AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 206 AM EDT Mon Mar 23 2026 .WHAT HAS CHANGED... Increased snow/sleet accumulation along I-90 this morning, which could bring travel difficulties for morning commuters. Still monitoring potential for scattered snow showers or squally activity, which could impact this evening`s commute. && .KEY MESSAGES... - Rain continues along the south coast this morning, with a transition over to a slushy mix of sleet and wet snow around either side of the Mass Pike during the pre-dawn hours thru late morning. Possible travel issues for the Monday morning commute. - Periods of scattered heavier snow showers/possible squally activity late this afternoon through midnight tonight in eastern and central MA/CT. - Dry and seasonable Tuesday becoming unsettled again after mid-week with a few rounds of showers. No significant precipitation expected. && .DISCUSSION... KEY MESSAGE 1...Rain continues along the south coast this morning, with a transition over to a slushy mix of sleet and wet snow around either side of the Mass Pike during the pre-dawn hours thru late morning. Possible travel issues for the Monday morning commute. A messy forecast for today. The sagging cold front continues to slowly seep southward as of early this morning, with steadiest rain lying along the south coast; however the overnight suite of models continue to show a second area of precipitation now taking shape over central PA, which will be falling into cooling air. This supports a wintry mix of sleet and wet snow, most likely developing around or within 20 or so miles of the Mass Pike from Westfield to Boston. This transition looks to start as soon as the early pre-dawn hours (approx. 3-5 AM) continuing into the mid to late morning hours. Still uncertainty in terms of how much precip falls and how intense it might fall, and that will drive if we get any slushy accumulation on pavement. Part of the uncertainty has to do with t-storms across the Ohio Valley; some of the higher resolution solutions (NAM, recent HRRR runs) brings part of this modeled moisture northward and generates quite a bit of QPF and notable snow and sleet accumulations (e.g. as much as 4" using positive snow depth approaches, which should perform better given marginal thermal profiles/temps in the low-mid 30s). We view these higher totals as high outliers, with up to 2" snow/sleet either side of the Mass Pike, mainly on grassy non- paved surfaces. If heavier bands materialize, the potential exists for slushy accumulation on pavement, which could lead to travel difficulties this morning. Because this scenario probably falls short of reaching Winter Weather Advisory snowfall totals but could still result in travel issues, we`ll consider a special weather statement to bring some awareness. If we don`t get the higher precip intensities, any snow or sleet would be hard pressed to stick on the pavement. Key Message 2...Periods of scattered heavier snow showers/possible squally activity late this afternoon through midnight tonight in eastern and central MA. Stuck under a dreary overcast after AM activity moves offshore with northeast winds keeping temperatures today only in the 30s. We`re not entirely out of the woods from precipitation either, but it turns more scattered, showery and hit- or-miss. The next potential period of precip (snow/rain showers) comes early to midafternoon, as dynamic forcing from a potent shortwave trough moving in from the Great Lakes could blossom another round of precipitation. Not everyone would see this activity with best chance over interior Southern New England. Any accumulation would be on the light/minimal side. Of more concern from an impacts perspective is development of scattered narrow bands of snow showers, which look to develop as soon as late this afternoon and pivot south and east into the early to mid- evening hours. Most models are keying on this scenario, being focused by an inverted trough with steeper lapse rates/some shallow instability from the potent shortwave driving heavier snow showers or possible squally activity. While not everyone would see this activity, as is typical of snow showers, those that do could see reduced visibilities and coatings to a couple inches of new snow which has a better chance to stick on pavement given not much warming today and the locally/briefly higher precip rates. The best chance of seeing this snow shower activity would be mainly across eastern MA, but some chances could exist into interior Southern New England as well. Thus the potential for a slippery PM commute is possible. KEY MESSAGE 3...Dry and seasonable Tuesday becoming unsettled again after mid-week with a few rounds of showers. No impactful precipitation expected. Conditions will continue to dry out Tuesday morning as surface high pressure builds into southern New England. This will yield a brief period of fair weather, with sunshine and light NW