Area Forecast Discussion
Issued by NWS Boston, MA

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125 FXUS61 KBOX 190911 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 411 AM EST Mon Feb 19 2018 .SYNOPSIS... A warm front will bring showers late today and tonight. This will set the stage for near record high temperatures Tuesday and especially Wednesday, so long as enough sunshine is realized. Cooler temperatures work into the region Thursday into the weekend, but still expecting them to remain above normal. Best chance for unsettled weather will be sometime Friday into next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Calm winds continue across most of the region at 08Z as seen on latest observations, though noting some light/variable winds starting to stir across NE Mass as well as on Block Island and Nantucket. While temps have fallen to the mid and upper teens across N central and NW Mass and down the CT valley thanks to the radiational cooling, readings elsewhere have held in the 20s. Also, noting more mid and high clouds streaming eastward out of NY and PA on the GOES-East Air Mass RGB composite satellite imagery, so should see high clouds thicken through daybreak. As the high pressure pushes offshore today, S winds will increase during the day. May see gusts up to 20-25 mph mainly along the coast and across the higher terrain. A warm front will ride NE from the mid Atlantic states on the backside of the exiting high, bringing isentropic lift ahead of it. Will also see increasing PWAT moisture plume working NE with the approaching front. Scattered showers will push into western areas by early afternoon, covering the entire area by evening. PWAT values up to about 1 inch will move in by evening. Expect temps to top off in the 40s today. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Tonight... With continued S-SW wind flow in place, will see good chance for showers through most of the night. Will see QPF amounts on order of 0.1 to 0.2 inches. Will also see patchy fog develop, though may be locally dense along S coastal areas at times. Some question whether dense fog will linger and become more widespread with the steady S-SW winds in place. Showers may start to taper off across northern areas after midnight. Will see non-diurnal temp trends across the region tonight with the mild wind flow in place. Lows in the upper 30s to mid 40s expected early, which may reach close to 50 toward daybreak along the coastal plain. Tuesday... A few showers and patchy fog may linger along S coastal areas early, then should push offshore by around midday. However, clouds will likely linger across most areas through the day. The big question will be whether the clouds will break during the midday and afternoon hours across the interior. If the clouds do break, temps could soar higher than currently forecast. At this point, the clouds should linger but still have forecasted temps reaching the lower 60s away from the S coast where temps will hold in the lower 50s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Highlights... * Wednesday: Near all time February record highs might be approached if enough sunshine is realized * Cooler Thu/Fri into next weekend but temps still above normal * Unsettled weather possible sometime Friday into next weekend with ptype favoring rain although a bit of ice/snow can not be ruled out Details... Tuesday night... Massive southeast upper level ridge will result in an anomalous southwest flow of very mild air into southern New England. Low temps may not drop below 50 away from the cooler marine influence of the south coast. Some low clouds and fog are certainly possible...especially near the Cape/Islands with high dewpoint air moving over the relatively cool ocean. Wednesday... Anomalous upper level ridge of 594 decameters off the southeast coast will pump an incredibly mild airmass into our region for late February standards. This will result in 850T rising to between +12C and +14C. Given southwest flow...high temperatures will climb well into the 60s to lower 70s inland from the cooling marine influence of the southeast New England coast. If this ends up being the case...record highs would be broken and near all time February record high temperatures would be challenged. The one fly in the ointment is if we are jammed up in a bunch of low clouds. NAM soundings suggests this as a possibility...but often southwest flow is able to allow for these to break up. However...if the low clouds remain in place high temps would be cooler than currently forecast. Something later shifts will have