Saturday December 18 2021 Forecast (9:20AM)

92 Comments

DAYS 1-5 (DECEMBER 18-22)

A weak area of low pressure skirts just south of the South Coast later today through early Sunday. This will give us a minor precipitation event, snow to start out for many (except rain Cape Cod and immediate South Coast), with a rain/snow line progressing northward from the South Coast and westward from the eastern shores as time goes along. There will be some sleet in the mix/change area, as well as some potential freezing rain pockets especially in central MA where temperatures may sit just below freezing. This system exits early Sunday followed by fair but colder weather as high pressure moves into the region. This high will sit right over us Sunday night (coldest night of the season so far) and Monday with fair and cold conditions. The high shifts to the south with a tiny moderation in temperature Tuesday, before a cold front slips down from the northwest and turns it a little colder again by midweek. We’ll have to keep an eye on the evolution of low pressure to the south and east of New England by later Wednesday as it could end up close enough to bring a snow shower threat.

TODAY: Cloudy. Scattered snow/sleet/rain South Coast and a few snow showers southern NH and northern MA this morning. Steadier precipitation as mostly rain South Coast / Cape Cod, snow elsewhere eventually mixing with and changing to sleet and rain with pockets of freezing rain interior areas (mostly west of I-495). Snow accumulation under 1 inch immediate coastal areas, 1-2 inches away from the coast except 2-4 inches north central MA through interior southern NH Highs 32-37 inland, 38-43 coast. Wind NE 5-15 MPH.

SATURDAY NIGHT: Overcast with rain coastal areas, rain with pockets of freezing rain and sleet interior areas but some snow still possible higher elevations of north central MA and southwestern NH, tapering off overnight. Lows 30-37. Wind NE 5-15 MPH shifting to N.

SUNDAY: Cloudy with lingering rain/sleet/snow showers early, then increasing sunshine. Highs 36-43. Wind N to NW 5-15 MPH, higher gusts, diminishing late.

SUNDAY NIGHT: Clear. Lows 12-19. Wind calm.

MONDAY: Sunny. Highs 28-35. Wind NW 5-15 MPH.

MONDAY NIGHT: Clear. Lows 17-24. Wind W up to 10 MPH.

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

TUESDAY NIGHT: Partly cloudy. Lows 25-32. Wind SW 5-15 MPH shifting to NW.

WEDNESDAY: Sun giving way to clouds. Highs 32-39. Wind NW 5-15 MPH.

DAYS 6-10 (DECEMBER 23-27)

Temperatures near to below normal. Offshore storm may bring some snow showers or a period of snow early December 23. Weak disturbance may trigger a few snow showers Christmas Eve and low pressure approaching from the west may bring some precipitation around December 26. No major storms are expected.

DAYS 11-15 (DECEMBER 28 – JANUARY 1)

Similar pattern of frequent but not too powerful systems with additional opportunities for some precipitation. Temperatures near to below normal.

92 thoughts on “Saturday December 18 2021 Forecast (9:20AM)”

  1. Seeing the usual around social media weather circles again today like we’re being let down from what was supposed to be a major snowstorm or something. These are people who largely pay attention to social media pages run by weather weenies (a weenie to me is not a weather enthusiast but somebody who decides to play weather forecaster and gets a thrill out of being the first one to break the “big news” even though they usually make up the news by looking for a model run however many days in advance they can that erroneously shows a bigger storm system than we’ll see and deciding that has to be right and they are going to be the only one to spot it first and tell all their “faithful” (read “gullible”) followers). You know, the same people who will tell them after the “forecast” blows up things like “don’t worry, the weather is unpredictable”, “it’s ok, things change, you’re still better than the professionals” etc etc etc – blah blah blah blah. The same bullshit time after time after time, and they fall for it time after time after time. Turns out that only very minor adjustments were made to the “first guess” that myself and other actual meteorologists made on this system, and it’s pretty much going to behave in the ballpark of expectation, and not “damn, the blockbuster isn’t going to happen, what a BUST!” Y’all know better. 😉

    Thanks for listening to the rant and following WHW. 🙂

      1. I guess it all kind of follows along the same general through processes. When I have made occasional visits to these page and delivered what I feel to be valuable educational information, it’s generally just ignored, so I very seldom do it these days. It’s really come down to the sad probable truth that someone will end up injured or worse making decisions based on unqualified people’s information.

