Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 242337 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 737 PM EDT Sun Sep 24 2017 .SYNOPSIS... High pressure covering much of the Eastern USA will bring warm and dry weather to Southern New England the first part of this week. Cold front approaches southern New England during Wednesday afternoon and triggers scattered showers. Cold front slowly moves through southern New England on Thursday and offshore Thursday night. Maria will bring swells to the south coast, but the center is expected to pass well southeast of New England late this week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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No major changes to the forecast this evening. Expecting mostly a repeat of last night, with areas of fog overspreading much of southeast MA. Thinking the western extent should be the I-95 corridor in MA, maybe getting into RI. Brought the forecast back in line with observed trends. Previous Discussion... High pres brings light winds and mostly clear skies. However, stratus deck lurking SE of New Eng is expected to overspread the Cape and Islands this evening with light onshore flow. The low clouds and patchy fog may expand along the south coast but lower confidence on areal extent of stratus and fog tonight. Otherwise, some patchy valley fog may develop overnight in the normally prone locations in the CT Valley. Min temps mostly in the low/mid 60s.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday... Strong subtropical ridge remains in control across New Eng with sunshine and unseasonably warm conditions. However, stratus may linger through the morning across Cape/Islands. Similar 850/925 mb temps suggest temps close to today with upper 80s to around 90 interior but cooler along the immediate coast where sea breezes are likely. Monday night... As Maria lifts north across SE US waters, higher PWAT air and KI values will approach SNE from the east along with increasing elevated instability. This will lead to a risk of showers across SE New Eng and have chc PoPs for Cape/Islands. Otherwise, the guidance is indicating stratus and fog may be more expansive across SNE as higher dewpoints move in. Low temps will be in the 60s. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Very warm temperatures persist into Wednesday * Scattered showers Wednesday afternoon through Thursday night * Maria will bring swells to the south coast but will sharply recurve out to sea southeast of New England late in the week A weakening high pressure ridge should linger across southern New England Tuesday into the first part of Wednesday. Light flow will likely mean seabreezes, with lower temperatures along the immediate coast. A surface cold front should cross our region Wednesday night into Thursday. Given the summer-like warmth ahead of this front, some isolated thunderstorms are not out of the question. The increasing southwest flow ahead of this cold front might also be strong enough to tap into some tropical moisture from Maria. If this moisture is available, it could lead to locally heavy downpours. Some question as to how quickly this cold front will move offshore, particularly once it reaches the coastal plain of RI and southeast MA. High pressure should build in from the west Friday into Saturday. Besides a chance of some lingering showers Friday morning across the Cape and islands, much of this period will be dry. It will also be noticeably cooler, with below normal temperatures expected. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/... Tonight...Expect stratus and fog across Cape/Islands which may expand along the south coast and southeast MA during the night. VFR elsewhere, except for patchy fog upper CT valley. Monday...High confidence. VFR, but areas of IFR stratus and patchy fog may linger over Cape and Islands into the afternoon. Uncertain timing of improving conditions over the Cape and islands. Monday night. Moderate confidence. IFR stratus and patchy fog may become more expansive across SNE but areal extent uncertain. KBOS TAF...High confidence. Seabreeze redevelops by 16z Mon. KBDL TAF...High confidence in TAF. Outlook /Tuesday through Friday/... Confidence...High. Tuesday...Mostly VFR except for patchy early morning fog. Wednesday...Mostly VFR but scattered MVFR ceilings/visibilities in showers, main during the afternoon. Wednesday night through Thursday...MVFR ceilings and areas of IFR ceilings and visibilities in scattered showers and fog. Friday...Mainly VFR. Lingering MVFR in scattered showers across the Cape and islands in the morning.
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&& .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/...High confidence. Winds will remain light through Mon night with high pres over the waters. However, increasing long period south swell from Hurricane Maria will be moving into the waters with potential for 7 to 8 ft seas over southern waters Mon/Min night. SCA for seas will continue. In addition, areas of fog will result in poor vsbys at times, especially south and east of Cape Cod. Outlook /Tuesday through Friday/...Confidence...High Relatively light winds are expected through this period. However, swells from Maria will propagate into the southern coastal waters, beginning late Sunday night or Monday. Small Craft Advisories will likely need to be extended due to rough seas for the waters south of the MA and RI coast for all of this period. The swells from Maria will likely produce another round of high surf and dangerous rip currents. OUTLOOK...Monday night through Friday Confidence...High Relatively light winds are expected through Friday. However, swells from Maria will impact the south coastal marine zones, and Small Craft Advisories will likely be needed due to rough seas for much of this week. The swells from Maria will likely produce continuing high surf and dangerous rip currents, probably lasting most of this week. && .TIDES/COASTAL FLOODING... Long period swell from Hurricane Maria will be moving north into the south coastal waters. WNAWave guidance indicating increasing swell to 7-8 ft with a period of 15 seconds moving into the south coastal waters Mon into Mon night and up to 9 ft on Tuesday. This will result in increasing high surf and dangerous rip currents. High surf advisory will continue and will extend through Tue, and it is likely the high surf will continue through the week even as Maria likely recurves out to sea well southeast of New England. && .CLIMATE...
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Record high today was broken at BDL with a temp of 92 degrees. Record high today was broken at ORH with a temp of 86 degrees. Another chance for record high temps Monday, when records are 85-90. Records jump up Tuesday to 89-95, while less mixing will lead to lower max temps. So the chance for new records diminishes Tuesday. The current record max temps for the three days are: BOS 90/1959 89/1926 95/1881 ORH 85/2010 85/1970 91/1930 BDL 89/1959 90/2007 93/2007 PVD 87/1959 89/1920 89/2007 Also, dew points in the 60s, while high for this time of year, are not unprecedented. The daily extreme high values for dew points are still in the low 70s, except for a couple of 68 and 69 values at Worcester.
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&& .BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None. MA...High Surf Advisory until 6 PM EDT Tuesday for MAZ020-022>024. RI...High Surf Advisory until 6 PM EDT Tuesday for RIZ006>008. MARINE...Small Craft Advisory for hazardous seas until 6 PM EDT Tuesday for ANZ235-237. Small Craft Advisory for hazardous seas until 6 PM EDT Tuesday for ANZ254>256.
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&& $$ SYNOPSIS...Belk/KJC NEAR TERM...Belk/KJC SHORT TERM...KJC LONG TERM...Belk AVIATION...Belk/KJC MARINE...Belk/KJC TIDES/COASTAL FLOODING...Staff CLIMATE...Staff

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