Thursday Forecast

154 Comments

7:38AM

DAYS 1-5 (DECEMBER 7-11)
I’ll keep it short and sweet today. We have high pressure in control today for a nice December day. A front sits offshore and will be the “train tracks” for a wave of low pressure that may bring a period of precipitation to southeastern areas Friday night. A second wave of low pressure is expected to pass by Saturday night. Then, an upper level energy will cross the region Sunday bringing a chance of snow showers. Weak elongated upper low pressure may hang in the region Monday with some clouds lingering. On to a detailed forecast…
TODAY: Sunny. Highs 42-48. Wind light SW.
TONIGHT: Clear. Lows 23-29. Wind light W.
FRIDAY: Increasing clouds. Highs 40-46. Wind light N.
FRIDAY NIGHT: Cloudy. A period of rain/mix/snow favoring RI and southeastern MA with some minor snow accumulation possible. Lows 30-36. Wind light N to NE.
SATURDAY: Mostly cloudy. Chance of light snow/mix/rain favoring eastern MA and RI early morning and again late-day and at night with additional minor accumulation of snow possible. Highs 36-42. Wind N 5-15 MPH.
SUNDAY: Variably cloudy. Scattered snow showers. Lows from the middle 20s to lower 30s. Highs from the middle to upper 30s.
MONDAY: Partly sunny. Lows from the middle to upper 20s. Highs from the middle to upper 30s.

DAYS 6-10 (DECEMBER 12-16)
Potential storm of snow/mix/rain December 12 followed by a blast of very cold air during the middle of next week. A weaker system may bring light snow around December 15-16 and a very slight moderation but still cold.

DAYS 11-15 (DECEMBER 17-21)
Trough resides in the northeastern US and a series of clipper type systems will deliver at least opportunities for precipitation and otherwise continue to reinforce cold air.

154 thoughts on “Thursday Forecast”

  1. Good morning and thank you TK.

    Here is a re-post of the 6Z GFS and NAM Kuchera Snow maps for Saturday:

    Here are the 6Z GFS and NAM Kuchera Snow totals and even
    these may be a tad high, but these are more realistic than
    the 10:1 maps, imho.

    https://imgur.com/a/TAM5Q

    The above represents a BIG shift from the 0Z runs. Not sure if it is real OR
    a function of the sparser data 6Z run????

    Waiting on 12Z runs.

  4. Thanks TK. No changes in my thoughts for the next couple days. Standing by my 0.25″+ QPF call at Logan. Will re-evaluate and possibly look at some snow numbers if necessary later today.

    For an early stab at it, I do think the NWS snow maps look good this morning. I agree with their most likely scenario and think the low end and high end maps capture the range of probabilities pretty well.

    2. So what’s your call for Boston ( Longwood area ) call in for salting . We get called in for sugarcoat as safety is at the highest level for patients & staff

      1. I would imagine there would have to be an extreme westward track to get that 6″ for Boston. A one in a gazillion shot probably but I guess in theory the potential is there.

      2. Ssk, if all you need for a call in is a coating, I would say it’s more likely than not you get the call. Keep checking back though.

        Philip, I would say a westward shift of about 50-75 miles from the current model mean forecast position would be required to get the high end map to verify. Unlikely, but at this range I would give it about a 1 in 10 chance, which corresponds to the 90th percentile represented by those maps. The most likely map is closer to the low end map since only a small shift east would remove almost any snow from the equation.

  6. Good morning boys and girls, the 12Z NAM is predicting the snowfall will
    be on the HIGH end of the NWS projections.

    Stay tuned for maps as the run gets far enough out.

    Looking closer and wetter. Fun times ahead.

        1. “about” 5 inches for Logan and nearing 8 inches
          West and SW of the City. This is Kuchera. 10:1 amounts
          are laughable.

          I will post both from the College of DuPage site in a few
          minutes. Waiting for 1 or 2 more panes of the run.

