AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 155 AM EST Tue Jan 20 2026 .WHAT HAS CHANGED... There have been no sifnificant changes since the last forecast update. && .KEY MESSAGES... - Cold and dry with wind chills in the teens or lower through Wednesday morning. - Near-normal to warmer than normal temperatures midweek as a weak clipper the system brings some higher terrain light snow and light rain for the coastal plain Wednesday night. - An Arctic airmass arrives Friday night with dangerous cold and wind chills and continues through the weekend. Monitoring a late- weekend coastal storm that poses a low risk at the moment for high impacts in Southern New England. && .DISCUSSION... Key message 1...Cold and dry with wind chills in the teens or lower through Wednesday morning. A cold front moving through early this morning will bring an arctic airmass to southern New England through Wednesday morning. With 925mb temperatures around -16C and 850mb temperatures near -22C, surface temperatures this afternoon will struggle to reach the mid- 20s. Any melted snow from yesterday will have already refrozen overnight, and untreated surfaces could be slippery for the morning commute. As winds pick up this morning to 15-25mph, wind chills/feel- like temperatures will plummet to near 0 for most of southern New England... low teens for the Cape/Islands. Winds drop off this evening as high pressure builds in just to the south. With clear skies, light winds, and fresh snowpack, overnight temperatures will drop into the single digits across the region, with low teens near the coasts. Key Message 2...Near-normal to warmer than normal temperatures midweek as a weak clipper the system brings low chances of higher terrain snow showers and light rain for the coastal plain Wednesday night. Temperatures will continue to moderate Wednesday night and Thursday as warmer southwest flow continues ahead of a broad, shallow mid level trough moving over the Great Lakes by Thursday. This will push 925 mb temps from -10C on Wednesday to around -1C on Thursday; we can expect this to result in much milder Thursday morning lows (20s to low 30s) and warmer than average highs Thursday (upper 30s to low 40s). This warm air is advected overhead on a robust LLJ, most of which should remain aloft overnight; however, we`ll see breezy conditions especially over the waters. This accompanies a progressive Alberta clipper that slides through to our north on Thursday, ahead of which we`ll see some light rain/high elevation snow showers Wednesday night. Very little moisture to work with with PWATs of 0.2" to 0.4" and as such expecting only a coating to a half inch of snow in the Worcester Hills and northern Berkshires. Key Message 3...An Arctic airmass arrives Friday night with dangerous cold and wind chills and continues through the weekend. Monitoring a late- weekend coastal storm that poses a low risk at the moment for high impacts in Southern New England. We continue to expect a significant pattern change to end the week and carry us through the weekend courtesy of an intrusion of truly arctic air into the eastern CONUS. In New England we`ll see a mostly dry cold front swing through sometime Friday ushering in the coldest air of the season so far. Global ensemble guidance has held steady (EPS) or increased (GEFS) the magnitude of the cold in the last 12- 24 hours with 850mb temps between -25 and -30C while ensemble situational awareness tables shows surface temps 3 standard deviations below normal. We`re looking at actual temperatures dropping into the negative single digits (high terrain) and single digits Friday night onward, and this is accompanied by gusty winds making temperatures "feel like" -15 to -20 (high terrain) and the negative single digits. Too soon to speak with any confidence on a storm that will be passing to our south late next weekend, potentially bringing a period of snow. At the moment signs point to the more significant impacts being contained south into the Mid-Atlantic and beyond. Again, low confidence as the exact track with dictate who gets snow and how much. What`s not in question is that we`ll have plenty of cold air around. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today: High Confidence. VFR. West winds gusting 20-25 knots, becoming light after sunset. Tonight: High Confidence. VFR. West winds 5-10 knots. Wednesday: High Confidence. VFR. Southwest winds 5-10 knots. KBOS Terminal... VFR. Gusty W winds 23-27 knots through this evening. KBDL Terminal... VFR. Increasing W winds through this evening with gusts of 20-25 knots. Outlook /Wednesday Night through Saturday/... Wednesday Night: Mainly VFR, with local MVFR possible. Breezy. Slight chance RA, slight chance FZRA, slight chance SN. Thursday: VFR. Breezy. Slight chance FZRA. Thursday Night through Saturday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Rest of Today through Wednesday... Cold front will bring a period of strong westerly winds to the waters tonight through Tuesday afternoon with gusts of 30-35 knots. Seas increase tonight highest in the southern waters at 10-13 feet, and 7-10 feet in the northern waters. Winds decrease quickly Tuesday night, with gusts dropping below 20 knots. Seas also gradually diminish to 4-6 feet. With cold arctic air moving offshore, expecting light freezing spray through Tuesday night as air temps drop into the 20s. Warming up Wednesday with lighter winds. Outlook /Wednesday Night through Saturday/... Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of freezing rain, slight chance of rain. Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Slight chance of rain. Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Friday Night: Strong winds with gusts up to 30 kt. Areas of rough seas. Freezing spray, slight chance of snow. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Freezing spray, slight chance of snow. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ230- 236. Gale Warning until 9 AM EST this morning for ANZ231>235-237- 250-251-254>256. && $$