Area Forecast Discussion
Issued by NWS Wakefield, VA

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456 FXUS61 KAKQ 171634 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1234 PM EDT Sat Mar 17 2018 .SYNOPSIS... Low pressure moves east across the Mid Atlantic region today, followed by a secondary low pressure system passing south through the Carolinas tonight. High pressure builds into the area Sunday, then moves offshore Sunday night. A trio of low pressure system are expected to impact the region Monday through Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Not much in the way of pcpn is reaching the ground with this initial s/w. Appears the moisture is going more toward moistening up the column. Thus, went no higher than chc pops as this feature moves across the area. In addition, subsidence behind the s/w will likely result in a several hr "lull" period where not much is going on this eve before the next s/w apprchs from the west. Thus, pt to mstly cldy sct shwrs. Highs upr 40s-lwr 50s north, mid-upr 50s south. Main adjustment to the fcst was to add chc thunder in across srn tier zones tonight and change pcpn type to more convective as the second and more potent s/w tracks across the Carolinas. SPC has areas from AVC-RZZ in a marginal risk with a slght risk just sw of the local area. Damaging winds to be the main threat.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... A second wave of energy associated with the sfc low currently near Kansas City tracks SE tonight and crosses the Carolinas overnight, then moves offshore before daybreak Sunday. Pcpn is expected to be better organized as it pushes SE across the SW 2/3rds of the FA this evening and overnight. Therefore, have 30-60% PoPs aligned along/south of I-64 tonight with highest PoPs from southside VA into NE NC. Pcpn probably tapers off prior to daybreak Sunday morning, except lingering over coastal NE NC thru 12z. There should be some clearing from N-S early Sunday morning as well, as the low pushes offshore and high pressure begins to build in from the north. Lows from the upr 20s to low 30s north where clearing occurs to the mid/upr 30s to nr 40 south where clouds and pcpn hold on the longest. High pressure builds over the area Sunday then pushes offshore Sunday night. Dry with a mostly sunny sky Sunday, then increasing clouds from west to east late Sunday night/Monday morning. H85 temps support high near 60 across the Piedmont, 50s along the coast Sunday. Lows Sunday night in the low-mid 30s. High pressure pushes farther offshore Monday and will be quickly followed by overrunning pcpn leading to a weak or in-situ CAD setup across the region. Meanwhile, a potent shortwave races eastward from the southern plains in the morning into the TN Valley by late in the day. QPF amounts during Monday are not expected to be all the much at this time. However, an overcast sky and onshore flow will lead to a chilly day. Highs from the mid/upr 40s N to the low/mid 50s NE NC. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Widespread pcpn in the form of rain is expected Monday night as the aforementioned shortwave reaches the Appalachians by around 12z Tue. Meanwhile, sfc low pressure organizes over the Carolinas Monday night before emerging off the mid-Atlantic coast and deepening Tuesday morning. Will carry likely to categorical PoPs Monday and Tuesday, although it does appears that the heaviest pcpn comes Monday night into Tuesday morning with high pressure briefly returning Tuesday afternoon for just some lingering clouds and light/spotty rain. Potent shortwave #2 will be on the hills of Monday night`s system as we head into Tuesday night/Wednesday morning. Again, shortwave #2 crosses the Carolinas Tuesday night while another sfc low develops and deepens off the mid-Atlantic coast Wed morning. The third piece of the puzzle, this time a northern stream shortwave dropping south from the Ohio Valley into the mid-Atlantic region on Wednesday, will bring a shot of colder air aloft into the area during Wednesday and may cause pcpn to turn over to snow into northern/Central VA and the lower MD Eastern Shore. There`s a lot of moving parts that will have to come together perfectly for this scenario to play out, but it`s one that does bear watching as both the GFS and ECMWF show this potential. The GFS is stronger and more negatively-tilted with the shortwave Wednesday which would lend to a better chance of snow as moisture lingers or gets forced westward into the colder air before the coastal low departs. The ECMWF shoves the coastal low out to see faster and is a touch slower with the northern shortwave and hence would have little to snow on Wednesday. This forecast package took a blend of these two solutions which allows for the possibility of a rain/snow mix across the western half of the FA Tuesday night/Wednesday. Before that, just expecting p-type to be in the form of rain Monday night thru Tuesday eve. Lows Tuesday night from the low 30s NW to the low 40s SE. Highs Wednesday 35-40, except low-mid 40s far SE. Pcpn ends Wednesday night with drier air returning Thursday/Friday. Lows Wednesday night in the upr 20s to mid 30s. Highs Thursday/Friday in the 40s to low 50s. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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VFR conditions across the area this aftrn despite the initial s/w moving across the area. Most of the moisture assctd with this feature is going to moisten up the column, so will only carry VCSH at RIC/SBY next few hrs where the best forcing is. Next s/w crosses the region aftr 03Z Sun. Latest models keep the most sgnfcnt moisture across the Carolinas but still can`t rule out sct shwrs across sern taf sites tonight. Thus, kept the VFR conditions with VCSH once again. Otw, decreasing cloudiness aftr 12Z Sun as high pressure builds in from the north. Outlook: Another window of flight restrictions late Mon thru Wed as a trio of low pressure systems impact the area. Rain for the most part may mix with or change to wet snow by Wed at RIC/SBY.
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&& .MARINE... Fairly benign conditions prevail across the marine area today with weak sfc high pushing off the NC coast this morning, followed by a weak area of low pressure progged to move across southern VA and NE NC late this aftn into tonight. NNW WINDS ~10 KT will become light/variable before turning to the E/SE later today. SEAS to avg 2-3 ft and waves 1-2 ft or less. As the sfc low moves off the NC coast late tonight/early Sun morning, will see a bit of a surge in NNE winds to ~15 kt. Very little in the way of cold air however, so do not anticipate needing and SCA headlines even though a few hrs worth of gusts to 20 kt will be possible early Sun morning. Otherwise, winds diminish to 5-10 kt or less Sun aftn while shifting to the E and the to the S Sun night. Conditions become much more unsettled and stormy later mon through at least midweek as the next low pressure system approaches from the TN Valley, then is progged to re-develop as a coastal low off the mid-Atlc coast on Tue. First low pushes off to the NE Tue aftn/evening with yet another low expected to develop off the SE Coast and then rapidly intensify while pushing NE# off the mid-Atlc coast Wed/Wed night. At least strong SCA conditions appear likely Mon night Through Wed, with a period of Gales even a possibility Tue and again Wed/Wed night depending on the exact track of these systems. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...JDM NEAR TERM...JDM/MPR SHORT TERM...JDM LONG TERM...JDM/MPR AVIATION...MPR MARINE...LKB is the U.S. government's official web portal to all federal, state and local government web resources and services.