Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 221801 AFDAKQ Area Forecast Discussion National Weather Service WAKEFIELD VA 201 PM EDT Wed Mar 22 2017 .SYNOPSIS... Canadian high pressure builds in from the north this afternoon into Thursday...then drifts offshore and settles off the Southeast Coast Friday into Saturday. Low pressure approaches from the west Sunday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update... Temperatures are proving to be pesky with variable warming/cooling by a degree or two with each passing hour depending on wind speeds versus daytime heating versus cooler Canadian air moving into the region from the north. Attempted to capture the trends with temps either remaining steady or falling a few degrees into this aftn when peak heating typically occurs. Clouds along/south of the VA/NC border have been slower to exit the area with sfc low pressure well SE of Cape Hatteras early this aftn. Made adjustments to cloud cover in these areas, otherwise sunny skies for the rest of today across cntrl/ern VA and the MD/VA Eastern Shore. Previous discussion... Current WV imagery depicts a shortwave trough tracking off the Carolina Coast with radar imagery showing some bands of light showers or sprinkles across SE VA/NE NC. This activity should exit the area around 13z/9 AM. A cold front is entering nrn VA/NE MD as of 11z/7 AM. Temperatures ahead of the front are in the upper 40s to low 50s, and even rise a few degrees with mixing associated with the front. Drier/cooler air arrives later this morning in the wake of the front with a gusty NNW wind as 1036mb high pressure builds from the Great Lakes into the nrn Mid Atlantic. Temperatures drop to the upper 30s/low 40s N behind the front, and should remain in the upper 40s/around 50 S. Temperatures then remain steady or only rise ~5F today with strong CAA with aftn highs ranging from the mid/upper 40s across the Ern Shore to the low/mid 50s farther inland; cloud cover quickly decreasing from NW-SE this morning. A NNW wind will increase to 15-25mph with gusts up to 30-35mph and 35-40mph along the coastlines. Min RH values today range from 18-25% across the Piedmont to ecntrl VA, 25-35% across the Ern Shore/interior NE NC, and 30-40% for far SE VA/coastal NE NC. The combination of stronger winds and lower RH will be maximized over the Ern Shore, however this should be offset by near to above normal rainfall over the past 2 weeks. Therefore, dry/windy conditions will just be highlighted in the FWF. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... 1038mb high pressure becomes centered from central PA to nrn VA tonight, with some pressure gradient/weak CAA lingering near the coast. Mostly clear and colder with lows ranging from the low 20s across the N to the upper 20s/around 30 for coastal SE VA/NE NC. These values are generally 10-15F below seasonal averages. The high becomes centered over the region Thursday and remains ~1036mb. Mostly sunny and cool with highs ranging from the low/mid 40s over the Ern Shore to the upper 40s/around 50F farther inland. High pressure remains centered in vicinity of the coast at least through 06z Friday, before beginning to shift offshore. Mostly clear Thursday evening with increasing high clouds late as WAA commences aloft. Temperatures should drop quickly Thursday evening, before becoming steady or even rising a few degrees across the Piedmont. Forecast low temperatures range from the upper 20s/around 30 across the Ern Shore and coastal plain, to the low 30s for coastal SE VA/NE NC and the Piedmont. A warm front aloft will lift through the region Friday, with the best frontal forcing and any associated showers well N of the local area. Partly sunny N to mostly sunny S and milder with highs ranging from the mid/upper 50s across the Ern Shore, to the low 60s along the RN shore of the Bay to the mid 60s along and W of the I-95 corridor. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Dry and mild conditions to start off the weekend as offshore ridge keeps pcpn west of mts through at least 04Z Sun. Lows Fri night 45-50. Highs Saturday in the mid-upr 60s along the coast, lwr-mid 70s west of the Ches Bay. Moisture increases ahead of an approaching frontal boundary Saturday night. Low chc pops after midnight with lows in the upr 40s to lwr 50s. Low pressure and associated frontal boundaries progged to track over the region Sunday. Key to any thunder chcs will be location of warm front, which is progged across the northern portions of the FA. GFS suggests best support for pcpn will be north of the boundary but will err on side of caution and keep likely pops across the north and west with chc pops south and east. Will also limit thunder chcs to the southern half of FA. Highs in the 60s north to lwr 70s south. Low slowly tracks towards the coast by 12Z Monday keeping chc to likely pops going Sunday night. Lows in the mid 40s north to lwr 50s south. Moisture lingers Monday/Tuesday as it gets trapped under high prs to the north along with weak disturbances moving east across the rgn. Chc pops with highs Monday from near 60 across the Eastern Shore to around 70 south. Lows in the 40s. Highs Tuesday in the 50s across the eastern shore to the upr 60s across the south. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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Low pressure now well off the coast with strong high pressure centered over the Great Lakes. The pressure gradient remains strong and N to NW winds avg 15-20 kt with gusts to 25-30 kt at all TAF sites. Skies have become mainly clear and this will continue through the 18Z TAF period (VFR conditions). As the high pressure system builds into the region this evening into tonight and settles over the region Thursday, winds will diminish (though will stay somewhat elevated near the coast tonight). Much lighter winds Thu (mainly 10 kt or less). The high settles off the coast Friday into Saturday, allowing winds to shift around to the SSW with VFR conditions to persist. Showers will be possible later Sunday as low pressure approaches from the W.
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&& .MARINE... A strong north to northwest surge is ongoing this morning as a secondary cold front now pushing south of the region. Winds avg north at 25-30 kt with gusts to 35-40 kt over the Bay and coastal waters, with gusts to 35 kt in the the lower James so have added the lower James to the Gale Warning headlines. Maintaining SCA headlines for the remainder of the rivers with gusts genly < 34 Kt. This scenario thanks to strong pressure rises and strong boundary layer winds. Low pressure slides off the Southeast coast today as strong Canadian high pressure builds southwestward into the Ohio Valley. Cold air advection wanes by aftn, but strong pressure rises on the order of 6-9mb in 6 hours and low level winds around 35 knots will keep gale conditions ongoing. Low level winds begin to subside through the afternoon, with gale conditions diminishing to SCA in the Bay. Coastal waters and the Currituck sound remain under gale headlines through early this evening. Seas build to 5-9 feet (highest southern coastal waters) this afternoon, with waves of 4-6 feet. SCA conditions persist through the overnight period as high pressure slowly builds southward over the region. High pressure settles over the waters Thursday morning, with winds becoming north to northeast at or below 15 knots. Seas diminish north to south Thursday morning, finally dropping below 5 feet in the southern coastal waters Thursday afternoon. High pressure slides offshore Thursday night with flow becoming southwest Friday. Speeds increase to 15-20 knots Friday afternoon as a storm system develops over the Midwest. The next front crosses the waters early next week. && .EQUIPMENT... Radar KDOX remains inoperable due to a bad spectrum filter. Part is on order and estimated (though possibly unstable) return to service is Wednesday, March 22nd. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...High Surf Advisory until 7 PM EDT this evening for NCZ102. VA...None. MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ635>637. Gale Warning until 4 PM EDT this afternoon for ANZ630>632-634- 638. Gale Warning until 7 PM EDT this evening for ANZ633-650-652- 654-656-658. && $$ SYNOPSIS...AJZ NEAR TERM...AJZ/BMD SHORT TERM...AJZ LONG TERM...MPR AVIATION...LKB MARINE...LKB/SAM EQUIPMENT...AKQ is the U.S. government's official web portal to all federal, state and local government web resources and services.