Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 071140 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 640 AM EST Thu Dec 7 2017 .SYNOPSIS... A frontal boundary remains nearly stationary off the Mid Atlantic coast through Saturday. A series of low pressure systems will track northeast along this boundary through Saturday. Cold high pressure builds into the area Saturday night into Monday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Frontal boundary remains (well) S and E (off the coast) today. Initial weak s/w aloft in SW flow exits early this morning...w/ a general trend to RA (now mainly invof NE NC) settling a bit farther SE. Otherwise...expecting widespread mid-high clouds to stream NE over much of the FA today. PoPs (blo 20% - highest invof NE NC) after 12Z/07. Near seasonable temps w/ winds VRB blo 10 mph. Highs within a degree or two either side of 50F. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... Frontal boundary will remain offshore nearly parallel to the SW aloft through early Sat. A series of disturbances will move through the region tonight through Sat morning. Flow aloft backs a bit Thu night-Friday...allowing moisture to push a bit NW... and increase precipitation chances back toward central VA and lower SE MD. Surface temperatures through 00Z/09 (Sat) expected to be warm enough for all liquid pcpn. The 00Z through 15Z/09 (Sat) is the time period where potential snow could occur across the region. All models keep sufficient spacing between a weak s/w in srn stream tracking ENE from the gulf states to the mid-Atlantic/SE coast and strong low pres (in the nrn stream) plunging SE into/through the Great Lakes. This spacing will prevent phasing of the two air streams and any development of low pres invof E coast. Thus...there will be difficulty in pulling back higher pcpn rates inland (away from the coast). Lighter pcpn (inland) and marginal low thermal profiles will limit extent of SN mixing w/ RA. Will be hanging onto a slight slushy accum inland (less than 1/2 in)...primarily along a corridor from AVC/EMV on NE to SBY. Wet SN could mix w/ RA closer to the coast...esp later Fri night/early Sat as the moisture begins to retreat E. Given warm temperatures recently...and warm road temps...expect little impact from the SN. Pcpn...RA or RA/SN mix...gradually moves offshore by early Saturday afternoon...w/ a surge of colder air and partial clearing moving into the local area by Sat afternoon/evening. Temperatures average a few degs F blo normal tonight through Sat. Lows tonight in the around 30F far NW to the u30s/around 40F at the immediate coast in SE VA-NE NC. Highs Fri in the l-m40s. Lows Fri night from the u20s to m30s away from the Bay/Ocean to the u30s at the coast in SE VA-NE NC. Highs Sat in the m-u40s. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Long term period characterized by a broad (and amplifying) Eastern U.S. trough. In general, 12Z/06 suite of models, and their respective ensemble means, continue to be in good agreement with the overall setup. However, temporal/spatial differences remain and become greater later in the period. The period begins with deep/cold upper level low pressure centered over the NE CONUS Sat night/Sunday, with shortwave energy aloft brushing NE zones of the CWA. Cold Saturday night with temperatures most areas dropping well into the 20s. Partly cloudy except mostly cloudy NE where will have a ~20 PoP for snow showers. Flow becomes temporarily less amplified Sunday through Monday, with a slow moderation in temperatures starting Sunday night, under clear to partly cloudy skies. High temperatures Sunday only around 40-45 F (highest SE), with low temps Sunday night again mostly in the 20s (with some upper teens possible well inland). Highs Monday in the upper 40s NW to lower 50s SE. Next shortwave trough amplifies the flow Monday night through Tuesday, with the attendant Arctic cold front moving through the area late Tuesday/Tuesday night. This front is expected to be accompanied at least scattered showers, with enough low level warm air intrusion ahead of the system to keep the precipitation mainly in liquid form initially. Lows Monday night in the lower 30s, with highs Tuesday mid/upper 40s to lower 50s (SE). By Tue night into Wed, any lingering moisture will change to snow as much colder air moves in from the NW. This is period where the models diverge, the GFS developing sfc low pressure later and farther south than the ECWMF. Latest WPC guidance and model consensus will be followed for now, with a chance for snow into the forecast late tue night/wed morning, but not as high as what the 12Z GFS would suggest. Turning very cold Wed with highs only in the 30s. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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Frontal boundary remains (well) S and E of the local area through the 12Z/07 TAF forecast period. BKN-OVC VFR CIGS (mainly aoa 10kft) continuing. Area of -RA has settled just SE of NE NC. Winds mainly VRB blo 10 kt. The frontal boundary remains off the coast through Sat with a series of weak low pressure areas tracking ENE along it but remaining offshore. BKN-OVC CIGS/occasional pcpn expected at KORF/KECG...and possibly KPHF (by late) tonight/Fri. Pcpn may trend NWWD Fri afternoon/night and reach KRIC/KSBY. Pcpn...possibly as a mix of rain/snow...is expected to move offshore by 18Z Sat. VFR conditions are expected for the upcoming weekend after Saturday morning.
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&& .MARINE... The cold front that impacted the region yesterday has moved offshore and will remain nearly stationary off the coast through Saturday. Winds are expected to shift to the WNW at 10 to 15 knots and will continue through Thursday, before winds turn northerly as low pressure develops off the southeast coast Friday/Friday night. The consensus forecast still keeps low pressure not intensifying until it is well offshore Fri night through Sat, which means winds will generally remain below Small Craft Advisory criteria Friday through Saturday. Low end Small Craft conditions may be possible across the far southern VA and NC coastal waters Saturday, mainly due to 5 foot seas. Strong cold front passes through Sat night and SCA conditions look to prevail for all zones Sunday (potential for a few brief gusts to Gale force Sun morning). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...ALB/MPR NEAR TERM...ALB SHORT TERM...ALB/WRS LONG TERM...LKB AVIATION...ALB MARINE...AJB

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