Area Forecast Discussion
Issued by NWS Wakefield, VA
Issued by NWS Wakefield, VA
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056 FXUS61 KAKQ 060043 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 843 PM EDT Wed Jun 5 2024 .SYNOPSIS... Unsettled weather continues through Thursday. Additional scattered, hit or miss style, showers and storms continue late today and tonight. A cold front pushes across the region late Thursday into Thursday evening, with a few strong to severe storms possible. Behind the front, cooler, drier conditions push into the region for Friday and Saturday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 305 PM EDT Wednesday... Key Message: - Scattered showers and thunderstorms are expected late this afternoon and this evening. A few stronger storms are possible, but locally heavy rainfall remains the main threat from any of today`s storms. - Remaining mostly cloudy, warm and muggy tonight, with a few lingering showers overnight. Latest analysis ~1020mb high pressure off the mid-Atlantic coast. To the NW, deepening ~988 mb sfc low pressure was analyzed over the Canadian Prairies, with a weak quasi- stationary boundary extending SSE across the upper Great Lakes and along/just S of the Mason-Dixon line to the upper eastern shore. Aloft, a dampening upper level ridge has built over the eastern seaboard, with quasi-zonal mid-level low over the region. The first in a series of shortwave troughs/MCVs has pushed offshore of the eastern VA coast. The second, centered over the VA piedmont, will cross (mainly) north of the region from SW to NW through this evening, with the third, extending from the eastern OH River Valley into the mid-South, crosses the region this evening into the early overnight hours (~00-06z). 19z temperatures vary from upper 70s to low 80s across the northern and central CWA, with mid to upper 80s over SE VA into NE NC. CAMs are generally struggling with convective signal, mainly a result of the weak forcing today. Scattered showers and storms continue to develop over the next few hours. Given PW in the 1.6-1.8" range, locally heavy rainfall is the main hazard, especially as better deep- layer shear values look to remain along and just north of our area over to the eastern shore (a Marginal Risk from SPC remains across our far northern tier of counties). That said, it does appear possible that a few stronger storms will also be possible along a differential heating boundary that could very well develop this aftn across far SE VA into NE NC. PoPs remain in the 20-40% range over much of the area, ticking up into likely range across the northern neck Richmond/Westmoreland counties (VA) over to the MD eastern shore. Given the multiple perturbations crossing the region and the moist antecedent airmass, areal coverage (ISO-SCT wording) remains the best fit for the forecast late today and tonight, with showers and storms of the pulsy, loosely organized convection of the hit- or-miss variety the expected storm mode. The greatest coverage and intensity of convection slides over the SErn counties this evening. While CAMs have largely misdiagnosed the setup to a decent degree, modest instability, a small uptick in lapse rates and the crossing shortwave all point to this area seeing a few more showers and storms (20-40% coverage), with an isolated stronger storm or two possible over southside Hampton Roads and NE NC in the respective wet microbursts. The last shortwave crosses the area this evening, with at least a few additional isolated to widely scattered showers expected to persist into the late night hours. Rain chances taper late as the wave weakens and exits. Some spotty low stratus and fog is likely, and added mention of patchy fog overnight over the MD eastern shore and northern neck. Lows late tonight in the upper 60s to low 70s under a partly to mostly cloudy sky. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... As of 300 PM EDT Wednesday... Key Messages: - Remaining warm and muggy Thursday. - Early morning showers and storms followed by more numerous showers and storms Thursday afternoon and evening preceding a crossing cold front. - A few strong to severe storms are possible over the region. Locally heavy rain, gusty winds, and frequent lightning are the expected hazards in any storms Thursday afternoon into Thursday evening. Low pressure trundles slowly east toward E Ontario/James Bay region tomorrow, with its surface cold front crossing into the eastern Great Lakes and eastern OH/TN River valleys by sunrise Thu morning. The front then slowly slides east toward the area through the day on Thursday. The WPC Excessive Rainfall Outlook remains in place for portions of the area Thursday, with PW values remaining near climo daily maxes (~1.7-1.8"). More showers and storms look redevelop along the pre-frontal trough by late Thu morning into early afternoon, as the cold front swings east of the central Appalachians. The pre-frontal environment over the local Aurea is expected to be characterized as marginally unstable, with MLCAPE on the order of 1000-1500 J/kg along with a modest increase to deep layer bulk shear of 25-30 kt (W-SW) and mid- level lapse rates ~6-6.5 (C/km). The modest uptick in 3-8 km shear could easily help to focus developing convection a little bit more as the front drops through the region, allowing for a marginal strong to severe/quasi-linear storm mode to be favored. The best chance for a few strong to severe storms Thu aftn is along and E-SE of I-95 into eastern VA and NE NC, but a few damaging wind reports are possible area wide. SPC has upgraded to a Marginal Risk across the entire region for Day 2. Again, gusty winds are the main storm threat, but locally heavy rainfall/urban flood issues are also a concern. Finally, given the quasi-zonal flow aloft and rather moist low-level airmass, any storms that fire will likely also be rather prolific lightning producers as well. Timing for storms looks to be 18-21z west (2-5 PM EDT) in the west and 20-02z (4-10PM EDT) east of I-95. Highs in the mid to upper 80s Wed (highest SE) and upper 80s to lower 90s Thu expected. Showers and storms taper off from W to E Thu evening, with drier air filtering into the region late Thu night into Fri morning. