Monday December 20 2021 Forecast (8:06AM)

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DAYS 1-5 (DECEMBER 20-24)

If you were / are up and outside early this morning you felt the coldest air we’ve experienced in a while, sans wind, as high pressure sat atop the region with a perfect set-up for radiational cooling. This high pressure area will continue to govern our weather today and tomorrow with dry weather, a cold day today and a slightly milder Tuesday for the Winter Solstice (10:59 a.m. EST). We are in the midst of a pattern change as we head into astronomical winter, and as noted previously, our opportunities for systems to produce frozen precipitation for at least parts of there region increase. While we won’t experience any big storms, we will see a couple opportunities during this 5-day period – not today or tomorrow obviously. After the moderation in temperature for Tuesday, a cold front will slip through the region that evening with a slightly cooler air mass behind it. Wednesday, we’ll “dodge a bullet” in terms of an important storm system, as low pressure that originated well to the south (a rarity in this regime) moves offshore to the southeast of New England and a weaker disturbance passes by to the northwest. These 2, had they been closer, may have combined to give the Northeast a more important storm system, but that’s not going to happen. It is the southern system that will scrape us with the northwesterly edge of its precipitation shield on Wednesday – most likely in the form of rain for southeastern MA & RI, but a few pockets of freezing rain and some sleet may occur a little further to the north and west over central through northeastern MA and into southeastern NH as well. I’m not expecting significant travel issues from this, but it could get a little slippery on untreated surfaces where it is cold enough for freezing rain to occur. Areas that see the icing would still likely rise above freezing for high temperatures sometime during the day, putting an end to the icing issue. Even just wet roads can create less traction for tires, so keeping in mind the pre-holiday traffic volume this week, use extra caution if you will be out. This bout of unsettled weather will be short-lived, and we get a fair and seasonably chilly day Thursday courtesy a high pressure area with centers in eastern Canada and south of New England. The southern bubble will slide off to the east and be the weaker of the 2, while the northern high center will stay a little more stubborn in eastern Canada, feeding in some cold air. While this happens, and first part of a weakening frontal boundary from the west will move into the region on Friday (Christmas Eve) with the chance of some light snow or snow shower activity. While it is still several days away and in the model guidance uncertainty zone, this type of pattern usually produces something that will equate more to “festive flakes” rather than becoming a travel issue, but it will be something to keep an eye on…

TODAY: Sunny. Highs 30-37. Wind NW 5-15 MPH.

TONIGHT: Clear. Lows 20-27. Wind W up to 10 MPH.

TUESDAY: Mostly sunny. Highs 36-43. Wind SW 5-15 MPH.

TUESDAY NIGHT: Increasing clouds. Lows 23-30. Wind SW 5-15 MPH shifting to NW.

WEDNESDAY: Cloudy. A period of rain likely southeastern MA & RI. A chance of rain with pockets of freezing rain and sleet southeastern NH through northeastern and central MA to northeastern CT. Highs 35-42, except 42-49 Cape Cod & Islands. Wind NE 5-15 MPH.

WEDNESDAY NIGHT: Clearing. Lows 23-30. Wind NW 5-15 MPH, gusty.

THURSDAY: Mostly sunny. Highs 35-42. Wind NW 5-15 MPH.

THURSDAY NIGHT: Increasing clouds. Chance of light snow overnight. Lows 23-30. Wind variable up to 10 MPH.

FRIDAY (CHRISTMAS EVE): Cloudy with a chance of light snow morning. Variably cloudy with a chance of snow showers afternoon. Highs 31-38. Wind variable up to 10 MPH.

DAYS 6-10 (DECEMBER 25-29)

A frontal boundary and wave of low pressure along it should bring the chance of rain/mix/snow for Christmas Day – timing and details uncertain. Low pressure pulls to the east and strengthens while an upper disturbance crosses the region Sunday December 26 with a chance of snow showers. Generally dry and seasonably cold weather is expected thereafter, though we may need to watch for a weak system to impact the region at the end of the period.

DAYS 11-15 (DECEMBER 30 – JANUARY 3)

A weak system may impact the region with some precipitation early in the period, with another possible somewhere around the first of the new year, but based on previously-mentioned conditions with guidance and the pattern, no detail is possible this far in advance. Temperatures near to below normal.

81 thoughts on “Monday December 20 2021 Forecast (8:06AM)”

  2. Thanks TK.

    This morning the coldest of the season for Boston (Logan) at 21F. Rather appropriate for the last day of fall I suppose.

    1. Yes, I know what you mean. With not much wind, the cold is quite invigorating. I rather don’t like the cold with the wind howling.

  4. Good morning and thank you TK.

    Down to 19 here. Not the coldest of the season, but coldest in a while.

    Looks disappointingly WET on Wednesday. Oh well, par
    for this season so far.

