Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 232358 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 758 PM EDT Sun Apr 23 2017 .SYNOPSIS... Low pressure will linger off the southeast coast through Tuesday, then slowly lift northeast off the Mid Atlantic coast Wednesday. High pressure builds into the area for the second half of the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... High pressure over PA is progged to move off the northern Mid Atlantic coast tonight. Meanwhile, upr level energy over the SE will transfer its energy and form a new low off the SE coast Monday. Deepest moisture progged well inland as this process commences. One caveat in the forecast is that the pcpn has had a harder time moving north into the drier air from the high. This has kept down qpf amounts some today except for swrn zones where it has been raining most of the day. Models in decent agreement that the next wave of moisture produces periods of mdt rainfall this evening across western half of fa (cat pops) with lighter amounts and a slow increase in pops through 06Z across the north and east. Again, changed pcpn type to stratiformed rain vs convective shwrs. Coastal boundary develops ivof gulf stream but the high to the north appears strong enough to keep it there and any chc for thunder across the Outer Banks. Lows upr 40s northern zones to mid to upr 50s along sern coastal zones. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... System becomes negatively tilted Monday allowing sfc low to reform off the Se coast. Exiting high pressure to the NE keeps cool wedge in place with periods of rain, drizzle and patchy fog. Any thunder remains ivof the Outer Banks. Nothing to get excited here on Monday as the deepest moisture stays south of the fa. Thus, expect another cloudy, cool and wet day. Likely to cat pops all areas. Highs mid 50s NW to around 70 SE. QPF amounts btwn 1/2 to 1 inch Monday. The forecast concern comes Monday night and Tuesday when the tropical moisture off the Florida coast gets entrained then rotates nnw around the system as it drifts north along the Mid Atlantic coast. This is where the main batch of mdt to hvy rain will be possible. However, some data indicating a dry slot cutting off the heavy rain Tuesday. Given the uncertainty, no flood watch or river flood warnings will be issued at this time. Still plenty of time to access the situaton. Do expect the pcpn type to go back to more of a convective one as this moisture moves across the area with any thunder confined to coastal sections. Lows Mon nite from near 50 NW to the lwr 60s SE. A bit more humid Tues with highs in the low-mid 60s NW to low-mid 70s SE. Pcpn tapers off west to east Tuesday night with lows in the 50s. Decreasing cloudiness and warmer Wed. Highs in the 70s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Long term period will feature above normal temps with mainly dry wx. For Wed night/Thu, deep SWly flow develops across the eastern seaboard as the aforementioned low pushes off to the NE. An upper- level ridge then builds in through the weekend allowing for warm temps and dry wx as most of the energy aloft will stay N and W of the local area. At most a 20% chance of a late day shra/tstm Fri and Sat. High temps Thu through Sun in the 80s, pushing upper 80s on Sat. Low temps in the 60s. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 23z...Weak high pressure was south of New England and a complex area of low pressure was over Georgia and northern Florida. The area of low pressure will slowly spread into the Carolinas during the 00Z TAF period. Dry air that is a result of the high to the north was keeping SBY mainly dry and VFR. In the meantime...areas of light rain were moving through the rest of the TAF sites with periods of MVFR conditions. Expect rain to become more widespread with IFR ceilings increasing in coverage from south to north. Winds will continue from the northeast and will be gusty at times (15-23 kts) especially near the coast. OUTLOOK...Low pressure will strengthen near the Carolina coast Monday night and Tuesday spreading heavier rain and more consistent IFR conditions to the area. Winds will be mainly from the east and will be gusty over eastern portions. As low pressure moves up the coast rain and degraded aviation conditions will begin to diminish by early Wednesday. Dry weather is in store Thursday and Friday as high pressure builds over the Southeast States. && .MARINE... SCA hazards continue for tonight into Mon as sfc low pres develops near the SE coast in association with a mid-level cutoff low. Mainly 15-20 kt NE winds this eveng...increasing to 20-25 kt over the Bay and coastal wtrs after midnight. Seas build to 5-7 ft tonight. The sfc low slides up the NC coast through Tue, with sustained winds Mon through Tue of 20-25 kt over the Bay and coastal wtrs, gusting up to 30 kt (slightly lwr over the rivers/Sound). Could see some occasional gusts up to 35 kt, but confidence is not high enough to issue a gale warng attm due to strong WAA preventing much of the winds from mixing down to the sfc. Seas up to 8-11 ft. SCA headlines currently end Tue during the 4th period, but may need to be extended in future updates. Marine conditions then steadily improve Wed into Thu as the sfc low pulls off to the NE, and a weak pres gradient on the back side of the low. && .TIDES/COASTAL FLOODING... Tidal departures are averaging 1 to 1.5 feet thanks to persistent onshore flow. Tidal departures will build through midweek as onshore flow prevails ahead of an approaching area of low pressure. Majority of the tidal locations in the bay and Atlantic coast will reach action stage tonight, with minor flooding possible but not likely for areas along the James River. However, tidal departures increase to 1.5 to 2 feet Monday. Minor coastal flooding is expected during high tide Monday night and again on Tuesday, especially in the lower Chesapeake Bay and Atlantic waters. Depending on the exact track of the low, high end minor to low end moderate coastal flooding is possible Tuesday night. Departures subside Wednesday as low pressure lifts along the Northeast coast and flow becomes offshore. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 1 AM Monday to 7 AM EDT Tuesday for ANZ635>637. Small Craft Advisory until 1 PM EDT Tuesday for ANZ630>632-634. Small Craft Advisory until 7 AM EDT Monday for ANZ633. Small Craft Advisory until 7 AM EDT Tuesday for ANZ638. Small Craft Advisory until 7 PM EDT Tuesday for ANZ650-652-654- 656-658. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...MPR LONG TERM...MAS AVIATION...LSA MARINE...MAS TIDES/COASTAL FLOODING...

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