Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 210610 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 210 AM EDT Sat Oct 21 2017 .SYNOPSIS... High pressure remains over the Mid Atlantic region through the weekend...with temperatures gradually warming. The next cold front is expected to impact the region Monday night and Tuesday. && .NEAR TERM /THROUGH TODAY/... High pressure results in another clear night ahead. Models show best chcs for patchy fog dvlpmnt will be over srn VA / ne NC and a bit on the ern shore. Otw, seasonable with lows 45-50 inland to the low/mid 50s at the immediate coast. && .SHORT TERM /TONIGHT THROUGH MONDAY/... High pressure sfc-aloft remains anchored invof FA through Sat...then slowly shifts off the coast Sat night-Sun. Other than possible patchy/areas of FG Sat night...dry-continued seasonably warm wx expected Sat-Sun. Highs Sat in the mid/upr 70s...low 70s right at the coast. A few more clouds possible by Sun afternoon as the low level flow becomes more SE ahead of the next cold front (which will be entering the OH-TN valleys late)- so may become partly sunny vs mostly sunny. Lows Sat night in the upr 40s to low 50s inland to the mid/upr 50s at the coast. Highs Sun ranging through the 70s. By Monday, low pressure deepens over the Deep South/lower MS Valley while a strong upper ridge remains in place along/just off the East Coast. ECMWF and GFS showing some subtle timing differences with respect to how quickly the precip from the southern low is able to spread east into the Mid-Atlantic. Based on 12z suite of models, have trended precip arrival a bit slower on Monday, favoring just slight chc PoPs (~20%) across the Piedmont toward evening. Clouds will be on the increase from west to east Monday. Highs again the the mid/upr 70s, after morning lows in the 50s to low 60s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Still a lot of uncertainty as to how next weeks system plays out as models offer up different timing and moisture field solutions. What is agreed upon is that a full latitude trof will move across the region Tue, what is yet to be determined is the scope and track of several s/w`s embedded in the trof and timing of a cold frontal passage across the area. GFS slower/much wetter as copious amounts of GOM moisture gets transported north ahead of the front. ECMWF faster/drier with the fropa with a dry slot cutting the pcpn off. Decent low level jet and theta-e advection progged ahead of the front for at least some instability to develop. Went ahead and bumped up pops to between 70-80% late Mon night through 18Z Tue with pcpn tapering off and ending west to east late Tue aftrn and Tue night as the deepest moisture pushes offshore. Added moderate rain and slight chc thunder for Tue morning. Later shifts can adjust as needed. Warm and humid Mon nite with lows in the 60s. Breezy Tue with highs 70-75. Cooler Tue nite with lows in the upr 40s west to upr 50s along the coast. Slight chc pops Wed as upr level energy lingers. Cool with highs in the low to mid 60s. The upr level low lifts NE Thu allowing high pressure to build across the southeast. Dry Thurs and Fri. Highs Thurs in the low to mid 60s. Lows in the 40s. Highs Fri 65-70. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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Predominantly VFR conditions expected through the 06Z TAF forecast period as sfc high pres dominates. Another round of patchy/areas of FG expected through early this morning...w/ potential for IFR/LIFR from time to time...esp PHF/ECG. Sfc hi pres shifts off the coast tonight-Sun. A little better coverage of FG possible late tonight/early Sun due to light SE winds. A cold front is forecast into/across the local area late Mon night and Tue w/ chcs for MVFR to lcl IFR conditions in RA and low CIGS.
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&& .MARINE... A weak sfc cold front has pushed off the New England coast, and winds over the local area have shifted to the N to NE at around 10 kt. Bay waves are 1-2 ft with coastal seas of 2-3 ft on avg. Tonight, a broad area of sfc high pressure over the region will allow for generally benign conditions over the waters and waves in the Bay and rivers should be 1 foot or less except for 1-2 ft at the mouth of the Bay with coastal seas of 2 to 3 feet. Light ENE flow will prevail on Sat, shifting to the ESE on Sunday, with favorable boating conditions as wind speed will mainly avg 5-10 kt. The next chance for significant weather over the waters does not come until early next week as a strong cold front approaches from the west on Monday and slowly crosses the waters on Tuesday. The pressure gradient will lead to increasing southerly flow ahead of the front later Monday into Tuesday, shifting to the WNW behind the front Tuesday night into Wednesday. Small Craft Advisories will likely be needed for most or all of the area Mon night/tue as the pressure gradient should be strong enough for winds of 15-25 kt with higher gusts. Coastal seas build to 6-9 ft with waves of 3-5 ft in the Bay likely. A fair amount of uncertainty remains Tue night/Wed regarding how strong the pressure gradient will be as the models tend to keep the cold air and strong winds off to our NW over the Great Lakes until Thu. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...ALB/JDM NEAR TERM...ALB SHORT TERM...ALB/JDM LONG TERM...MPR AVIATION...ALB/MPR MARINE...LKB

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