    I am NOT impressed with anything on the horizon so far.

    BORING….. Ho Hum. Santa better install some wheels on his ole sleigh.

    1. Most models show rain and the ones that show mix, are really showing sleet as mentioned by TK above. The colder air aloft
      will remain just to our North and West. Too bad, because
      we could have a nice little festive snowfall.

      If only. We’ll see what the trends are for today. 🙂

    2. A phasing probably would have resulted in more of a snow event, at least away from the South Coast, but it’s a moot point anyway. Not joining forces.

  11. The disturbance in south central Canada as depicted on the NAM at 84 hours is the one that gives us the chance of flakes on Christmas Eve.

    In yet another example of crap models, the GFS, just yesterday and the day before, had high pressure in that same place at that same time on its forecasts. Now, the GFS has the disturbance there and the high pressure area several hundred miles further east.

    As the mets on here have said…… (you can fill in the rest yourself by now). 😉

    2. Several of our local Mets have said the same. I’m thinking there is a way to forecast without using the models but what methods do you use?

      1. Well there’s the pre-model method of course.
        Guidance is still “ok” to use, but more than ever one must know its biases and limitations.

        1. Thanks. It seems most if not all who are reputable do understand. I do consider all of our Mets reputable 🙂

          It seems as if it might be an interesting challenge

      1. Depending on your model of choice between 4AM and 7AM.
        It just according to today’s runs and at least now we are
        about 48 hours or so out, so hopefully, it is better than
        previous runs.

  15. If only we had today’s airmass over us this past weekend. A white Christmas would have been assured as any snow wouldn’t have melted much this week anytime soon. Oh well. 🙂

    4-6”+ (what “could” have been)

    2. It doesn’t really work that way…

      And given the change in the guidance’s portrayal of even Wednesday’s situation in the last 24 hours, don’t rest on anything yet.

  20. 18Z HRRR keeps us DRY on Wednesday. SO there ya go.
    Which model would like?

    Pin them on a wall and throw a dart.

    Perhaps tomorrow there “might” be a little more consistency. 🙂

    1. Hey JP,

      We have the best Mets in the business on this blog. So we have a good idea of what will happen. But I think this is the best time as a surprise could be in store. Will see…

    2. Well, I think you’d probably like dry over rain, so maybe you’re not as ticked off as you think you are. 😉

      1. Well, at this point, I really don’t give 2 craps whether it is dry or it rains. The point is, it ain’t gonna snow. 🙂

  24. A small personal FYI: I had my annual cardiology check-up today. Grade: A+ 😉

    My atrial flutter episodes have been decreasing in frequency and I have not had an atrial fib episode in over a year.

    BP & all the other #’s were perfect.

  25. As I sit outside watching my granddaughter ride her scooter, it is a cool winter feel 36 degrees. But no wind

    2. If it phased sooner, then perhaps we would have been looking
      at more of a snow event? Oh well, when you’re screwed, you’re
      SCREWED!

  29. The model waffling we’re seeing on the Wednesday system is exactly why I encouraged not writing it off too early; I think a miss or light graze is still most likely, but you can see how close it was to a significant coastal storm. It’s also an example of model agreement getting worse the closer to an event you get, which we’ve seen a few examples of this season.

    In terms of snow, it looks like the thermal profiles would make it a moot point either way. Seems tough to get good cold in December these days.

    After this brief appearance from the southern stream, it’s back to the pattern we’ve been in for weeks: active northern stream with a screeching polar jet, frequent Southeast ridging, temperatures averaging fairly close to normal, precipitation below normal. West Coast continues to hold the storminess. That’s what I’m seeing the next 10-14 days at least!

    1. According to Harvey, too warm “above” for snow on Wednesday. Maybe a wintry mix Christmas Eve night/Christmas Day?

      1. Too warm in pretty much all of the lowest 5,000 feet Wednesday. Keep expectations measured for the Christmas Eve and Day system(s), but yes, there is a chance for some light wintry precip.

        1. I am not holding out much hope. I see hints of a little something, but it would be mood snow at best should anything materialize at all. And then it could easily flip to rain. We have a few more days, so perhaps it will look better, but I seriously doubt it.

          Trend is your friend and trend is porking us royally. 🙂

  31. I think most people would rather “mood snow” than a sizeable winter storm for Christmas Eve and/or Christmas Day. 🙂 Not that mother nature cares what we want. 😉 JP Dave you don’t count because I know that unless it’s a biggie, it’s not impressive. 😉 haha!

    1. I agree. I’ve never hoped for a big storm at Christmas. It might keep families from being together and family is fir me what it is all about.

      1. Yup. I mean if it happens it happens and we can’t change it, but seeing mood snow is more comforting to me than knowing somebody might not be able to be with a loved one because they can’t get there.

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