  3. Good morning and thank you TK.

    I was thinking this morning that if it were colder, we might be looking at some ocean effect snow before the main precipitation field. But, sadly, it is NOT cold enough. It is barely cold enough
    to support snow in the first place. 🙂

    1. With mid December water, we’d need a pretty cold air mass. We definitely don’t have that quite yet. 🙂 The Arctic has been doing business elsewhere in recent days….

  4. Thanks TK.

    “Weather weenie”, I’ll have to remember that term. 😉

    I am glad that the only social media I go to is here at WHW or Covid-19 pages. I have never been on Facebook in my life. Not even as a curiosity.

    1. The term has been around for a while. I think it really started as a more affectionate term for weather enthusiasts, but has shifted to being used more for the social media hype-masters. 😉

      There are pages out there run be people who have not had a single day of actual meteorology training, people who have taken it upon themselves to decide where watches and warnings need to be issued, what rating tornadoes need to get, how strong a hurricane should be classified, etc, etc. It’s a total disrespect to the actual profession. And I’m not talking about somebody who has an opinion on it but is open to learning. I’m talking about the people who decide they are the official source of information but have no business doing such a thing. It’s going to get someone in real trouble if it hasn’t already. Funny thing is, when you ask a person like this to explain something scientifically, they can’t do it. They either don’t answer, or they block you, after which the followers will applaud them for the action. 😉

  5. Thank you TK!!
    No weather weenies for this guy. I only trust the three wise men
    TK, SAK and Wx Watcher!!

  6. Thanks TK !

    Per obs, there are some pretty good dew point depressions at Logan points north and northwest for some cooling, at least at low levels, for now ………..

  7. Ok, Mr. Rosenthal, I know you are a WHW reader, and I hope you don’t mind that (since I have heard you do a hair commercial before) that I thought of you when I saw this TV ad today…

    https://www.youtube.com/watch?v=styYsyR1yw8

    They actually have a Jack Skellington one for you Nightmare Before Christmas fans too. 😉

  8. Another example, I think, of ignoring the models beyond 3 days.

    I think the GFS has had some runs lately projecting a pretty chilly to even downright cold Christmas Day and then last night´s 00z GFS runs and projects an almost mild day and an incredibly warm SE and Gulf Coast.

    1. It’s not a bad example at all. Those runs are going to show so many different things, which is why things like this are important…

      -Ensembles.
      -Knowing the indices.
      -Knowing model biases (which is always a learning process as they change with upgrades, different patterns, etc.)
      -Separating hype from actual info.

      WxW noted here recently that the SE ridge, even in a weakened state, would still play a roll. We know that this feature is often present in a La Nina. That’s a good solid brick for the foundation of a forecast. Always start with the things that are known, then the analysis can begin on what works with and against those things. A meteorologist can do this over and over in a single day. Meanwhile, you just have a set of people out there who have no idea that this is the process (not talking about WHW’s model watchers, they know this). One of our fellow mets here has been told this by a wx weenie: (Paraphrased) “I know how to read the models, so I can forecast.” No. If you know how to “read” the models, you might be able to tell people what the models say (assuming you read them correctly). That’s not forecasting. 😉

    2. I should add, maybe “ignoring” is not quite the term for beyond day 3. Not trusting them, yes. That’s not really a bad thing. Knowing not to trust what is on them beyond day 3 doesn’t necessarily mean they are not useful as a tool. As I mentioned, we have ensembles, we can watch trends, and knowing biases, make adjustments.

      That whole A.M.E. (anticipated model error) thing that I do is my own version of the above. We all have our ways to do this, and it must also be understood that this process is not always going to lead the meteorologist to the correct solution. But I’d rather being wrong doing the process correctly than be right just because of a lucky guess as to which model was right. Over time, the correct process will yield much better results, but some blind followers will dismiss all of the bad results and focus on the one time their “hero” got it right, regardless of the fact that they most likely got it right by accident, because they had no real idea what actually happened. 😉

      1. I know what you mean 🙂

        At the same time, here anyway, I was thinking we might just be all plain rain, so at least its something frozen.

