Area Forecast Discussion
Issued by NWS Boston, MA

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000 FXUS61 KBOX 050206 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1006 PM EDT Sun Jun 4 2023 .SYNOPSIS... Unseasonably cool, raw conditions will continue tonight into Monday, especially in eastern Massachusetts. Scattered showers will linger into Monday in eastern New England. Warmer Tuesday with more seasonable temperatures and a chance for thunderstorms. Things then turn cooler for the rest of the week. Unsettled weather pattern will persist through the end of the week with signs up a warmer and drier pattern by next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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10 PM update... Upper low has moved just of the New Eng coast and will shift east of Cape Cod overnight. Scattered showers rotating around the upper low are moving south across eastern half New Eng. Meanwhile, deep moisture plume backing in across Maine will begin to push southward overnight as the upper low shifts to the east. This will result in more widespread rain, currently over Maine, moving south across eastern MA overnight. However, do expect scattered showers to make it further W from portions of central MA into RI. Should remain dry in the CT valley. Previous Discussion... Stubborn upper level low and associated sfc coastal low will continue to meander around the Gulf of Maine, making little eastward progress. Composite radar imagery as of 300 pm shows areas of rain showers ongoing across central and eastern MA, with steadier light rains further across NH and ME. With moisture levels slowly increasing/spreading onshore and little to modest warm advection, expect continued OVC skies with lowering cloud ceilings and periods of steady light rain. While rain amounts won`t be significant or substantial, it will add to the raw conditions. Onshore/northeast breezes will also continue and make temperatures feel even more unseasonably cold for early June. Lows in the mid 40s to around 50, only falling a couple degrees. Along the coastal zone, while the weather would be far from ideal for beachgoing, because of seas over 7 ft against shore on N/NE winds, high surf advisories are in effect for the eastern MA coast for the risk of high surf and rip currents through Monday.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... 345 PM Update: Monday and Monday Night: Monday will continue with the cooler and raw weather with overcast for most of the day across eastern MA; more optimism to a mix of clouds and sun across CT and western MA where high temps have a better chance at reaching 70 degrees. As the sfc and upper air low will make greater eastward inroads into the Canadian Maritimes/NS vicinity through the afternoon, expect covg of showers to diminish and clouds scattering in central/eastern MA and RI, though it will take until late aftn to evening before we see overcast break across Cape Cod and SE MA. Highs in central and eastern MA into RI only reach into the low to perhaps mid 60s, which are some 10 degrees cooler than early June normals. While there may still be some clouds around for Monday night, conditions probably would be best described as partly cloudy. Looks like our dewpoints/moisture levels dry out some for the evening and winds should stay up just enough such that the risk for patchy fog should be minimal. Lows mainly mid 40s to lower 50s. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Continued periods of unsettled weather each day under a mid level trough * Temperatures remain cooler than average until a warm up toward the weekend * Chance of showers and thunderstorms on Tuesday, a few of which could be strong to severe but not expecting widespread severe weather Details... Tuesday... Tuesday continues with more of the same as far as the synoptic weather pattern goes. This features a deep and persistent mid level trough over the eastern U.S. with periodic disturbances rotating around the base through much of the week. Tuesday, though, looks to feature the best chance of thunderstorms rather than garden variety showers. This is because of the combination of a cold pool aloft with diurnal heating at the surface which will lead to low level lapse rates approaching 7.5-8.5C/km and mid level lapse rates of 6- 8C/km. This, in combination with dewpoints potentially rising into the mid to upper 50s for some locations, will lead to mixed layer CAPE values between 500 and 1000 J/kg ahead of the cold front. A few potential complications will be how much clearing we can get early Tuesday to heat the surface...a cloudier outcome would generate less instability. There is also some model disagreement as to how far north those elevated dewpoints can push; something that will become clearer soon as we`re just approaching the windows of some of the higher-res guidance. Either way, widespread severe weather doesn`t look likely since the greater instability doesn`t overlap with the necessary bulk shear. Current thinking is we`ll see mainly typical pulse thunderstorms with sub severe hail possible and some strong winds given an inverted-v look to forecast soundings (though low/mid level flow isn`t impressive). However, a few severe storms are possible given the impressive lapse rates (potential for larger hail). Temperature-wise Tuesday will continue the warm up ahead of the front, into the low to mid 70s. On another note, as we get