Area Forecast Discussion
Issued by NWS Wakefield, VA

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954 FXUS61 KAKQ 231819 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 219 PM 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 1000 am, light rain is moving across central/ern VA, with moderate to heavy rain across NE NC. 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 overspread most of the area through this afternoon, but may wait until late aftn and the evening for the MD Ern Shore. 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 the mid/upper 60s across much of the area to the low 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 /18Z TUESDAY THROUGH SUNDAY/...
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Poor aviation conditions will continue through much of the TAF period. A frontal boundary is currently located just south of the region with waves of showers riding along the boundary. A more potent low pressure system will track along the boundary this evening. MVFR to IFR conditions with low clouds and reduced visibilities due to periods of moderate/heavy rain will persist through tonight. Heavier rain departs the area mainly after 06Z, but low ceilings and the potential for fog will persist through Wednesday morning. Outlook: A cold front is expected to impact the region Wednesday afternoon and into Wednesday night bringing the chance for more showers and thunderstorms/adverse aviation conditions. Scattered afternoon showers, and potentially a few thunderstorms, are expected to develop on Thursday allowing for the chance of more sub-VFR conditions. Dry/VFR conditions return for Friday and Saturday.
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&& .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...
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MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 10 AM EDT Wednesday for ANZ630>632- 634. Small Craft Advisory until 4 AM EDT Wednesday for ANZ638. Small Craft Advisory from 10 PM this evening to 4 PM EDT Wednesday for ANZ650-652-654. Small Craft Advisory from 10 PM this evening to 4 AM EDT Wednesday for ANZ656-658.
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&& $$ SYNOPSIS...JDM NEAR TERM...AJZ/JDM SHORT TERM...AJZ/JDM LONG TERM...SAM AVIATION...AJB MARINE...MPR TIDES/COASTAL FLOODING...

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