Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 122011 AFDAKQ AREA FORECAST DISCUSSION National Weather Service Wakefield VA 411 PM EDT Wed Aug 12 2020 .SYNOPSIS... A trough of low pressure east of the mountains, will keep numerous showers and and thunderstorms in the forecast through Friday. A cold front pushes into our area Friday night into Saturday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 400 PM EDT Wednesday... Thunderstorms have fired along the surface trough, generally extending from Farmville through RIC and NE into the eastern shore. Very little movement to these storms that have prompted flash flood warnings and advisories for parts of the area already. Expect the convection to fill in further west late this afternoon into this evening as outflow from the initial storms help to develop new storms in the NW Piedmont. As such, will maintain the flash flood watch as is. Expect the convection to diminish after sunset, however will need to maintain chance pops for the entire area tonight due the trough remaining across the area. The 12z HREF continues to show the possibility of heavy rain across the northern neck and even into the eastern shore late tonight into tomorrow morning. As such, have placed the highest pops in this area. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... As of 400 PM EDT Wednesday... Latest guidance is in excellent agreement in showing the inverted surface trough axis over the area on Thursday. In addition, the NWP suggest the weak low over the Carolinas/Georgia will slowly move northward along the boundary on Thursday. This will allow for increase low level moisture convergence and low level theta-e advection which should renew another round of showers and thunderstorms with locally heavy rain. Much of the area is under a slight risk of excessive rainfall on Thursday per WPC. The CAMS suggest that the heaviest rainfall main be closer to the low generally along/south of I-64 but in reality any location could see heavy rainfall given the high precipitable water values of 2 inches, slow storm motion and deep warm cloud depth near 15000 ft. Will likely need another flash flood watch for Thursday, but will let the current flash flood watch for today end and allow the mid shift to try to fine tune any watch needed for Thursday. Guidance starts to diverge on Friday, with the ECMWF and Canadian showing the trough pushing just south of the area while the NAM and GFS generally keep the front stationary over the area again. Without a significant upper trough, it is very hard for troughs/fronts to push south of the area this time of year. As such, have opted to trend more toward the GFS/NAM solutions for Friday and keep likely pops across the area generally across the southern half of the area. Continued unsettled into Saturday with the front remaining across the area with additional heavy rainfall possible especially along/west of I-95. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 400 PM EDT Wednesday... Unsettled weather continues into Sunday and even into Monday with the surface trough remaining in place. A upper trough finally digs into the Great Lakes and northeast early next week. Unfortunately, it is unclear if this trough will allow the front/trough to actually clear the area. Model guidance suggests that it will continue to hang up nearby through midweek. As such, will need to maintain chance Pops each afternoon/evening through the extended. Am not expecting as much heavy rainfall as the precipitable water values will not be as high. Otherwise, temperatures should be seasonable with highs in the mid-upper 80s and lows in the mid 60s/lower 70s. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... As of 200 PM EDT Wednesday... Mostly VFR conditions outside of thunderstorms this afternoon into this evening. Best chance for thunder this afternoon is RIC/SBY and PHF where those sites could briefly drop to IFR as well as seeing some gusty winds. Showers and storms will diminish after sunset. Cannot rule out MVFR vsby and cigs overnight where it rained especially RIC and SBY. Outlook: Shwrs/tstms become more widespread Thurs thru Sat as moisture increases along the sfc trof/cold front. && .MARINE... As of 400 PM EDT Wednesday... Fairly benign marine condition through the end of the week. An inverted trough is located inland across the Mid-Atlantic. This has lead to SE winds 5-15 kt across area waters. There will be a threat of locally gusty winds near thunderstorms Thursday and Friday afternoon (possibly as early as late morning). An area of surface low pressure will move off the VA coast Friday night and into Sunday morning. In combination with a high pressure system across New England, winds will become NE 10-20 kt this weekend (highest winds for coastal waters off Delmarva). Chance of thunderstorm will decrease for the weekend. Waves in the Chesapeake Bay will be 1-2 ft through the forecast period. Seas will build from 1-2 ft Thursday and Friday to 3-5 ft this weekend. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...Flash Flood Watch until midnight EDT tonight for MDZ021-022. NC...None. VA...Flash Flood Watch until midnight EDT tonight for VAZ048- 060>062-064-067>069-075-076-509>517-519-521-522. MARINE...None. && $$ SYNOPSIS...MPR/MRD NEAR TERM...MRD SHORT TERM...MRD LONG TERM...MRD AVIATION...MPR/MRD MARINE...CP

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