Tonight: Lo 35 °F
Friday: Hi 54 °F
Dew Point: 28.9°F
UV Index: 0.0 None
Barometer: 30.12 in S
Rain Rate: 0.00 in/hr
Rain Today: 0.00 in
Rain Wednesday: 0.00 in
Visibility: 10 miles
Gusts: 1 mph
National Weather Service Boston / Norton, MA
Point Forecast Updated Thu Dec 3, 2020 6:33pm EST
Lo 35 °F
Mostly cloudy, with a low around 35. Southwest wind around 8 mph.
Mostly Cloudy then Slight Chance Light Rain
Hi 54 °F
A slight chance of rain after 3pm. Mostly cloudy, with a high near 54. Southwest wind 7 to 12 mph. Chance of precipitation is 20%.
Chance Light Rain
Lo 40 °F
A chance of rain before 5am, then a chance of rain and patchy fog. Cloudy, with a low around 40. West wind 2 to 10 mph. Chance of precipitation is 40%. New rainfall amounts less than a tenth of an inch possible.
Hi 40 °F
Rain and patchy fog before 1pm, then rain and snow between 1pm and 5pm, then rain and snow likely. Cloudy, with a high near 40. North wind 5 to 18 mph. Chance of precipitation is 80%. New snow accumulation of around one inch possible.
Rain And Snow Likely
Lo 30 °F
Rain and snow likely before 2am. Mostly cloudy, with a low around 30. Northwest wind 15 to 18 mph. Chance of precipitation is 70%. New snow accumulation of 1 to 3 inches possible.
Hi 38 °F
Mostly sunny, with a high near 38. Northwest wind 12 to 15 mph, with gusts as high as 25 mph.
Lo 25 °F
Partly cloudy, with a low around 25. West wind 7 to 10 mph.
Hi 37 °F
Mostly sunny, with a high near 37. West wind 7 to 12 mph.
Lo 24 °F
Mostly clear, with a low around 24. Northwest wind 5 to 8 mph.
Hi 37 °F
Mostly sunny, with a high near 37. Northwest wind 5 to 8 mph.
Lo 24 °F
Partly cloudy, with a low around 24. West wind around 6 mph.
Hi 42 °F
Partly sunny, with a high near 42. West wind 3 to 8 mph.
Lo 31 °F
Partly cloudy, with a low around 31. Southwest wind around 8 mph.
Hi 46 °F
Mostly sunny, with a high near 46. West wind 6 to 10 mph.
National Weather Service Boston / Norton, MA
Updated Thu Dec 3, 2020 8:00pm EST
000 FXUS61 KBOX 032341 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 641 PM EST Thu Dec 3 2020 .SYNOPSIS... Increasing cloud cover tonight with quiet weather as high pressure nudges in from the south. Light rain spreads in later on Friday and Friday night as a warm front lifts in from the incoming system. A strong storm system will impact the region Saturday into Saturday night bringing the heavy rain, and strong winds along the coast, and accumulating snow. The storm exits Sunday, then mainly dry and colder weather Monday and Tuesday with a moderating trend Wednesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 645pm update... going forecast is on track. Satellite shows upstream mid/high clouds headed this way. this should keep temperatures on a slow/steady fall overnight. Only modification was to factor the current obs into the forecast for this evening. Otherwise, see below for the full discussion by the previous shift.... Highlights * Dry and quiet weather expected tonight with increasing cloud cover. Mid level ridge axis flattens over the TN/OH Valley due to the cutoff over the Mid Mississippi River Valley and cyclonic flow over the Great Lakes. Surface high will nudge into southern New England from offshore of the Carolinas tonight. Quiet weather across the region tonight. Will see mid to high clouds moving in due to southern cutoff and northern stream mentioned above. The high will keep the pressure gradient relaxed, but cloud cover should hinder strong radiational cooling. Went with the 25th percentile of guidance, which results in lows generally in the 30s across much of the region. The coastal plain will see readings in the low to mid 40s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Friday... * Mild and cloudy with light rain spreading in from southwest to northeast on Friday. Light rain continues Saturday night. Northern stream shortwave trough will be located near Upper Michigan and will dig into the eastern Great Lakes. This is all while the southern stream cutoff begins lifting into the TN/OH Valley and interacting with the northern stream trough. Low pressure will deepen over the TN/OH Valley and a warm front will lift into the Mid Atlantic. Becoming cloudy across southern New England as the warm front lifts into the Mid Atlantic. Aloft flow will become more south- southwesterly, which will advect more moisture into the region. Should see light rain chances increase from southwest to northeast during the afternoon as moisture advects in. Good consensus amongst guidance for this, but any precipitation should be light. Expect it to be above normal temperature wise for southern New England with SW to SSW warm air advection at 850 and 925 hPa. Highs will generally be in the 50s though there will be some mid to upper 40 degree readings across the higher elevations of western portions of the CWA. Friday Night... * Light rain continues, but some of the higher elevations across the eastern slopes of the Berks may see precipitation change over to a rain/snow mix. Southern stream cutoff continues to phase with the northern stream trough as it digs into the eastern Great Lakes. The surface low will deepen as it moves into the Mid Atlantic. The warm front associated with the low will lift to just south of southern New England. Still good consensus amongst guidance for light rain across southern New England. Though the intensity may pick up toward late Friday night/early Saturday as the surface low moves near VA/DE. Should stay fairly mild as southwesterly warm air continues to advect in. Lows will be in the 30s across the interior and 40s elsewhere. && .LONG TERM /SATURDAY THROUGH THURSDAY/... 