Area Forecast Discussion
Issued by NWS Wakefield, VA

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201 FXUS61 KAKQ 281816 AFDAKQ Area Forecast Discussion National Weather Service WAKEFIELD VA 216 PM EDT Tue Mar 28 2017 .SYNOPSIS... A cold front approaches from the west today and crosses the region late this afternoon and tonight. High pressure builds in from the north on Wednesday. The high retreats to the northeast on Thursday as the next system approaches from the west. A strong system is expected to impact the region on Friday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Area of showers with embedded tstms now pivoting NE through the Peninsula/Middle Peninsula/northern neck and approaching the mid-upper Bay. Elsewhere, SPC mesoanalysis and lightning trends suggest there will not be any tstms through at least noon so have taken mention of storms out of the forecast for the rest of the morning (though likely PoPs remain for awhile most zones). Expect diminishing PoPs to 20-40% most areas from late morning through early-mid aftn, then as the upper level trough continues to push into the area, will eventually see some redevelopment of showers/tstms with likely PoPs most areas again after about 18-19Z. SPC continues to highlight a marginal risk for most of the CWA (except over the far NE). The current showers are likely to have a negative effect on the severe threat later today, due to only a small window of opportunity for the atmosphere to recover after this morning pcpn exits. Thinking best chance for any strong storms will be from about 19Z through 01Z over the far southeast portions of VA/and northeast NC where the atmosphere may not be as worked over as other areas. Shear is also expected to be greatest in this region (effective shear to 30-35 KT), while areas farther NW generally have <30 KT of effective shear since they will be more displaced from the track of shortwave aloft. It will remain mild today despite plenty of clouds. Highs in the low to mid 70s, except cooler 60s at the ern shore beaches. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... Will limit chance PoPs to areas along/east of I-95 by late this evening as the Piedmont dries out, then drying out all the way to the coast after midnight with lows mainly 50-55 F (except upr 40s ern shore). Becoming partly/mostly sunny Wed after some early clouds (especially south) as drier air moves in from the N. Somewhat cooler but still a little above avg with highs 60-65F near the coast and in the upper 60s to lower 70s well inland. Upper ridge axis quickly moves back into the region by Thu, allowing return of mid/high clouds during the day. With fairly low mixing and overrunning clouds, expect a cooler day with highs mainly ranging from the mid 50s to around 60. Kept it dry through the day despite the increase in clouds ahead of the next system. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A complex low pressure system approaches from the west late Thu night and early Fri before slowly crossing the region Friday/Friday night. Guidance in good agreement with respect to potential for widespread showers/tstms and potential for heavy rain during Fri. Will limit pops to 20-30% along west of I-95 prior to 12z Fri before increasing to 60-80% all areas during Fri (highest west). Will keep similar pops Fri night with a slow exit of pcpn expected. Dry wx and high pressure returns for Sat aftn thru Sun night. Yet another system may approach fm the west late Mon. Highs in the upper 50s to upper 60s Fri, in the 60s to near 70 Sat, in the mid 60s to lower 70s Sun, and in the 60s to near 70 Mon. Lows in the 40s Thu night, in the upper 40s to mid 50s Fri night, in the 40s Sat night, and in the mid 40s to near 50 Sun night. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... This morning began with widely scattered showers with isolated thunder, and showers are still occurring east of Interstate 95 as of 28/1800Z this afternoon. Clearing can be seen in satellite imagery over central and western VA, and additional upper level support from a decent shortwave (and subsequent cold pool aloft) will aid in the redevelopment of showers and thunderstorms the rest of this afternoon into this evening. The presence of a dry slot in water vapor imagery (currently over far SE VA/NE NC) indicates that these areas will need to be closely monitored as convection moves closer to the coast. Isolated strong wind gusts will be the primary threat with thunderstorms today, however hail could pose a lesser threat. Cigs/VIS expected to briefly drop to MVFR flight conditions under stronger storm cores. Kept VCTS in forecast at all TAF sites through this afternoon/evening until more definitive storms develop. Predominantly southwest winds 10-15kt rest of today gusting up to around 20kt; stronger and more erratic in vicinity of thunderstorms. Once the surface cold front clears the coast after midnight, winds shift to the north with speeds averaging 5-10kt. Low stratus is expected to develop late tonight as the atmosphere saturates from the recent rainfall. Cigs should average 500-1500ft AGL. Fog not anticipated to be an issue with the winds above 5kt. Skies will scatter out and lift from north to south on Wednesday as high pressure slowly builds into the region from the north. Dry with VFR conditions through Thursday. However, clouds should increase in coverage on Thursday in a light onshore/northeast wind regime with shortwave energy/moisture dropping through the region from the northwest. Clouds then thicken and lower Thursday night as the next low pressure system approaches the area. This system should bring widespread showers and thunderstorms to the area Friday/Friday night as it crosses the Mid Atlantic States. && .MARINE... Latest obs reflect SSW flow across the waters. Surface high pressure continues to linger along and just offshore of the Mid Atlantic and Southeast coast this morning, as a cold front approaches from the Ohio and Tennessee River Valleys. Pressure gradient will gradually tighten today, allowing gradual increase in winds this afternoon and tonight...before the front crosses the waters late this evening and overnight. SSW winds become NNW post frontal late tonight and continue through Wed, as high pressure starts to build in fm the N. While experimental wind probs are indicating a small chance for a few gusts to low end SCA in the Ches Bay Wednesday morning through midday, still do not expect predominate SCA conditions to be met thru Wed. However, winds will be marginal for much of the morning and early afternoon in the lower Chesapeake Bay and Currituck Sound, and will need to watch marginal SCA gusts during that time. Will also need to watch encroaching SSE swell on Wednesday, owing to developing system crossing south of Bermuda this morning. NWPS and WaveWatch in general agreement in depiction 5 ft seas mainly south of hatteras and offshore of the Mid- Atlantic waters, and thinking at this time is much of this energy stays well offshore. Thus, will hold Significant wave heights at 3 to 4 ft, just below SCA thresholds. Waves 1-2 ft today...building to 2-3 ft on Wed. Otherwise, cool high pressure will continue to build in from the north Wed night into Thu morning, before it slides out to sea Thu aftn and night. NNE winds 10-15 kt Wed night and early Thursday, become NE 5 to 10 kt by Thu aftn. E-NE winds 5 to 10 kt Thu night become SE 10-15 kt by Friday morning, and southerly by afternoon as a warm front lifts across the waters. Seas subside during this period of diminishing winds Wed-Thu, but increase again Friday afternoon and evening ahead of next cold front, which crosses the waters Saturday morning. Seas build back to 4-5 ft, highest toward outer waters in pre-frontal south flow. A brief period of SCA headlines is possible over the coastal zones, mainly for seas. Seas subside back into the 2-4ft range over the weekend in NNW flow aob 15kt as surface high pressure rebuilds over the waters. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...JDM NEAR TERM...JDM/LKB SHORT TERM...JDM/LKB LONG TERM...TMG AVIATION...BMD MARINE...MAM is the U.S. government's official web portal to all federal, state and local government web resources and services.