Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 171956 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 356 PM EDT Mon Jul 17 2017 .SYNOPSIS...
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A stalled frontal boundary will allow for continued showers and scattered thunderstorms across extreme SE VA and NE NC through Tuesday. A strong upper level ridge gradually builds toward the Mid Atlantic for the middle and later portion of the week... bringing a return to hot humid conditions.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Update...Isolated to scattered showers have developed this aftn along seabreeze boundaries near the coast and along the higher terrain of the Blue Ridge Mts. Have adjusted the forecast to include mention of POPs farther west than previous forecast. Adjusted sky cover to expand farther west as well. Rest of forecast on track through this evening. Previous discussion... GOES water vapor imagery clearly shows a continued stream of moisture from the Gulf through the SE states and into far eastern VA. This moisture combined with the weak frontal boundary across SE VA has helped to allow for numerous showers for much of the morning across NE NC. Showers subsided somewhat this afternoon as the weak upper disturbance moved through. However, showers and storms are expected to redevelop later on this afternoon especially with any heating. The HRRR and other CAMS suggest the best chances for development will be close to the frontal boundary, but given that pop up showers are already developing across the Delmarva, have opted to include PoPs everywhere late this afternoon. No major changes to the current forecast thinking planned. It looks like the upper trough over the Great Lakes will generally miss the middle Atlantic. As such, there will be no major push to allow the moisture near the coast to move offshore. In fact, it looks like the frontal boundary and associated moisture may attempt to move north slightly as the trough amplifies to the west. As such, will maintain chance pops tonight across the Tidewater and NE NC tonight. Precipitable water values are only slightly above normal for this time of year, and as such do not expect any heavy rainfall, especially even if an isolated thunderstorm occurs.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
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It looks like the upper trough will finally start to move east on Tuesday. Will need to maintain chance pops across SE VA/NE NC on Tuesday with the moisture continuing in advance of the trough. Will also go with isolated storms across the remainder of the area Tuesday afternoon given the upper trough axis is overhead. The trough axis passes over the area Tuesday night, with a drying trend expected on Wednesday (however a few sea breeze or bay breeze afternoon thunderstorms cannot be ruled out Wed). Big story starting Wednesday will be the return to the heat/humidity. Behind the upper trough, heights immediately build across the interior US and the middle Atlantic as the subtropical ridge extends into the south central US. As such, after a near normal temperature day on Tuesday, expect temperatures to rise to above normal with places in the low-mid 90s. There will likely be some mixing on Wednesday, so dewpoint values will most likely drop into the middle and upper 60s. So, heat index values should only rise into the upper 90s (maybe 100F in isolated spots) on Wednesday. The more significant heat index values will be Thu/Fri.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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Bermuda High settles over the central Atlantic the rest of this week as very persistent troughing continues across the Eastern Seaboard. Mid Atlantic Region remains well ensconced in a warm sector throughout the long term forecast. Expect periods of unsettled weather with showers/storms developing each aftn/evening...especially invof lee trough axis which develops Wednesday and persists through at least Saturday. Otherwise, warm and muggy conditions continue with dewpoints in the upper 60s NW to around 75F SE. Meanwhile, high temps will be in the mid-upper 90s Thu/Fri/Sat (possibly pushing 100 degrees in cntrl VA on Friday) and low-mid 90s Sunday. Lows in the 70s each night. The combination of heat and humidity will support widespread heat indices in the 100-105 range with 105-109 possible SE for Thursday through Sunday.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/... A weak frontal boundary lingering in vicinity of the NC coast this afternoon may cause a passing shower at KORF with better shower chances a KECG into tonight. Elsewhere, expect a low chc of diurnally driven convection thru sunset. MVFR stratus and patchy fog possible late tonight, primarily along and west of the I-95 corridor where better clearing takes place. Minimal chc of aftn/evening showers/tstms will continue Tuesday and less into Wednesday. An upper level ridge will build over the Southeast Conus by Thursday/Friday with primarily dry conditions expected. && .MARINE...
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A weakening frontal boundary remains across cntrl VA up to Delaware Bay this aftn. Isolated to scattered showers have developed this aftn along seabreeze boundaries near the coast and may impact the waters at times through this evening. Although winds support better movement of storms today...heavy rainfall, locally gusty winds, and frequent lightning will be the primary impacts from any thunderstorm. Showers/storms become more focused over srn waters tonight into Tuesday as an upper level trough digs over the coastal plain of NC with sufficient shortwave energy present to support thunderstorms. Upper trough shifts far enough ewd to bring overall precip to an end by Wed morning. Otherwise, the Bermuda High settles over the cntrl Atlantic as upper level troughing persists over the Eastern Seaboard. Expect periods of unsettled weather and generally south winds aob 15kt through the end of the forecast period (Fri night). Seas 2-3ft. Waves 1-2ft.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...AJZ/MRD NEAR TERM...BMD/MRD SHORT TERM...MRD LONG TERM...BMD AVIATION...AJZ/JDM MARINE...BMD

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