AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 550 AM EST Wed Jan 21 2026 .WHAT HAS CHANGED... Biggest question of the forecast period is how much impact the late weekend/early next week winter storm brings to SNE. Snow is looking increasingly likely but details remain uncertain 4+ days out from this system. && .KEY MESSAGES... - A weak clipper system brings some light snow to the higher terrain areas and light rain for the coastal plain tonight. -Temperatures surge above normal Thursday with gusty winds 25-35 mph. - Arctic front arrives Friday night, with dangerous cold and wind chills expected this weekend and into next week. - A late- weekend coastal storm could bring impactful snow to Southern New England Sunday into Monday but confidence in details is low. && .DISCUSSION... KEY MESSAGE 1...A weak clipper system brings some light snow to the higher terrain areas and light rain for the coastal plain tonight. High pressure to our south moves offshore today and an upper-level trough moves through New England this afternoon. Winds shifting to the southwest on the backside of the high will bring a surge of slightly warmer, more moist air. This new airmass combining with the upper-level trough will initiate a few hours in the evening of light snow showers across the interior. Snowfall will be light in nature with snow totals of a coating to an inch in the higher terrain areas. Areas further south and east will have slightly elevated temperatures compared to the interior, and will most likely see rain showers instead of snow. KEY MESSAGE 2...Temperatures surge above normal Thursday with gusty winds 25-35 mph. Continued southwesterly flow and warm air advection helps warm 850 mb temperatures to -2C to -5C and 925 mb temperatures to near 0C Thursday and allows surface temperatures to surge above normal... afternoon highs in the upper 30s in the higher terrain to low 40s in the coastal plain. The pressure gradient begins to tighten as another low pressure system move through the Great Lakes and high pressure stalls over the Atlantic Ocean. Winds will pick up during the afternoon hours as the land rapidly warms... expecting gusts to increase to 25-35mph through the afternoon. Key Message 3...Arctic front arrives Friday night, with dangerous cold and wind chills expected this weekend and into next week. After a warm Thursday, Friday will be quite the transition into the coldest weekend of the winter. This comes thanks to a dry arctic front which sweeps through SNE on Friday. Temperatures should make it into the upper 20s and low 30s for a time on Friday before plummeting into the single digits on either side of 0. This airmass is unusually cold, with 850 mb temps as cold as -25 to -30 C and the aforementioned low temps 3 SDs below average for late January. This is dangerous cold, especially when combined with the strong LLJ overhead which model soundings suggest will mix down very efficiently in the strong CAA. At the moment gusts 30-40 mph are most likely, which would make temperatures Saturday morning feel like -10 to -20 F in the high terrain, -5 to -15 everywhere else. This will likely necessitate some Cold Weather Advisories, with Extreme Cold Warnings more than likely contained to the highest terrain of the Berkshires. Though Saturday morning will be the coldest period of this stretch of below normal temperatures, the unusual cold is sticking around into the beginning of next week. Highs on Saturday will be in the single digits to mid teens, warming to the teens/mid 20s Sunday and Monday. Additionally, the combination of strong winds and extremely cold temperatures are likely to generate moderate to heavy freezing spray on our waters Friday night through Sunday morning. Key Message 4...A late- weekend coastal storm could bring impactful snow to Southern New England Sunday into Monday but confidence in details is low. After the dangerous cold attention turns to a late weekend storm that has most of the eastern half of the country`s attention at this point. This exceptional outbreak of cold coinciding with a large high pressure anchored over the northern tier of the country together with a frontal zone and plume of subtropical moisture will bring snow and ice from the southeast U.S. into the Mid Atlantic Sat/Sun and then has the potential to bring impactful snowfall to New England Sunday into Monday. This, as a surface low forms along the frontal boundary deepening as it passes off the eastern seaboard. Given this storm is over 4 days from its anticipated arrival in SNE it`s not unusual for there to be significant question as to the details, which is indeed the case here. It will be partially dependent on the eventual track of the surface low. A pass near the 70/40 benchmark would be most impactful for the I-95 corridor with lesser impact if it passes further south. A look at ensemble member low locations in the EPS and GEFS shows an extremely wide spread in the envelope of possible tracks with individual members depicting snow totals from a few inches to 10+. Latest model runs indicate at 40-60% chance of AOA 6" of snow. For now, suffice to say the better chance of major impacts remains to our southwest, but we are in play for that potential as well. Stay tuned. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 12Z update... Today: High Confidence. VFR. Southwest winds 5-10 knots. Tonight: Moderate Confidence. Increasing mid-level cloudiness. Low-end MVFR cloud bases around 3000 feet possible with scattered -SN arriving as early at 00-03z, from west to east, and -RA for the Cape/Islands. Thursday: High Confidence. -SN/-RA moves out after midnight. Conditions improve to VFR with SW winds gusting up to 25 kts. KBOS Terminal...High Confidence in trends. Moderate Confidence in timing. KBDL Terminal...High Confidence in trends. Moderate Confidence in timing. Outlook /Thursday Night through Sunday/... Thursday Night: VFR. Breezy. Friday: VFR. Windy with local gusts up to 30 kt. Friday Night: VFR. Windy with gusts up to 30 kt. Saturday: VFR. Windy with local gusts up to 30 kt. Saturday Night: VFR. Breezy. Slight chance SN. Sunday: Mainly VFR, with local IFR possible. Breezy. Chance SN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today through Thursday... High pressure moves to the south of the coastal waters today, and conditions calm briefly today. Southwesterly winds increase tonight to above 25 knots across the outer waters and persist through Thursday. Seas subside to below 5 feet today, but begin to build once again tonight. Seas further build Thursday to 5-8 feet across the outer waters. Outlook /Thursday Night through Sunday/... Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 30 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 35 kt. Areas of rough seas. Freezing spray, slight chance of snow. Saturday: Moderate risk for Small Craft Advisory winds with areas of gusts up to 30 kt. Areas of rough seas. Freezing spray, slight chance of snow. Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Freezing spray, chance of snow. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Freezing spray, chance of snow. Visibility 1 nm or less. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 7 PM this evening to 7 PM EST Thursday for ANZ232-233-235-237. Small Craft Advisory until 7 PM EST Thursday for ANZ250- 254>256. && $$