500 pm update... Mother Nature is making us use all of our winter storm forecasting tools and definately not making it easy. A very highly uncertain forecast for Saturday indeed. Let me spend most of my time focussing on this event, since it's really the highlight in the long term. Models: still quite a bit of variation and the models are struggling with exactly how a northern stream disturbance currently diving south along the Ontario/Manitoba border and southern stream energy across the ArkLaTex region will merge later tomorrow. The model sensitivities to small differences in analyzed intensity of these systems is huge. So although confidence is high that rapid cyclogenesis will occur somewhere along the mid-Atlantic Friday night/early Saturday, those important details of exactly when, where and what path elude us. A 50 mile difference in track, or 6 hour timing difference in development means all the difference. What I'm trying to say here is make sure you have big error bars around the forecast. This is a great situation where probabilistic forecasts are much better than a single deterministic one. But since I've got to make a deterministic forecast, we'll just have to work with it. Scenario: so after quite a bit of coordination with neighboring offices and WPC, generally taking a middle of the road scenario. NAM is believed to be a little too far east. More or less went with a 12z Canadian/ECMWF concept. This would bring developing low pressure inside of the 40N/70W benchmark, and just from pattern recognition, the heaviest snows would be inland. Also looks to be a big slug of moisture with the system, but most of this will stay out in the warmer side of the storm. 2" of precipitation across parts of RI and SE MA is not out of the question. During the day Saturday we should see the lower levels cool thanks to dynamic processes and wet bulb effects. So initally most everyone starts as rain, and by mid- day we should see a change to snow across the interior -- mainly ORH westward. Boundary layer temperatures are marginal for snow, but would think that as heavier precipitation starts to fall, the cooling should turn it over to snow. With temperatures in the lower to mid 30s, it will be a wet snow. As we get into the evening, the low will be moving rapidly east of the region and colder air starts filtering in. Think that even at the coast the precipitation ends as some snow. Snowfall: Since there is uncertainty as to how much QPF will be rain before turning to snow, that makes it tough to come up with an accumulation forecast. Snow ratios appear to be on the low side (as mentioned above...a heavy wet snow). I went with about 7-8:1 ratios during the day Saturday. As we get into the evening, rising to 9-11:1. For those playing at home and viewing snowfall predictions from online weather models, please be aware that most use a strict 10:1 ratio which will get you into trouble more often than not. Although I'm going with the lower snow ratios, there is an unknown if we end up getting a mesoscale band or well developed comma head forming. If that were to happen, that means we've got strong vertical motion in the snow growth zone resulting in large dendrites and a much higher SLR. After putting everything in a blender, I came out with amounts over 6" across higher elevations of MA with 2-4" widespread at lower elevations. Perhaps an 1" as you get just inland of the coast. Chances of my forecast being perfect? Pretty low. Snowfall amount probabilities suggest the potential for 10"+ across the higher terrain. Later forecasts will hopefully fine tune things. Rainfall: Juicy system, so I've got a swath of 1-2" across RI and SE MA. Not thinking any hydro issues at this point, but if we see amounts pushing 2.5" then some of the smaller rivers will be reaching action stage. Again, something for later shifts to look at. If this storm ends up tracking further east, then those heavier rainfall totals fall over the ocean. Winds: Quick look at model soundings in BUFKIT suggest we could see gusts upward of 50mph across the Cape and Islands. 