Area Forecast Discussion
Issued by NWS Boston, MA

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349 FXUS61 KBOX 191936 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 336 PM EDT Thu Oct 19 2017 .SYNOPSIS... High pressure will maintain dry weather and warmer than normal temperatures through the weekend. The risk of showers will increase by the middle of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... High pressure is in general control of our weather, bringing dry weather tonight. With light pressure gradient and sunset, expect the southwest winds to diminish early tonight. A shortwave will race across the Northeast tonight and pull a weak cold front through Southern New England middle to late night. As noted, not much moisture about and thus not expecting much in the way of clouds. What may be noticed is a wind direction shift where there are winds, with northwest winds toward morning. Many protected spots that will have light wind. The resulting radiational cooling will again allow patches of fog to form. Dew points will lower a few more degrees, general range upper 30s and 40s...which is about normal. Expect min temps in the 40s and low 50s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... High pressure remains in control with dry weather and mainly clear skies. Main difference from today will be that winds will be from the northwest and bringing slightly lower dew points. Mixing during the day will reach 925 mb or a little higher, similar to today, with temps at that level supporting max sfc temps of roughly 65-70F. At night, light wind with dew points 35-45 will allow radiational cooling to bring min sfc temps in the upper 30s and 40s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Highlights... * Warm and dry this weekend lasting into Monday * Unsettled weather pattern with showers at times Tue into Thu Overview... Strong subtropical ridge along the east coast will maintain warm and dry conditions into early next week. Then models signal a pattern change with significant amplification of the large scale flow as northern stream trough digs south from the Great Lakes to the SE USA and interacts with southern stream energy with an eventual high amplitude trough setting up across the eastern seaboard. With downstream ridging shifting over the Atlantic, there could be a period of unsettled weather sometime in the Tue to Thu timeframe but timing and details remain uncertain in this developing complex pattern. Saturday through Monday... High pres in control with building mid level ridge will result sunshine and unseasonably warm weather. With 925 mb temps 17-18C should see highs reach well into the 70s this weekend but somewhat cooler along the south coast with SW flow. Warm and dry conditions last into Mon. Tuesday through Thursday... Unsettled with showers at times as amplifying trough sets up to the west with slow moving frontal boundary approaching and multiple shortwaves moving through the flow. Timing and details of rainfall remain uncertain but it appears there will be one period of rainfall sometime Tue into Tue night with lead southern stream shortwave lifting to the NE. Then possibly a break followed by another period of rain Thu and beyond as frontal boundary stalls with another system approaching. Very complex pattern so further forecast changes expected. Temps above normal through Wed, but lower confidence Thu. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/...Generally high confidence. Tonight... A weak cold front crosses the region tonight, but with very limited moisture, so few clouds if any. The main effect will be a shift of diminishing winds with winds coming from the northwest overnight. Radiational cooling will allow patches of fog to develop later tonight, especially in parts of the CT River Valley and in the usual fog magnets. Vsbys could drop to 1/2 mile in spots after midnight. Friday and Friday night... VFR conditions continue. Areas of fog will dissipate first thing Friday. Northwest winds will pick up a little, with late morning and afternoon gusts near 20 knots. Winds then diminish with sunset. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Saturday through Tuesday/... Through Monday...High confidence. VFR, but patchy late night fog possible in the typical locations. Tuesday...Moderate confidence. MVFR possible in developing showers. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday Night/...High confidence. Tonight...Southwest winds gust 20 to 25 knots late afternoon but diminish this evening. Seas on the outer waters will hover around 5 feet, and while the flow is from the southwest these 5 foot seas may work into RI Sound as well. Winds will shift from the northwest later tonight, at which point the seas will diminish. A Small Craft Advisory will remain in effect for the most of the waters through this evening, and on the outer waters overnight. Friday...Northwest winds will gust around 20 knots during the day. Seas will remain 4 feet or less through the day. Friday night...Winds remain 15 knots or less, and seas remain at 3 feet or less. Outlook /Saturday through Tuesday/...High confidence. Great boating weather through Mon with SW winds below 20 kt and seas below SCA thresholds as high pressure prevails. Increasing southerly winds Tue as low level jet develops. High prob of SCA winds with low risk for gales. Increasing threat of showers with reduced vsbys Tue. && .FIRE WEATHER... Ahead of a very weak cold front, southwest winds will gust 20-25 mph across much of the region through this evening and then diminish. With an overall recent lack of precipitation, there could be an elevated fire weather potential through the evening. A Special Weather Statement continues to highlight this risk. Winds shift from the northwest overnight. On Friday these northwest winds will gust around 20 mph, with minimum RH values reaching 30-35 percent across much of the region. Thus there could again be some risk of elevated fire weather potential. A new Special Weather Statement will highlight this potential. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ231>234-250- 251-254. Small Craft Advisory until midnight EDT tonight for ANZ230-236. Small Craft Advisory until 7 AM EDT Friday for ANZ235-237-255- 256. && $$ SYNOPSIS...WTB/KJC NEAR TERM...WTB SHORT TERM...WTB LONG TERM...KJC AVIATION...WTB/KJC MARINE...WTB/KJC FIRE WEATHER... is the U.S. government's official web portal to all federal, state and local government web resources and services.