Area Forecast Discussion
Issued by NWS Wakefield, VA

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231 FXUS61 KAKQ 221649 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1149 AM EST Sun Jan 22 2017 .SYNOPSIS... One area of low pressure will track from eastern North Carolina northeast and off the Delmarva coast during today. A second stronger area of low pressure over the Lower Mississippi Valley will lift east northeast and across the Mid Atlantic region tonight through Monday night. That low will move away just off the New England coast during Tuesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... More adjustments needed to the grids this afternoon. Moisture associated with a s/w to the south has dissipated as it moved north past few hours. Meanwhile, region remains wedged in with ovc skies, areas of fog/drizzle. Weak disturbance across the mts will slowly drift east this afternoon enhancing the rainfall threat a bit. Thus, forecast will reflect a damp afternoon ahead with light rain/drizzle/fog likely. Not much movement in temps expected so lower mins even further. Highs generally in the low-mid 50s except some upr 50s to near 60 across NE NC zones late. After looking at some of the 12Z data, went ahead and dropped thunder chcs through 03Z. Any thunder chcs look to be late this evening through the overnight hours as the associated stacked low and associated warm front approach the area. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... The second area of low pressure will then lift fm ESE TN east northeast and acrs the Mid Atlc region tonight thru Mon night. This low and its associated warm front will provide strong lift and pull in deeper Atlc moisture, resulting in showers (slgt chc of tstms srn third) with heavy downpours possible tonight into Mon morning. Lows in the upper 40s to lower 50s. QPF averages between 0.5 inch to 1 inch with locally higher amounts possible in any banded convection that may occur. Sfc triple point progged to move north of the area Mon morning with the trailing upr level low crossing the region Mon aftn into early Tue morning. Pops will still range fm slght chc to likely fm later Mon morning into early Tue morning, as the upper level low slowly moves NE acrs the area to just off the NJ coast. Highs on Mon will range fm the mid 50s to the mid 60s. The low moves away just off the New England coast during Tue. NW winds usher in drier air with increasing sunshine fm SW to NE expected. Highs in the 50s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Overall, the models are in good agreement in the extended period with only a few minor differences on the timing of the frontal passage on Wed night into Thursday. But those differences are minor and the 12z GFS has moved closer to the 00z ECMWF. In the wake of the storm that will move through by Tuesday, a shortwave ridge builds in Tues night into Wednesday. This will allow for W to SW flow and should be a mild dry period. However, the upper level pattern will begin to flip with a broad trough developing over the eastern half of the country for the second half of the week. This trough will enter the region Wed night into Thursday as a sfc cold front slides into the area. This front will be lacking moisture so have limited the pops to slight chance to chance range. The best opportunity for rain looks to be in the southeastern part of the area where a little additional Atlantic moisture may be available. The timing on the front is still a little up in the air. The ECMWF moves the boundary through more quickly, while the GFS develops a wave and is slower. But the trend has been toward the ECMWF timing so focused the highest chance on Thursday. Will also need to watch the timing on the cold air arrival as well as this could impact the pcpn type, but for now don`t think the cold air will arrive until after any pcpn is gone. For Thursday night into Saturday, the region will be dominated by strong NW flow which will drop temperatures back down into the 40s for highs and lows in the upper 20s to low 30s. Have kept the fcst dry too, but will have to monitor shortwaves rotating through the upper trough as with this polar airmass, if one of these waves amplifies a bit, some snow showers would not be out of the realm of possibility. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... A complex upper level trough is affecting much of the Southeastern Conus and Mid-Atlantic early this morning. One wave of low pressure is passing off the VA capes as of 06z with an area of rain extending from central VA to the Ern Shore, with some lingering showers across coastal SE VA/NE NC. IFR/LIFR cigs prevail, although the lower cigs occasionally scatter and reveal a 1.5-2.5kft layer, and this trend of lower cigs occasionally scattering should continue the next 6-9 hours. Some improvement in cigs is possible by aftn, but should fall again tonight. Vsby drops to 1-3sm in heavier rain, with some fog developing at ECG, which could expand to RIC/PHF after 09z. Another wave of low pressure will bring occasional showers by midday into early aftn, with the main frontal system lifting across the region tonight into early Monday morning bringing periods of moderate to heavy rain and reduced vsby. The wind will generally be E to NE at 5-10kt today into this evening, and is expected to increase to 10-15kt (locally 15-25kt at SBY) late tonight into early Monday morning. The upper system will lift across the area Monday aftn bringing another chc of showers. Drier air gradually returns Monday night into Tuesday as high pressure builds in from the NW. Low pressure tracks through the Great Lakes Wednesday, and pulls a cold front through the area later Wednesday night into early Thursday. This will bring a chc of rain, before drier air arrives from the NW later Thursday. && .MARINE... A complex low pressure system extends from the Gulf Coast States across the Carolinas and into the Mid-Atlantic early this morning. One individual wave of low pressure is pushing off the VA Capes coast early this morning, with a stationary front extending back into central NC. The wind is generally NNE 10-15kt N of the boundary and SW 5-10kt S of the boundary. (Near) Coastal obs indicate vsby of 1sm or less S of Cape Henry, so the marine dense fog advisory has been extended through 10 am for the ocean S of Cape Charles and the Currituck Sound. Another wave of low pressure will track along the front today, with the primary low tracking newd across the area late tonight through midday Monday. A strong pressure gradient and modest pressure falls develop late tonight through midday Monday and will be strongest N of Cape Henry, and especially for the ocean N of Parramore Island. The SCA N of Parramore Is. has been upgraded to a gale warning for and E-NE wind of 25-35kt with gusts to around 40kt, with the SCA to the S extending through Monday night as seas remain aob 5ft. Seas build to 8-12ft N to 4-7ft S Monday in response to the period of strongest wind. SCA flags have been issued for the Bay/Lower James/York/Rappahannock. The wind will be strongest in the Bay N of New Point Comfort, and low-end gale gusts are possible N of Windmill Point. The low stalls in vicinity of the NJ coast Monday aftn into Monday night as high pressure builds in from the NW. The wind should by NW 10-15kt/15-20kt ocean. High pressure gradually builds into the region Tuesday night and slides offshore Wednesday ahead of a cold front. This cold front crosses the coast later Wednesday night into early Thursday. && .TIDES/COASTAL FLOODING... Low pressure pushes off the Delmarva coast late Sunday night through midday Monday resulting in a brief but modestly strong onshore wind. This has the potential to push tidal anomalies to 1.5-2.5ft above normal Monday into Monday night. Some locations including the Atlantic coast from Chincoteague to Ocean City and portions of the middle and upper Bay may come within 0.5ft of minor flooding thresholds during high tide, but the current forecast generally keeps water levels below minor flooding. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 4 AM to 10 AM EST Monday for ANZ635- 636. Dense Fog Advisory until 1 PM EST this afternoon for ANZ632>634-637-638-656-658. Small Craft Advisory from 1 AM to 1 PM EST Monday for ANZ630- 631-634. Small Craft Advisory from 1 AM to 10 AM EST Monday for ANZ632. Small Craft Advisory from 1 AM to 7 AM EST Monday for ANZ638. Small Craft Advisory from 1 AM Monday to 6 AM EST Tuesday for ANZ654-656-658. Gale Warning from 1 AM to 1 PM EST Monday for ANZ650-652. && $$ SYNOPSIS...TMG NEAR TERM...MPR SHORT TERM...MPR/TMG LONG TERM...ESS AVIATION...AJZ MARINE...AJZ TIDES/COASTAL FLOODING...

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