35-45mph across eastern MA. As the system pulls away Saturday night, there could be a fairly strong pressure rise couplet along with deeper mixing on the backside of the storm to give a period of some strong winds as the direction switches to the northwest. Maybe be dealing with a marginal high wind situation requiring an advisory or warning. Again, later shifts will look at that detail more as well. Coastal Flooding: Although we'll have some strong onshore easterly winds, and a rapidly deepening low pressure, at this point it looks like the astronomical tides are low enough that any surge from the storm won't cause any problems. Phew. I think that kinda hits the highlights. thanks for making it through the rambling. For the rest of the extended, I stuck with the NBM. Doesn't look like any other big storms. Upper flow trends toward a zonal flow by mid-week, so although cooler than normal to start next week, we'll get to more or less seasonable temperatures for mid week. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00z Update Overall high confidence. Tonight and through about 18z Friday...VFR area wide. Thin cirrus early overnight will slowly transition to thicker mid level cloud deck by Friday morning. Southwest winds generally light, though some gusts near 20kt possible across the Cape and Islands. After 18z Friday...clouds will continue to lower and thicken. MVFR ceilings develop from west to east. Should start to see some light rain develop across the western half of the region just prior to sunset. Shouldn't pose any restrictions to visibility however. After 00z Saturday...expecting MVFR ceilings to develop area wide. May start to see some MVFR visibilities as well, especially at BDL terminal as rain gets a little steadier. As we get later at night, and beyond the TAF forecast period, would expect IFR conditions to develop. KBOS TAF...High confidence in the TAF. KBDL TAF...High confidence in the TAF. Outlook /Saturday through Tuesday/... Saturday: Mainly IFR, with local MVFR possible. Strong winds with gusts up to 45 kt. RA, chance SN. Saturday Night: Mainly IFR, with areas MVFR possible. Strong winds with gusts up to 45 kt. Chance SN. Sunday: Mainly VFR, with local IFR possible. Windy with local gusts up to 30 kt. Sunday Night through Monday: VFR. Breezy. Monday Night through Tuesday: VFR. && .MARINE... * Gale Watch for all waters Saturday into early Sunday. Have taken down the Small Craft Advisories and hoisted a Gale Watch for all waters for the system expected to impact southern New England Saturday into Sunday. Confidence high enough in the majority of waters seeing at least Gale Force gusts if not higher, but still need to pin point the details given the differences in the track and intensity of the system. Mariners will want to stay tuned to the forecast. Winds will be WSW to SW tonight and on Friday with speeds of 15-20 kts and gusts of 20-25 kts. Wave heights generally 4-6 feet with the highest waves across the outer waters. Winds diminish to 5-15 kts Friday night ahead of the incoming system and the direction gradually shifts to the NE with gusts of 10-15 kts. Seas falling to 3-4 feet across the eastern waters and remain around 4-6 feet across the southern waters. Outlook /Saturday through Tuesday/... Saturday: Low risk for gale force winds with gusts up to 45 kt. Areas of rough seas. Rain. Visibility 1 to 3 nm. Saturday Night: Moderate risk for gale force winds with gusts up to 45 kt. Rough seas up to 15 ft. Chance of rain. Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 12 ft. Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Monday: Winds less than 25 kt. Seas up to 5 ft. Monday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Storm Watch from Saturday morning through Sunday morning for MAZ002>006-008>010-026. RI...None. MARINE...Gale Watch from Saturday morning through Sunday morning for ANZ230>237-250-251-254>256. && $$ SYNOPSIS...BL/Nash NEAR TERM...BL/Nash SHORT TERM...BL LONG TERM...Nash AVIATION...BL/Nash MARINE...BL/Nash
Note: Rain measured automatically by weather station. Rain totals do not necessarily include melted frozen precipitation.
For more accurate, manually measured rain data, see the Local Precip Data page.
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No alerts/warnings active for Southeast Middlesex County.
Alerts active nearby in: Block Island Sound; Boston Harbor; Buzzards Bay; Cape Cod Bay; Central Middlesex County, MA; Cheshire, NH; Coastal Waters extending out to 25 nm South of Marthas Vineyard and Nantucket; Coastal Waters from Montauk NY to Marthas Vineyard extending out to 20 nm South of Block Island; Coastal waters east of Ipswich Bay and the Stellwagen Bank National Marine Sanctuary; Coastal waters from Provincetown MA to Chatham MA to Nantucket MA out 20 nm; Eastern Franklin, MA; Eastern Hampshire, MA; Eastern Hillsborough, NH; Interior Rockingham, NH; Massachusetts Bay and Ipswich Bay; Nantucket Sound; Narragansett Bay; Northern Berkshire, MA; Northern Worcester, MA; Northwest Middlesex County, MA; Rhode Island Sound; Southern Berkshire, MA; Vineyard Sound; Western And Central Hillsborough, NH; Western Essex, MA; Western Franklin, MA; Western Hampden, MA; Western Hampshire, MA