Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 250809 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 409 AM EDT Tue Apr 25 2017 .SYNOPSIS...
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Low pressure tracks across the North Carolina coastal plain today...then continues northeast along the Mid Atlantic coast tonight and Wednesday. High pressure builds into the area Thursday. A cold front stalls north of the region on Friday.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Latest GOES water vapor imagery depicts compact/deep upper low over South Carolina. Associated surface low is centered over southeast North Carolina with a coastal boundary extending northeastward into northeast North Carolina. Latest radar depicts a band of heavy rainfall associated with theta-e advection and marginal instability just south of the local area, spreading into central North Carolina. As the best moisture flux and theta-e advection spreads northward ahead of the advancing surface low, expect widespread showers to spread into southeast Virginia between 4 and 6 am. Increasing low level winds will also result in a ramp up of east winds, with gusts of 30 to 40 mph (45 mph along the coast) early this morning. Latest hi-res guidance indicates the heaviest precipitation south of the region will begin to wane (decreasing rainfall rates) as the air mass is slightly drier and more stable over the forecast area. However, warm air advection and favorable dynamics will still result in moderate to locally heavy rainfall as the band lifts northward over the region through the morning hours. Categorical POPs have been maintained this morning. Band of deepest moisture and strongest moisture flux pushes north of the forecast area late morning/early afternoon as the surface low lifts into the southeast portion of the local area. Energy wrapping around the upper low and cold air advection aloft will keep scattered to numerous showers in the forecast through the afternoon across much of the region. Theta-e advection and temperatures warming into the 70`s across the far southeast local area will maintain at least some marginal instability. Given the steepening lapse rates and marginal instability, have kept mention of thunder across the southeast. Main threat would be locally heavy rainfall. Additional rainfall amounts expected to range from around one half inch over the Piedmont to around 1 inch along the coast. Minor/nuisance flooding is possible given the rainfall of late, but based on latest 3 hour flash flood guidance and anticipated rainfall, no headlines needed. Easterly winds subside this morning first across the south, and then northward through early afternoon. Wind advisories remain in place along the immediate coast. Surface winds become north to northeast inland this afternoon, diminishing to 5-15 mph. Cloudy conditions will prevail (again!) for the day with a large temperature gradient from the Piedmont to the coast. Highs generally in the upper 50`s/low 60`s inland to the low to mid 70`s across southeast Virginia and northeast North Carolina.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
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Upper/surface low pressure lifts along the Mid-Atlantic coast this evening, and then north of the local waters late tonight. Wrap around moisture keeps chance to likely POPs across the northeast local area through late tonight. Given the recent rainfall and saturated soils, have included patchy fog across much of the region. However, cloud cover and light winds will limit the overall coverage. Lows tonight generally in the mid to upper 50`s. Low pressure lifts along the Northeast coast Wednesday as an upper level ridge builds over the region. Thermal soundings indicate mid level moisture trapped beneath a strong subsidence inversion aloft, which will help keep clouds around through the day. However, given the late April sun, anticipate several breaks in the clouds inland. Soundings also indicate very little mixing, but given height rises and warming low level temps/thicknesses, forecast highs are generally in the mid to upper 70`s. Cooler along the coast. Mild Wednesday night under a partly clear to mostly clear sky. Lows forecast in the upper 50`s to low 60`s. Ridge axis slides offshore ahead of an approaching cold front Thursday. Increasing return flow and 850mb temps around +14 to +16C (around +1 standard deviation) result in warm (and dry) conditions with highs generally in the 80`s. Cooler along the coast. Plenty of sunshine expected.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Long term period will feature above normal temps with mainly dry wx. For Thu night/Fri, deep SWly flow continues across the eastern seaboard as an upper-level ridge then builds in through the weekend allowing for warm temps and dry wx as most of the energy aloft will stay N and W of the local area. At most a 20% chance of a late day shra/tstm Fri and Sat. High temps Fri through Sun in the 80s, pushing near 90 Sat and Sun. Low temps in the mid/upr 60s. