Area Forecast Discussion
Issued by NWS Boston, MA

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323 FXUS61 KBOX 300226 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1026 PM EDT MON AUG 29 2016 .SYNOPSIS... Weak high pressure brings dry weather into Tuesday night. Warm and humid weather returns Wednesday ahead of another cold front, which will bring scattered showers and a few thunderstorms Wednesday night, lingering along the south coast on Thursday. Large high pressure will build out of central Canada, bringing dry, seasonable conditions into the upcoming holiday weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... High pressure builds over New England with clear skies overnight. Lingering north winds should diminish after midnight, and winds in interior sections should become light/variable. The result will be radiational cooling across the interior. Surface temperatures and dew points at 10 pm averaged 2-3F lower than forecast. We have adjusted hourly temps and the forecast min temps down approx 2F. With dew points in the 50s and lower 60s, a similar range works well for min temps. With temps and dew points close to each other, expect fog patches after 2 am. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tomorrow... High pres will crest then gradually shift to the S of the region thanks to slackening of the upstream ridge aloft. This will allow return flow to develop rather quickly, so only expect the NW flow to linger into early afternoon. Still H85 temps will have dipped closer to +13C, and with the cooler start, highs should only reach into the low-mid 80s. These numbers will be capped even further by sea breezes at coastal locations. Tomorrow night... The return flow mentioned above will lead to a slow increase in column moisture. This suggests increasing clouds and dwpts through the night which will limit cooling to mainly the upper 50s and low 60s...still pleasant but not as cool as Mon night. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGHLIGHTS... * Scattered showers and thunderstorms late Wed into Thursday * Dry weather and seasonable temps into the Holiday weekend * Rough surf and rip currents could be an issue mid to late week due to SE swells from distant Hurricane Gaston. OVERVIEW... The 12z guidance is in overall agreement for the period. Still some minor differences in timing, but overall high confidence in the forecast. The EC has slowed the front up a few hours then its 00z run aligning more with the NAM, whereas the GFS is the faster of the guidance. However, the NAM does appears to have some convective feedback so did not use it for this forecast. Because of the difference continued with a blend in the guidance. Behind the front Canadian high pressure will filter in resulting in near or slightly below average temps into the weekend. Strong ridge, near 2 std above normal, will build into the region Sunday into Monday resulting in high pressure and moderating temperatures. DETAILS... Wednesday into Thursday...High confidence in trends, moderate confidence in timing. Zonal flow on Wednesday will lead to an upper level trough for Thursday. Shortwave moving through the flow will push a surface cold front across Southern New England late Wednesday into Thursday. Anticipate temperatures to climb a few degrees above normal on Wednesday before the front swings through. Showers and thunderstorms will develop along this front. Believe that precip chances will be mainly scattered across the region as Gaston and/or TD eight may rob a lot of our moisture chances. Showers could linger into Thursday as the latest guidance as well as the ensembles have slowed the timing down a few hours. So continued with a slight chance. Otherwise with upper level trough over the region and cloudy skies, temperatures will be below average with highs in the upper 70s to low 80s. The threat for rough surf and high risk for rip current development should continue through the mid to late week due to SE swells from distant Hurricane Gaston. Friday into Labor Day...High Confidence. Upper level trough over the region on Friday before potent ridge builds in Saturday into Monday. Cold pool aloft on Friday may be enough to trigger a spot shower or sprinkle north of the Mass Pike, but otherwise expect dry weather into Monday. Temperatures will also be cooler on Friday with high temps in the low to mid 70s. Dewpoints will be in the mid to low 50s so very comfortable weather to start the Holiday weekend. As the ridge build temperatures will begin to moderate with upper 70s on Saturday and low 80s on Sunday. Temperatures and humidity will begin to rise on Monday as temps reach into the mid 80s. The threat for rough surf and high risk for rip current development should continue through the mid to late week due to SE swells from TD eight. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through tomorrow night...High confidence. Mainly VFR outside of a few patches of fog late tonight and again tomorrow night at typically prone terminals. North winds 5 to 10 knots weaken to near calm overnight. Sea breezes likely tomorrow on all coasts. KBOS Terminal...High confidence in TAF. A NE-SE sea Breeze develops starting around 14z. KBDL Terminal...High confidence in TAF. Outlook /Wednesday through Saturday/... High confidence in trends but some uncertainty in timing. VFR through the period. Cigs and vsbys restrictions possible Wednesday night/Thursday am in scattered showers and thunderstorms. Sea breezes possible on Thursday and Friday. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Through tomorrow...moderate confidence. North to northeast winds diminish overnight. However, continued swell from the S and SW from both Gaston and TD-8 will lead to near 5 ft seas into S New England. Therefore, will allow outer water small craft advisories to linger. Tomorrow night...moderate confidence. Swells combined with SW flow will lead to higher seas in the Gulf of Maine than elsewhere. Small craft advisories may need to be shifted to the N, with none for the remainder of the S New England coastal waters. Outlook /Wednesday through Saturday/... Moderate confidence through the period as there is a large uncertainty on TD eights impact for southern New England waters. Linger swell and return flow across the NE outer waters could result in SCA issues. Otherwise conditions should be below SCA for Thursday. However, beginning Friday and into the weekend, the southern waters will begin to be impacted from the swell of TD eight. This may result in another round of SCA especially for seas through the weekend. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT Tuesday for ANZ250-254. Small Craft Advisory until 3 PM EDT Tuesday for ANZ255-256. && $$ SYNOPSIS...Doody/Dunten NEAR TERM...WTB/Doody/Dunten SHORT TERM...Doody LONG TERM...Dunten AVIATION...Doody/Dunten MARINE...WTB/Doody/Dunten is the U.S. government's official web portal to all federal, state and local government web resources and services.