AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1242 PM EST Thu Mar 5 2026 .WHAT HAS CHANGED... No significant changes to the forecast...but appears the there will be more sleet than freezing rain tonight into Friday morning north of I-90. A small area across the southern Worcester Hills and southern Berks have the best chance of seeing freezing rain/ice accretion near or in excess of 0.25". Lastly...there is a low risk sleet changes to a burst of plowable snow across northern MA late tonight into Friday morning before the precipitation tapers off by Friday afternoon. && .KEY MESSAGES... - Rain develops today into early this evening & transitions to sleet & freezing rain across the high terrain as well as areas near and north of I-90 tonight into Fri am. Greatest risk for 0.25"+ ice accretion high terrain of southern ORH Hills/southern Berks with an inch or two of sleet possible near and north of I-90. Lastly, low risk of a brief burst of plowable snow across northern MA before things tapers off by Fri afternoon to light rain/drizzle. - Pattern change towards milder weather this weekend with a few rain showers followed by very warm temperatures next week. && .DISCUSSION... KEY MESSAGE 1...Rain develops today into early this evening & transitions to sleet & freezing rain across the high terrain as well as areas near and north of I-90 tonight into Fri am. Greatest risk for 0.25"+ ice accretion high terrain of southern ORH Hills/southern Berks with an inch or two of sleet possible near and north of I-90. Lastly, low risk of a brief burst of plowable snow across northern MA before things taper off by Fri afternoon. A rather complex forecast today into Friday with a lot of moving parts...so we will break it down below. First off...any patchy dense ground fog that develops should scour out by mid morning or so. Otherwise...the focus will turn to a wave of low pressure that will be approaching from the west today. This will combined with a strong 1040+ mb high pressure system building into Quebec. The result will be a developing cool moist NE low level flow of air into southern New England. This will result in extensive low clouds today and high temps will be held in the upper 30s to near 40. As the low approaches from the west...mainly areas of light rain may overspread CT late in the morning and may reach RI/SE MA by early afternoon. However...dry low level air across northern and especially northeast MA will keep much of the region dry until perhaps until late afternoon or maybe early evening. The main concern though revolves around the weather tonight into Fri morning. Low pressure tracking towards the south coast will induce an area of modest speed convergence around 700 mb across southern New England. This will result in a period of good frontogenetic forcing resulting in the bulk of the precipitation tonight into Fri morning. Dynamic and adiabatic processes will result in precipitation changing to sleet and freezing rain near and north of I-90 as well as the higher elevations. In the lower elevations...Ptype will favor rain but there also might be some sleet involved. Some of the guidance and soundings indicate a fair amount of sleet across northern MA with 925T on the order of -3C to -5C. This would actually be a good thing as it would save much of the region from significant ice accretion. So hopefully this will keep ice accretion in the few hundredths to under 0.25 range for most locations. That being said...we will have to watch small area that perhaps may receive near or just over 0.25" of ice accretion. Greatest risk for that would be across the high terrain of the southern Berks/southern Worcester Hills where surface temps will be cold enough for an extended period of icing if the depth of the cold air remains shallow enough. While this risk looks to be over a small area...this will have to be watched for potential power outages if higher ice accretion is realized. Otherwise...near and north of I-90 appears the depth of the below freezing layer reaches 5000 feet. This should result in a lot of sleet and its possible areas near and especially north of I-90 receive an inch or two of mainly sleet. Lastly and perhaps the biggest wildcard in this event will be the potential for northern MA to flip to a burst of plowable snowfall late tonight into Fri morning before things taper off. Appears to be a low probability type of event...but soundings are very close to isothermal and if that happens a burst of accumulating snowfall may occur. Greatest risk for this appears to be in northern and especially northeast MA. Certainly something that forecasters will need to watch closely. A small difference in thermal profiles will make the difference between mainly sleet or a burst of several inches of snow. Regardless...the Fri am commute looks messy north of I-90 as well as for the higher terrain. Meanwhile...the lower elevations south of I-90 may see some sleet and perhaps isolated pockets of freezing rain with temps in the 32-34 degree range. However...probably most roadways end up wet especially with any bit of treatment. We should see precipitation taper off to mainly light rain/drizzle Fri afternoon as deeper forcing departs. However, areas of light rain/drizzle and fog look to continue especially across the eastern half of the region with moist shallow onshore flow. KEY MESSAGE 2...Pattern change towards milder weather this weekend with a few rain showers followed by very warm temperatures next