Area Forecast Discussion
Issued by NWS Wakefield, VA

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318 FXUS61 KAKQ 231040 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 640 AM EDT Tue May 23 2017 .SYNOPSIS... A frontal boundary draped across northeast North Carolina this morning will lift back north into southeast Virginia this afternoon, as a potent low pressure system tracks along the boundary through this evening. Unsettled conditions continue Wednesday and Thursday as an upper level trough approaches from the west. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A frontal boundary is just south and east of the local area this morning with high pressure situated over the OH Valley. As of 630 am, starting to see some steadier rain moving into southern portions of the FA. The frontal boundary to our south will gradually creep back northward into SE VA this afternoon and will be the focusing mechanism for our well-advertised rain event through tonight. A series of low pressure systems will ride NE along this boundary today allowing for multiple bouts of rain, some of which may be heavy at times. The most potent of these sfc lows is expected to move across SE portions of the FA late this aftn and evening, and should provide our best chance of locally heavy rain. With deep layer moisture returning, categorical PoPs quickly ramp up from SW to NE and overspread the entire area by mid to late morning into the afternoon. 23/00z suite of models (NAM/GFS/GEFS/ECMWF) still all over the place with timing and placement of heaviest QPF today and exact track of the strongest low late today into tonight. As mentioned above, the general consensus is for this low to track across southeast portions of the VA late today into tonight and so that is when/where we`ll show our highest QPF amounts. The threat for heavy rain and possible minor flooding will continue to be mentioned in the HWO, but have opted against a flood watch at this time as 6hr FFG is generally 4-6" across much of the area, with some values of 3-4" across the Piedmont and MD Ern Shore. QPF through 06z Wednesday averages 0.5-1" north to 1-3" south, and higher amounts are possible. Highs today will range from 65-70 Piedmont to the low/mid 70s along the Albemarle Sound. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... The potent shortwave/surface low pushes offshore Tuesday evening with a secondary wave moving offshore around/after 06z. Will carry likely/categorical PoPs (55-85%) in the evening, then tapering off overnight into Wed morning. Lows Tues night in the mid 50s west to mid 60s SE coast. Yet another wave approaches from the SW Wednesday aftn as an upper low approaches from the W. This wave tracks across the region Wednesday evening through the early overnight hours bringing another round of likely PoPs along with a chc of embedded thunderstorms. Current 00z guidance suggests the best instability remains southeast. However, the potential for some strong to severe storms will need to be monitored with 500mb height falls and strengthening/veering flow at the 500mb level. SPC currently has our SE counties in a marginal risk. Unsettled conditions continue into Thursday with chc to likely PoPs continuing along with a chc of thunder. Mostly cloudy to overcast Tuesday night through Thursday. Highs Wednesday/Thursday ranging through the 70s most places. Lows Wed night in the 60s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Trough axis tracks across the region Thursday night as the surface low tracks just north of the region. Will keep mention of chance POPs across the northeast portion of the local area Thursday night. Dry conditions and a clearing sky is forecast Friday as the trough axis and deepest moisture push offshore and westerly flow aloft commences. Temperatures Friday generally around average in the mid to upper 70`s. Upper level flow becomes northwest Friday night and Saturday ahead of an upper level ridge building over the Ohio Valley. A warm front lifts into the region Saturday, providing a focus for showers and thunderstorms, but overall moisture is expected to be limited. Will keep only slight chance POPs for the Piedmont Saturday at this time. Warmer, with highs in the upper 70`s to low 80`s. Better chances for showers and thunderstorms are expected Saturday night as upstream convection develops and tracks along the frontal boundary and into the region. However, spatial and timing differences exist so have capped POPs in the low end chance range. Thereafter, unsettled conditions persist Sunday through Monday as an upper level trough tracks across the Midwest into the eastern CONUS. A great deal of uncertainty exists in the medium range guidance, but it appears moisture return will be limited. Will keep mention of low end chance POPs in the forecast. Highs both days generally in the low to mid 80`s. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... MVFR to IFR CIGS are prevalent this morning with LIFR CIGS at KPHF/KORF. Rain will continue to increase in coverage and spread north through the morning, then continues most of the day. The rain may be heavy at times, especially this aftn/eve, helping to reduce visibility and keeps CIGS low. IFR ceilings will be widespread into tonight. OUTLOOK...Other low pressure systems will impact the area but not to the extent as the one today. Nevertheless...aviation conditions will be reduced at times through Thursday. High pressure builds over the area Thursday night and Friday with drying. Moisture returns with a chance for precipitation developing during the weekend. && .MARINE... Rather challenging forecast with respect to confidence and timing of any SCA level winds due to a wide range of model solutions even in the short term. Low pressure progged to lift NE along a frontal boundary late today / tonight. The actual strength of the low as it tracks across the lwr Ches Bay and off the Delmarva will determine just how strong the NNE winds will be. Believe there is just enough agreement for a 6-10 hour period of SCA winds across the Ches Bay from 22Z through 08Z tonite to post marginal SCA headlines. Not enough confidence hoist any headlines along the coastal waters so held off there. This includes seas as they are running about a foot below current forecast. Seas may eventually reach 5 feet out near 20 nm, but expect this would be more swell driven from the low moving offshore rather than wind driven. The next front pushes offshore Thursday night, with increasing southwest winds Thursday ahead of the front. Minimal SCA conditions are possible. && .TIDES/COASTAL FLOODING... Higher astronomical tides results in above normal water levels this week. Rather wide spread in model guidance as to where the low actual tracks makes for a difficult forecast. Expect some northern sites to reach action stage during the afternoon high tide cycle today. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 4 PM this afternoon to 4 AM EDT Wednesday for ANZ632-634. Small Craft Advisory from 7 PM this evening to 1 AM EDT Wednesday for ANZ630-631. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...AJZ/JDM LONG TERM...SAM AVIATION...JDM MARINE...MPR TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.