to monitor closely. Wednesday night and Thursday... While the southeast upper level ridge will remain in place, 1040+ MB surface high pressure system will approach from the west and force a cold front south of the region Wed night/Thu. The result will be significantly cooler temperatures Thursday with high temperatures mainly in the 40s. At this time...the bulk of the period looks dry but we can not rule out a period of mainly ana frontal showers which are depicted in some of the GEFS/EPS ensemble members. Friday through Sunday.... Low confidence forecast particularly with timing, but the potential exists for a couple rounds of unsettled weather Friday into next weekend. Certainly not expecting the entire period to be a washout...just impossible to try to time individual shortwaves this far out. The southeast ridge remains pretty strong...so ptype favors mainly rain. However...if a couple Canadian high pressure systems are slower to retreat it could be marginally cold enough to support a bit of snow/ice. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...High confidence. Through 12Z...VFR. Winds becoming light S toward daybreak. Today...Mainly VFR. May see patchy MVFR VSBYS push into central and western areas after 18Z in scattered showers. S winds gusting up to around 20 kt from late morning into mid afternoon. Tonight...Areas of MVFR CIGS/VSBYS in scattered -SHRA and patchy fog. Local IFR possible toward the south coast, including the Cape and islands. S winds gust up to 20 kt across Cape Cod and the islands. Tuesday...MVFR VSBYS/MVFR-IFR CIGS in scattered -SHRA and patchy fog early, improving to VFR. However, MVFR to local IFR conditions may linger along the S coast through early afternoon. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Tuesday Night through Friday/...Moderate confidence. Tuesday Night: MVFR/IFR conditions possible. Slight chance SHRA, patchy BR. Wednesday: Mainly VFR, with local IFR possible. Breezy. Slight chance SHRA. Wednesday Night through Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA. Thursday Night: VFR. Friday: Areas of MVFR/IFR possible. Breezy. Chance RA with a low risk of some ice/snow across the interior. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...High confidence. Today...S winds will increase with some gusts up to around 25 kt on the eastern outer waters where Small Craft Advisories have been issued. Seas will build up to 5-6 ft there as well. Scattered showers will move in this afternoon with some visibility restrictions. Tonight and Tuesday...S winds gusting up to 25 kt on the outer waters from time to time. Seas will build up to 5-6 ft across the southern waters into Block Island and RI sounds. Small Craft Advisories have been issued for these areas. Scattered showers and patchy fog will bring reduced visibility tonight, then should improve on the eastern waters Tuesday. Reduced visibility lingers Tuesday on the southern waters. Outlook /Tuesday Night through Friday/...Moderate to High confidence. Tuesday Night: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers, patchy fog. Areas of visibility 1 to 3 nm. Wednesday: A period of southwest wind gusts of 20 to 25 knots possible with the strongest winds near shore. Areas of rough seas. Slight chance of rain showers, patchy fog. Local visibility 1 to 3 nm. Wednesday Night: Winds less than 25 kt. Local rough seas. Chance of rain showers. Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Thursday Night: Winds less than 25 kt. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain. && .CLIMATE... Record Highest Observed Temperature for February... (since records began) Boston.........73 (2/24/2017) Hartford.......73 (2/24/1985) Providence.....72 (2/24/1985) Worcester......69 (2/24/2017) Record High Temperatures... February.......2/20......2/21 Boston.........68 (1930) 63 (1906) Hartford.......69 (1930) 63 (1930) Providence.....69 (1930) 63 (1930) Worcester......65 (1930) 59 (1930) Record Warmest Min Temperature... February.......2/20......2/21 Boston.........46 (1930) 45 (1994) Hartford.......50 (1981) 49 (1981) Providence.....48 (1981) 50 (1981) Worcester......47 (1981) 43 (2002) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 3 AM to 5 PM EST Tuesday for ANZ235-237. Small Craft Advisory from 10 AM this morning to 5 PM EST Tuesday for ANZ250-254. Small Craft Advisory from 6 PM this evening to 5 PM EST Tuesday for ANZ255-256. && $$ SYNOPSIS...Frank/EVT NEAR TERM...EVT SHORT TERM...EVT LONG TERM...Frank AVIATION...Frank/EVT MARINE...Frank/EVT CLIMATE...Staff

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