Sunday Forecast


DAYS 1-5 (DECEMBER 24-28)
No changes to yesterday’s discussion. Short range models will be fine-tuning the details of rain/snow line to guide us along but the overall thought process remains the same. Still expect the rain/snow line to spend most of its time near to southeast of I-95 for the Christmas morning event and a burst of heavy precipitation with possible thunder at the end. It should all by out of here by midday so afternoon travel plans will be less impacted. Current expected accumulation: 3-6 inches across north central CT, all of central to interior northeastern MA and southern NH, or basically the I-84 belt and central and northern portions of the I-495 belt with pockets of 6-8 inches favoring higher elevations, 1-3 inches along the I-95 belt including Boston and its immediate suburbs west and southwest, down through northern RI and parts of interior southeastern MA which would be closer to the 2, and then a coating from the South Shore to about the Cape Cod Canal at the end of the event. The remainder of the day would be windy and colder with a few light snow showers around. Tuesday and Wednesday we will find ourselves immersed in a cold northwesterly fair flow delivering arctic air and presenting the chance of a few passing snow showers in otherwise mainly dry conditions. An even colder reinforcement of air arrives Thursday. To the detailed forecast…
TODAY: Partly sunny. Highs 35-43. Wind NW 5-15 MPH.
TONIGHT – CHRISTMAS EVE: Clouding over. Precipitation arriving late as rain Boston south, mix/snow elsewhere. Lows 26-34. Wind light E shifting to N.
MONDAY – CHRISTMAS DAY: Overcast through mid morning with snow except rain changing to snow southeast. A brief burst of heavy snow possible with a slight risk of thunder. See discussion above for expected snow accumulations. Breaking clouds and passing snow flurries midday and afternoon. Early-day highs 28-40, warmest southeastern MA, then falling temperatures. Wind N to NW increasing to 15-25 MPH with higher gusts possible.
TUESDAY: Partly cloudy and windy. Slight chance of snow showers. Lows in the 10s. Highs from the middle 20s to lower 30s.
WEDNESDAY: Partly cloudy and windy. Slight chance of snow showers. Lows from the middle 0s to lower 10s. Highs in the 20s.
THURSDAY: Mostly sunny. Lows in the 0s. Highs from the middle 10s to middle 20s, coldest interior and north, least cold Cape Cod.

Watching 1 or possibly 2 low pressure areas that may impact the region with wintry precipitation and favoring December 30 to early 31 at this time, but there is a fair chance a lot of this may pass south of the region. Temperatures below normal.

DAYS 11-15 (JANUARY 3-7)
Similar pattern, below normal temperatures, additional threat or 2 of a winter precipitation event.

254 replies on “Sunday Forecast”

  1. Sounds like 2-4 in Natick. Works for me! Like seeing snow end week as the 30-31 as opposed to 29-30–will help with my travel plans. Go Pats!

    1. That latest Euro snow map has Boston literally on the fence between no snow and tons of snow (relatively speaking) if I am reading it correctly.

      Thisclose either way. Wow!

  2. Good morning and thank you TK.

    I Was typing this while you posted the new blog.

    JpDave says:
    December 24, 2017 at 8:23 AM

    At this point I have GIVEN UP on tomorrow. It is mainly a rain event
    for Boston, barring a surprise which I am not expecting. I am not pleased, but then again what can I do about it.

    Re: 12/31
    Ha Ha Hardy har har.
    ALL except the EURO have an Out to Sea scenario. Even the Euro has a pass
    well off shore, however, it features some heavy snow due to an inverted trough.
    (Well It looks like that to me anyway)

    Here are the surface showing the trough and the 24 hour snow map

    It will probably be totally gone by the 12Z run today.

    1. When Dave Epstein said that Logan “may” get a half inch, I pretty much gave up on a white Christmas for Boston as well…a lump of coal for most of us I guess.

      And I gather things not looking good for next weekend as well? Cancel the bread & milk run this week!!

      1. Well, it ain’t over yet for next week, but the early returns
        aren’t looking so good. Let’s see if the 12Z Euro still has
        any semblence of a system for 12/30-12/31 ish.

  3. Thank you, TK.

    The frustrating thing is that we’ve had and are going to have periods of really cold air, yet twice in one week the predominant precipitation in Boston will be rain (freezing rain in the first instance; plain rain followed by a touch of snow in the second). Unless one understands meteorology (and I can’t claim to understand it, but I have some rudimentary knowledge), this week’s weather makes no sense.

