Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 250804 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 404 AM EDT THU AUG 25 2016 .SYNOPSIS... High pressure is expected to dominate the overall weather pattern through the upcoming weekend into early next week. Warmer and more humid conditions return Thursday into the weekend. && .NEAR TERM /THROUGH TONIGHT/...
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Latest GOES water vapor imagery depicts anomalous upper level high over the Deep South. Energy associated with yesterday`s convection over the Midwest is also visible dropping over West Virginia. That energy is expected to drop into the region this morning, resulting in mid-high level cloudiness. Otherwise, near seasonable lows observed across the region. Surface ridge pushes south of the region today, resulting in return flow. The upper level high builds northeast over the TN valley, as 850mb temps warm to 18-19C (+1 standard deviation). Highs warm into the upper 80`s to low 90`s. Pressure falls ahead of an approaching cold front will result in a lee/thermal trough. Warm temperatures aloft and limited moisture will keep the forecast dry, but do anticipate a partly cloudy to perhaps mostly cloudy sky as additional energy drops into the region in the northwest flow aloft. Shortwave energy pushes offshore this evening as the upper high continues to build into the region. Clouds will also push offshore with a mostly clear to partly cloudy sky forecast tonight. Lows generally in the upper 60`s to low 70`s, or roughly 10 degrees warmer than this morning.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/...
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The anomalous upper high centers over the Mid-Atlantic states Friday, as a weak cold front attempts to drop into the forecast area. 850mb temperatures warm to 18-20C (approaching +2 standard deviations) across the region, resulting in a hot day. Highs forecast solidly in the mid 90`s inland (cooler along the coast). The front drops into the region late Friday as the surface trough weakens. Based on the position of the upper level high and anomalous temperatures aloft, expect only afternoon cu, even with a warm and relatively unstable air mass. Moisture also limited with precipitable waters at or below 1.5 inches. Have lowered POPs to silent. Mixed layer dewpoints progged in the upper 60`s to low 70`s, so do not anticipate dewpoints to mix lower than the upper 60`s. The result will be heat indices in the upper 90`s to around 100. The weak front stalls over the northern local area Friday night. Lows forecast in the low to mid 70`s. Surface high pressure builds over the Canadian maritimes Saturday as the upper high remains centered over the Mid-Atlantic. While heights rise slightly over the region, 850mb temps and low level thicknesses decrease slightly as flow becomes onshore. Still warm though, with highs generally in the low 90`s (cooler near the coast). Afternoon cu expected across the south, but the forecast remains dry.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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Benign and mainly dry conditions are expected to prevail Sunday through Wednesday as a mid/upper level anticyclone becomes anchored over the Southeast and Mid-Atlantic, which will keep the primary upper jet energy displaced well to the north of the local area. Very isolated sea-breeze convection is possible Sunday/Monday aftn, but dry conditions and a lack of upper support will limit coverage. 25/00z. 25/00z GFS/ECMWF suggest that the upper ridge begins to dampen by Tuesday/Wednesday allowing for wnw flow across the nrn Mid- Atlantic, and the potential for tropical energy to push into the ne Gulf and Southeast. There is still no strong support for pcpn but given the weakening of the ridge a minimal (20%) chc of showers/tstms is forecast for Tuesday/Wednesday. Highs Sunday through Wednesday should range from the mid 80s at the coast to the upper 80s/low 90s inland. Lows through the period average in the upper 60s to mid 70s.
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&& .AVIATION /08Z THURSDAY THROUGH MONDAY/... A ridge of high pressure has located over the southeast local area early this morning. The result is a light southerly flow inland, but calm winds near the coast. Statistical guidance continues to indicate some patchy fog at KECG, but confidence is low based on the dry air mass. Will mention a tempo group from 10-12Z. Otherwise, a mid level deck visible on satellite over the Piedmont is expected to expand and move south and east, reaching KRIC around day break. Guidance indicates the deck to be broken to locally overcast with decks 4-6k feet AGL. Thanks to an inversion aloft, mid level moisture will likely linger through the afternoon, resulting in scattered to broken cumulus through mid afternoon. Decks remain 4-6k feet AGL. Southerly winds all sites increase to 5 to 10 knots today. High pressure slides farther offshore tonight with lingering mid level clouds over the region. Winds light and southerly. OUTLOOK...A cold front approaches the area Friday. This front is expected to weaken and move to the north during the weekend. Otherwise dry weather is expected through Monday. && .MARINE...
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High pressure will slide farther offshore today into tonight. A southerly wind will average 10-15kt today, and potentially reach a solid 15kt across the Bay and nrn ocean zones tonight. A very weak cold front approaches from the nw Friday and crosses the area late Friday night into Saturday. The wind will remain southerly ahead of the front Friday, but diminish to 5-10kt. High pressure then settles off the New England coast Sunday into early next week resulting in a potential period of prolonged onshore flow, although the wind should be aob 15kt. Seas average 2-3ft through Saturday with 1-2ft waves in the Bay. Tropical cyclone Gaston is expected to track to a position east of Bermuda by early next week. This should result in long period swell propagating toward the coast, with seas building to 3-4ft, and possibly 5ft out near 20nm.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...BMD/JDM NEAR TERM...SAM SHORT TERM...SAM LONG TERM...AJZ AVIATION...SAM/LSA MARINE...AJZ

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