Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 271907 AFDBOX Area Forecast Discussion National Weather Service Taunton MA 307 PM EDT Tue Jun 27 2017 .SYNOPSIS...
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Upper shortwave and associated jet stream will maintain showers and thunderstorms through this evening. A few of the storms may contain gusty winds and small hail. High pressure builds fair and dry weather for Wednesday. A warming trend begins for the latter half of the week with a return to summer heat and humidity Friday and Saturday. A warm front may bring some showers and some thunderstorms Thursday night, with more showers and thunderstorms possible Friday through the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Showers and thunderstorms have bubbled up and will linger through the evening. Strong low level winds and cold temps aloft are contributing to the strength of these storms. SPC has maintained a Marginal Risk for severe weather for areas west of I-95. Considering all of this, we will maintain some enhanced wording for strong winds and small hail in the forecast. Once the convection dies down, expect dry weather the remainder of the night. Light winds and mostly clear skies will allow fog to form in some spots, especially parts of the CT Valley. Dew points in the upper 40s and 50s should leave room for temps to cool down into the 50s most places by early morning.
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&& .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
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The upper trough is overhead along with its cold pool. So continued support for lift. But the airmass will be much drier with a moist layer limited to the 750-850 mb layer. Expect diurnal clouds but precip is unlikely. Temps aloft will be equivalent to 8-10C at 850 mb, supporting max temps 75-80. High pressure maintains mostly clear skies and light wind should allow overnight temps to reach the 50s, with lower 60s in the urban areas.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Highlights... * Thunderstorm chances increase Thursday night through Sunday * Heat and Humidity return Friday, lasting into the weekend Pattern Details... 00z guidance is in general agreement synoptically with some difference in strength and timing for each wave late in the week. Upper level trough axis will begin to push offshore on Wednesday resulting in a quasi-zonal flow for the region beginning on Thursday. The upper level pattern will become more amplified by the weekend resulting in a broad trough over the Great Lakes with sub- tropical ridge building over the weekend. Because of the ridging over the East Coast and the Midwest trough, a cold front will be come nearly stationary with very little eastward progress this weekend. Ridging out West by Sunday will push towards the Great Lakes by early next week, pushing the broad upper level trough over the Northeast. Details... Wednesday night into Thursday... Dry day to start on Thursday as high pressure will slide offshore. The flow will turn more active with zonal flow aloft and a few weak waves passing through. Impressive warming aloft as surface warm front pushes through the region. This will push southern New England in the warm sector resulting in increasingly warm and humid temperatures. A weak shortwave will move through the flow Thursday evening/night. With zonal pattern and both 850mb isotherms and winds becoming parallel, appears that anything the fires across upstate NY will ride through the flow moving into the area. In fact, guidance is indicating a lingering MCS will move through the flow late in the afternoon/evening which could result in a few strong storms, esp north of the Pike. However, new convection could refire along its southern edge given the strong low level jet and moisture over the area. Trends will have to be watched. Depending on the outcome of convection and cloud cover, temperatures will remain in the low 80s. But it will feel warmer as humidity will be on the rise. Showers and thunderstorms will continue during the overnight hours keeping temps in the upper 60s. Friday into Sunday... Unsettled weather pattern for this time period as southern New England remains in the warm sector with heat and humidity. 850 mb temps warming to 17-18C as well as southwesterly flow, will allow for the summer heat to returns to the region. Appears that the potential for 90 degrees is possible on Friday and Saturday as the back door cold front continues to remain well north of the region. Heat headlines may be needed as 70F dewpoints beginning to pool into the area. There remains a chance for showers and thunderstorms each day, but difficult to place the exact timing and location of any strong storms due to lack of surface boundary. Daytime heating will allow for scattered showers and thunderstorms to develop on Friday. Another shot for scattered showers and thunderstorms will develop on Saturday, but western locations have the better shot thanks to approaching pre-frontal trough. Lower confidence for eastern locations as subtropical ridge will build in pushing a dry slot into the area on Saturday. Cold front will approach on Sunday triggering another round of showers and thunderstorms for southern New England. Through this period, the potential for strong to severe weather appears possible as the region remains in the warm sector. Plenty of instability and moisture will continue to pool into the area with 0- 6 km shear values around 30 kts. Main risk will be strong gusty winds as well as heavy downpours as PWATs will be above 1.5 inches. Still uncertainty with this portion of the forecast so stay tuned for updates. Monday... Cold front will slowly pass through the region on Monday, however is appears that it may get hung up. Cyclonic flow aloft with southwest flow in the mid-levels may trigger another round of showers for the area. Low confidence on this portion of the forecast as there is still a spread in the guidance.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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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 Wednesday Night/...High confidence. This evening and tonight... Areas of MVFR cigs/vsby in showers/tstms. Hail and strong wind gusts possible. Showers diminish and skies clear after 02Z/10 PM. Areas of fog possible after midnight with the best chance in the CT River Valley north of Springfield. Wednesday... VFR and drier weather. Showers/tstms will fire again north of Mass, but all quiet in Southern New England. West-northwest winds. Wednesday night... VFR. Light winds and clearing skies. Patchy fog possible late at night. KBOS Terminal...High confidence in TAF. Showers and T-storms likely this evening. A few of the stronger storms may contain small hail and gusty winds. KBDL Terminal...High confidence in TAF. Showers and T-storms diminish this evening. Outlook /Thursday through Sunday/... Thursday...High confidence. Mainly VFR. Afternoon/evening showers possible in the interior with showers/t-storms possible all SNE Thu night. Gusty SW winds to 25-30 kt developing, especially coastal plain. Friday into Saturday...Moderate confidence. Patchy early morning fog each day. Otherwise mainly VFR, except local IFR in possible strong thunderstorms, mainly during the afternoon and evening hours through the period.
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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 Wednesday Night/...High confidence. Tonight... Showers and thunderstorms over land will move over parts of the waters this evening. Best chance will be along the Massachusetts North Shore. Southwest wind continues with gusts between 20 and 25 knots on the southern waters this evening before diminishing. Small Craft Advisory continues through the evening and then ends around 8 PM as winds diminish. Seas generally 3 feet or less. Wednesday and Wednesday night... Winds become WNW at modest speeds. Seas 3 feet or less. Outlook /Thursday through Sunday/... Thursday...Moderate confidence. Small craft advisories will likely be needed. Increasing SW winds with gusts to 25+ kt likely, especially over nearshore waters. Building seas may reach 6 to 8 ft over southern waters Thu night. Friday into Saturday...Moderate confidence. SW winds continue, mainly 20-25 kt with building seas. Scattered thunderstorms, some with reduced visibilities and strong gusty winds for each day.
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&& .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230>237-251. && $$ SYNOPSIS...WTB/Dunten NEAR TERM...WTB SHORT TERM...WTB LONG TERM...Dunten AVIATION...WTB/Dunten MARINE...WTB/Dunten

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