      1. It seems a lot of weather events these days are unprecedented that never occurred in previous centuries including the 20th itself.

  4. If next weekend’s storm goes OTS here, does the Mid-Atlantic get clobbered? I plan on calling some of my relatives tomorrow. Should I give them a heads-up?

  5. Even though were days out I would let them know that there is a POSSIBILITY of storminess and to check in through the week to their local forecasts because as we get closer will have a better idea what is going to happen.

    1. Thanks Jimmy. Since that area will likely be closer to any potential storm track, I would imagine that their local mets will be hyping things up. I will definitely inquire about it with them in my conversation.

      It seems that no matter how much notice in advance, those areas always still end up unprepared to deal with even several inches.

    1. One thing I will say about the NAM… I don’t think it has the changeover
      to snow fast enough. When it goes, I think it will be virtually instantaneous.

      Even though the above doesn’t look good, the back lash could be intense, although not long, intense enough to throw down a few inches. We shall see.

  6. JPDave a snowlovers dream with that EURO control run with a 959 mb low at the benchmark. I will be shocked if the EURO control one happens but nice to look at.

  7. I’m sure the computer runs later will show the more snow scenario. It’s nice to see the sun .

  8. Thanks TK !

    With all the cold around mid and late week, maybe if winds can turn N on occasion, the cape and immediate south shore coastal areas can get some bouts of ocean effect snow showers ????

    1. Next Sunday my son and I are going to our very first patriots game and will be sitting in the end zone . So of course I’m rooting for no snow than .

  9. Re: Operational, Ensemble, Control runs of Weather Models

    I wanted some clarification on the above given that awesome Euro control run JJ
    posted. So what are the differences?

    Here is what I found. I trust TK will correct if any errors:

    Operational run = high resolution model, no change to initial conditions

    Control run = operational model but a lower resolution model (i.e. less horizontal and vertical grid points)

    Ensemble run = the lower resolution model (same as control run) but with small changes to initial conditions

    More on Control Run:

    No the control is a “control” when it differs from the op then you know the resolution is having an effect on the outcome.

    Helps identify when the Ensemble spread is due to initial condition variations as opposed to resolution issues

  10. The lack of cold air in New England today is the tell tale sign of west-southwest flow aloft and the current position of the trof. The cold temp gradient is to our north. All signs that the developing low will be close to the coast.

    At least this thing will have some pretty good dynamics to make it somewhat interesting to the northwest of Boston. Perhaps even Boston can briefly get a good burst of snow near the end of the precip. I think I’m just going to be too far south and east to get clipped by that on the system’s backside.

      1. I think it will. A heavy burst of snow with those silver dollar size snowflakes. I think the lowest few hundred feets temp is the problem holding back accumulation. It may be 34 to 36F in this brief window of heavy snow, falling to 32F or 33F during the heaviest. It will look awesome, but how much will accumulate ?

  11. Here is something I find most interesting….

    I just ran the whole loop for the 12Z 3KM NAM run for 850 mb temperatures.
    They remain BELOW freezing in BOSTON for the duration of the event.


    I don’t have access to the NAM 925 mb temps, but I find this mighty interesting.

    Here is the loop

    1. So, for Boston it looks like boundary layer issues due to that warm ocean out there. The second the wind turns more to the North, WHAM the Snow will
      commence. The problem is, the winds may not turn soon enough. Could be
      an interesting morning.

  12. Thanks, TK…
    Go Pats! A little nervous. Bills playing for a playoff berth. Buffalo hasn’t been to the playoff dance since 1999. Could be a trap game.

    Wishing you all a beautiful, fun and peaceful holiday! Enjoy your family and friends!

    1. I’m nervous as well. Pats coming off an emotional game last week, now facing a team that is hungry, not only to get a playoff berth but to strike revenge on Gronk. The pats have a hard time with situations like this when a team wants it more

  13. Thanks TK!

    Yesterday was quite a day. I regret not seeing the potential colder scenario from farther out. Even the hi-res guidance was simply way too warm. We see that all the time up in central NH when I’m at school with cold air damming, but it’s less common down here for cold air to hold so strong as it did yesterday. Did some clean-up this morning; several very sizable tree limbs cleared away.

