Provincetown MA to Chatham MA to Nantucket MA out 20 NM Marine Forecast
| Today...N Winds 5 To 10 Kt, Increasing To 15 To 20 Kt With Gusts Up To 30 Kt This Afternoon. Seas 2 To 4 Ft. Wave Detail: Nw 3 Ft At 4 Seconds And S 2 Ft At 8 Seconds. Snow. A Chance Of Rain This Morning, Then Rain This Afternoon. Vsby 1 Nm Or Less. |
| Tonight...N Winds 25 To 30 Kt With Gusts Up To 40 Kt. Seas 4 To 6 Ft, Building To 6 To 9 Ft After Midnight. Wave Detail: N 6 Ft At 6 Seconds And S 2 Ft At 9 Seconds, Becoming N 8 Ft At 7 Seconds And S 3 Ft At 10 Seconds. A Chance Of Snow Showers In The Evening. Light Freezing Spray After Midnight. Vsby 1 Nm Or Less, Increasing To 1 To 3 Nm After Midnight. |
| Mon...Nw Winds 20 To 25 Kt With Gusts Up To 35 Kt. Seas 6 To 9 Ft. Wave Detail: Nw 7 Ft At 7 Seconds And N 6 Ft At 8 Seconds. Light Freezing Spray Likely In The Morning. |
| Mon Night...W Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 4 To 6 Ft. Wave Detail: N 5 Ft At 7 Seconds And Se 2 Ft At 10 Seconds. |
| Tue...W Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Morning. Seas 3 To 5 Ft. Wave Detail: W 4 Ft At 6 Seconds And Ne 2 Ft At 7 Seconds. |
| Tue Night...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Increasing To 15 To 20 Kt With Gusts Up To 30 Kt After Midnight. Seas 2 To 3 Ft. Wave Detail: Sw 3 Ft At 5 Seconds And N 1 Foot At 5 Seconds. |
| Wed And Wed Night...Sw Winds 20 To 25 Kt, Becoming W 15 To 20 Kt. Gusts Up To 30 Kt. Seas 3 To 5 Ft. |
| Thu...S Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. |
| Thu Night...S Winds 20 To 25 Kt With Gusts Up To 40 Kt. Seas 5 To 7 Ft. Showers Likely. Seas Are Reported As Significant Wave Height, Which Is The Average Of The Highest Third Of The Waves. Individual Wave Heights May Be More Than Twice The Significant Wave Height. |
| Area Forecast Discussion National Weather Service Boston/Norton MA 620am EST Sunday Dec 14 2025 Synopsis Fast moving low pressure will bring accumulating snow to the region into midday especially south of the Massachusetts turnpike. The snow will linger into the afternoon across Rhode Island and especially across far eastern Massachusetts where it may persist into this evening. A brief shot of arctic air follows tonight into Monday, with wind chill values dropping to between 0 to 10 below zero. Cold weather continues Monday night into Tuesday but with much lighter winds. A warming trend begins Wednesday and especially by Thursday when high temperatures of 50+ are possible. Unseasonably mild temperatures will be accompanied by a round of showers sometime later Thursday into early Friday with perhaps a period of strong southerly winds and heavy rain. A brief shot of much colder weather with another period of strong winds possible later Friday into Saturday. Near Term - Until 6pm This Evening Key Messages... * Accumulating snow ends by lunchtime across western MA/CT, but persists into the afternoon especially across eastern MA * Hourly snowfall rates generally on the lighter side...but brief bursts of moderate snow possible near the south coast Trend in high res guidance has been to shift the timing of the end of the steadiest snow from mid morning to the afternoon for much of Rhode Island and Eastern Massachusetts. Model guidance, namely the HRRR (High-Resolution Rapid Refresh) and NAM3km have also begun to resolve an inverted trough and wrap around ocean effect snow extending from low pressure as it pulls away. Trough will be a good focus for vertical motion and moisture as omega increases to -10 to -15 ubar/sec. Sharply colder air filtering behind departing low pressure will introduce non-zero MLCAPE values which could help with ocean enhancement of any snowbands. Despite these favorable parameters, daytime will likely be limited by marginal surface temps in the mid and even upper 30s. Temps may be locally lower under any ocean effect bands but its really going to take considerable rates to cool the PBL from the influence of 45-47F water temps. As a result, still think that advisory level snow totals 2-4" for RI/SE MA with localized 5-6" amounts possible near the south coast and Cape Cod. Short Term - 6pm This Evening Through 6pm Monday Key Messages... * Very cold with wind chill values near or below zero * Windy conditions with gusts up to 40 mph Sunday Night and Monday The coldest airmass of the season thus far will move in behind the snow for Sunday night as 850mb temps crash into the -15C to -20C range. This will result in overnight low temperatures bottoming out in the single digits across the interior, to the low teens near the coastal plain. A