Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 202040 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 340 PM EST Sat Jan 20 2018 .SYNOPSIS... High pressure slides off the Southeast coast through the weekend. A cold front crosses the region Tuesday morning. && .NEAR TERM /THROUGH TONIGHT/... Latest surface analysis features a ridge of high pressure the southeast. Aloft, a weakening shortwave continues to push across the Gulf coast this afternoon...with flat, quasi-zonal flow in between this feature and a northern shortwave moving across S QC. Meanwhile to the west, a strong shortwave is pushing east across the Desert SW toward the Southern Rockies. Dry, mild flow aloft and light SW winds at the sfc have allowed for another mild afternoon across the local area. High temperatures across the area generally in the lower 60s the m50s to around 60F over the eastern shore. Upper trough over the SE slides offshore late tonight. Clear sky and light winds will allow temperatures to drop off quickly this evening. Potential for patchy fog after 06z late tonight/early Sun. Early morning lows mainly in the 30s, with some upper 20s possible in the piedmont. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... Short term period generally characterized by dry and gradually warming temperatures. Upper level trough out west will gradually deepen/close off as it lifts onto the plains Sunday...and to the Mid-Mississippi Valley on Monday. At the surface, SW flow continues as the surface ridge slowly lifts over the local area. Upper low and associated sfc low lifts across the western Great Lakes, with the attendant cold front crossing the area Late Mon night into Tuesday. ECMWF/GFS blend still nicely captures the slower ECMWF and the more progressive GFS. Highs Sunday similar to today...mainly u50s to l60s inland...55 to 60 along the eastern shore. Highs Monday will be a challenge, and partially dependent on clearing low clouds out to begin the day. Highs expected to be in the l-m 60s inland. However, if clearing occurs a bit quicker than modeled, thickness tools and some GEFS/EPS members pointing at potential highs in the u60s to near 70 inland. Lows Monday night remain mild ahead of the front...mainly in the 50s. Rain chances increase quickly after midnight Monday night/Tuesday morning. SHERB/SHERBE (QLCS) parameters continue to point towards potential for another round of sct thunderstorms, or some gusty line segments Monday night. For now, given 06-15z timing will keep thunder mention out. Showers do lift out by midday Tuesday out west, early evening along the coast. Highs Tuesday in the 60s once again, slightly cooler 50s out in the piedmont. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... Models are in very good agreement in the extended range from 00z Wed through Saturday with the long wave trough pulling out of the Northeastern US Wed and Thursday with a shortwave ridge building in for Friday and Saturday. At the surface, the period begins with NW flow as the surface low over deepens over the nern US. The surface low will lift NE into the Canadian Maritimes by Wed evening. With the NW flow, expect the clouds to clear Tues night into Wednesday but with the cold advection, temperatures will be cooler into the upper 40s to lower 50s. Another shortwave will move through the eastern trough on Tuesday and will bring a reinforcing cold front to the area. This will knock temperatures down a couple more degrees on Thursday, but with little moisture expect to see just a few clouds across the northern portion of the CWA. High pressure will build into the area on Thursday night into Friday. The high will remain in place through Saturday before slowly sliding off the coast by late Saturday with SW flow returning. This will allow for good radiation cooling both Thurs and Fri night with temps in the u 20s to l30s Thurs night and low to mid 30s Friday night. For Friday should see lots of sun with highs around the mid 40s over Lower MD and near 50 in southern VA. On Saturday with the return flow the models are indicating return moisture getting in and some showers possible late day, but at this point, not ready to introduce pops so have gone with just slight chance values in the 15 to 20% range. High should continue to modify into the low to mid 50s. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... VFR conditions continue through the 18Z TAF period as sfc hi pres to the S dominates. Light SW wind ~10 kts through this evening becoming light overnight. Some SCT-BKN Stratus develops this evening across the piedmont, but should mix out quickly after sunrise Sun morning. Outlook: Sfc hi pres settles off the SE coast Sun and Mon w/ SKC and dry conditions continuing. Another night of low clouds/patchy fog possible Monday morning. Otherwise, the next chance for widespread precipitation and flight restrictions comes Monday night with a passing cold front. High pres returns later Tue. && .MARINE... Generally benign conditions over the waters through the weekend as high pressure dominates the weather pattern. South/Southwest winds increase today with a slightly increasing pressure gradient. Expect S-SW winds around 10 to 20 knots over the coastal waters this afternoon and 10 to 15 knots over the Bay/Rivers. Winds diminish tonight into Sunday and briefly become N-NW. Winds become S-SW around 10 knots by Sunday afternoon. A cold front approaches the region from the west Monday night then crosses the water on Tuesday. There are some timing issues that still need to be worked out amongst the models with respect to whether the front passes first thing in the morning or in the afternoon. Either way, expect SCA conditions to be possible Tuesday with the fropa. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...MAM NEAR TERM...MAM SHORT TERM...MAM LONG TERM...ESS AVIATION...ALB/MPR MARINE...AJB/JDM is the U.S. government's official web portal to all federal, state and local government web resources and services.