    Tonight/tomorrow… again, no real changes to my thoughts. Unlike yesterday’s storm I think I’ve had this one read a little better with the warmer scenario involving more rain for eastern MA. Inland low is going to be too strong to allow the secondary to develop in a way which would give us more snow. Still, I pretty much agree with TK’s numbers, though I could definitely see over 6″ further northwest outside 495. Will watch for a potential heavy backlash band as the low pulls away. That seems to be the wildcard for mid-morning tomorrow. Questions are, does it happen as some of the hi-res guidance shows, and how far southeast would it extend. Could be a nowcast situation tomorrow morning.

    Next weekend… big storm potential still very much on the table, despite models being all over the place.

    1. You have been outstanding with your forecasting with this one WX as I told you last week . Ch 4 has coating for Boston tomorrow . We shall see.

    2. Thanks for reminding me I did not include the “6-8 inch pockets”. I also sent the forecast with a 2-4 instead of a 1-3 initially. I was not fully awake on this update. 😉

      All fixed now!

  14. With the regular EURO, it still dumps 5-10 inches of snow region ride even that far out.
    GFS : is not showing much, but its ensembles are putting out .5 to 1 inch of liquid which = 5-10 inches in a 10-1 ratio and with the cold air, that could = 10-15 inches.
    I am not using the GFS past its day 3.
    The canadian has the most agreement with its ensembles
    Remember what people were saying, storms will come and go on the models just to show up or vise versa. I feel this is one of those times. We get something before the new year.

  15. Not much to say on late-week threat right now. I need to focus on tomorrow’s because there may be a situation that is very serious for travel for a short period of time.

      1. 8AM-NOON window for the region overall. Doesn’t mean every location for 4 hours. It will probably be 1 hour peak for any given spot. Will try to pin it down.

        1. How much snow are you thinking for Longwood Tk and around the start and finish when you can no rush .

          1. Wildcard: If they start as snow they get a quick coating.

            I think a period of rain is inevitable. I do think they switch back to snow between 4AM and 8AM and end with a burst of moderate to heavy snow by 9 or 10AM. For that area a quick 1 or 2 inches may take place depending on the switch time and how heavy the last band is. Should be gone by late morning.

  16. TK – Where is I-86 located? There used to be an I-86 many years ago from Sturbridge MA to Hartford aka Wilbur Cross Parkway. Now it is I-84.

    Is this 86 a new stretch of highway or a rename of an old one? Just wondering.

  17. What do you think around 11-1pm period 495 to rt 2. I am guessing the worst will be done. in the area but not sure.

  18. So for Boston Tk is it primarily rain & is there a chance they stay all rain in my area . I’m expecting a call around midnight

    1. Makes me glad that I work on Sundays 7-3 so that I miss most of the game by the time I get home. 😉

      As long as they win in the end. 🙂

  19. 1/2 time.

    Re: Pats
    So what else is new. Nothing I didn’t expect. Brady does NOT look good, sorry.
    He just does not.

    re: Weather
    Tonight and Tomorrow

    HRRR “appears” to be leaning more snow.
    Euro has snow a bit more South and East than previous runs

    Watch for more Snow in Boston that previously expected.

    re: Next week
    Euro keeps getting funky on us, but has a Healthy dose of near a foot. Still watching that one.

    re: Wed
    I have not a clue, other than being warned, I shall now watch.

    1. Whatever we get all seem to have it moving pretty fast . I am holding onto hope for 2:00 dinner with the fam.

  20. Yea, Brady hasn’t looked the best for a few weeks. I think he’s injured. Defense can’t get off the field on 3rd down. Although they’ve only given up 6 points.

    1. Nope. Their QB is so-so but they have a solid team. No easy game with these guys who have something to play for.

      1. I never said anything about being a fan. I simply displayed their
        current map. Of course, I would have rathered it showed something. 😀

  21. Hmmm
    As I can continue to pour over the HRRR data. This is REALLY close for Boston.

    925 MB and 850 MB got above freezing in Boston around 7-8 AM.

    it actually looks like it could snow in boston until somewhere around 6-8AM, rain for a an hour or 2 and go back to snow for the duration.

    Will be busy this evening, but will peek at the HRRR when I can.

    FWIW, 18Z NAM not a whole lot of promise, although 3Km NAM shows more
    snow than the others.

    1. No way it’s not snow . I’m right on the water in Winthrop and it’s cold . More snow than rain count on it . I bet surprise totals

          1. Yes and it’s going to get colder . I think this storm might over perform . I’ll probably be called around midnight I’ll report when I get in. It’s cold

  22. As cold as it is (33 as of 4:00 obs.) it is hard to believe that Boston gets mostly rain tomorrow morning. If it was fairly mild out today, then I could understand. Weather just makes absolutely NO sense nowadays.

