Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 221941 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 341 PM EDT Thu Jun 22 2017 .SYNOPSIS... Bermuda high pressure begins to shift back towards the Eastern Seaboard through tonight. The high becomes centered off the Southeast Coast Friday and Saturday...as a surface cold front approaches the region from the northwest. Tropical moisture from the remnants of TD Cindy will push across the region ahead of the front for Friday night through early Saturday...before the front shifts offshore late in the weekend. && .NEAR TERM /THROUGH TONIGHT/... Latest weather analysis features Tropical Depression Cindy moving N-NE over the Arklatex region of the lower Mississippi River Valley. Out ahead of the system, a broad plume of mid to upper level clouds has pushed across the Mid-South into the Carolinas. To the north, a quasi-stationary boundary remains in place along and just north of the Mason-Dixon line, extending NW into the western Great Lakes. Meanwhile, the Bermuda High is settling in off the Southeast Coast and will remain there through at least Saturday. 12z soundings indicate SSW flow has allowed for quick moistening out ahead of the system, with PW values already ~1.50"...running just a bit faster than model timing. Slight to low end chance (20-30%) POP continues for isolated to widely sct convection over the southern 1/3 of the area (mainly US-460 south) this aftn. A couple of lobes of shortwave energy out ahead of TD Cindy lift ENE from the TN Valley/SE States this afternoon. Given that shear is still on the low side, expect activity over the local area to drop off quickly with loss of heating, with most pcpn remaining to our w-sw through midnight. Overall, increasing clouds, very warm/muggy for the balance of this aftn with highs reaching into the lower 90s most areas and dewpoints around 70F. More widespread area of showers pushes in late tonight as theta-e ridge pushes across the piedmont toward the Eastern Shore late tonight into Friday morning. Expect a period of moderate to locally heavy rainfall during this time frame, and have therefore continued likely pop mainly NW of a FVX-RIC-SBY line. Farther south, have gone with a low chance pop for some isolated showers over south central VA and NE NC. Warm and muggy overnight with lows in the 70s. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... The core remnants of TD Cindy will merge with the approaching cold front on Friday, and lift NE from the Mid-South toward the central and southern Appalachians Friday afternoon and night before crossing the local area late Friday night through Saturday morning. Out ahead of the system, rain showers associated with lead shortwave/Theta-e ridge will push across the northern tier of counties Friday morning. Expect a brief period of partial clearing behind this initial wave, which should allow for strong surface-based instability. PW values will creep to and above 2" by Friday morning. Additionally, expect 0-6km deep layer shear will be on the order of 35-45 kt, with Hi-Res models showing a pronounced low level jet streak of ~50 kt just to the north by mid to late afternoon. The caveat to all this thunderstorm potential is that regional soundings continue to indicate a fairly substantial capping inversion that will need to be overcome to realize the strong convective threat. Given strong amount of lift to the north, expect that best chance for T-Storms tomorrow afternoon will be across our northern tier of counties, and have oriented a high end pop for Scattered T-Storms Friday afternoon. Farther south, removed from the better dynamics, have tapered back to a 20-30 pop tomorrow afternoon. Very warm and humid tomorrow with highs again u80s to low 90s inland. Warm and muggy Friday night with lows in the 70s. After another brief lull tomorrow night, the actual remnants of Cindy track across the approaching cold front Early Saturday morning. Given favorable dynamics and PW values AOA 2", expect a period of moderate to locally heavy rainfall across the northern half of the region. Despite short-lived heavy rain rates in the tropical airmass Sat morning, progressive nature of system should preclude too many flooding issues. However, important to note that flash flood values are lower than they typically would be for this time of year, especially along the I-64 corridor. Therefore, we will have to watch this time frame closely. Front will push to the coast and then offshore by Saturday evening, with POPs gradually diminishing Saturday afternoon and early evening. Locally heavy rainfall possible along the coast and southern zones into the early evening hours on Saturday. Remaining warm and moderately humid Saturday. Highs mainly in the mid to upper 80s to around 90 SE zones. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Cold front stalls along the Southeast coast Saturday night into Sunday as an upper level trough deepens over the Great Lakes region into the Ohio Valley. Deepest moisture pushes south of the local area Saturday night, but have kept low end chance POPs across the far southeast forecast area. Frontal boundary expected to remain in the vicinity of northeast North Carolina Sunday due to southwest flow aloft. Isolated to scattered diurnally driven showers and thunderstorms are possible across the southeast Sunday afternoon, nearest the boundary and better instability, but expect much of the forecast area to remain dry Sunday. Highs generally in the mid 80`s. Thereafter, medium range guidance drops a stronger cold front Monday/Monday night as additional energy dives down the back side of the upper trough. Guidance indicates the moisture and instability will be limited ahead of the front, but given the dynamics, have kept chance POPs Monday afternoon. Cooler Monday, with highs ranging from the low to mid 80`s. Trough axis swings across the region Tuesday as the front pushes offshore. Drying conditions expected Tuesday, but have kept slight chance to low end chance POPs across the far southeast given model uncertainty with respect to the front. Highs generally around 80 Tuesday as 850mb temperatures level off at 10-12C (-1 standard deviation). Inland locations (and along the immediate coast) could only warm into the upper 70`s. Dewpoints mix into the 50`s, resulting in pleasant afternoon conditions. Dry conditions forecast Wednesday as the trough pushes offshore and heights build over the Ohio Valley. Surface high pressure settles over the Mid-Atlantic. Highs Wednesday generally in the low 80`s. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... VFR conditions are expected through this afternoon and evening. Mid and high level clouds will continue to increase this afternoon as shortwave energy from TD Cindy tracks ENE from the TN Valley/SE States. Patchy rain showers will work into primarily western and northern portions of the region overnight, potentially impacting RIC and SBY. There will also be the potential for MVFR stratus, particularly at RIC, tomorrow morning. Winds increase out of the SW on Friday afternoon, gusts in excess of 20 knots will be possible. Outlook: Additional showers and thunderstorms are expected to redevelop on Friday afternoon and again on Saturday as the remnants of TD Cindy arrive just ahead of a cold front. Periods of MVFR will be possible in heavier showers on Friday and Saturday. The front exits the NE NC coast by Sunday morning with winds shifting to the NW and conditions improving to VFR as cooler, drier air arrives in its wake. && .MARINE... High pressure is situated off the Southeast coast early this morning as TS Cindy moves onshore along the nrn Gulf coast. Additionally, a weak front is immediately north of the local marine area. High pressure is expected to prevail off the Southeast coast through Saturday as the remnant low of Cindy tracks through the Tennessee Valley Friday and Friday night, and then across the nrn Mid-Atlantic Saturday. A SW wind will average 10-15kt today through tonight and Friday, with 2-3ft seas and 1-2ft waves in the Bay. A cold front will push into the Ern Great Lakes Friday and this combined with the approach of the remnant low will result in a tightening pressure gradient and strengthening low- level jet Friday night through midday Saturday. A SW wind will increase to 15-25kt (gusts up to 30kt possible in the ocean/Bay), with 4-6ft seas possible out near 20nm mainly north of Parramore Island, with 3-4ft seas farther south. SCA conditions are increasingly likely Friday night into Saturday. A cold front pushes across the coast Saturday night, followed by a stronger cold front Monday night with high pressure building over the region through the middle of next week. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 10 PM Friday to 6 AM EDT Saturday for ANZ630>632-634. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MAM LONG TERM...SAM AVIATION...AJB/BMD MARINE...AJZ

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