strong pressure gradient will result in gusty winds overnight, around 25-40 mph. This will bring the windchill index/feels-like temperatures down to the 0F to -5F range, with -5F to -15F in the high terrain. MONDAY High pressure helps to keep an Arctic air mass in place through the day on Monday as GFS (Global Forecast System) and Euro ensembles keep temperature anomalies near 10 degrees colder than normal. Other story Monday will be a steep pressure gradient keeping a stiff NW wind in place for the region. Wind gusts between 25 and 35 mph will make high temperatures in the teens (at higher elevations) and 20s elsewhere feel more like the single digits to lower teens at their warmest. Long Term - Monday Night Through Saturday Key Messages... * A few brief snow showers possible Monday night, otherwise diminishing winds with low temps mainly in the teens * Dry & chilly Tue...Highs mainly in the lower to middle 30s * Turning milder Wednesday with continued dry weather & highs into the 40s * Showers with heavy rain & potential briefly strong southerly wind gusts later Thu into early Fri with unseasonably mild temps * Brief shot of much colder temps returns behind the front later Fri into Sat with another round of strong winds possible Details... Monday night into Tuesday... A weak shortwave may bring a few brief snow showers to the region Monday night. Otherwise...still chilly Monday night into Tuesday but with light winds. Low temperatures Monday night will mainly be in the teens. Highs on Tuesday will range from the upper 20s in the highest terrain to mainly the lower to middle 30s elsewhere. Wednesday... The developing -PNA and high pressure to our south sliding further east will allow for the beginning of a pattern change and milder temperatures. While it will remain dry on Wed, gusty southwest winds developing will push high temperatures well into the 40s. Thursday into Friday morning... Strong shortwave energy over the northern plains will move eastward into the Great Lakes. As this happens...strong surface low pressure perhaps sub 980 mb will pass well to our north across Quebec. Given the potential strength of the surface low pressure system...the long range guidance is indicating a strong southerly LLJ nearly 3 standard deviations outside climatology. Not only will this bring up unseasonably mild temperatures and PWATs (Precipitable Waters) exceeding 1 inch. This will combined with strong forcing ahead of the cold front and bring showers with perhaps brief heavy rain sometime later Thu into Fri. In addition...given the magnitude of the southerly LLJ we will have to watch for a brief period for strong surface wind gusts if the inversion is able to mix out. It is way too early to assess that...but depending on the timing temperatures may rise well into the 50s Thu night/early Fri and may even flirt with 60 degrees. If we are able to get mild enough...the potential for a period of strong winds to be realized will increase. Again...way too early to say much more than that but something to watch in the coming days. Later Friday into Saturday... Briefly turning much colder later Friday into Saturday behind the cold front. Mainly dry weather expected, but another period of strong winds this time from the west is possible immediately behind the cold front. Marine Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Today Through Monday Night ...High confidence. Light N/NW winds through the early afternoon. Winds quickly increase to gales around 21z and gales continue through 20z Monday. Strong cold advection allows for ample mixing resulting in wind gusts between 35-40kts Sunday evening through Monday afternoon. Areas of very light freezing spray possible 00z Monday - 19z Monday. Elsewhere, small craft advisory conditions expected in Narragansett Bay and Boston Harbor. Outlook /Monday Night through Thursday/... Monday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Slight chance of snow showers. Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas locally approaching 5 ft. Wednesday: Strong winds with gusts up to 30 kt. Areas of rough seas. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Thursday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...Winter Weather Advisory until 7pm EST this evening for MAZ017>024. RI...Winter Weather Advisory until 7pm EST this evening for RIZ001>008. Marine Small Craft Advisory from 4pm this afternoon to 3pm EST Monday for ANZ230-236. Gale Warning from 7pm this evening to 1pm EST Monday for ANZ231>235-237-250-251-254>256. |
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