    1. No Freakin way it starts as RAIN. I can tell you that much.
      However, it is very likely to flip to rain for a few hours. The final totals
      will depend upon how short we can keep that rain period and how
      much snow comes down after it flips back.

      It looks to me as if it is a snow to rain to snow situation for Boston.

  23. 21Z HRRR showing more snow still for Boston.
    IF this trend continues, boston will become an all snow event. 😀

    1. As I said trend is your friend . I think the higher amounts will shift back towards Boston now old salty.

  24. Last I heard Santa’s been downing 5-hour energy drinks as he traverses Western Asia and Eastern Europe. He’s had a rough night. Weather has not been a factor with the exception of a tropical storm in southeast Asia. But, the sleigh’s 4th engine stalled in Australia, and an hour later his GPS malfunctioned which put him and the reindeer in the demilitarized zone between North and South Korea, rather than a Seoul suburb. A quick-thinking Rudolph guided Santa et al. to safety, using his nose’s strobe light setting to temporarily blind North Korean border guards. All is now well as Santa starts distributing gifts to lasses and lads on the British Isles. Soon, he will visit the North American Continent, and if you stay up late you may catch a glimpse of the portly fellow. I’ve never had the privilege of meeting the man in action. Maybe tonight.

    1. I absolutely love this. We have been following him but the color behind this is awesome

      I plan to sit on the deck in a bit and watch. Let’s hope we all get a glimpse

    1. Well I need to report at 3:30 unless we get called in earlier . Tk is it possible we can get this cleaned up and I can make 2:00 dinner in Plymouth. For Longwood area do you think 4-5 inches towards the 5 thinking snow may hold on with no changeover

  25. Dave Epstein tweeted that there will be some nowcasting and likely surprises tomorrow. I will enjoy seeing it unfold.

    1. I said that above I have a strong feeling Boston all snow . It’s a lot colder there than here in pembroke . I was just right on the waters in Winthrop and it was cold

      1. Winthrop…lived there from ’94-’03. About 300 yards or less from the beach. Pretty cold when the wind whipped in from the NE.

          1. I’m sure!! And am I correct that you now live in Hingham? I thought you did unless I’m mixing you up with someone else.

            Where in Winthrop did you live? I lived on Shirley in a white/grey two family that had a couple of decks on the top two floors (where we lived).

            1. Keith, you seem to have crossed paths with more than one here. You and I had to have done the same in Madison Nh or Red Jacket in North Conway.

            2. Yes I live in Hingham now.

              When I lived in Winthrop (in my teens) it was on Terrace Ave. – used to ride my bike to WCAT every Saturday. Nice Lil town.

              1. WCAT…brings back memories as well as Vicki’s mentions of Madison NH (Edelweiss Complex) and the Red Jacket….

                1. Funny, isn’t it how life intertwines….or perhaps it is as it is intended. For a large world…it is sometimes awfully small

  26. What ever the case tomorrow, sharp cutoff between the higher amounts and nothing at all. Of course this cut off will happen some where North and west of Boston in my area.

  27. Most think it’s going to be hard for Boston to accumulate especially with the wind direction and water temperature which I think I saw 42-or 46 I believe it was 46.

    1. To answer your earlier questions, I don’t think Boston comes close to 4 or 5, but whatever falls should be able to be cleaned up in time for you to get to dinner. Good luck!

      1. Tk looking like Boston is mostly rain with the backend snow for a quick burst. C-2 than done between 10-11 . Heading in 3 hrs

        1. That’s about right, but the change to snow may take place a little faster than guidance has. Good luck.

  28. NWS playing the waver game. The pushed the R/S line southeast and their latest map has Boston change from zero to 1-2 inches.

    As far as I’m concerned I see no need to make any changes to the forecast posted above at this point.

  29. I think it is spitting SNow here, but it is up to 37 dp 29, so it is possible it is rain.
    Not enough coming down to know for sure.

  30. FWIW, Tim Kelly said 3 inches for Boston. He also said column is cold enough for snow.
    We shall see.

    looks to RAIN here before a changeover. I won’t be staying up late enough to see, unless I wake up later. 😀

  31. HRRR advertising 850 MB temps below freezing in Boston for most of event. Looks
    to slip above for 2 hours tops. Ditto 925MB temps.

