Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 261955 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 355 PM EDT MON SEP 26 2016 .SYNOPSIS... A warm front will weaken as it snakes its way across the mountains tonight. A cold front will move southeast across the region Tuesday morning, then stall along the coast Tuesday afternoon and night before moving farther offshore late Wednesday. An upper level low will track across the area later in the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Latest MSAS showing the old frontal boundary that cooled the region off a few days ago is snaking it way across the mts late this afternoon. This boundary will weaken as it continues to drift back north as a warm front this evening. Shwrs will accompany this boundary with low chc pops over the piedmont through midnite. Cold front to slowly cross the mts overnight with its position just entering NWRN most zones by 12Z. Good moisture surge out ahead of it for a band of likely/categorical pops across NWRN half of fa, chc pops SERN half. Instability is marginal but will keep slght chc thunder across the north ahead of the approaching boundary. Enuf lift and moisture influx seen for some moderate to possibly heavy downpours north of I64 and VA ST RT 360. Lows in the low-mid 60s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Still a rather complex forecast for Tuesday. Latest data supports the front sagging SE across the fa during the morning but stalling across the SE after 18Z. The reason for this is twofold, first is a weak wave progged to ride NE along the boundary and second is an area of tropical moisture off the Carolina coast that causes to boundary to slow its SE movement. Am a bit concerned about this offshore moisture as to whether any of it gets entrained into the stalled frontal system along the coast. This could enhance rainfall across the SE in areas that got drenched a few days ago. Something to watch over the next 12-24 hours. Upshot here is for a wet day with likely pops most areas, categorical across the SE after 18Z. Thunder will shift towards the SE after 18Z closer to the boundary. Somewhat drier air is progged to filter in behind the front across NWRN zones. Despite the dry air aloft, enuf moisture noted to continue chc pops back through the piedmont. Again. some moderate to lclly heavy downpours possible across the SE. Highs in the low 70s north to mid-upr 70s south. Boundary gets hung up along the coast Tues nite then shifts a bit farther east Wed. Likely pops continue along the coast Tue evening with chc pops all areas after midnite through Wed as moisture from the approaching upr level low crosses the mts. Lows upr 50s NW to near 70 SE. Highs Wed in the mid-upr 70s. Thunder possible across the SE Wed afternoon. Models differ a bit with the actual cut off low position by mid week, but anyway you look at it it appears unsettled with sct shwrs. NAM slower and further west than GFS/SREF but can`t rule out aftrn tstrms once the cold pool aloft crosses the mts. Lows Wed nite in the 60s. Highs Thurs in the 70s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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Long term forecast is complicated by the presence of an upper-level cutoff low over the E/NE CONUS for the duration of the period. This will lead to below normal temps and frequent chances for rain. Difficult to time the precip this far out in time but at this point the best chances will be Thu night/Fri (30-50% pops). As the cutoff low slides NE through the period, the chances of rain will slightly decrease through the end of the week. As for temps, highs will avg in the mid 70s each day with lows ranging from the mid 50s over the Piedmont to the mid 60s near the coast.
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&& .AVIATION /20Z MONDAY THROUGH SATURDAY/... VFR conditions start off this forecast period despite the onshore flow. Moist mid levels resulting in BKN-OVC SC between 3-5K ft. These conditions to continue past 00Z. Moisture in the form of showers will overspread the area west-east after 06Z. Digital aviation grids will reflect likely to categorical pops for both RIC/SBY late tonight and Tuesday morning. Thus, MVFR conditions with prevailing showers are forecasted for now. Thunder chcs are possible with the actual fropa at RIC/SBY Tue morning, but timing of thunder at any one site this far out is rather problematic so left it out attm. Locally lower vsbys possible in heavier shwrs. Pcpn not expected to get into the SERN taf sites until after 12Z and more toward the end of the 18Z forecast period. OUTLOOK... Showers will linger through much of the work week ahead as an upper level low tracks across the region. && .MARINE...
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Latest sfc analysis shows high pressure centered offshore with a frontal boundary approaching from the west. Southerly flow increases tonight ahead of the frnt as the pressure gradient increases. Maintained the SCA hazards in place for the entire Bay and Rappahannock River for winds up to 15-20 kt. Conditions will be marginal and winds do not appear to be high enough to warrant a SCA over the ocean and other rivers. The front drops into the area Tue with winds decreasing through the day as the front stalls and weakens in the vicinity. Waves of low pressure then form along the front through the end of the work week as an upper-level cutoff low persists over the E/NE CONUS. Expect mainly 1-2 ft waves over the Bay and 2-4 ft seas over coastal waters through this period.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 4 AM EDT Tuesday for ANZ632-634-635. Small Craft Advisory until 7 AM EDT Tuesday for ANZ630-631. && $$ SYNOPSIS...MPR NEAR TERM...MPR SHORT TERM...MPR LONG TERM...MAS AVIATION...MPR MARINE...MAS

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