        1. 🙂
          I want snow, but I fear I am NOT going to get it.
          And I do not believe I will see a White Christmas either.
          There’s still a chance. Even TK has the chance of some white stuff in the forecast. One never knows, but the way things have been going, I wouldn’t bet on it.

  11. I check in, from time to time, to the North Conway, NH webcam.

    It has a nice view of a part of town center.

    Might be nice later today.

  12. Just watched the Movie “13 Minutes”. It is about a bad tornado in Oklahoma. (i would guess it has taken much from the Moore, OK and perhaps El Reno tornadoes of several years ago)

    The movie is a bit slow setting up the characters who would become victims. Many social issues are played out in this movie.

    Not a blockbuster movie, but in my opinion, much more realistic than the movie “Twister”.

    Overall, a very nice job. For weather enthusiasts, a must see movie.

    I enjoyed it. Hope you will as well should you decide to view it.

    I actually purchased it from Google Play for $9.95, so I can watch it again whenever I want. 🙂

    Btw, it is 41 degrees here, so I expect rain or rain/sleet mix
    to start.

    Off chance it could be rain then snow after some
    Evaporative cooling ( cooling of the air due to latent heat absorption of water molecules. When water evaporates, the evaporation process requires taking heat from the environment in order for the evaporation to occur. With the removal of heat from the air, the air cools.) and then sleet then rain. We shall see.

    Not feeling it for sure today.

  13. 12Z NAM Kuchera Snow

    https://maps1.pivotalweather.com/maps/models/nam/2021121812/048/snku_acc.us_ne.png

    12Z 3KM Nam Kuchera

    https://maps1.pivotalweather.com/maps/models/nam4km/2021121812/048/snku_acc.us_ne.png

    12Z HRRR Kuchera

    https://maps2.pivotalweather.com/maps/models/hrrr/2021121812/048/snku_acc.us_ne.png

    15Z HRRR

    https://maps2.pivotalweather.com/maps/models/hrrr/2021121815/017/snku_acc.us_ne.png

    Any snow just seems to be North. SCORE One for the SE RIDGE!

  15. Piggy-backing on the discussion of unqualified morons who think they are meteorologists, my favorite “Facebook Forecaster”, once changed his snowfall forecast 13 times in the 24 hours leading up to a storm that was similar to today’s. He then claimed to have better accuracy than all of the professionals out there. When I pointed out that it was impossible to verify his forecast because he kept changing it, he replied with: “If we get a single snowflake then my forecast verifies”

    The other thing about these people is that they love to use their follower count on Facebook/Twitter to justify who good they are. “I have 10,000 followers and you don’t, so obviously I’m better than you”. (If this moron only knew that my forecasts are heard on the radio by 10 times that many people in various parts of the nation every day his head would explode)

      1. Yes, could translate to dry if the NAO is too strong but I’ll take my chances with that….just need to get some sustained cold in here first and that would be a good start.

        1. Kill joy! Looks more promising when you run loop….that southern stream looks like it wants to ride up the coast. Alas, we are wasting finger strength talking about the NAM at hour 84 🙂

  20. Biblical amounts of snow forecasted out west over the next two weeks, especially in the Sierras, with another atmospheric river event coming with more waves of heavy snow.

    Check out this run total GFS Kuchera snow map….

    https://www.pivotalweather.com/model.php?m=gfs&p=snku_acc&rh=2021121812&fh=384&r=us_sw&dpdt=&mc=

    That’s another 10 to 20 FEET of snow projected, on top of the 7 to 10 feet they have received over the last 10 days. Man did their snow season turn around in a hurry!

  21. If we can’t get a white Christmas then maybe at least a white New Years Eve/Day. That can be festive as well. 🙂

    3. Mac’s Brookline cousin is visiting her son and family in Tahoe. We chatted by phone last night and they’d had four feet as of that time.

  26. Tom, I saw your comment re the North Conway web cam. I love to watch it. Keith sent me the link a few years ago. I’m pretty sure the building where it is mounted is the old Carroll Reed ski shop. It was the place to buy any and all ski apparel and be fitted for equipment. If the cam isn’t on that building, it is next door. Directly across as you know is the street that leads to Cranmore. I do love that area

    https://skihall.com/hall-of-famers/carroll-p-reed/

  28. Thanks TK.

    Started out as some pellets here in Wrentham, all rain now. Like I mentioned the other day, sometimes you can get decent overrunning snow/ice even in SNE with systems like this, but the preceding air mass was way too warm.

