Area Forecast Discussion
Issued by NWS Wakefield, VA

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633 FXUS61 KAKQ 231635 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1135 AM EST Mon Jan 23 2017 .SYNOPSIS... Low pressure will track from western North Carolina eastward across the Mid Atlantic region during today, then lifts northeast just off the northern Mid Atlantic and southern New England coasts tonight through Tuesday. The low will then move away from the New England coast Tuesday night into Wednesday, as high pressure builds into the area. A cold front will cross the region late Wednesday night into Thursday morning. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Latest GOES water vapor imagery centers anomalous upper level low pressure over the Carolinas. At the surface, associated ~990mb low pressure is centered over western North Carolina with a warm front extending eastward into southern Virginia. Ongoing overrunning precipitation has spread northward into central and northern Virginia, with lingering light precipitation across southern Virginia. Latest RAP/NAM12 isentropic surfaces are handling the area of precipitation well, with the brunt of the showers expected to continue to lift northward through late morning. Favorable mid level lapse rates, effective shear, and modest instability will result in a few rumbles of thunder in the strongest cells. Otherwise, anomalous precipitable water values and moisture flux (thanks to strong onshore flow around the northern periphery of the upper low) results in periods of moderate to locally heavy rainfall. Rainfall amounts through mid morning have generally been around one half inch, with localized amounts up to three quarters of an inch. Thanks to strong flow (showers are moving at 40-50 mph), no flooding threat is expected. The surface low pushes off the North Carolina coast mid to late afternoon as the upper low centers over the Mid-Atlantic region. Deepest moisture pushes northward along with the best moisture flux. Best chances for precipitation will push northward across the north to northeast forecast area by mid afternoon. Due to the potent upper low lifting into the region, expect scattered activity elsewhere, even with decreasing moisture. Limited elevated instability and favorable mid level lapse rates will keep a mention of thunder in the forecast. Locally heavy rainfall remains the greatest threat. Trended temperatures downward today, as temperatures will likely warm very little compared to current temps. Highs range from the upper 40`s northwest to mid 60`s southeast under a cloudy sky. NC. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... This evening thru Tue morning, the sfc low will lift NNE just off the Delmarva and NJ coasts as the upper low moves fm ern NC NE to off the MD/DE coast. This will result in more showers likely over ENE counties, with chc pops diminishing to slgt chc pops over the WSW counties. Lows tngt will range fm the upper 30s to mid 40s. Low pressure will finally move away off the New England coast late Tue aftn into Tue night. Thus, have lingered likely to slgt chc Pops for the Lower MD and VA ern shr, portions of the VA nrn Neck down into Hampton Roads and coastal NE NC into early Tue aftn. Lingered slgt chc/chc pops over ern Lower MD thru Tue aftn. But, should see increasing sunshine over WSW counties during Tue. Highs will range fm the upper 40s to the upper 50s. H5 ridge and sfc high pressure over the SE states builds into the area for Tue night into Wed aftn. Becoming clear or mostly clear Tue night with lows ranging fm the mid 30s to lower 40s. Partly to mostly sunny on Wed with highs ranging fm the upper 50s to mid 60s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A broad trough of low pressure will enter the region Wed night into Thursday as a sfc cold front slides into the area. The front is expected to cross the local area Thursday morning but just how much moisture it has to work with is still up in the air. The GFS is more bullish with pcpn compared to the ECMWF and would provide a better opportunity for meaningful rain areawide. The ECMWF is drier with any pcpn limited to far SE locations. Consensus is to lean closer to the drier ECMWF solution and therefore will have no higher than 30% PoPs Wed night/Thu morning. Lows Wed night in the 40s to near 50. Highs Thursday in the 50s. For Thursday night into next 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. The forecast looks to remain dry. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Strong low pressure will lift ENE acrs the Mid Atlc region and off the srn New England coast today thru Tue. Widespread IFR/LIFR conditions will continue over the area into early Tue morning. Off and on rain or showers will affect the region thru this time period with some heavy at times. During this aftn, improvement to VFR or MVFR can be expected ovr SE VA and NE NC, as drier air temporarily filters in to that area. Strong NE or E winds expected today, especially at SBY and ORF with gusts over 30 knots at SBY. OUTLOOK...The low moves away to the northeast during Tue with showers gradually ending acrs ENE counties. High pressure builds into the area for Tue evening into Wed. There will be a chance for showers Wed night into Thu with dry conditions expected for Thu aftn through Fri. && .MARINE... A complex low pressure system is centered over wrn NC early this morning, with a warm front off the NC Outer Banks. Pressure falls of -8mb/3hr have been observed over central NC as of 09z and this is expected to shift toward the VA/MD coast between 12-18z as low pressure becomes reorganized off the Mid-Atlantic coast. The combination of modestly strong pressure falls and a tight gradient will drive an E-NE wind of 20-25kt with gusts to around 30kt for the Bay and ocean S of Parramore Is. for a 3-6hr period this morning where SCA flags remain in effect. N of Parramore Is., the wind is expected to increase to 25-35kt with gusts to around 40kt for a 3- 6hr period this morning through midday with gale flags continuing. The rivers with the exception of the upper James should generally experience an E wind of 15-20kt with gusts to around 25kt this morning. The Sound may briefly have wind gusts to 20kt through 12z, but not for a long enough period to justify an SCA. Seas build to 8- 14ft N to 4-7ft S. The low stalls in vicinity of the NJ coast this aftn into tonight, and will be slow to lift to the NE Tuesday. Meanwhile, high pressure builds in from the NW. The wind become N-NW and increase to 15-25kt (gusts to ~30kt possible early Tuesday with the strongest pressure rises) for the Bay/ocean later tonight into Tuesday, with speeds averaging ~15kt for the rivers/Sound, with 20kt possible. A lull of less than 12 hrs is expected for the Bay so the SCA has been extended through Tuesday aftn. For the srn ocean zones the SCA has been extended through 06z Wednesday as seas will be slow to subside. 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. High pressure builds in from the W Thursday night into Friday. && .TIDES/COASTAL FLOODING...
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A high surf advisory remains in effect for the Maryland beaches and Accomack County today. Some minor beach erosion is expected. Low pressure pushes off the Delmarva coast late through midday today resulting in a brief but modestly strong onshore wind. This will push tidal anomalies to 1.5-3.0ft above normal today into tonight/Tue morn. Coastal locations from Wachapreague to Ocean City will reach minor flooding thresholds this afternoon, with areas from Chincoteague to Ocean City coming close to moderate flooding thresholds. Have added Accomack County to the coastal flood advisory for this afternoon. Portions of the middle and upper Bay will come within 0.5ft of minor flooding thresholds during the high tides through tonight.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...High Surf Advisory until 1 AM EST Tuesday for MDZ025. Coastal Flood Advisory until 7 PM EST this evening for MDZ024- 025. Wind Advisory until 1 PM EST this afternoon for MDZ021>025. NC...None. VA...Coastal Flood Advisory until 7 PM EST this evening for VAZ099. Wind Advisory until 1 PM EST this afternoon for VAZ099. High Surf Advisory until 7 PM EST this evening for VAZ099. MARINE...Small Craft Advisory until 1 PM EST this afternoon for ANZ635- 636. Small Craft Advisory until 4 PM EST Tuesday for ANZ630>632-634. Small Craft Advisory until 1 AM EST Wednesday for ANZ654-656- 658. Gale Warning until 4 PM EST this afternoon for ANZ650-652.
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&& $$ SYNOPSIS...TMG NEAR TERM...SAM SHORT TERM...TMG LONG TERM...JDM AVIATION...TMG MARINE...AJZ/JDM TIDES/COASTAL FLOODING...AKQ

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