Tuesday December 22 2020 Forecast (8:26AM)

58 Comments

DAYS 1-5 (DECEMBER 22-26)

Drying air eliminates any patchy fog early today and then we will see a sun/cloud mix as an upper level disturbance crosses the region, but with only a minimal chance of a passing snow flurry. This system will result mainly a shot of chilly air with gusty winds developing. It will remain cold but become more tranquil Wednesday as high pressure crosses the region. This high shifts offshore and allows temperatures to moderate on Christmas Eve as a low pressure area heads northeastward into southeastern Canada via the Great Lakes. The strong cold front trailing from this low will develop a wave of low pressure over the Appalachians which will move through NY in the early hours of Christmas Day and whip the front through the region with a short period of rain showers and very mild air, then a quick temperature drop behind it with drying weather and just a chance of a few snow showers surviving the trip from the Great Lakes region. Look for a chilly and breezy but dry Saturday between low pressure in the Canadian Maritimes and high pressure in the Appalachians.

TODAY: Any early freezing fog patches dissipate but watch for areas of black ice. Sun/cloud mix. Slight chance of a passing light snow shower. Highs 34-41. Wind NW 5-15 MPH, higher gusts.

Mostly cloudy. Snow showers likely, except rain or snow showers South Coast. Highs 35-42. Wind W 5-15 MPH, higher gusts.

TONIGHT: Clearing. Lows 15-22. Wind NW 5-15 MPH, higher gusts.

WEDNESDAY: Mostly sunny. Highs 31-38. Wind NW 5-15 MPH, diminishing.

WEDNESDAY NIGHT: Mostly clear. Lows 18-25. Wind SW up to 10 MPH.

THURSDAY: Partly sunny. Highs 38-45. Wind S 5-15 MPH.

THURSDAY NIGHT (CHRISTMAS EVE): Cloudy. Rain showers likely. Temperatures rise to 48-55. Wind S 15-25 MPH, higher gusts, as high as 40-50 MPH especially in coastal areas and higher elevations,.

FRIDAY (CHRISTMAS DAY): Cloudy start with rain showers possibly ending as snow showers, then a sun/cloud mix with a possible snow shower. Highs 50-57 early then temperatures fall through the 40s and into the 30s. Wind S 15-25 MPH with higher gusts, shifting to W.

FRIDAY NIGHT: Variably cloudy with a chance of snow showers. Lows 18-25. Wind W 15-25 MPH and gusty.

SATURDAY: Sun and passing clouds. Highs 28-35. Wind W 10-20 MPH and gusty.

DAYS 6-10 (DECEMBER 27-31)

Fair and seasonably cold December 27. A storm threat in the December 28-29 period. Fair and seasonably chilly weather returns to end the year.

DAYS 11-15 (JANUARY 1-5)

2021 may begin with a rain/mix/snow threat followed by dry weather, a cold shot, then moderation.

58 thoughts on “Tuesday December 22 2020 Forecast (8:26AM)”

  3. Trend should be for a little less rainfall & a little shorter period of significant showers as we move through today’s guidance for Thursday night / Friday morning.

    Wind will be an issue, but I don’t think the full potential will be realized for convection being less than modeled.

    Temperatures for Thursday daytime are being over-forecast by guidance. Thursday night’s temperature spike will not be as high as shown either, and the “warm” air won’t be around for very long on Friday.

    It may not be a Currier & Ives white Christmas, but most of the region is going to have a white Christmas, by definition, this year.

    1. The tv mets are touting 1-2 inches of rain followed immediately by a flash freeze on Christmas Day.

      I hope your forecast verifies as I don’t want a skating rink for my morning commute when I go back to work Saturday.

      1. Oh we’ll have some issues with freezing, for sure. Don’t need much rain for that. All we need is a warm up and a quick drop.

      2. I never said we wouldn’t have heavy showers, nor did I say we wouldn’t have strong winds (at least 40-50 MPH for gusts).

        But we are not going to have hours of heavy rain and strong wind, like you would see in a powerful inside runner. The low pressure area that forms on the front won’t even really be that strong at first and will start to deepen as it moves through NY. The wind will be southerly gradient wind ahead of the front, and pretty good westerly wind behind it as the low does start to intensify as it moves away.