into Tuesday, depending on how much cloudcover we have you may notice increasingly hazy skies as guidance shows smoke from the Canadian wildfires once again blowing over southern New England. Wednesday through Friday... The aforementioned closed low continues to stall overhead through the end of the week leading to more cool, cloudy, and unsettled weather each day. Given the cold pool and cyclonic flow aloft we`ll likely see a good amount of clouds each day with periodic showers as difficult to time disturbances rotate through the base of the trough. As mentioned by the previous forecaster, it still doesn`t seem like a washout for any day but there will likely be showers around each day. Given temperatures dipping down into the 3-5C range with clouds we can expect highs in the 60s to low 70s each day. Next weekend... Encouraging signs as we go into next week that we`ll get at least a brief respite with a pattern change around Saturday/Sunday. Global guidance is indicating a breakdown in the pattern with the trough finally exiting east and a mid level ridge building in. Confidence in this outcome is low at this distance in time but this would mean warmer temperatures and drier days ahead. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 00z TAF Update: Tonight: High confidence in trends, moderate on timing. MVFR ceilings mostly from Worcester eastward; VFR in the CT Valley. While VFR should prevail for BAF-BDL, downward trends in ceilings/categories elsewhere as we move into the evening. NE to N winds 15-20 kt with gusts 25-30 kt (Strongest Cape airports and ACK), with gusts decreasing slightly into the overnight. Monday: High confidence in trends, but moderate on timing of improvement. BKN-OVC VFR continues in CT Valley. Elsewhere IFR-MVFR ceilings experience slow lift/improvement as winds become NNW, but will emphasize that categorical improvement is likely to be slow with no better than MVFR thru the daytime hrs Mon. N to NW winds 10-20 kt, gusts to 25 kt for Cape Cod and the Islands. Monday Night: High confidence. Any lingering sub-VFR should improve to SCT-BKN VFR early Monday evening. NW winds decrease to 5-10 kt. KBOS Terminal...High confidence in TAF/trends but moderate on timing. MVFR ceilings to deteriorate to IFR very soon. NE winds around 15 kt (gusts low 20s kt) back slightly to due N, but won`t see NW winds develop until late- morning Mon at earliest. KBDL Terminal...High confidence in TAF. Outlook /Tuesday through Friday/... Tuesday through Tuesday Night: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA, isolated TSRA. Wednesday through Wednesday Night: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA. Thursday: Mainly VFR, with local MVFR possible. Chance SHRA. Thursday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Friday: Mainly VFR, with local MVFR possible. Chance SHRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Through Monday Night: High confidence. Persistent northerly wind gusts around 25 to 30 kt will continue tonight into early Monday as a low-level jet of 35 kt moves over the waters. NW winds gradually diminish Monday afternoon and into the evening. Strong N winds will continue to produce rough seas on near shore and coastal waters which may make conditions difficult to navigate for less experienced boaters. Seas should diminish into Monday night but they may stay up enough to warrant extending existing SCAs on the eastern waters. We should see steadier rains that may at times reduce visibility to 4 miles tonight into Monday; expect showers becoming more intermittent for Monday afternoon and Monday evening. Outlook /Tuesday through Friday/... Tuesday through Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, isolated thunderstorms. Wednesday: Winds less than 25 kt. Chance of rain showers. Wednesday Night through Friday: Winds less than 25 kt. Slight chance of rain showers. && .TIDES/COASTAL FLOODING... Key Points: * Pockets of Minor coastal flooding for tonight`s high tide for eastern MA coast, possibly again for Monday night`s high tide. Coastal Flood Advisory remains in effect for the eastern MA coast for tonight. Coastal flood headlines may be needed for Monday night`s high tide as well. A storm surge around 1+ ft combined with 7-10 ft seas offshore will be enough for minor coastal flooding along the eastern MA coast during the high tide near midnight tonight. Similar conditions and tides are expected during the Monday night high tide so another round of minor coastal flooding is possible along the eastern MA coast. Along the South Coast, surge values will be lower due to offshore flow (N winds). Locations such as Providence are forecast to remain well below flood stage. && .CLIMATE... Record Low Max Temps for Sunday June 4th. BOS...52/1891 PVD...55/2012 BDL...59/2018 ORH...51/2018 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...High Surf Advisory until 8 PM EDT Monday for MAZ007-015-016- 019-022-024. Coastal Flood Advisory until 2 AM EDT Monday for MAZ007-015- 016-019-022>024. RI...None. MARINE...Small Craft Advisory until 2 PM EDT Monday for ANZ230-233>235- 237. Small Craft Advisory until 8 PM EDT Monday for ANZ231-232-250- 251-254>256. Small Craft Advisory until 8 AM EDT Monday for ANZ236. && $$ SYNOPSIS...Loconto NEAR TERM...KJC/Loconto/BW SHORT TERM...Loconto LONG TERM...BW AVIATION...Loconto/BW MARINE...Loconto/BW TIDES/COASTAL FLOODING... CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.