Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 241910 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 310 PM EDT Sat Oct 24 2020 .SYNOPSIS...
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A cold front will move across southern New England this evening, followed by northwest winds and colder but seasonable temperatures. Showers are expected for the start of the work week, but not expecting a washout. High pressure will bring dry weather Wednesday. Another system should bring rain showers Thursday into Friday with a cool down by Friday.
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&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A cold front was along the MA/New York border at mid afternoon. This front will move across Srn New England, exiting Cape Cod by early tonight. Winds will turn out of the northwest, and eventually from the north. This will bring in clearing skies, colder air, and lower dew points. How low? Dew points will range from the upper 20s inland to the 30s in the coastal plain. Thus expect min temps in the 30s, except 40s along the immediate coast from Boston south, and on the Cape/Islands. Frost Advisory continues for coastal Essex Co MA, and for interior Plymouth County. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Overview... Broad upper trough centered over the Plains, leaving a west- southwest upper flow over Srn New England. A shortwave moves along this flow and up the coast from Florida, approaching the Srn New England coast late Sunday night. Sunday... High pressure builds over New England with the center passing across Quebec and the Maritimes. This means lots of subsidence and sunny skies. The flow around the high will turn surface winds out of the northeast and then east. Temps at 950 mb and 925 mb suggest max sfc temps in the upper 40s to mid 50s. Even higher-level temperatures support this range. Ocean temperatures are 57-59 along the east MA coast, and 60-63 along the south coasts of MA and RI. Expect increasing clouds in the afternoon, especially late afternoon, as the upper southwest flow rides over the top of the surface layer easterly flow. Sunday night... The upper trough moves through during the night, bringing an increasing chance of showers. Amounts look limited with the greatest amounts of precip remaining offshore. Certainly no drought-buster! Clouds and east flow through the night. Look for min sfc temps in the upper 30s to mid 40s. && .LONG TERM /MONDAY THROUGH SATURDAY/...
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Highlights... * Scattered showers expected Monday and Tuesday * Drier and milder Wednesday * Rain chances return Thursday-Friday Details... Flow becomes more zonal as the subtropical ridge is suppressed further to our south allowing for a more active weather pattern. This as the northern stream becomes more influential and brings more typical fall weather. Plenty of cloudcover is expected to start the week, but a ridge of sfc high pressure extending from the maritimes should keep showers from being too widespread over us. More wet weather is expected to our northwest in closer proximity to a wave of low pressure passing to our north. Additionally, mariners will need to plan for wet weather as a weak low passes well offshore to our southeast. Given the messy nature of the setup have leaned heavily on ensemble data for Mon-Wed, which indicates the best chance of appreciable rainfall in northwest MA and on the southeast coast Monday, with only isolated to scattered showers in SNE on Tuesday. The GFS continues to show another low bringing more rain on Tuesday, but it remains the outlier, so keeping POPs lower on Tuesday for now. By mid week high pressure will bring mostly dry conditions for Wednesday. The next shot at widespread rain comes Thursday into Friday as the remnants from a system from the Gulf of Mexico pass somewhere in our vicinity. It remains too early to lock in on specifics, but at the moment guidance would take it south of us, placing the best rain chances along the south coast. Temperatures this week won`t stray too far from normal, but overall look to be on the cool side, in the 50s. The warmest day will be Thursday as a surge of warmer air brings highs in the upper 50s before a cold front cools things down significantly for Friday into Saturday.
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&& .AVIATION /19Z SATURDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. High confidence in TAFs. Mixed VFR and MVFR ceilings with unrestricted visibility. A cold front moves through this evening, turning winds from the west and northwest. This will bring in colder/drier air and clearing skies. Temperatures away from the coast will reach the low to mid 30s, so expect frost on exposed surfaces. High pressure Sunday brings fair skies much of the day. But clouds start moving north again during the afternoon and especially at night. Cloud bases will remain above 3000 feet most places through the night, but 2000-3000 foot ceilings along the South Coast and the Berkshires overnight. Showers possible overnight, especially along the South Coast. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Monday through Thursday/... Monday: Mainly VFR, with areas IFR possible. Breezy. Chance SHRA. Monday Night: Mainly VFR, with local IFR possible. Chance SHRA. Tuesday: Mainly VFR, with areas MVFR possible. Breezy. SHRA likely. Tuesday Night: Mainly VFR, with local IFR possible. Chance SHRA. Wednesday: VFR. Slight chance SHRA. && .MARINE... Small Craft Advisories continue for all waters except Boston Harbor and Narragansett Bay. Seas of 7-9 ft are due to southeasterly swell from distant Hurricane Epsilon through Sunday morning. These long period seas will bring rough surf and a high risk of rip currents to southern/eastern exposed beaches this weekend. A cold front crosses the waters early tonight, turning winds from the west and northwest with gusts of 25-30 kt. Winds then turn out of the north overnight. High pressure building over Northern New England Sunday will further turn winds out of the northeast and east during the day. Winds diminish to 15 kt and seas will diminish to 5-6 feet. A weather system moves up the coast Sunday night and may bring showers to the waters, mostly after midnight. Winds will be less than 25 kt, but rough seas of 5 feet will linger along the outer waters. Outlook /Monday through Thursday/... Tuesday: Winds less than 25 kt. Seas up to 5 ft. Rain showers likely. Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely. Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Frost Advisory from midnight tonight to 8 AM EDT Sunday for MAZ007-018. RI...None. MARINE...Small Craft Advisory until 11 AM EDT Sunday for ANZ231-232. Small Craft Advisory until 8 AM EDT Sunday for ANZ233>235-237. Small Craft Advisory until 5 PM EDT Monday for ANZ250-254>256. Small Craft Advisory until 8 PM EDT Sunday for ANZ251. && $$ SYNOPSIS...WTB/BW NEAR TERM...WTB SHORT TERM...WTB LONG TERM...BW AVIATION...WTB/BW MARINE...WTB/BW is the U.S. government's official web portal to all federal, state and local government web resources and services.