week. A western Atlantic mid level ridge/surface high pressure then moves into place over the weekend and persists to some extent through at least the middle of next week with only one frontal system to speak of which suppresses it Saturday night into Sunday. Otherwise this spells a much different weather pattern than recently with dry and increasingly mild weather. For the weekend warm SW flow advects in a much warmer airmass overhead with 850 mb temps 12-13C. Boundary layer mixing, while poor on Saturday and unable to tap into the true warmth, improves going into next week. Regardless of shallow mixing and thick cloudcover Saturday, temps will be much warmer than Friday as surface flow finally backs to the SW with the exit of high pressure over QC; highs still make it into the low 50s in spots. After a weak frontal system brings scattered rain showers overnight, more sun arrives Sunday into next week accompanying the warmer airmass. Thus, high temperatures increase each day through at least Tuesday when mid to upper 60s are on the table! EPS ensemble guidance even wants to place a 40-50% chance of 70F in the Connecticut River valley on Tuesday...GEFS isn`t as excited and we`re a ways out but those hoping for an early taste of Spring can hold onto some hope. The next shortwave/cooldown arrives mid to late week. Aside from the rising temps, dewpoints will also be rising into the upper 40s will also contribute to quick melting of our snowpack, leading to potential for some rising rivers and streams late weekend into next week. Get ready to see some of those plants that have been buried since late January. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18z TAF Update... Rest of Today...Moderate confidence. Widespread MVFR-IFR with localized LIFR conditions expected to overspread the region from southwest to northeast as the afternoon goes on, but mostly VFR north of the MA/RI/CT border at this time. Pockets of light rain already impacting CT/RI/SE MA. The rain is slowly to advancing north, and some showers are already making their way into Middlesex Co. in MA. ORH is currently reporting rain as well, but still seeing VFR conditions that may deteriorate over the next few hours. The rain may also begin to mix with sleet this evening near and north. NE winds increasing to between 5 and 15 knots during the afternoon with the strongest of those winds near the coast. Tonight and Friday...Moderate confidence. IFR/LIFR conditions dominate in freezing rain and sleet in areas north of I-90 as well as parts of the high terrain tonight. Sleet will probably be favored over freezing rain to the north of I-90 by the mid evening hours. South of I-90 in the lower elevation, ptype mainly will be rain but some sleet may be mixed in at times. Ptype may mix with or change to snow late tonight into Fri morning for northern MA with the greatest risk north of route 2 into into northeast MA near the NH border. The risk for snow has also shifted slightly south into BOS after midnight. Precipitation tapers to mainly light rain/drizzle by Friday afternoon but IFR/LIFR conditions likely persist along with areas of fog due to continued onshore flow. NE winds 5 to 15 knots with some 20-25 knot gusts possible near the coast. Friday Night...Moderate confidence. Mostly IFR. Winds weaken, but remain NE. With all the moisture left behind by the Thu night/Fri system, widespread areas of fog are a possibility overnight. Low chance for some precip for northern and western MA into central CT in the early morning hours of Saturday. KBOS Terminal...Moderate confidence in TAF. KBDL Terminal...Moderate confidence in TAF. Outlook /Friday through Tuesday/... Friday: Mainly IFR, with areas MVFR possible. Windy with local gusts up to 30 kt. Chance RA, areas BR, FZRA likely, chance PL. Friday Night: MVFR/IFR conditions possible. Slight chance FZRA. Saturday: MVFR/IFR conditions possible. Breezy. Slight chance RA, slight chance FZRA. Saturday Night: Mainly VFR, with areas IFR possible. Breezy. Chance RA. Sunday: VFR. Breezy. Slight chance RA. Sunday Night through Monday: VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today through Friday...High confidence. Low pressure will approach from the west later today and pass to our south Friday morning. At the same time...a 1040+ mb high pressure system will build across Quebec. This will generate increasing NE wind this afternoon into Friday. We expect NE wind gusts of 20 to 30 knots to develop later today and continue at times into Friday...so we have gone ahead and issued small craft advisories for most of our waters. Seas will also become quite choppy! Outlook /Friday through Tuesday/... Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain, areas fog. Areas of visibility 1 to 3 nm. Friday Night: Winds less than 25 kt. Areas of rough seas. Saturday: Winds less than 25 kt. Seas up to 5 ft. Saturday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 8 ft. Chance of rain. Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Monday: Winds less than 25 kt. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory from 5 PM this afternoon to noon EST Friday for CTZ002>004. MA...Winter Weather Advisory from 5 PM this afternoon to noon EST Friday for MAZ002>015-026. RI...Winter Weather Advisory from 5 PM this afternoon to noon EST Friday for RIZ001-003. MARINE...Small Craft Advisory until 7 PM EST Friday for ANZ231>235-237- 254>256. Small Craft Advisory until 7 PM EST Friday for ANZ250-251. && $$