Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 211739 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 139 PM EDT Sun May 21 2017 .SYNOPSIS... A frontal boundary will remain stalled over the Carolinas today, and will lift back north as a warm front tonight. A cold front is expected to cross the Mid Atlantic region Monday into Monday night, with low pressure tracking along the boundary Tuesday into Tuesday night. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The latest wx analysis and visible satellite imagery depict a stalled frontal boundary oriented from SE NC back into western VA/NC. A small area of enhanced rain in the form of showers and embedded tstms over south central VA has now dissipated with mostly cloudy to overcast conditions for much of the area, aside from some breaks in the cloud cover across interior SE VA/NE NC. Temperatures are generally 60-65F across the region this morning. Otherwise, high pressure remains situated NE of the area today as the front remains stalled across the Carolinas. Moisture continues to increase in the 950-850mb layer this aftn and this should result in mostly cloudy to overcast conditions persisting or overspreading much of the region. High temperatures will be cool ranging from the mid-upper 60s to around 70 across much of the area, with low 70s across far SE VA/NE NC. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... The front begins to lifts N as a warm front later tonight, with moisture and lift aloft limited through at least the early evening hrs and corresponding PoPs aob 20% across the E, and increasing to 20-40% over the Piedmont. Moisture advection and lift then increase fairly rapidly overnight with PoPs rising to likely or categorical along and NW of an AVC-RIC-XSA line with 20-40% PoPs farther E where moisture remains more shallow. Lows range from the 50s NE to the 60s elsewhere under a mostly cloudy to overcast sky. Models depict potential for reduced vsbys across the Piedmont after 06Z with the moist SE flow and increasing dew pts/low level moisture. Still think this will be more form lowering stratus than actual fog and will keep vsbys at 1-2SM for now. Monday continues to look unsettled with a cold front crossing the area later in the day, then slowing down and stalling over SE VA/NE NC Monday night. There is a decent upper jet over the Ern Great Lakes and shortwave energy supporting a 60-70% PoP, mainly across the Piedmont I-95 corridor through midday, and then shifting toward the coast during the aftn and early evening. Instability is limited (500- 1000 J/kg of 0-1km MLCAPE) and 0-6km bulk shear is generally less than 25kt, so any threat of severe tstms is very minimal. However, locally heavy rain is possible with the combination of decent forcing and pw values of +1-2 st dev. High temperatures range from the mid 70s W to the lower 80s SE. The front lingers near the coast Monday night with some drying aloft behind it from the N. However, the NAM/GFS each show some lift lingering overnight especially across the S. Likely pops E through midnight, with chc pops west during the evening. PoPs of 20% N and W to 40% SE overnight with some lingering lift. Lows range from the mid 50s NW to the Mid 60s SE. Latest GFS/NAM/ECWMF all agree on the flow aloft remaining SW on Tuesday, with another wave lifting newd across the Carolinas during the aftn. There are some differences in timing and location and strength of this wave of low pressure, but the general theme is for a potent system with deep anomalous moisture transport per strong H925-H700 southerly flow and PWat values climbing to ~1.75". While forecast has not gone with the very high widespread rainfall amounts of the GFS (2-4"+ on Tue), heavy rain will certainly be possible as even a consensus forecast is for a swath of 1-2" of rain somewhere within the CWA. Have this mentioned in the HWO for most of the CWA, current indications are that the far SE and far NW sections of the CWA will tend to have somewhat less in the way of QPF amounts. PoPs look to increase back to likely/70% by late morning and aftn from S to N. High temperatures Tuesday have been trended downward more due to the combination of NE flow, cloud cover, and likely rain. The current high temperature forecast now shows generally low/mid 70s SE to the upper 60s/around 70 F central and NW. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Long term period starts off wet with near to slightly below normal temps. Forecast remains complicated mid to late week by a an upr- level trough across the eastern CONUS...with transient shortwave troughs and sfc lows passing up the Eastern Seaboard. Pattern therefore favors frequent chances for rain, with much uncertainty over the timing. For now...will forecast mainly likely ~60% PoPs Tue Night and Wed, dropping to 40-50% Wed night and Thu. Lower chance into Fri as the upper-level trough starts pulling off to the east. As for temps, highs will be in the 70s Wed through Fri, with low temps in the mid 50s to mid 60s. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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MVFR/VFR ceilings across the region early this afternoon. MVFR ceilings are generally between 1500-2500 feet. Satellite imagery showing low pressure system over the Great Lakes with a cold front into Texas and a warm front over the Mid Atlantic region. A good cloud shield accompanies the fronts and guidance indicates increasing clouds through the evening and overnight with rain over the region by early morning. The cold front approaches from the west late tonight and moves through the Mid Atlantic States Monday. Expect deteriorating conditions overnight with IFR conditions possible, especially at RIC after 06Z. Rain becomes likely well inland after 06Z/Mon at RIC and gradually shifts east through the day Mon, with showers and thunderstorms likely by Monday afternoon. MVFR/IFR conditions will continue during heavier precipitation during the rest of Monday into Monday night. Unsettled weather is expected to continue Tuesday and IFR conditions will be possible. By Wed/Thu a series of frontal passages and low pressure systems affecting the Mid Atlantic region. Periods of deteriorating conditions are possible though will tend to become less widespread.
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&& .MARINE... ENE winds persist across the waters this morning but speeds have come down enough to cancel SCAs for the Ches Bay, lower James River and the Currituck Sound. Will maintain SCAs for the coastal waters with seas still hovering around 5 ft. Sfc high pressure slowly slides east across New England today with local winds becoming more ESE this afternoon while maintaining speeds of 10-15 kt. Given the reduction in wind speeds today, there is some uncertainty as to whether or not seas will remain above 5 ft into this afternoon. Wave guidance is also showing the possibility of seas building again across the northern waters late today into tonight. Given the current SCA for the coastal waters goes thru 6 pm will opt to leave as-is and give the next shift ample time to discern whether or not the SCA can be cancelled or extended. Winds become S then SW on Mon ahead of the next frontal system approaching from the west. The front crosses the area Mon night into Tue morning. Unsettled conditions are expected much of the coming week with the possibility of SCA conditions late Tuesday and Wednesday. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ650- 652-654-656-658. && $$ SYNOPSIS...LKB NEAR TERM...AJZ/LKB SHORT TERM...AJZ/LKB LONG TERM...MAS AVIATION...LKB/JEF MARINE...JDM

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