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... Ceilings have improved across southeast Virginia early this morning, but widespread IFR conditions still observed across much of the region. Low pressure has centered over eastern North Carolina early this morning, with a frontal boundary extending northeastward along the Mid-Atlantic coast. Brunt of the shower activity remains south of the local area, but light rain/drizzle continues inland reducing visibilities to IFR at times. VFR conditions across southeast Virginia are expected to be short lived as the surface low slowly builds northward. Expect widespread showers (locally heavy at times) to develop and lift northward across the region through the morning hours. IFR conditions prevail, except KECG. Initial band of showers lifts north of the region by late morning/early afternoon as the upper level low lifts along the Southeast coast. Areal coverage of the precipitation decreases across the region mid to late morning, but still expect light rain/drizzle and IFR conditions to persist. Additional scattered to numerous showers expected across the region this afternoon as the upper low lifts over the region. Easterly winds ramp up 06-09Z this morning with gusts of 25 to 35 knots. Winds diminish at or below 10-15 knots this afternoon as the surface low lifts over the region. Outlook: Precipitation lifts northeast of the region overnight, but IFR conditions expected to persist through late tonight. Conditions begin to slowly improve late tonight into Wednesday as the system moves farther north. Dry weather is in store for Thursday and Friday as high pressure builds over the southeast states. && .MARINE... Deteriorating marine conditions for tonight as E/NE flow strengthens in response to sfc low pres developing near the SE coast in association with a mid-level cutoff low. Mainly 15-25 kt winds this eveng...increasing to 20-30 kt over the Bay and coastal wtrs after midnight. Seas build to 5-8 ft tonight. The sfc low slides up the NC coast through Tue, with gale warnings in effect for 35-40 kt gusts for the entire marine area except the Upr James/York/Rappahannock Rivers where gusts up to 30 kt are expected. Think much of the wind may stay aloft due to strong WAA, but with decent pres falls over the area, upgraded the northern Bay and Sound to gale warnings also. Seas up to 8-11 ft, with a high surf advisory remaining in effect for 8-9 ft waves in the surf zone. Marine conditions then steadily improve Wed into Thu as the sfc low pulls off to the NE, and a weak pres gradient is expected on the back side of the low. && .TIDES/COASTAL FLOODING... Current tidal departures are averaging around 1 to 1.5 feet in the lower Bay and southern coastal waters due to ongoing onshore flow. Have issued another round of coastal flood statements for the high tide cycle tonight. Levels are expected to stay below minor flooding thresholds. Increasing easterly flow ahead of low pressure lifting over the Carolinas tonight will push tidal departures toward 2 feet Tuesday morning. Depending on the exact track of the low, high end minor to low end moderate coastal flooding is possible Tuesday night. Departures subside Wednesday as low pressure lifts along the Northeast coast and flow becomes offshore. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...High Surf Advisory until 6 PM EDT this evening for MDZ025. Wind Advisory until 1 PM EDT this afternoon for MDZ025. NC...Wind Advisory until 8 AM EDT this morning for NCZ017-102. High Surf Advisory until 11 AM EDT this morning for NCZ102. VA...Coastal Flood Advisory from 8 AM this morning to 2 PM EDT this afternoon for VAZ089-093-523>525. Coastal Flood Advisory until 11 AM EDT this morning for VAZ095>097. Wind Advisory until 8 AM EDT this morning for VAZ098. High Surf Advisory until 11 AM EDT this morning for VAZ098. High Surf Advisory until 6 PM EDT this evening for VAZ099-100. Coastal Flood Advisory until 11 AM EDT this morning for VAZ099- 100. Wind Advisory until 1 PM EDT this afternoon for VAZ099-100. MARINE...Gale Warning until 1 PM EDT this afternoon for ANZ630>632-634- 654-656-658. Gale Warning until 4 PM EDT this afternoon for ANZ650-652. Small Craft Advisory until 4 PM EDT this afternoon for ANZ635>637. Gale Warning until 10 AM EDT this morning for ANZ633-638.
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&& $$ SYNOPSIS...MPR/SAM NEAR TERM...SAM SHORT TERM...SAM LONG TERM...MAS AVIATION...AJB/SAM/JEF MARINE...MAS TIDES/COASTAL FLOODING...

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