163 FXUS61 KBOX 061729 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1229 PM EST Sun Dec 6 2020 .SYNOPSIS... Strong low pressure over the Maritimes will continue to move farther away this afternoon and tonight. Another storm will pass well out to sea Monday night and Tuesday. Mainly dry and colder weather is expected through Wednesday, then a moderating trend toward the end of the week as high pressure builds into the region. The risk of showers increase next Saturday as a system approaches from the west. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Dry air in place with dew points in the upper teens and 20s and PW values below 0.25 inches. Expect this dryness to remain through the rest of the day. Clouds lingering over the Berkshires extend across Hartford and Springfield. Expect this to erode as subsidence takes over this afternoon. Also lingering clouds across the Outer and Mid Cape on northwest winds across Cape Cod Bay. These will slowly slip east as winds diminish later afternoon. Morning soundings show a mixed layer, reaching 850-mb at ALY and 875-mb at CHH. Observed temperatures at these levels are equiv to -10C to -13C, suggesting max sfc temps of 35 to 40, possibly a smidge lower in the higher hills of Western Mass. Northwest winds in the layer 30-35 kt, which would allow gusts of 30-40 mph, diminishing this afternoon as the Maritime low pressure moves farther away. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... Tonight... With mostly clear skies and diminishing winds, have utilized the 25th percentile of guidance to yield upper teens to mid 20s for lows away from the immediate coast. Monday... Another colder than average day with highs again in the mid 30s to low 40s with forecast 925mb temperatures around -7C. Normal highs are in the low to mid 40s for this time of year. Winds will be considerably lighter than on Sunday so it wouldn't feel quite as cold. Expect another day of mostly quiet weather although there is a chance for some snow showers north of the MA Pike during the afternoon hours that is associated with a shortwave that peels off from a cut off low across Western PA. Confidence is low at this time so have opted to leave out mention of PoPs. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Highlights... * Mainly dry and colder through midweek then a moderating trend * Shower chances increase next Sat Monday night into Tuesday... An upper level low will pass just south of New Eng Mon night then move offshore Tue. A fairly large storm will track well south and east of New Eng with no impacts for SNE. However, colder air moving into the region with 850 mb temps -8C over the mild ocean will generate enough instability to support a few ocean effect snow showers which may impact Plymouth county coast to Cape Cod late Mon night into Tue. Otherwise dry and cold conditions with temps several degrees below normal. Wednesday into Friday... Temps remain below normal temps Wed and mainly dry but a fast moving northern stream shortwave moving SE from the Gt Lakes may bring a few snow showers Wed night, then a moderating trend Thu/Fri as heights rise behind departing shortwave and ridging moves in from the Gt Lakes. Saturday... High pres moves offshore with strong storm cutting across Gt Lakes. Risk of showers increase as warm front approaches. Low confidence temp forecast will depend on position of warm front. GFS is considerably colder than ECMWF as it keeps the front to the south. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. This afternoon...High confidence. VFR. Northwest winds gusting 25 to 35 kts, diminishing during the afternoon. Tonight...High confidence. VFR. West-northwest winds at 10 to 20 kts. Monday...High confidence. VFR. West-northwest winds at 5 to 10 kts. KBOS TAF...High confidence in the TAF. KBDL TAF...High confidence in the TAF. Outlook /Monday Night through Thursday/... Monday Night through Tuesday: Mainly VFR, with local MVFR possible. Breezy. Tuesday Night through Wednesday: VFR. Wednesday Night: Mainly VFR, with local IFR possible. Breezy. Slight chance SHSN. Thursday: VFR. Breezy. && .MARINE... Changed at 1230 PM... Extended the Gales on the waters east of Mass until 4 PM. Midday observation from buoy 013 (Mass Bay) shows 34 kt. This should diminish during afternoon. Remainder of discusion... Low pressure moving off through the Maritimes with northwest winds over the New England waters that are strong but diminishing with time. Gale Warnings will continue through midday in the waters east of Massachusetts. Winds south of MA and RI are diminishing, and so the Gales on Nantucket Sound and the southern outer waters will be converted to Small Crafts. Small Crafts continue on the remaining southern waters. Diminishing west-northwest winds with gusts around 35 kt early diminishing to around 30 kt in the afternoon. Seas 5-7 feet. West-Northwest winds continue to diminish tonight and Monday. Lingering 25 kt winds early tonight, diminishing below Small Craft levels overnight. Seas 5 to 7 feet tonight diminish below 5 feet on Monday. Outlook /Monday Night through Thursday/... Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of snow showers. Tuesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers, slight chance of snow showers. Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers. Thursday: Winds less than 25 kt. Seas up to 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 1 AM EST Monday for ANZ232>235-237- 255-256. Small Craft Advisory until 10 PM EST this evening for ANZ230- 236. Gale Warning until 4 PM EST this afternoon for ANZ231-250-251- 254. && $$ SYNOPSIS...KJC/Chai NEAR TERM...WTB SHORT TERM...Chai LONG TERM...KJC AVIATION...WTB/KJC/Chai MARINE...WTB/KJC/Chai