Area Forecast Discussion
Issued by NWS Wakefield, VA
Issued by NWS Wakefield, VA
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774 FXUS61 KAKQ 232350 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 750 PM EDT Mon Sep 23 2024 .SYNOPSIS... High pressure builds south along the Mid-Atlantic coast early this week. Meanwhile, a series of shortwave troughs will slide across the region in northwest flow aloft bringing unsettled conditions through midweek. Temperatures will be on the cool side of seasonal averages Tuesday and gradually moderate through midweek. && .NEAR TERM /THROUGH TUESDAY/... As of 330 PM EDT Monday... Key Message: - A chance for showers tonight, especially west of I-95. - A chance for showers lingers into Tuesday morning. GOES water vapor channels depict a building ridge over the Ohio Valley with an upper low drifting SE well offshore. At the surface, 1022mb high pressure is centered over Atlantic Canada and continues to ridge to the SW along the Mid-Atlantic coast. The backdoor cold front from yesterday has become rather diffuse, but is still noted by stratus over western NC and NW SC. Mostly cloudy this afternoon across the NW 2/3rds of the area, and partly sunny SE. There are some light showers/sprinkles from N and NW of the RIC metro to the Northern Neck and MD Eastern Shore associated with some shortwave energy sliding across the northern Mid-Atlantic. Temperatures are primarily in the lower to mid 70s. The upper ridge axis shifts toward the Mid-Atlantic coast tonight into Tuesday with additional shortwave energy rounding the northern periphery of the ridge. Showers potentially move into the Piedmont this evening, then scattered showers develop along and W of the I-95 corridor overnight into Tuesday morning. PoPs diminish Tuesday afternoon as shortwave energy lifts NE of the local area. QPF overnight into Tuesday is generally 0.1-0.25" but some locally higher amounts are possible. A few rumbles of thunder are possible over the SW Piedmont with some elevated instability. Mostly cloudy to overcast tonight into Tuesday. Lows tonight are mainly in the lower to mid 60s. Considerable cloud cover will keep highs in the upper 60s to around 70F over the NW Piedmont Tuesday, with lower to mid 70s elsewhere. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 330 PM EDT Monday... Key Messages: - Cloudy with multiple chances for showers, primarily west of I-95. The upper ridge axis moves offshore Tuesday night into Wednesday allowing deeper SW flow to develop over the Mid- Atlantic, with a closed anticyclone developing offshore. This should allow the residual boundary to lift N and the surface high should nudge offshore. Additional shortwave energy will bring a chc of showers and embedded tstms Tuesday night. Higher rain rates are possible with this system given deeper moisture, especially over the Piedmont. Current storm total QPF (including tonight into Tuesday morning) is generally 0.4-0.6" W of the I-95 corridor, but higher amounts are certainly possible. Lows Tuesday night are mainly in the 60s. Warmer and more humid Wednesday with highs ranging from the mid 70s NE to the lower 80s SE. The closed upper high eventually links with a ridge over the Midwest Wednesday night into Thursday between the potential tropical cyclone over the Gulf and a trough over the Saint Lawrence Valley. This will result in diminished rain chances. Lows Wednesday night will mainly be in the mid to upper 60s, followed by highs Thursday in the upper 70s to lower 80s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 330 PM EDT Monday... Key Message: - Multiple low-end chances for rain late this week from the potential development of a tropical system in the Gulf of Mexico. Friday has the highest rain chances (especially to the SW of the local area) around 40-50%. There is some uncertainty on direct impacts as the rainfall will be correlated to the current low pressure system building in the Caribbean Sea that is likely to become a tropical system. There is decent model agreement on the cutoff low over the midwest absorbing the potentially tropical low pressure. This could keep the bulk of the rainfall to the local area`s SW. It is still too early to determine impacts to the local area at this time. The majority of the area on Saturday and Sunday have a slight chc of showers. Temperatures won`t feel like autumn yet with highs in the upper 70s on Saturday and mid 70s on Sunday and Monday. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 750 PM EDT Monday... VFR/MVFR CIGs were prevailing across the area this evening. This will be the case at the TAF sites from this evening into Tue evening, with isolated IFR CIGs possible at RIC Tue morning. Winds will be NE-SE 5-10kt through the TAF period. Chc of showers increases overnight into Wed (esply inland/RIC). MVFR and locally IFR flight restrictions are possible with the chance of rain Tue and Wed. Thu will be drier, but chc of showers returns on Fri. && .MARINE... As of 330 PM EDT Monday... Key Messages: - Small Craft Advisories remain in effect for all coastal waters through Wed due to elevated seas. - Persistent long period swells keep seas elevated through this week. - Southeast to northeast winds may become elevated this weekend. Low pressure continues to linger well