  4. Thank you, TK

    Is rain due in fairly early Christmas Eve? The neighborhood is lining our two streets with luminaries. And we will visit Macs tree on Sutton common. Since Thursday itself looks good we can plan to go earlier

    And good news. Zoom is again waiving the 40 minute limit for Christmas Eve, Christmas and New Years.

    https://blog.zoom.us/zoom-together/

    1. I’d plan as early as possible to be safe. But I think most of the rainfall will occur after midnight.

    1. I think the 40-50 will be far more common. But the stronger gusts can’t be ruled out for places like exposed coastline & a Blue Hill Observatory, for example.

            1. As long as they don’t crash on to your roof or car some day. Of course since they are not on your actual property, not much can be done anyway.

    1. Interesting, Captain.

      My Sutton church worked hard to figure out how to live steam so we can see family service Christmas Eve which my oldest grand loves…..especially when they dim lights and everyone has a candle. I got candles for here.

      Our framingham church…sister to sutton…..is having family service and then a 10:00 service on stories of Christmas and carols. I am really looking forward to that also.

      1. I am going to the 4 pm Christmas Eve service. I actually have e-tickets on my phone to get into the church this year!

  9. Thank you, TK., for your response above. We are now going to common during the day. Sounds as if the luminaries will be fine since the candles only last 6-8 hours. Although I am a bit concerned with wind for those.

  10. Thanks TK
    In the I can dream category with this tweet from meteorologist Ben Noll
    Poleward pulses of high pressure will keep the U.S. weather pattern busy through the end of 2020…
    The weather map to start 2021 is intriguing and the climate drivers suggest volatility will last through January

  11. TK – Could some areas get “2-inch” amounts? I assume there will be massive basement flooding, just what I DON’T need.

    1. They’ll be the exception. Unless you live on the South Shore or South Coast, the snow pack would absorb a lot of water. We’re not really going to see “massive” flooding of any kind.

  12. TK – Did you get to see the alignment last evening? From what I can tell, none of the tv mets did due to all the clouds.

    What about tonight? What time?

  13. This is not a high-quality image, taken with my phone camera on the night view setting, using a street light to trick the camera into a shorter exposure time because it was a hand-held shot.

    A darker view would have resulted in a longer exposure and a very shaky result – hands were pretty cold from taking pics and holding binoculars. 😉

    So here are Jupiter & Saturn at Great Conjunction.

    https://scontent-bos3-1.xx.fbcdn.net/v/t1.0-9/132614789_10159030097417265_3573728506469526527_o.jpg?_nc_cat=107&ccb=2&_nc_sid=8bfeb9&_nc_ohc=AKHFiiMUmjcAX9h5qCN&_nc_ht=scontent-bos3-1.xx&oh=662a382f70c07a2c9bed9aaf4e978956&oe=6009088D

    The next shot is of Mars and the waxing moon at first quarter. This was high in the southeastern sky at the same time the Great Conjunction was ongoing low in the southwest.

    https://scontent-bos3-1.xx.fbcdn.net/v/t1.0-9/132172621_10159030502762265_1010536985037253396_o.jpg?_nc_cat=105&ccb=2&_nc_sid=8bfeb9&_nc_ohc=uZYpi3E9rSsAX-Q2T1J&_nc_ht=scontent-bos3-1.xx&oh=c83e049ea0606bea46d7809bd784b553&oe=60073000

  14. 12z operational GFS is pretty models on rainfall in eastern MA (except Cape Cod where it has heavier). Otherwise the heaviest is in the Berks to the west.

    Rain will be the least issue. Wind will be a bigger one.

    Also talking with colleague and taking note of what will be a very impressive LES band in western NY. Haven’t had the perfect set-up for that too many times early season, but getting it this time.

    1. Amazing how there are never any questions with rain events. Unless there is a current drought…always set in stone. 😉

      Even within 36 hours, the tv met proudly shows his/her snowfall map, still there are “questions”…

      1. That’s not true at all. We have plenty of questions with rain events. It’s already happened several times during the last few months. In fact, there are questions with this one. There’s the potential that some areas end up with very little rainfall from this thing. I can see the scenario where one heavy batch goes well west of Boston and another one peels to the east and goes over Cape Cod.