    1. I think we are seeing some interaction with the system moving in from
      the Great Lakes. Perhaps a bit of a Norlun effect or at the least the GL system
      is pulling moisture back from the offshore wave. Something is up here.

    2. ya know, JPD, I was just thinking that even if nothing pans out for Saturday, your enthusiasm and your models have made it seem as if it will. That alone makes me smile!

      1. Well, They are not my models, but rather just posted links
        and images of the model runs. I am home today, so I have
        more time to dabble in this.

        I “think” you get your snow for the 9th, all that remains is
        fine tuning how much.

        Really waiting on the 12Z Gfs and most especially the Euro.

        Also doing some work on ye ole weather app.

          1. Not that I ask too much….well, perhaps this time I am….It would be the pièce de ré·sis·tance if it were to start as rain. I figure I’m being somewhat fair since I’m not asking for thunder snow. There are limits after all 🙂 😉

  8. Thanks, TK.

    JpD– I continue to appreciate all of your links to maps and your discussion. 🙂

    Looking for Day 6 on the slopes this weekend – hoping Northern NE inland gets a bit of snow

  9. Thanks WxWatcher for your analysis. Many storms over the years have shifted 50 miles either way which is a relatively short distance in meteorological terms. It may be more interesting than expected.

  10. 12Z GFS is on the SNOW TRAIN, but not quite so vigorously. Maps shortly.
    Perhaps 3.5 to 4 inches or so Kuchera for Boston.

  12. Some interesting data.

    Here are the 12Z GFS Kuchera snow totals for Saturday into Sunday from
    the College of DuPage Site:

    https://imgur.com/a/0pBYi

    Additionally you will note the total QPF for both the GFS and The NAM.

    Note: GFS is about 0.55 inch for Boston area while the NAM is at 0.82 inch.

    That’s a fair amount of qpf and looking at Kuchera snow, it shows the effects
    of boundary layer and surface temperatures on the accumulation. If temps were
    in the teens to mid 20’s, we would be talking accumulations of 8-15 inches
    or so.

    Still, I’ll happily take it if either of these models verified or come close
    to verifying.

    Now, waiting on 12Z Euro and also the 12Z GFS for the Tuesday event. 😀

  13. So far, GFS is bring the Tues clipper just a bit farther South than last night’s run.
    Could we have redevelopment? Could be. Watching.

      1. 850 MB temps stay OK, but we have boundary layer issues.
        Too bad. BUT, it is still a ways out there, so this could and probably will change.

  14. “A Date Which Will Live in Infamy”

    At 7:55 a.m. Hawaii time, a Japanese dive bomber bearing the red symbol of the Rising Sun of Japan on its wings appears out of the clouds above the island of Oahu. A swarm of 360 Japanese warplanes followed, descending on the U.S. naval base at Pearl Harbor in a ferocious assault. The surprise attack struck a critical blow against the U.S. Pacific fleet and drew the United States irrevocably into World War II.

    http://www.history.com/this-day-in-history/pearl-harbor-bombed

    I am sure a good many of us remember the stories told by our parents or grandparents.

      1. My father used to mention the radio broadcast a lot. He was 11 years old at the time so he was more than old enough to remember WW II and its effects stateside. Thanks Vicki. 🙂

  15. Just curious isn’t this storm more or less for parts of the cape with any snow fall accumulation. I haven’t really looked anything over today

  17. Tweet from NWS Boston:

    Anyone traveling into eastern New England Sat/Sat night? Keep an eye on the forecast as currently the greatest risk for 4+ inches of #snow is across #RI, eastern #MA into NH and ME. Travel may be impacted on interstate 95 across this region. #Boston

      1. Thanks JP! I’m a spectator everyday. Your enthusiasm for snow is infectious. I do believe we see accumulating snow from this offshore system.

    2. So, Debbie, what’s the deal?

      Did anyone say anything about BIG snow?

