Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 241825 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 225 PM EDT Mon Oct 24 2016 .SYNOPSIS... Low pressure pushes off the southern New england coast early this morning, pushing a dry cold front through the local area late this morning and afternoon. Cool Canadian high pressure builds in from the northwest tonight through midweek. Low pressure will track northeast through Great Lakes Thursday and Thursday night. && .NEAR TERM /THROUGH TONIGHT/... The current surface analysis shows ~1027 mb high pressure centered along the Gulf coast. To the north, ~988mb low pressure was noted over eastern Canada...with an open wave pushing e of Cape Cod. The associated sfc cold front extends WSW of this system back into the OH Valley, with a sfc trough also in place to the lee of the Appalachians. Low-level sw flow ahead of this system is resulting in a mild morning, with temperatures in the low/mid 60s as of 10 am. The trough and associated low pull offshore later this morning with the trailing cold front pushing through the area during the aftn. The frontal passage will be dry and produce deep mixing, and caa will be delayed until tonight with downslope flow. This will allow for slightly warmer temperatures today with highs ranging from from the low to mid 70s under a mostly sunny sky, with some sct aftn cu (mainly e of i-95). 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 F. Not expecting much more than patchy frost over the piedmont. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... Sunny and much cooler on Tuesday as models remain in good agreement with strong/ 1032mb+ high pressure centered over the Great Lakes and ridging SE into the Carolinas. N/NW low level wind flow and NAM/GFS 850mb temperatures plummeting to -1 C over the MD eastern shore would only support high in the mid- upper 50s there, with highs near 60 F/lower 60s across interior VA/NC (850mb temps of +3 to +5C). The high continues to build in from the NNW Tuesday night. This appears to be the coldest night through midweek (and probably of the season so far, with lows ranging from the mid/upper 30s over much of the CWA (with the potential for a light freeze in a few of the coldest spots in the Piedmont), with low/mid 40s near the immediate coast. This will bring the potential for frost except along the coast. One thing that could keep temperatures a little warmer is that the models continue to show modest mid-level 700-850 mb WAA, which could result in some clouds (mainly W). If this were to occur, the potential for frost would be lower. Continued cool Wednesday under a partly to mostly sunny sky with highs in the upper 50s N, to low 60s S. There is the potential for highs to hold in the 50s CWA-wide if more clouds do develop. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A series of northern stream disturbances will impact the region through the extended period. The first developing upper trough will drop over the Great Lakes Wednesday night and Thursday, pushing a cold front into the Mid Atlantic region Thursday afternoon. Moisture return will be limited in west to southwest flow aloft, with precipitable waters progged around one inch. Best dynamics also expected to pass north of the region, but sufficient height falls and winds aloft will provide forcing for ascent along the cold front for chance to solid chance POPs south to north across the forecast area on Thursday...with lingering chc pops Thursday night. Highs Thursday range from the low 60`s northwest to upper 60`s southeast under a partly cloudy to mostly cloudy sky. High pressure builds into the region Friday for dry wx all areas. Highs generally in the mid to upper 60`s. Confidence decreases thereafter as medium range guidance struggles to handle the evolution of the next northern stream disturbance. GFS is generally more progressive with the late week system, pushing it quickly offshore Friday night/Saturday. ECMWF suggests cyclonic flow will linger over the Northeast into Saturday. The main difference becomes the next trough that will impact the region late in the weekend into early next week. The associated cold front will impact the region late weekend into early next week. For now, will introduce chances for precip Saturday/Saturday night across the north to northeast forecast area. Saturday looks to be the warmest day with highs in the upper 60`s to around 70. Highs Sunday generally in the mid to upper 60`s. Mild overnights are forecast Thursday night through Saturday night, with lows generally in the mid/upper 40`s to low 50`s. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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A cold front is located along a line near CHO-SBY as of 18z. This front will continue to push to the se through the aftn. The frontal passage will be dry, and mainly result in a wind shift from w to nw along with occasional wind gusts up to 20kt. Expect sct cu ~5kft at SBY this aftn, with a brief period of few-sct cu across se VA late this aftn/early evening. 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. Dry and VFR conditions are expected through Wednesday. 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.
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&& .MARINE... As of 10 AM... Latest observations indicate a west wind of 15 to 20 knots over the waters late this morning. While marginal SCA conditions are observed in the Bay, speeds have dropped at or below 15 knots in the lower James river and the Currituck Sound. Have opted to cancel those SCA headlines early. Still anticipate a lull in SCA conditions for the waters this afternoon, before northwest winds ramp up late today and tonight. Previous Discussion... SCA conditions will continue for much of the marine area this morning with SW-W winds of 15-25kt. Pressure gradient relaxes briefly late this morning into mid-afternoon as a cold front approaches and then crosses the waters. Expect another northwest surge late this afternoon through tonight with a NW-N wind of 15 to 25 knots. Winds expected to remain below SCA levels on the rivers with the second surge but may briefly reach 15-20 kt on the Currituck Sound. Due to low confidence will not extend SCA for the Sound past Noon at this time. Seas 3-5 feet (up to 6 ft southern outer waters tonight). Waves 2-4 feet. Seas will linger AOA 5 ft across the southern waters thru Tuesday morning so have extended SCA for the southern waters until 1 pm Tuesday. High pressure builds in from the northwest Tuesday, with sub-SCA conditions expected through mid week. The next cold front pushes across the waters on Thursday. && .TIDES/COASTAL FLOODING... West winds have resulted in negative tidal departures in the middle to lower Chesapeake Bay and the Atlantic coastline this morning. Water levels of -0.8 to -1.2 feet MLLW are expected during low tide cycles late this morning into early afternoon. Low water advisories are in effect for the lower Bay, James and York Rivers, and the coastal waters off the Virginia Eastern Shore. Tidal anomalies will begin to rebound this afternoon and tonight as winds become northwest. No additional low water conditions are anticipated. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...None. NC...None. VA...None. MARINE...Low Water Advisory until 4 PM EDT this afternoon for ANZ637. Small Craft Advisory until 10 AM EDT Tuesday for ANZ630>632- 634-650-652-654. Small Craft Advisory from 7 PM this evening to 10 AM EDT Tuesday for ANZ633. Small Craft Advisory from 7 PM this evening to 7 AM EDT Tuesday for ANZ638. Small Craft Advisory until 1 PM EDT Tuesday for ANZ656-658.
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&& $$ SYNOPSIS...LKB NEAR TERM...AJZ/LKB SHORT TERM...AJZ/LKB LONG TERM...SAM AVIATION...AJZ/LKB MARINE...JDM TIDES/COASTAL FLOODING... is the U.S. government's official web portal to all federal, state and local government web resources and services.