Area Forecast Discussion
Issued by NWS Boston, MA

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980 FXUS61 KBOX 250537 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 137 AM EDT Mon Sep 25 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 THIS MORNING/... As per observations and GOES16 fog product, fog and stratus are advecting onshore across Cape Cod/Vineyard/Nantucket. There have been a couple of reports of 1/4 mile vsbys, but most spots show 2-4 miles at most. There is still a reasonable chance of widespread dense fog developing by midnight, but not enough to go to an advisory at this time. We will continue to monitor. Fog product also shows increasing fog potential all along the eastern Mass waters with light east to southeast winds in place to move any fog onshore. With this as well, no observed fog reports at this time. Patchy light fog also showing up in a couple of traditional fog spots, due to radiation fog. To sum up... fog forecast remains likely and the forecast will continue in this direction with both advection and radiation fog in play. Otherwise, high pressure brings clear skies and light wind. Fari dry weather overnight with min temps mainly in the low to mid 60s. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... 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 NIGHT 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 /06Z 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 Tuesday/... Overnight...Fog and low clouds will linger through the night on the Cape and Islands. Areas of 1/4 mile vsbys or less expected. VFR elsewhere with patchy fog in the traditional fog spots. Light wind. Monday...High confidence. VFR, but areas of IFR in low clouds and fog early on the Cape and Islands. Light east to southeast winds. Monday night. Moderate confidence. Low clouds and fog move back over Cape Cod and Islands with areas of 1/4 mile vsby. Patchy IFR possible inland. Otherwise VFR. KBOS TAF...High confidence in TAF. Seabreeze redevelops by 15z, becomine south toward 00Z-02Z. KBDL TAF...High confidence in TAF. Outlook /Tuesday Night 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...
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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 Tuesday/...High confidence. Winds will remain light through Mon night with high pressure 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 Night 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.
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&& .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. Two of four climate sites broke max temp records yesterday. Another chance for record high temps again today, 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 two days...Today and Tuesday...are: BOS 89/1926 95/1881 ORH 85/1970 91/1930 BDL 90/2007 93/2007 PVD 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... 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 ANZ235-237-254>256. && $$ SYNOPSIS...Belk/KJC NEAR TERM...WTB/Belk/KJC SHORT TERM...KJC LONG TERM...Belk AVIATION...WTB/Belk MARINE...WTB/Belk/KJC TIDES/COASTAL FLOODING... CLIMATE...

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