Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 201740 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 140 PM EDT WED JUL 20 2016 .SYNOPSIS... Weak cold front drops over the area this morning, stalling over North Carolina today. The front dissipates tonight as high pressure builds over the region. High pressure prevails through the weekend. && .NEAR TERM /THROUGH TONIGHT/... Latest surface analysis depicts a cold front just to the north and west of the local area with high pressure over the Great Lakes. Earlier shower/thunderstorm activity has diminished, but a shortwave dropping over the region may help enhance some showers over the Northern Neck early this morning in an area of elevated instability. Will maintain isolated to widely scattered showers from the Northern Neck to the Maryland Eastern shore. Elsewhere, only isolated showers linger over the southern Piedmont into south central Virginia. Showers expected to dissipate by daybreak as the wave drops into North Carolina. Guidance still hinting at patchy fog early this morning, but has not been verifying thus far. Will keep mention inland due to moist air mass. Diffuse frontal boundary expected to drop into the southern forecast area late this morning. Dry conditions expected to persist through the morning hours. Any morning fog quickly burns off by 8am. A weak convergence boundary is expected along the coast this afternoon with onshore flow. The diffuse boundary across southeast Virginia/northeast North Carolina and along the Eastern Shore will provide a focus for isolated to scattered showers and thunderstorms as weak waves drop over the region in northwesterly flow aloft. SPC maintains a marginal risk for severe weather across northeast North Carolina due to steep low level lapse rates and better boundary layer moisture. High`s generally in the mid 80`s today under a generally partly cloudy sky. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... Anomalous upper trough over the nations mid section continues to build eastward Thursday and Friday. Upper level trough remains over the western Atlantic. High pressure slides off the coast Thursday with onshore flow suppressing the heat for one more day. Similar thicknesses and low level temps to today will result in highs back in the mid to upper 80`s. Dry with a mostly sunny sky. Lows Thursday night in the upper 60`s to low 70`s under a mostly clear sky. The upper ridge expands eastward Friday, with 850mb temperatures of 22C (+2 standard deviations) reaching the Piedmont. High`s forecast in the low to mid 90`s, just slightly above normal. A southwest wind around 10 mph will help mix dewpoints into the mid 60`s, resulting in heat index values in the mid to upper 90`s. Pressure falls along the lee side of the mountains will sharpen a thermal trough over the Piedmont, but a lack of moisture and appreciable forcing results in silent POP`s. However, will see more afternoon cumulus. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Long term period will feature mainly dry conditions and above normal temps. For Friday night/Saturday, dry wx expected as surface high pressure stays off the se coast and a broad upper-level ridge slides east into the eastern Conus. Cannot rule out an aftn/eveng shra/tstm, but chance for rain is less than 20%. Very similar conditions for Sun with a weak thermal trough over the Mid Atlc and weak zonal flow aloft. Expect hi temps in the mid/upr 90s both days, and with dewpoints in the lo/mid 70s, aftn heat indices will reach near 105F (heat advsry criteria). Temps a bit lower for Mon/Tue...but still hot with highs in the 90s. Mainly climatological PoPs (20-30%) in the aftn/eveng. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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Isolated showers had developed along the sea breeze as of 18z over the lower portion of Eastern Shore and the Peninsula moving into the james River. These showers have remained clear of the TAF sites. The CU field was expanding across the entire region and periods of SCT- BKN ceilings between 3-4 kft can be expected at all TAF sites through 00Z. Showers activity and possible a few storms should remain confined to the sea breeze and could come close to SBY...ORF and ECG late afternoon and early evening. Expect VFR conditions to prevail though this afternoon and evening. Overnight some patchy fog is possible, but not likely. Do not restrictions at the TAFs site overnight. The only exception could be ORF where some models try to develop some stratus over the lower Bay, advecting it into ORF between 10z and 12z Thursday morning. There is not a lot of confidence in this and will only add SCT008 to the ORF TAF for now. OUTLOOK...Dry weather and mainly VFR conditions are expected Saturday. Only flight restrictions would be from the low chance for patchy fog or some low stratus from 08-12Z Thu morning.
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&& .MARINE... No headlines necessary over the next several days as a weak frontal boundary drops south of the waters this morning with high pressure building in from the north later today. The high becomes centered off the mid-Atlantic/SE coast Thu-Fri as another weak front moves in from the NW Fri night and washes out across the area on Sat. Winds will become NE around 10 KT later this morning, and will shift to the E at 5-10 KT most areas this afternoon. Winds then transition to the E/SE Thu then S/SW Fri. The pressure gradient will increase a bit on Fri, so winds will avg around 15 KT fri afternoon/evening ahead of the front. Waves over the Bay will avg 1-2 ft, with seas over coastal waters 2-3 ft (3-4 ft Fri afternoon/evening). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...SAM NEAR TERM...SAM SHORT TERM...SAM LONG TERM...MAS AVIATION...LKB/JAO MARINE...LKB

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