    However, there is a pretty stiff ENE wind off of that warm ocean which could easily
    kill the boundary layer for snow. It needed to get steady about an hour ago.
    I fear before steady precip arrives, surface temps will be near 40 + or -. Not good for snow. IF we can get some intensity before the warming aloft, then “maybe”, but
    looks like Boston Snow comes after the passage of low, which means 1-2 inches tops
    in the city.

    I wish it would start.

  32. 37 in the city it’s been raining pretty steadily. Tk we are wondering if we need to worry about a freeze over tonight or should we be ok . I’m thinking everything should dry up today.

  33. Merry Christmas! 22 degrees here in Groveland and snowing good. I just measured 2.25 inches…there seems to be a very sharp temperature gradient in eastern ma

  34. Merry Christmas all.

    Down to 30 here in JP and SNOWING.

    After spitting a bit of snow last night, it RAINED. Warm ocean was the problem.

    At 3:30 it was pouring and 35.

    It was 37.2 at 2:20 AM

    HRRR calling for 2-3 inches in Boston.

    it is NOT heavy snow at the moment.

  35. Ice melted from our trees yesterday and most walkways. I was surprised that ice still coated trees and walkways in Uxbridge last night. Snow is not heavy so hopefully won’t take many branches etc

  36. Good coating on roads from mix never all snow . Tk is it off at 10 or 11 . Not plowable in the city with this one just a salter

    1. I’m not outside. I did not see any sleet pellets bouncing, so I assumed it was snow. Looked like snow to me here.

  37. Pretty decent snow going on here. Visibility is down to less than half a mile. Pounding snow and about 3 inches so far, close to 4”.

      1. Thank you, Vicki. It’s been rough for us.

        Nonetheless, a white Christmas! Very pretty to look at – not so good for traveling. Our lights have been flickering.

        1. I’m sorry to hear that. I hope things are improving.

          Lights flickered here a couple of times. Daughter glared at me when I got excited

  38. Those winds are going to be gusting when this low pressure departs. Anyone who got a new winter coat for Christmas your going to be using it this week.

  39. The heaviest snow has yet to reach Boston. The wind-down is only a lull, not an end. Heaviest snow between 9:30AM and 11AM in the city and then it should shut down quickly.

  40. Tk we are being told in Boston this is going till 2 and we just were told freezing up tonight is this accurate.

    1. Snow should be over in about 3 hours. Yes, tonight will get very cold so anything wet will freeze. Boston would have been better off all snow with heavier amounts.

  41. It’s like a Hallmark card outside the window right now. Winds have died down a bit. About 2” of heavy wet snow on the ground.

  42. Merry Christmas WHW gang! So glad for my son that it’s a white one.

    Be safe today and thank you all for giving me something that I can look forward to when it storms – learning from and enjoying your lively chatter!

  43. Just took a walk outside. There ain’t no sleet here. It is SNOW.
    Not all that heavy, but picking up.

    Roads are a mess around these parts.

  44. On radar, it looks like the heavier stuff is about to descend upon the City.
    Let’s see if its bark is worse than its bite. 😀

  45. Down to 24 here and still falling.
    Snow has picked up. Vis around 1/2 mile, but some of that is blowing snow
    as wind is also picking up.

  46. I think it is SNOWING out.
    White out or near white out conditions in VERY HEAVY SNOW!!!!


  47. All appears on track with the storm. I don’t believe it was much “colder” than modeled, but the backside snow band seems a little thicker than most of the models showed. Should be plenty to get most places into their expected ranges.

  48. Still heavy snow but Unless it fills in, looks to be pulling away here. I have not measured but appears to be 4ish inches.

  49. Thundersnow here as well, from the strike W of the city.

    I have under 1/4 mile vis now. Pretty insane.

  50. No thundersnow in Wrentham, but without a doubt one of the most impressive snow bands I’ve ever experienced. Near zero visibility at times. Almost out of it here.

  51. I am jealous of you guys experiencing thunder snow. I have never experienced it in my life and I am hoping this is the winter I get a chance to experience it.

  52. Heads up for those traveling today. Tweet from meteorologist Ryan Hanrahan
    That’s going to be a hideous flash freeze around Boston. Really ugly look for the roads in E Mass right now.

  53. Rain went to a one minute heavy sleet shower, then to snow.

    Flash freeze now topped by a thick coating of snow.

  54. To qualify as a true white Xmas, does at least 1” of snow have to be on the ground by daybreak on Xmas morning? When I got up it was raining and miserable, no snow on the ground. About an hour ago it transitioned to heavy snow. Winding down now and we MIGHT have squeeked out 1” from it.

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