some opportunities for mountain snow showers depending on the amplitude and depth of embedded shortwaves in NW flow in the wake of the cold front. At the moment, periods of snow showers look relatively brief with light (sub-advisory) accumulations most likely through Monday night, but there will be some CAPE/saturation/lift overlay into the DGZ Monday into Monday night along and west of the Allegheny Front. If these dynamics can come together long enough and overcome the higher mid-March sun angle, at least isolated higher amounts would be possible. In addition, a stray sprinkle or flurry could travel east of the mountains as inversion heights rise, but again this will depend on the strength of any forcing waves passing by. && .LONG TERM /TUESDAY THROUGH FRIDAY/... On Tuesday, while a rex block persists over the western U.S., a longwave trough will encompass the central/northern Great Plains and points eastward. This highly amplified flow should keep temperatures below average as modified Canadian air spills in from the northwest. Heading toward the middle of the week, deterministic models agree on some de-amplification of this trough as heights turn slightly more zonal. At the same time, a stagnant southwestern U.S. closed low finally makes its eastward push toward the Four Corners. This particular system is of interest as it may bring wet conditions toward the end of the work week, possibly into the following weekend. Looking more closely at Tuesday`s forecast, behind a series of cold fronts, the northwesterly flow regime will keep chilly weather in the picture. Forecast highs sit in the mid 40s to mid 50s, but with wind gusts up to 20 to 25 mph. This would contribute to wind chills in the 30s to low 40s. Meanwhile, across the mountains, highs mainly are confined to the 30s with it feeling more like the teens to mid 20s. Additionally, some upslope snow showers continue along the Allegheny Front. Amounts will be determined by the strength and position of the forcing, direction of the flow, and extent of moisture. And given it is the Vernal Equinox (March 19), the solar angle should bring an additional challenge to snow accumulations. Farther east, expect dry weather with mostly cloudy skies. For the middle to latter portions of the work week, temperatures will moderate as thicknesses increase and heights rise. The uncertainty in the temperature forecast does increase considerably at this time as shown by the ensemble spread. This variability is dictated by how much the southwestern U.S. system impacts the local weather late in the week. Any rainfall likely holds off until Friday, with further impacts into the weekend. While beyond the scope of this forecast period, the Climate Prediction Center continues to highlight a slight threat for heavy rainfall and strong winds in the March 23-25 period. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are forecast at the TAF sites through Monday night, with most if not all precipitation relegated to areas along and west of the Allegheny Front. Passing clouds are possible at times (both mid/high level clouds and some cumulus at times). Blustery NW winds take over behind a cold front Sunday, with gusts to around 30 kts possible at times. Slight decreases in winds are expected at night, but similar gusts are possible again during the day Monday when a stray sprinkle or flurry can`t totally be ruled out. Any snow shower activity should remain in the Alleghenies on Tuesday. While some stray flurries could drift off to the east, do not expect any impacts at the area terminals. Thus, VFR conditions are anticipated through Wednesday. Skies will be mostly cloudy on Tuesday, but ceilings should stay VFR. Otherwise, the bigger story will be the blustery west-northwesterly winds. Afternoon gusts up to 20 to 25 knots are possible on Tuesday. Expect a repeat into Wednesday as well as an additional cold front pushes through. && .MARINE... Periods of increased NW flow will necessitate SCAs at times through early next week. A period of stronger winds is most likely Monday into Tuesday as cold advection reaches its peak. It is during this time that gale-force winds are possible. Dry weather is anticipated this weekend into early next week. In the wake of multiple cold frontal passages, blustery winds persist over the area waterways. These west-northwesterly winds may gust up to 20 to 30 knots on Tuesday, locally a bit higher toward the southern waters. There will be a potential for gales over this area through midday Tuesday. Therefore, expect Small Craft Advisories during this period while the threat for gales will be monitored. Winds relax a bit into Tuesday night before ramping back up on Wednesday as the cold front enters the region. Additional advisories may be needed for Wednesday as well. && .TIDES/COASTAL FLOODING...
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Decreasing winds this morning have allowed tidal anomalies to begin increasing again. Southerly winds develop by this afternoon, which will aid in additional increase of anomalies and many sites are expected to reach Action Stage by this afternoon. The usual sensitive locations like Annapolis, Straits Point, and the D.C. Southwest Waterfront could reach Minor on Sunday morning. A shift to northwesterly flow behind this front should minimize the threat for coastal flooding during the subsequent high tide.
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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 Sunday for ANZ530>532-535-536-538-539. Small Craft Advisory from 6 PM this evening to 6 AM EDT Sunday for ANZ531>534-537-539>541-543.
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&& $$ SYNOPSIS...DHOF NEAR TERM...DHOF/KRR SHORT TERM...DHOF LONG TERM...BRO AVIATION...BRO/DHOF MARINE...BRO/DHOF TIDES/COASTAL FLOODING...BRO/KRR

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