Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 150853 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 353 AM EST Fri Dec 15 2017 .SYNOPSIS...
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High pressure retreats to a position off the New England coast today. Meanwhile, low pressure develops just off the coast this afternoon, then tracks northeast and away from the area tonight. High pressure returns for the weekend.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Sfc high pressure centered over the Delmarva this morning will gets squeezed to the NE today as low pressure and an upper trough pivot through the Great Lakes. Meanwhile, a weak wave of low pressure is expected to develop invof the northern OBX by mid to late morning, then quickly track NE off the mid-Atlantic coast late this afternoon and evening. Latest guidance brings a swath of moisture across the northern tier of the FA around midday, then over the Eastern Shore this afternoon and early evening before exiting the coast by 10 pm. Some enhancement of the moisture is noted by the latest hi-res guidance with support from the 00Z suite of models this aftn/eve as it crosses the Eastern shore, particularly across northern Dorchester County. Bufkit soundings suggest about a 3-5 hour period of pcpn between 18Z-00Z with pcpn possibly lingering near OXB thru about 02Z Sat. Have slight chc PoPs (~20%) north of RIC late this morning/midday, then increasing to likely/categorical (55-80%) over the MD Eastern Shore this afternoon. Otherwise, dry south of I-64. Thermal profiles suggest mainly snow across Dorchester County, with a buffer area of a rain/snow mix to snow across Caroline County, the Northern Neck, and the rest of the interior lower MD Eastern Shore. Most likely it`s just plain rain along the MD coast, mixing with or changing to snow briefly before ending. Sfc temps will primarily remain above freezing during the event, limiting snow accumulations before falling by sunset. For that reason, kept snow accumulations limited to the lower MD Eastern Shore. Generally under one-half inch expected, but with highest amounts up to ~1" possible across northern Dorchester County. In coordination with neighboring offices, will not be issuing a Winter Wx Advisory at this time due to minimal snow accumulations and temps AOA freezing. However, timing of the heaviest snowfall will occur around the late aftn/eve commute so motorists should be prepared to take necessary precautions. Highs today mid-upr 30s north to low mid 50s NE NC.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
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Any lingering snow shower push of the MD coast by late eve with decreasing from west to east. Lows mid 20s NW to lwr 30s SE. High pressure builds over the sern states Sat then moves offshore Sun. Dry through this period. Highs Sat in the mid-upr 40s. Lows Sat night mid 20s NW-mid 30s SE. Highs Sun upr 40s N to mid 50s S.
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&& .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A welcomed return to south-southwesterly flow on Sunday will bump temperatures into the middle 50s. High pressure slowly meanders offshore to the east on Sunday night and into Monday, allowing for an uptick in moisture advection across the south. The European is beginning to lean towards a drier, GFS-like solution for Monday. Better chances for measurable rainfall exist across our NC counties and extreme southeastern VA Monday aft/eve. Temperatures during the day will rise into the upper 50s, so no worries about any wintry precip. Tuesday`s temps will strive for the low 60s in the afternoon, with one caveat being cloud cover. The GFS and EURO begin to disagree during this timeframe, with the EURO being much drier at the mid levels than the GFS. As such, the GFS is more bullish on cloud cover and rain chances Tuesday afternoon and evening. Leaned more towards the EURO solution, trimming back PoPs Tuesday...will wait for better model agreement to increase confidence on Tuesday being any drier than currently forecast. The spigot abruptly shuts off early Wednesday morning as any moisture slides off the coast. Expect highs Wednesday and Thursday to be 7-10 degrees cooler than Tuesday. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... High pressure moves off the coast during today and a coastal low pressure system passes offshore of the region this afternoon/evening. Precipitation is expected to develop mainly after 18Z and impact primarily SBY/Eastern Shore. The precipitation will most likely be in the form of snow at SBY, bringing the potential for MVFR TO IFR CIGS/VSBYS between 18Z and 00Z. MVFR CIGS will also be possible between 18Z and 00Z at ORF and PHF. Outlook: The coastal low pressure system moves well offshore Friday night and high pressure builds back into the area for the weekend. VFR conditions are expected through the weekend before a weak disturbance potentially impacts the region on Monday. && .MARINE... Coastal low continues to exit into the western Atlantic while weak high pressure over the Ohio Valley continues to slide east and will be over the waters tonight into Early Friday. The next system will be a wave of low pressure that slides off the Carolina Coast and deepens quickly Friday afternoon. Expect an increase in winds across the southern waters late in the day, getting close to SCA levels late in the day for the southern bay and coastal waters. With the values being marginal SCA values of around 20 KT in the Bay and gust to 25 kt over the coastal waters, will not raise the SCA flag yet. But the model trend has been gradually getting stronger with this system and if that trend continues the SCA will be needed. Behind this wave, cold advection will increase after 6z on Sat through about 18z, which should cause more sca level winds, especially in the northern coastal waters. High pressure moves back over the area late Saturday afternoon and will remain in control of the regions weather through the weekend. This will allow for a period of light winds, going from a northerly direct Sat night to a southwest direction by Sunday afternoon. Winds will remain light on Monday, but expect a strong increase on Tuesday as a frontal boundary and developing surface low approach the area, followed by another shot of cold air for the midweek time frame. && .CLIMATE... Went w/ MM for high temp Thursday at RIC. Climate focal point looking into potential of erroneous temps. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM/MPR LONG TERM...AJB AVIATION...AJB/JDM MARINE...ESS CLIMATE...AKQ

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