Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 231956 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 356 PM EDT MON MAY 23 2016 .SYNOPSIS... Low pressure lingers over the Mid Atlantic today and then gradually moves offshore tonight into Tuesday. High pressure builds in from the west for the remainder of the week. && .NEAR TERM /THROUGH TUESDAY/... Series of weak perturbations/disturbances on the back side of persistent upper low will continue to set off some additional sct showers with some iso thunder possible along and west-northwest of I-95, where some modest instability (MUCAPE ~500-750 j/kg) is noted per MSAS data. The upper system gradually pushes offshore and begins to fill tonight. Some additional upper energy wraps around the low as it slides offshore this evening, so likely POPS have been maintained for the Nrn Neck over to the Ern Shore this evening. PoPs this evening taper off to 30-40% for central/se VA/coastal ne NC, and 20-30% from the sw Piedmont counties to interior ne NC. The chc for showers then diminishes sw-ne after midnight. Early morning low temperatures are expected to be in the low to mid 50s. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... Conditions drastically improve Tuesday, as the upper trough continues to weaken as it ejects northeast toward the northeast/New England coast. While a gradually clearing sky and dry wx is anticipated inland (mostly sunny by afternoon in the piedmont), mostly cloudy conditions and some slight to low end chance pops continue along coastal third of the area. This is in association w/one last upper disturbance rotating through behind the upper trough. Again, while surface-based instability looks to be minimal, LI`s and Showalter numbers indicate some modest, albeit mainly elevated instability. Warmer with highs ranging from the upper 70s to around 80 inland,and mid 70s closer to the coast (low 70s at the immediate coast). Broad upper level ridging builds northeast from the Deep South into the Mid-Atlantic and Southeast region Tuesday night into Wednesday, before sliding overhead into Thursday. 850mb temperatures rise to ~15C by Wednesday afternoon...and 16-17c by Thursday afternoon. BL mixing will reach to around 850mb, and should result in highs reaching the mid/upper 80s inland, with low/mid 80s closer to the coast, and upper 70s for the immediate Atlantic coast of the Ern Shore. After morning lows in the 50s to near 60, high temperatures creep up about a category area wide into the upper 80s/around 90 inland (low to mid 80s coastal sections) on Thursday. Forecast soundings/model cross-sections indicate rather dry conditions aloft,owing mainly to subsidence and light downslope flow aloft. Will therefore keep pops in silent range <10% on Wed, with only slight chc for more seasonally typical diurnally-driven pulse convection on Thursday afternoon and early evening. Light downslope flow will likely keep areal coverage of any convection on the low side, and will also serve to mix dewpoints down into the mid/upper 50s in the mid to late afternoon hours both Wed/Thu. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Bermuda sfc high pressure resides over the wrn Atlantic Ocean through the long term periods as mid-upper level ridging moves over the ne CONUS during this time. Although the GFS is trying to develop low pressure over the Caribbean/Bahamas during Thu night/Fri and then tracking it into the Carolinas Sat-Mon, the ECMWF is keeping this system suppressed farther south due to mid-upper ridging well-rooted across the ne CONUS through at least Sun night before beginning to impact the Mid Atlantic Region. WPC forecast is also very similar to the ECMWF and am starting to lean more twd this warmer and drier solution... especially since GFS ensembles support the GFS as more of an outlier at this point. Will trend the long range forecast in this direction regarding precip and temperatures. High temps continue to run above normal throughout the extended forecast periods and are now closer to being around 10 degrees above normal Fri (highs in the upper 80s inland...upper 70s to mid 80s immediate coast). For Sat-Mon, temps are around 5-7 degrees above normal (highs in the mid 80s Sat/Sun and lower 80s Mon). Low temps also still trending around 5-10 degrees above normal Thu-Sun nights (lows generally in the mid 60s). && .AVIATION /20Z MONDAY THROUGH SATURDAY/... Low pressure continues off the coast bringing showers onto the coast and over the CWA. The low will gradually but slowly move NE over the TAF period and most of the rain is expected to end by sunset. TAF sites are generally VFR this afternoon although with clouds cigs from 3500 to 10K feet and periods of rain. Winds are mostly from the N-NE 10-15 Kt with some gusts up to 25 kt along the coast. Gradual improvement expected overnight as the surface low moves away. OUTLOOK...With all of the moisture from previous day`s rains, if it clears out Mon night, it is conceivable that some fog could develop especially at KRIC which would have the best chance for winds becoming light. Otherwise...high pressure builds across the area for the rest of the week leading to a more late spring/early summer pattern across the region. Generally, VFR conditions would be expected unless patchy fog develops overnight. && .MARINE... SCA flags cancelled for srn Ches Bay/Sound/Lower James River as of 330 PM. North winds averaging 10-15kt this aftn...with gusts to around 20kt over the coastal waters. Winds will diminish through this evening as sfc low pressure located about 200 miles east of Ocean City (as of 300 PM today) tracks nnewd well off the NJ coast overnight. Meanwhile, seas are averaging 4-5ft (up to 6ft possible near 20nm) and are expected to subside below 5ft after midnight tonight. Waves 2-3ft. A secondary surge in wly winds is possible late tonight into Tue morning from the mouth of the Bay to the coastal waters south of Cape Charles Light as sfc high pressure starts to build into the region from the west. Speeds will stay aob 15kt during this surge, therefore additional SCA flags are not anticipated during this time. Conditions finally quiet down Tue through Sat as stacked high pressure settles over the area. Winds will generally be s-sw aob 15kt. Seas 2-3ft/waves 1-2ft. Although the GFS model is trying to develop low pressure system over the Caribbean/Bahamas during Thu night/Fri and then tracking it into the Carolinas Sat-Mon, the ECMWF is keeping this system suppressed farther south due to mid-upper ridging well-rooted across the ne CONUS through at least Sun night before beginning to impact the Mid Atlantic Region. Therefore WaveWatch guidance, which is based on the GFS, was not utilized for seas for Fri-Sat. && .CLIMATE... As of 20 UTC/4 pm EDT Observation at Richmond (KRIC), unofficial rain total for the day is 0.72". This would bring monthly total to 8.53" for May. May 2016 is currently the 4th wettest month of May on record at Richmond. Top 5 wettest months of May at Richmond 1. 9.13" 1889 2. 8.87" 1972 3. 8.59" 2003 4. 8.53" 2016 (to date) 5. 7.73" 1946 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 1 AM EDT Tuesday for ANZ650-652-654- 656-658. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...AJZ/MAM LONG TERM...BMD AVIATION...TMG/JEF MARINE...BMD CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.