off the East Coast, with a strong high pressure over New Brunswick this afternoon. Winds this afternoon were generally E/NE ~10 kt. E/ESE winds briefly increase to 10-15 kt this evening across the Ches Bay and rivers before diminishing overnight. Winds will be nearly the same as today for Tue with a brief surge to ~15 kt with a few gusts up to 20 kt possible in the late afternoon/evening. Winds then remain generally SE 5-10 kt through Thu night before increasing to 10-15 kt with gusts up to 20 kt Fri. Forecast uncertainty increases Fri into the weekend as the winds will depend on how Potential Tropical Cyclone Nine (PTC 9) interacts with a large cutoff low moving into the MS Valley. The exact strength and track of both the tropical system and the cutoff low will be key to determining the local impacts to wind. For now, there still appears to be a potential for SCA winds (15-20 kt) from either SE winds Fri or ENE winds this weekend. However, confidence has decreased. Winds on the 12z models aren`t as high due to high pressure building in to the NE of the local area Fri, helping the tropical system curve away from the local area (to the W) and placing the better pressure gradient SW of the local waters. Expect forecast changes in the coming days as details regarding both the cutoff low and PTC 9 become more clear. Waves and seas this afternoon were generally 1-2 ft (2-3 ft at the mouth of the bay) and 4-6 ft (6-7 ft across the northern coastal waters) respectively. Expect seas to remain elevated through this weekend. As such, have extended SCAs (for seas) through Wed (with future extensions likely). Additionally, there will be a brief period where waves at the mouth of the bay may reach 3-4 ft Tue evening with the brief surge. However, confidence is too low to issue SCAs with this update. && .TIDES/COASTAL FLOODING... As of 700 PM EDT Monday... Key Messages: - Long duration coastal flood event continues across the region (see section below for info on this being a record at a few sites). - Coastal Flood Warnings remain in effect from Windmill Pt/Tappahannock northeastward to the bay side of the MD Eastern Shore, with advisories elsewhere. - At least minor flooding is likely to persist through Tuesday, possibly into Wednesday in portions of the mid/upper Bay. Various headlines remain in effect (see latest CFWAKQ for details). Tidal departures continue to average +1.5 ft to +2.0 ft above astro tide levels across the region. Solid moderate tidal flooding is being observed from the Rappahannock/Potomac to the bay side of the MD Eastern Shore with the evening`s high tide cycle. Sites farther south mainly saw minor flooding this afternoon. Additional moderate flooding is expected across the tidal Potomac/Rappahannock and bay side of the MD eastern shore through Tuesday as winds veer to the E-SE and long period easterly swell remains in place over the ocean, allowing water trapped in the Bay to shift northward. As such, Coastal Flood Warnings remain in effect through Tuesday evening. Went ahead and converted the remaining warnings farther south to Coastal Flood Advisories, which run through the Tuesday aftn/evening high tide cycle. While localized moderate flooding is possible at Bayford tonight and Tuesday, Kiptopeke/Oyster will only see minor flooding so feel an advisory is fine for the VA Eastern Shore. Elsewhere in the advisory area, only minor flooding is expected through Tuesday. Don`t have any headlines for the MD Beaches, inland Worcester County, and Eastern Currituck County...but may levels may approach minor flood thresholds on Tuesday with the higher of the two astronomical tides. Water levels should gradually fall this week with decreasing astronomical tides, but minor flooding is expected through much of the week in areas near/adjacent to the mid/upper bay. As of 345 AM EDT Monday: Consecutive high tides reaching at least Minor Flood with this event: - Lewisetta (P.O.R. since 1979): 13 (with several more to come), previous record was 8 in Oct 2021, Oct 2019, Oct 2015. - Cambridge (P.O.R. since 1980): 7 (with several more to come), previous record was 5 in Oct 2021, Oct 2019, Sep 2018, Oct 2011. Consecutive high tides reaching at least Moderate Flood with this event: (this event is unlikely to break records listed). - Lewisetta (P.O.R. since 1979): 3 (so far), ***record is 7 in Oct 2015*** - Cambridge (P.O.R. since 1980): 1 (so far), ***record is 4 in Oct 2019*** In addition, a High rip current risk is in effect today and Monday. A High rip current risk will likely continue through at least Tuesday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Coastal Flood Warning until 2 AM EDT Wednesday for MDZ021>023. NC...None. VA...Coastal Flood Warning until midnight EDT Tuesday night for VAZ075-077. Coastal Flood Warning until 10 PM EDT Tuesday for VAZ076-078- 085-521-522. Coastal Flood Advisory until 9 PM EDT Tuesday for VAZ083-518- 520. Coastal Flood Advisory until 6 PM EDT Tuesday for VAZ084-086- 095>098-523>525. Coastal Flood Advisory until 10 PM EDT Tuesday for VAZ089-090- 093-099-100. MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ650-652- 654-656-658. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ SHORT TERM...AJZ LONG TERM...KMC AVIATION...KMC/TMG MARINE...ERI/RMM TIDES/COASTAL FLOODING...AKQ