Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 130258 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 1058 PM EDT Thu Oct 12 2017 .SYNOPSIS... Strong high pressure builds southward into New England tonight and Friday, providing dry and seasonably cool weather. Warmer and more humid conditions arrive over this weekend as high pressure moves offshore and a cold front approaches from the west. This setup will also result in scattered showers at times, especially Sunday night. This front moves offshore sometime Monday, followed by drier, less humid and seasonably cooler weather early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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1040 PM Update... Noting FEW-SCT low clouds, around 2500-3000 ft, across the lower Cape, Martha`s Vineyard and Block Island over the last couple of hours, due to the E-NE flow bringing ocean effect clouds onshore off the warmer waters. Otherwise, skies were clear and winds were light E-NE or calm at 03Z as high pressure high pres ridge builds across interior New England. Also noting some patchy fog forming across interior E Mass, in the normally prone lower valley areas (KOWD and KTAN), which will likely continue off and on through the remainder of the night with dewpoint depressions at around 2 degrees, which will likely go lower as temps fall in the excellent radiational cooling. Near term forecast pretty much on track, but temps were running a degrees or two lower than forecast. Have updated to bring temps current and incorporate trends into the remainder of the overnight forecast. Also incorporated the patchy fog and lower clouds along the coast. Previous discussion... While at least a light E-NE breeze is expected closer to the shoreline, diminishing winds across much of the interior will allow for excellent radiational cooling. Temps are expected to dip into the mid and upper 30s away from the coast, with the potential for areas of frost to develop in the normally prone locations. A Frost Advisory remains in effect across interior MA, eastern MA away from the shoreline, and north central/NE CT. Temps across some higher terrain and near the coastline are expected to have somewhat milder temps, lows mainly in the 40s.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Friday... High pressure starts off the day extending from New Brunswick and Maine into our area, then the high begins to move eastward away from New England during the afternoon. Model soundings indicate a subsidence inversion lasting thru the day. There should be some increase in mid to high deck clouds during the day. Then with the winds becoming more SE, we start to see an increase in low level moisture that would be trapped under the inversion. So anticipating sunny skies to start, then transitioning to partly/mostly sunny in the afternoon. Dry conditions thru the day. Highs will range from 60- 65 at most locations, though could be a bit cooler across the higher inland terrain. Friday night... Increasing cloudiness expected as southern New England is positioned for a return flow/warm air advection pattern. An increase in moisture is expected as lower level winds shift to the S/SW, though models differ on the amount of moisture. NAM and GFS have backed off somewhat on shower potential, with just a low/slight chance pop for light QPF. Will continue to follow a model blend which produces slight chance pops Fri night. Overnight lows will be on the mild side thanks to increasing surface dew points and increasing cloud cover. Temps drop around 50 to the mid 50s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Highlights... * Warmer and more humid this weekend * Risk of scattered showers this weekend, mainly Sunday night * Trend toward drier, less humid and cooler weather early next week Rather quiet pattern expected for our region much of next week. Strong mid level ridge across the southern USA this weekend will gradually move offshore early next week. This will open the door for a mid level trough to arrive Sunday night into Monday. Guidance is in reasonable agreement with the amplitude and timing, but not quite ready to set that in stone just yet. The main concern for this period will be the passage of a cold front late Sunday into early Monday morning. Expecting SW winds to increase ahead of this front. There is a possibility for 40 kt gusts, especially Sunday afternoon and evening. Some minor wind/tree damage is possible. This front will also provide a focus for showers through this weekend as it gets closer, especially late Sunday into Monday morning. Dry weather expected pretty much all of next week. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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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 Friday Night/...High confidence. Overnight...VFR. Light E-NE or calm winds. Patchy fog will likely develop, with brief IFR-LIFR conditions in some of the locally prone inland areas. Friday...VFR continuing, though there is a chance for localized MVFR cigs during the afternoon, the greater risk of this occurring would be along south coastal MA/RI. Clouds increasing over the course of the day. Friday night...Mainly VFR, then after midnight possible MVFR cigs developing across the interior. Also chance for MVFR cigs/vsbys in a few showers. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. May see brief patchy fog after 06Z with local MVFR VSBYS possible. Outlook /Saturday through Tuesday/... Saturday: VFR. Chance SHRA. Saturday Night: Mainly VFR, with local IFR possible. Chance SHRA, Patchy FG. Sunday: Mainly VFR, with local IFR possible. Windy with gusts to 30 kt. Chance SHRA. Sunday Night: VFR. Windy with gusts to 30 kt. Chance SHRA. Monday through Tuesday Night: VFR.
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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 Friday Night/... Winds and seas remain at or above small craft criteria over the open waters. Expect gusts up to 25 kt mainly on the southern waters, but seas remain around 5-7 ft. Overnight and Friday... Winds and seas remain at or above small craft criteria across the open waters. Expect gusts up to 25 kt mainly on the southern waters, but seas remain around 5-7 ft through the remainder of the night though may gradually subside on the eastern outer waters after 06Z or so. While the wind gusts diminish Friday, seas of 4 to 6 feet will remain along the southern outer waters. Small crafts continue for most of the waters. Friday night... High pressure departs. Visibility may lower in patchy fog and spotty showers. S winds around 10 kts. Outlook /Saturday through Tuesday/...Moderate confidence. High pressure moves offshore Sat with winds becoming SW then. Vsby may lower in patchy fog, spotty showers possible through Sun with showers most numerous Sun night ahead of a cold front. SW winds increase Sun with gusts up to 35 kt possible. Cold frontal passage early Mon, followed by diminishing winds. Dry weather and good vsby most of next week.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...Frost Advisory from 3 AM to 8 AM EDT Friday for CTZ002>004. MA...Frost Advisory from 3 AM to 8 AM EDT Friday for MAZ002>006- 008>014-017-018-026. RI...None. MARINE...Small Craft Advisory until 7 AM EDT Friday for ANZ235-237-250. Small Craft Advisory until 6 PM EDT Friday for ANZ254>256. && $$ SYNOPSIS...Belk/NMB NEAR TERM...Belk/EVT SHORT TERM...NMB LONG TERM...Belk AVIATION...Belk/EVT/NMB MARINE...Belk/EVT/NMB

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