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 300 PM EDT Wednesday... Key Messages: - Drier weather returns Friday through Sunday, with mainly dry weather to persist into early next week. - Near to below normal temperatures appear likely over the weekend into early next week, trending back to and above normal for the latter half of the week. Drier weather moves in Fri behind the departing cold front as dewpoints drop into the 50s. Pleasantly cooler and drier Friday night into Saturday, with dry weather expected. Aloft, an upper level low moves into the Great Lakes on Fri, lingering into early next week. Guidance is coming into better agreement with pushing the next weakening front though the region on Sunday night, but it still appears the upper level low is too close to the local area for enough instability for much in the way of widespread showers and/or storms on Sunday. Instead, only a slight chance for a few isolated showers/storms exists late Sun, with slight to low- end chance PoPs continuing along the coast into Monday. Highs mainly in the lower to middle 80s with lows in the upper 50s to 60s. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 845 PM EDT Wednesday... VFR conditions prevail as of 00z under SCT-BKN mid and high clouds with a SE to S wind of 5-10kt. Isolated to scattered showers and a few tstms are moving WSW to ENE from western to northern VA and into NE MD. SBY has the best potential for scattered showers (40-60%) and perhaps a tstm this evening, with only isolated activity (20% chc) farther S. Primarily VFR tonight, with the exception of SBY where MVFR cigs could develop after 06z and linger to 13-14z Thursday morning. The wind will become SSW overnight, and increase to 10-15kt at ORF, PHF, and ECG. A cold front approaches from the NW Thursday aftn. There is a potential for a line of tstms to develop out ahead of the front Thursday aftn/early evening. Brief flight restrictions are possible (mainly in vsby) along with some locally stronger wind gusts (potentially 30-40kt). Outside of tstms, a SSW wind of 10-15kt is expected with occasional gusts to ~20kt. Dry and VFR Friday and Saturday behind the cold front. Another cold front will bring a slight chc of showers/tstms later Sunday. A slight chc of showers/tstms lingers in to Monday, but overall VFR conditions should prevail Sunday and Monday. && .MARINE... As of 300 PM EDT Wednesday... Key Messages: - Small Craft Advisories have been issued for all local waters except the upper tidal rivers. - Chances for showers/storms could cause locally higher winds and waves this evening and again on and Thursday afternoon and evening. -Low rip current risk late this afternoon, with a moderate risk for the northern beaches Thursday and Friday. High pressure has moved well offshore ahead of an approaching trough and cold front over the Midwest. Flow aloft is rather weak across the local area with an upper trough moving into the western Great Lakes and a building ridge over the SW CONUS. Winds locally are from the S or SW 5-10 kt with waves/seas generally 1-3 ft. Expect the pressure gradient to tighten this evening and tonight as the cold front continues to approach the region from the NW. Winds increase to 15-20 kt with gust to 25 kt over the Ches Bay, lower James River, and Currituck Sound late this evening. Offshore, winds will be more marginal but there will be a period with gusts near or slightly higher than 25 kt. Confidence in seeing these winds is highest for the waters near and north of Cape Charles Light but opted to include all the coastal waters in SCA headlines to better match with neighboring offices. Winds diminish quickly Thursday morning but have extended the SCA headlines in the Ches Bay for a few more hours than previously forecast. Offshore, winds will also fall off quickly but there is some potential for 4-5 ft seas to linger into the afternoon hours for the waters north of Chincoteague. Will let subsequent shifts fine-tune the timing if necessary. The surface cold front moves through the waters late Thursday into the overnight with sub-SCA conditions prevailing late week and into next weekend. && .TIDES/COASTAL FLOODING... As of 300 PM EDT Wednesday... Some nuisance to minor coastal flooding is forecast this evening and tonight. Minor flooding is forecast for bay-facing portions of the MD Eastern Shore including Cambridge, Bishops Head, and Crisfield where a Coastal Flood Advisory has been issued. Nuisance flooding is possible along the tidal Potomac and Rappahannock Rivers tonight as well and a Coastal Flood Statement has been issued for this region. Otherwise, most tidal sites in the middle and lower bay, including up the James River, may see only very shallow flooding near the waterfront over the next couple days. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Coastal Flood Advisory until 7 AM EDT Thursday for MDZ021>023. NC...None. VA...None. MARINE...Small Craft Advisory until 1 PM EDT Thursday for ANZ630>632- 634. Small Craft Advisory from 1 AM to 10 AM EDT Thursday for ANZ633-637-638. Small Craft Advisory from 1 AM to 1 PM EDT Thursday for ANZ650- 652-654. Small Craft Advisory until 10 AM EDT Thursday for ANZ656-658. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MAM LONG TERM...MAM AVIATION...AJZ MARINE...RHR TIDES/COASTAL FLOODING...AKQ