    If you showed me the 96 hour surface and 500mb maps from the 12z Euro today, I would tell you the most likely outcome is that the 120 hour frame would show a 975mb low on the benchmark. However unlikely it may be, I’ll have to see the whites of its eyes before I’m fully convinced parts of SNE won’t see a major snowstorm Wednesday night… obviously not something I’d put in the deterministic forecast…

    Otherwise, medium range guidance is trending pretty strongly towards a stronger/more persistent Southeast ridge through the rest of the month, which I think is really just a result of the relentless -PNA. Still not a warm pattern for SNE, just one that I wouldn’t put much hope in if you’re looking for snow or temperatures averaging more than a little below normal, if at all.

      1. So close. We have to apply the “don’t trust beyond day 3” rule here as well. Models have struggled badly enough only having northern stream systems to deal with. Add in a rare (due to La Nina) appearance from the southern stream, and I won’t count my chickens before they hatch. ~Probably~ a miss but a case where it could go from 0 to 100 real quick if all the models are wrong. The deterministic and even ensemble runs seem suspiciously under-dispersive with their outcomes given what a close call it is.

        1. Thank you for your thoughts. I will certainly be watching.
          It would be way cool if it were to happen. 🙂

  29. Well, It did start as Rain here in JP, but it quickly mixed with snow and changed over shortly thereafter. Snowing here now.

  31. A gentle light snow falling here in Woburn. As I sit here and look out the window, totally enjoying what it looks like out there, I think about how media has conditioned so many people to think the only kind of storm is a big one. I’m so glad I can just enjoy these simple snow events. Festive flakes in the air, no there won’t be big amounts even for those who get mostly snow in SNE, but I love the mood the falling flakes add to my scenery here. I’m listening to a few Christmas albums that I grew up with. Talk about a nostalgia trip. 😉

  32. Still snowing here in JP.
    Beginning to show a very light coating of snow on roof tops and grassy surfaces.
    Down to 35 with dp 32

      1. Yup, at least a little. 🙂
        34, dp 32
        Whatever is coming down is so light now, I can’t even see it.
        It may, in fact, be raining now. I can’t tell.

        1. Back home (almost) in Dorchester, now raining. A bit of sugar coatings on grass, that’s all. No Christmas miracle this year.

  36. Unfortunately, the Pats team from the first 6 games has shown up for this one. Ugly game and tough to watch.

  37. Has not?

    Ugly ….hmmmmm. Ugly is better than a few words I’ve been using They keep almost getting in sync but then just can’t get there.

    Can’t win ‘em all. Sighhhhhh

      1. By this loss, it now makes the Buffalo game even more imperative. If they lose to Buffalo, a home playoff game may then be in jeopardy. Unless they totally collapse, they likely make the playoffs I believe.

        I would say Mac Jones still needs a little more seasoning. Maybe next year he leads us to AFC East/Championship/SB. Still good run for a rookie though.

        KC clearly has the edge for #1 seed now. Maybe even clinched for all practical purposes.

        One too many key penalties last night. It actually was a very winnable game at the end in spite being down by a lot. Oh well.

        1. For his first year Mac has shown incredible talent But that was expected before Cam was let go. The team as a whole had an off night. I just would have preferred it not be to the Colts. Sadly I think the Bucs game is another night game. Arghhhh. I love having two teams to cheer for

  38. TK – Would DT be considered a “weather weenie”? I noticed you guys haven’t mentioned him here in quite some time. Or is he a true met like you, SAK, WxW, JMA, etc.?

    Just wondering as I don’t even know what “DT” stands for.

    1. His name is
      David Tolleris
      He owns WxRisk.com

      As far as I know he is a full fledged Met, However, he is prone to making some wild predictions, none of which the Whw mets would make.,

    2. He is a met, not a weenie, and I tend to avoid looking at this stuff or commenting on it these days. He’s an odd duck, tons of knowledge, but behaves more like a weenie than a met, and is VERY combative with his followers.

      I haven’t read his stuff since about 2019 so I’m not sure if anything has changed since then.

  39. re game,
    Let me just say that I was disappointed in the Pats performance. They were due for one of these. Now, they should be fine the rest of the way, I hope

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