Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 190749 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 349 AM EDT Sat Jun 19 2021 .SYNOPSIS... High pressure lingers offshore through the weekend. A cold front approaches from the northwest today and weakens north of the local area on Sunday. Low pressure and associated tropical moisture slowly builds south of the area over the weekend, and will approach the area late Sunday into Monday. A cold front crosses the area from Tuesday to Tuesday night. && .NEAR TERM /THROUGH TONIGHT/... As of 345 AM EDT Saturday... Early morning wx analysis now shows high pressure well to our SE, with a cold front stretching from the Great Lakes to the central Plains. Fairly strong (for mid to late June) WNW flow aloft prevails from the upper Midwest to the nrn Mid-Atlantic, with ridging over the Desert Southwest. Potential Tropical Cyclone Three is now positioned along the Gulf coast of LA. Radar and Satellite composite imagery clearly shows multiple MCSs from SE Iowa to the Ohio Valley. Locally, it is dry with SSW winds of 10-15 mph (with SCT-BKN high clouds from the upstream convection. While the aforementioned cold front is progged to sag SE today, it will stall well before coming close to the area. The flow aloft is forecast to become westerly and strengthen across our area (especially north). The upstream MCS activity is expected to decay as it moves eastward this morning and the high clouds over the local area should thin out. It will be hot today as the low- level flow becomes WSW with 850 mb temperatures of 17-19C. This will allow temperatures to climb into the low-mid 90s (with 60s dew points). Meanwhile, a lee trough will be developing even as the cold front remains to our north. Isolated to scattered tstms will likely develop just to our NW between 1 and 4 PM afternoon in the vicinity of that lee trough, possibly aided by remnant boundaries from the decaying MCS activity. Will have 25-45% PoPs across most of our northern areas from 18-00z, with slight chc PoPs across interior south-central VA. Given the strong sfc heating and steep low-level lapse rates, strong to perhaps marginally severe wind gusts will be possible with the storms that do develop. The highest severe threat is across nrn portions of the FA where the stronger mid-level winds may allow for a bit more organized storms. Additional convection may drop E-SE across the MD Ern Shore (and perhaps the VA Nrn Neck) after 00z Sun/8 PM into early Sun AM, so have maintained chc PoPs through the first part of tonight over these areas. There will be a marginal wind threat with these storms as well through the evening, with the severe threat diminishing overnight with the loss of surface heating. Isolated showers are possible across the Ern shore after 06z/2 AM. Otherwise, it will become increasingly muggy with lows in the 69-75F range. && .SHORT TERM /SUNDAY THROUGH MONDAY/... As of 345 AM EDT Saturday... Sunday we`ll start to turn our eyes to the remnants of Potential TC Three slowly lifting ENE or NE across the Deep South before reaching SC by evening. The leading edge of the associated tropical moisture will likely reach far srn VA and NE NC by Sunday evening, with PWAT values increasing to 1.9-2.1". Locally, Sunday is still looking like a rain-free day for most areas until late, with 15-30% PoPs after 18z. Isolated diurnally-driven convection is possible across most areas west of the Ches Bay, with perhaps a bit more convection across far srn VA and interior NE NC on the leading edge of the richer moisture. The convection on Sunday is generally expected to be sub-severe, but SPC has included parts of interior NE NC in a Marginal Risk for severe wx (mainly due to a modest increase in low-level speed and directional shear across far srn portions of the area by late Sun). The latest 00z/19 model consensus is now forecasting the remnant low to track ENE to a position near the NC Outer Banks by Monday aftn. This track would continue to point toward the heaviest rainfall amounts remaining confined just to the south of the forecast area. However, rain chances do steadily increase over the southern half of the area (especially NE NC) from Sun night through Mon AM before diminishing late Mon aftn/Mon evening as the remnant low moves offshore. Have likely PoPs for all of NE NC, tapering to high chc across Hampton Roads, with just a few showers expected in central/nrn zones Sun night/Mon AM. The current forecast (which largely follows an average of deterministic models and WPC QPF) shows 0.2-0.8" of rain across Hampton Roads and NE NC. The latest 00z/19 ensemble guidance (GEFS/GEPS/EPS) is only painting 10-30% probabilities for >1" of rain from 2 am/06z Mon- 2 am/06z Tue across our far srn zones. Thus, while some locally heavier totals from downpours are likely across SE VA/NE NC coastal plain with wet-bulb zero heights aoa 13kft and PWs of 2.1-2.4" Mon morning into the aftn, the widespread flood threat remains low across our area at this time (Flash Flood Guidance values are generally 3-4" in 3 hours in NE NC). Very muggy Sunday night with lows in the low-mid 70s. Highs Monday generally in the mid-upper 80s SE and upper 80s-low 90s NW (where there will be more sun). && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 345 AM EDT Saturday... PoPs briefly diminish Mon night before attention then turns to a potent shortwave that is progged to track ENE from the far nrn Great Lakes to Quebec during the middle of next week. This feature will very likely drag a fairly strong early summer cold front through the region during the Tue-Tue night timeframe. Have maintained likely PoPs during the day on Tue and will continue chc PoPs into late Tue night across the SE to account for this (for showers and tstms...more specifics to come as it gets closer to the event given differences in timing between the models). Highs Tue are forecast to be in the mid- upper 80s. Cooler and much drier air then looks to return post- frontal on Wed and Thu as high pressure settles into the area. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... As of 120 AM EDT Saturday... Prevailing VFR conditions expected through the 06z TAF period. SCT-BKN high clouds from upstream convection have overspread most of the area. These high clouds will persist through much of the morning, before thinning during the day today. SCT CU is expected during the aftn, and isolated to scattered convection is possible by mid to late aftn, with the best chances at RIC/SBY, with PoPs aob 15% at PHF/ORF/ECG. Tstm chances increase to 50% by late aftn/evening at SBY as convection to the west approaches the MD Ern Shore (and potentially persists through 03-06z while pcpn chances diminish at the VA/NC terminals). Still too early to add tstms to the TAFs though. Regardless, brief IFR/LIFR VSBYs and gusty winds are likely in the strongest storms. Outlook...SW flow continues on Sun, with widely scattered late day showers/tstms possible, especially NW of the VA/MD terminals and south/southwest of ECG. Gradually more widespread showers/tstms possible Monday and Tuesday, with sub-VFR conditions likely in the heavier showers/tstms. && .MARINE... As of 300 AM EDT Friday... SW winds cont to gust to SCA levels so will keep the headlines up for the Bay and nrn coastal waters this morning. Droped SCA`s for the rivers (except lwr James) and Currituck Sound as winds there are below 20 kts. Gusty winds psbl in sct convection later today across the Ches Bay and cstl wtrs as a s/w moves ese. Will keep conditions below SCA levels Sun/Mon given the uncertainity of the remnant tropical low progged to track south of the area. SW winds 10-15 kt by Tue before a potent cold front crosses the region. Could see minimal SCA`s with this feature for the mid week period. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ632- 634-638-650-652. Small Craft Advisory until 7 AM EDT this morning for ANZ630- 631. && $$ SYNOPSIS...ERI/MAM NEAR TERM...ERI SHORT TERM...ERI/MAM LONG TERM...ERI/MAM AVIATION...ERI MARINE...MPR

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