Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 220834 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 434 AM EDT Sat Apr 22 2017 .SYNOPSIS... Several weak waves of low pressure will move across a nearly stationary front in place across the area today. The front will sink south toward Carolinas tonight through Sunday...as a slow moving area of low pressure tracks along the southeast coast Sunday and Monday. This system will bring periods of moderate to heavy rainfall to the region Sunday through early next week. && .NEAR TERM /THROUGH TONIGHT/... Latest weather analysis features surface frontal boundary draped across the forecast area early this morning, extending back into the Mid-south. A weak surface wave moving along the front continues to lift e-ne along the boundary across central and eastern VA early this morning. Radar mosaic showing isolated to scattered shower activity moving across the area early this morning, and expect occasional showers to continue early this morning as the surface wave moves offshore through mid-morning. Have lowered POP for the late morning/early afternoon time frame with CAMs pointing towards a slower progression of the front today. Therefore, expect showers and storms to re-fire along the boundary as it sinks south across the southern third of the area (Us-58 south). Convective parameters point toward slower onset of showers to allow for another day of strong heating. Therefore, given favorable deep layer shear, environment across the southern tier of the area will likely support some stronger storms, and a few supercell/multi-cell storms could develop along the boundary. Hail/damaging winds are the primary threats, again mainly across southern VA/Interior NE NC. SPC has nudged marginal across the southern half of the area. Farther north in the cool sector, occasional showers this afternoon. Remaining overcast and cooler. Highs have already occurred across the northern third of the area...with temperatures remaining nearly steady in the 60s this morning before slowly falling into the 50s by mid to late afternoon. Highs in the 70s to lower 80s across the southern tier of the area. Showers slowly settle south across NC this evening, with a brief lull in showers once again overnight as we await upper trough swinging east toward the region late tonight. This should add up to scattered to numerous showers through the overnight with plenty of low clouds and patchy fog developing. Lows in the 40s out in the piedmont, low to mid 50s along the coastal plain. && .SHORT TERM /SUNDAY THROUGH MONDAY/...
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A wet period ahead for the latter half of the weekend into at least Monday night with rainfall amounts between 1-3 inches through Monday, highest (2-3 inches) over the piedmont. Broad upper level low currently over the Plains into the Mid- Miss Valley will pivot SE into the deep south. The system then takes on a neg tilt as it deepens Sunday, spawning a surface low along the sern coast, which then is progged to get cut off from the main flow and drift ivof the Gulf Stream wall into the middle of next week. Models show both spacial and timing differences with the moisture fields but the jist of the forecast will be for waves of Atlantic moisture to rotate inland resulting in periodic showers (embedded tstrms especially over the sern coastal zones). Locally hvy downpours psbl starting Sunday and Sunday night. Meanwhile, high pressure to the NE results in a cool in-situ wedge setting up over the piedmont, along with areas of fog. Hydro wise, no flood headlines expected attm with numerous breaks in between bouts of rain expected. Do expect some healthy rises in local river by early next week, especially if the heavy rainfall falls over the headwaters. QPF is mainly a blend of the WPC preferred ECMWF/UKMET along with going forecast continuity...resulting in 2-3" west of i-95 to 1-2" to the east. Locally higher amounts are likely owing to developing convection. Highs mainly in the 50s to near 60 Sunday...lower to middle 50s inland...to mid 60s/nr 70 SE Monday.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Long term period will feature a trend towards drier and warmer conditions. For Mon night/Tue, mid-level cutoff low and associated sfc low continue to spin south of the area, allowing for moisture to stream in off the Atlantic. Bumped up PoPs to likely for most of the area Mon night and chance far NW, with models tending to push cutoffs lows offshore too quickly. Slightly lwr PoPs for Tue, with the best chance near the cst. Temps Tue slightly below normal...highs in the upr 60s most spots. Warming trend then commences for Wed as deep SWly flow develops across the eastern seaboard, lasting through the end of the week with temps reaching the 80s most areas Thu and Fri. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... As of 07z...a frontal boundary extends from the lower eastern shore to central Virginia to the Tennessee Valley. IFR stratus was present along the coast of the Lower Eastern Shore. AS the front moves to near the VA/NC border Saturday aftn...IFR ceilings are expected to expand across much of the area (north of the front) by Saturday afternoon. OUTLOOK...Low pressure will move out of the Mid-South to the Carolina coastal waters where it will linger into early next week. Unsettled conditions...widespread moderate to heavy precipitation and degraded aviation conditions are expected Sunday through Monday. Conditions slowly improve but some rain may continue especially toward the coast. Currently a dry forecast is in place for Wednesday and Thursday. && .MARINE... Latest surface analysis depicts a cold front over the waters with a weak area of low pressure over central Virginia. High pressure resides off the Southeast coast. The wind north of the boundary has become north to northeast, with a uptick in west to southwest winds south of the boundary thanks to showers. Waves generally 1-2 feet and seas 2-3 feet. Low pressure slides offshore mid morning as the front pushes south of the waters early afternoon. A lack of good cold air advection and gradient winds expected to keep north to northeast winds at or below 15 knots, but a few gusts to around 20 knots are possible early afternoon in the lower Bay. Seas build to 3- 4 feet this afternoon as flow becomes northeast over the coastal waters. High pressure builds in from the northwest tonight as low pressure lifts along the Northeast coast. Winds increase to 10-20 knots tonight, with gusts of 20-25 knots expected in the bay, sound, and coastal waters. Increasing northeast flow kicks seas up to 4-5 feet in the southern coastal waters tonight. Have raised SCA headlines for the aforementioned waters. Seas build to 4-5 feet in the northern waters Sunday morning. Gradient indicates SCA conditions may subside Sunday afternoon in the upper Bay, but speeds in the lower bay and lower James river increase to 15-25 knots. Gusts in the southern coastal waters increase to 25 knots. Seas build to 4-6 feet Sunday afternoon. Onshore flow prevails thru Tuesday as low pressure develops over the Southeast states then slowly slides offshore. As a result, an extended period of SCA conditions is anticipated with speeds of 15- 25 knots and seas building upwards of 5-8 feet (or higher). Current headlines run thru Sunday night (4th period). Improving marine conditions thereafter as the surface low weakens and pushes off to the northeast. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 6 PM this evening to 6 AM EDT Monday for ANZ632-634-654-656-658. Small Craft Advisory from 6 PM this evening to 10 PM EDT Sunday for ANZ633. Small Craft Advisory from 6 PM this evening to 10 AM EDT Sunday for ANZ630-631. Small Craft Advisory from 6 AM Sunday to 6 AM EDT Monday for ANZ638-650-652. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MPR/MAM LONG TERM...MAS AVIATION...LSA MARINE...SAM

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