winds. High temperatures will range in the 40s, which is right around normal for late March. These conditions will be short-lived as the upper level pattern transitions back to an active/unsettled regime by mid-week. Ensemble guidance shows general agreement on quasi-zonal flow aloft, bringing a series of shortwave troughs through the region. This setup will support a few rounds of showers Weds night through Friday. There are still subtle discrepencies in the timing of the waves, so exact timing of the showers are uncertain. A plume of above normal moisture advects into the region ahead of the first shortwave Wed night, gradually rising to 180-250% of normal by Thursday night. The first wave, will have less moisture/upper-level support to work with, so this will more likely yield scattered showers sometime Wednesday night into Thursday. The second wave should move through in the Thursday night into Friday timeframe and has more moisture and ascent aligned with it with a surface low tracking closeby. This will support more widespread precipitation. Ensembles look to range QPF in the 0.25 to 0.50" range for this system, so no strong signal for significant amounts. Temperatures lean above normal in the mid to late-week period with temperatures in the 50s. Overnight lows drop into the low-mid 30s across the interior higher terrain, and mainly upper 30s elsewhere. Model guidance has trended stronger with the warm advection with the Thu night-Fri system which has decreased probabilities for any snow mixing in in the early morning hours. A 60-70 kt southwesterly jet accompanies the system. The core of the highest winds pushes across southern New England overnight into Fri AM. Typically a nighttime surface inversion will inhibit the stronger core of wind/gusts from mixing down, but gusty winds are still possible. Ensemble guidance leans on the drier side to the start the weekend with cooler than normal temperatures. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 06z TAF Update: Through Tonight: Moderate confidence. IFR to MVFR conditions continue, with steadiest rain remaining south of the Mass Pike. A renewed burst of precipitation falling into colder air will support a wintry mix of sleet and wet snow along or within 20 miles or so of the Mass Pike by the pre-dawn hrs, continuing thru late morning. Coatings to up to 2 inches of snow/sleet are possible mainly on grassy surfaces with mostly wet runways, but TAFs that see heavier busts of accumulation could see minor, slushy accumulation on runways. This activity should continue thru 13-15z. NE winds increase to around 10-13 kt with gusts 20-25 kt. Ceilings may improve into the MVFR range, but will have to watch for possible scattered snow showers or even some snow squalls as soon as 20z Monday, which linger and/or move eastward thru 04z Tue. Best chance in eastern MA but could be possible anywhere from BDL to PVD to PYM north and west, with visbys locally dropping into the IFR range in snow showers. Improvement in ceilings toward all VFR more likely by daybreak Tue. NE to N winds around 10-15 kt thru midnight, then becoming NW and decreasing to around 5-10 kt after 06z Tuesday. Tuesday: High confidence. VFR. NW winds become light then shift to SW around 5-10 kt late in the day. KBOS Terminal...Moderate confidence in TAF. Two periods of possible slushy accumulation on runways: one from 09z-15z as ongoing rain changes to or mixes with snow/sleet. The next is in scattered, hit or miss snow showers/possible squalls from ~22z Mon-03z Tue. IFR continues with NE winds around 10-15 kt, only slightly improving to MVFR this afternoon. KBDL Terminal...Moderate confidence in TAF. Mainly rain this morning, ending by mid-morning. Possible scattered/hit-or-miss snow showers/squalls between 19-23z Mon. IFR trends to MVFR ceilings by late morning. Outlook /Tuesday through Friday/... Tuesday through Tuesday Night: VFR. Wednesday: VFR. Breezy. Wednesday Night: VFR. Breezy. Slight chance RA. Thursday: Mainly VFR, with areas MVFR possible. Breezy. Slight chance RA. Thursday Night: Mainly VFR, with areas MVFR possible. Breezy. RA likely. Friday: VFR. Breezy. Chance RA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through Tuesday...High confidence. Northerly wind gusts of 25 to 30 knots today. A few brief gusts near 35 knots are possible...but continued with the small craft headlines as any gusts near 35 knots will be rather short- lived. Northerly wind gusts diminish a bit Mon night...but gusts of 20-25 knots still possible along with rough seas persisting. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Local rough seas. Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain. Thursday: Winds less than 25 kt. Slight chance of rain. Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain. Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230>237. Small Craft Advisory until 2 PM EDT Tuesday for ANZ250-251- 254>256. && $$