        As far as snowfall events, we have more factors that go into detailing those, especially since the amount of snow that falls in any given area is 5 to 20 times more “sensitive” than rainfall amounts, given the snow:water ratio we deal with. Just physics at work.

    2. Large eddy sim? Tk one last question…..for now at least 😉 is there an idea of timing for wind arrival? Thank you.

      2. That actually made me laugh out loud. 😉
        Large Eddy Sim…that’s great. 🙂
        Lake Effect Snow is what it really means. 🙂

        As far as the onset of strongest wind, after midnight.

        1. Well hells bells. I looked up LSE and got Large-eddy simulation. Clearly for us acronym challenged folks you need to be more specific 🙂 🙂

  15. I have had plenty of questions with rain events. Not the least of which is the Christmas Eve / Christmas Day. Everything has been telling me that this should be more progessive, less rain, and I keep waiting for the GFS to come to the middle ground as its slightly lower resoultions can smooth out the edges and amps of the higher res output.

    Truth is, I was on a pretty great forecast and synoptic diagnosis run for most of the last 2 years, but despite having the early idea and timing of this December’s winter like pattern, I am struggling to really hone in on the practical daily outcomes. Even today, everything told me 38-40, maybe 42. But there are highs in SNE in the 44-47 range at 1pm. That’s warmer than, with the abundance of snow-cover, we should be getting to today. But, hey, all part of the fun.

  16. For all the talk otherwise, the 12z Euro is classic La Nina. Dominant Southeast ridge drives 3 storm systems west of us the next 10 days, including the Christmas one. That is ~probably~ a preview of what most of January/February will look like, but there is definitely still reason to believe the first couple weeks of January could be active in terms of winter weather.

  17. I am not buying anything with these forecasts models. 0z EURO had a coastal storm with wintry precipitation to close out the year.

  19. Well JMA, the GFS is coming down on its rain forecast, now to under 1.50 inch for pretty much the entire WHW forecast area.

    WxW, yes! I was noting that on today’s op ECMWF run. Not sure it happens THAT quickly, but it’s a preview of what’s to come.

  20. I’m predicting a high of 56 for Boston (Logan) on December 25. If this is correct, they will fall just outside the top 10 warmest Christmas Days. The top 10…

    1940: 58
    1965: 58
    1986: 58
    1915: 59
    1982: 59
    2014: 59
    1888: 60
    1964: 60
    2015: 62
    1889: 65

    1. I’m trying to recall the 2arm christmas when I was a teen. I got a much coveted tennis sweater……the rage of course….and walked around the reservoir just wearing it. 1975? Ish

    1. As long as we realize a PV split does not always translate to cold/snowy for New England. There’s a fairly decent chance that we put a trough in the Atlantic, underneath a ridge to the north, a trough in the western US, and a Southeast Ridge with a Great Lakes storm track.

      1. Yes indeed, we’ll have to see how it plays out. I’m just not convinced yet though that La Nina takes over and dominates for two months. I see a lot of other wildcards at play here that have the potential to offset that pattern.

        With respect to the Atlantic, the Euro is projecting a -NAO much of January. If it is right, wouldn’t that actually promote ridging in the Atlantic and more troughing in the East? Granted, whether that NAO is west or east based could affect the positioning of that trough. If the trough is too far west, we are more at risk for cutters and inside runners. We shall see.

  22. Latest Euro weeklies keep a -NAO rolling through the end of January. It’s a very blocky pattern, developing later next week. Coupled with the PV split that the models seem to be agreeing on, I have reason for some optimism as we head into January.

    Of course these features we are discussing are based on model output, and we know how the models can be. But I dont think it is all bad news down the road if you are looking for some winter weather opportunities.

  23. Just read that Boston’s new average seasonal snowfall is 48.7″.
    This is the updated average snow for the past 30 years (1991-2020). That is a huge jump from the previous 30 year average!

    1. Yes.
      Back on November 14th I had mentioned that when the new 30-year average was put into effect that their new average snowfall would be about 49 inches.

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