Area Forecast Discussion
Issued by NWS Wakefield, VA

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019 FXUS61 KAKQ 250057 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 857 PM EDT Mon Oct 24 2016 .SYNOPSIS... Cool Canadian high pressure builds in from the northwest tonight and remains over the region through Wednesday. A cold front approaches from the northwest Thursday morning and crosses the area during the afternoon and evening. High pressure returns Friday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Afternoon forecast in excellent shape. Cold front moving southward into the southern part of the region at 0045Z...and will continue southward this evening. Temps fell quickly around sunset, but have slowed their drop off as winds continue to provide some mixing, and cold air advection lagging surface front. Temps should get close to forecast mins, but may not do so until the 11Z-12Z time frame. Made minor adjustments to hourly temps and clouds near the bay, as latest guidance not as bullish on bay streamer developing. ...Previous Discussion...The current surface analysis depicts a cold front pushing through VA and the Delmarva this afternoon. Temperatures ahead of the front have climbed into the low/mid 70s, and should remain steady later this aftn as downslope nw flow will delay caa until this evening. The frontal passage will be dry, with sct cu, mainly across ne portions of the area. 1032mb high pressure will gradually build in from the nw tonight. There should be enough mixing tonight with caa to keep lows generally in the low/mid 40s (upper 40s se). However, the piedmont could decouple late, which will allow lows to fall into the upper 30s to around 40 under a clear sky. Localized cloud cover is possible over the Lower Ern Shore and coastal se VA late as a bay streamer potentially develops.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Sunny (outside of any streamers along the coast in the morning) and cooler Tuesday as caa continues, especially across the ne half of the area. 850mb temperatures drop to 0 to -2C across the ne Tuesday aftn, with 0-4C farther sw. This will result in highs ranging from the mid/upper 50s nw, to the low 60s across interior VA/NC. The high continues to build in from the nnw Tuesday night. This appears to be the coldest night through midweek (and probably so far this season), with lows ranging from the mid/upper 30s over much of the area, to the low/mid 40s for coastal se VA/ne NC. This will bring the potential for frost except along the coast. Some modest mid-level (700-850mb) waa is expected to commence late Tuesday night, which could result in some clouds (mainly w). The potential for frost will be less if this does occur. Continued cool Wednesday under a partly to mostly sunny sky with highs in the mid/upper 50s ne, to low 60s sw. There is the potential for highs to hold in the 50s for much of the area if more cloud cover develops. Shortwave energy will lift through the Great Lakes Wednesday night into Thursday morning, with the trailing cold front approaching from the nw Thursday aftn. Milder Wednesday night with lows generally in the 40s across the area, with low 50s se with increasing clouds from w-e late. Clouds continue to increase Thursday with much of the area becoming mostly cloudy to overcast. Chc PoPs (30-50%) for showers spread across the nrn 2/3rds of the area by afternoon. Moisture is limited with this system, so current QPF through 00z Friday is aob 0.1". Highs Thursday range from the low 60s nw to near 70 se. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Cold front forecast to push across the forecast area to begin the extended period Thursday night. Best dynamics associated with a potent shortwave trough progged to push across the Northeast Thursday night, with modest height falls and moisture return expected over the forecast area. Best chances for showers will be across the northeast forecast area, tapering off to low end chance south and west due to limited moisture/dynamics. The front quickly pushes offshore late Thursday night as high pressure builds in from the west for Friday. Dry with highs generally in the mid to upper 60`s. The next in a series of northern stream disturbances drops across the Great Lakes Friday night and into the Northeast states Saturday. GFS and CMC drop a cold front into the region Saturday and across the region Saturday night. However, the ECMWF is flatter with the shortwave and doesn`t push a front through the region until Sunday night. Will carry a slight chance to low end chance POP`s across the northern forecast area Saturday and along the coast Saturday night, but confidence is not high (hence low POP`s). Highs Saturday expected to push into the low to mid 70`s. Differences in frontal timing will have a drastic impact on temperatures Sunday, and possibly Monday. Have opted for a blend of the guidance until better agreement can be made. Highs Sunday and Monday are forecast in the 60`s. Will keep POP`s silent Sunday and Monday as any frontal boundary will likely be dry. Lows generally in the 40`s to low 50`s through the period. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... Dry and VFR conditions are expected through Wednesday. Reinforcing cold front moving southward into southern portions of the area as of 23z. Other than a few mid clouds, the frontal passage will be dry, and mainly result in a wind shift to the north, along with occasional wind gusts up to 20kt. The wind becomes more northerly overnight as caa begins and this could result in a bay streamer, which could produce sct- bkn cloud cover around 3-4kft at ORF late tonight into Tuesday morning. Latest hi- res guidance has backed off on this potential. Fog and/or low clouds are possible Thursday morning as high pressure moves off the coast and moisture increases over the area. Another cold front crosses the area Thursday/Thursday evening bringing a chance of showers. Dry weather and high pressure return for Friday. && .MARINE... Latest surface analysis depicts a cold front splitting the waters this afternoon. The parent low is centered over southeast Canada, with high pressure building southward into the upper Midwest. A brief lull in SCA conditions is observed over the waters this afternoon with west to northwest winds at or below 15 knots. Waves generally 1-2 feet and seas 2-3 feet. Cold front drops south of the waters late today, with a quick ramp up in north to northwest winds between 6pm and 8pm. Expect north to northwest winds of 15 to 25 knots. Strongest gusts expected a few hours either side of 11pm for the Bay and northern coastal waters with 30 knot gusts expected. Gusts taper off to 25 knots late tonight. Waves increase to 3-4 feet and seas 4-5 feet. Seas could reach 6 feet 20nm out. SCA headlines are in effect for all waters expect the upper James, York, and Rappahannock Rivers. High pressure nudges over the waters late tonight with the gradient expected to weaken shortly after daybreak. Sub-SCA conditions return to the lower James by 7am, the Sound by 10am, and the Bay and coastal waters by early afternoon. Expect a northwest wind of 10 to 20 knots Tuesday afternoon. High pressure prevails over the waters Wednesday with a north wind at or below 10 knots. Waves 1-2 feet and seas 2-3 feet. High pressure slides offshore Wednesday night and Thursday ahead of the next cold front. Flow becomes southerly and increases to 10-20 knots Thursday ahead of the front. Cold front drops across the waters Thursday night with another period of SCA conditions possible. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 PM EDT Tuesday for ANZ630>632-634- 650-652-654-656-658. Small Craft Advisory until 10 AM EDT Tuesday for ANZ633. Small Craft Advisory until 7 AM EDT Tuesday for ANZ638. && $$ SYNOPSIS...AJZ/LKB NEAR TERM...AJZ/WRS SHORT TERM...AJZ/LKB LONG TERM...SAM AVIATION...AJZ/WRS MARINE...SAM is the U.S. government's official web portal to all federal, state and local government web resources and services.