      3 or 4 or 5 inches is not big snow, but it sounds like that is a mythical
      amount in your eyes?

      Wave staying more off shore than depicted?
      Boundary layer issues?
      Warm ground?
      Charlie hole?

      So, please share. 😀

    1. I believe there is some sort of wide-ranging issue in the Canadian products today. 12z CMC hasn’t even attempted to run (would normally be done by now), and it appears the 12z RGEM failed beyond its initialization.

    2. Looks pretty consistent and in line with the others.
      Worth noting, this is NOT a 10:1 ratio map. It is some sort
      of Proprietary algorithm that takes into account temperatures at
      various levels.

      This is what it says: (Click on image to enlarge)

      https://imgur.com/a/tZ6No

  24. I for one am ecstatic at the possibility of a couple inches of snow over the weekend and a turn to cold temps. I think it will go a long way in getting people in the holiday spirit. It has felt nothing like the holidays so far, but maybe its just me.

    1. From what I am seeing, Looks like mainly a midday Saturday to midnight Saturday event for the bulk of the snow, obviously varying a bit depending on your location in SNE

  26. I for one would like to note that Arod is in the house………we all know what that means!!!

    Good to see you, Arod!!

    1. Edit…. not for one as I am late to the party and others have already welcomed you. But it is always the sign of good things to come when you join us!

  27. So do y’all remember when I said (paraphrasing myself) watch the Saturday potential, if it’s the main wave (and now it looks like it will be) it may end up further north and west? I’m still not ruling out even further shift than models currently indicate. If this had been 1 of 2 evenly spaced and nearly same-strength waves it would probably be about 200-300 miles further east.

    It may end up for enough west for a snow/rain line to go all the way through Boston and into the suburbs.

      1. Keeping it rain there is ok if others don’t mine. Here…this will be the one I truly want snow. I will be selfish on Saturday.

    2. 18Z Looks Farther N&W as you suggest, But seriously, let’s keep the Rain snow
      line S&E of Logan.

      I’d love to see Logan Rain and pick up 4-6 inches in JP. Would LOVE to see that.
      I would NOT like to see RAIN in JP and 4-6 inches in Natick. 😀 😀 😀

    3. I do recall that. Do you recall when I said I have confidence in the angel model. And I’m still willing to say uncle…,Sunday.

  29. Hi everyone…

    This is five days late, but the Middeboro High football team won the Division 6 football championship at Gillette, big time, over Littleton, 43-20.
    It was an amazing experience for the town, school and the kids!

    We are Channel 5’s and Mike Lynch’s High 5 tonight during the 6 o’clock newscast.

    Yes, TK, (answering your question from Saturday)…we are Orange and Black and the Sachems. Tanners are an awesome high nickname.

    I was (well, still am and always will be) a Green and White Hornet from Mansfield High.

    I think my favorite Massachusetts high school nickname is the Ashland Clockers!

    2. I saw the preview for the High 5. Looking forward to it! I was rooting for your team the other day of course!

    2. In typical fashion that NAM is probably a little TOO juicy, but it is in the ballpark if things move the way I think they will at this point. Still have some fine-tuning to do here. I’m going to take a shot with #’s very soon.

        1. If the GFS matches the NAM, I will probably buy it IF they both do the same thing on 00z’s run.

    1. Warm boundary layer. We don’t have a lot of cold air around and this early in the season with that ocean … you know the story. No STRONG east wind either but any component at all off the water is going to warm that lower air.

  33. REMINDERS:
    This will probably be less than 10:1, and the snowfall correction on Tropical Tidbits is for the 3km NAM only. Keep these in mind when viewing products.

  41. Ok my preliminary # for Boston only at the moment is 1-3 at Logan and 3-5 over the actual city with the lower side favored and a bit less on pavement.

    Will expand this a bit later for the entire area.

      1. Initial though it 3-5 out this way too. We may run into a couple warm layer issues that mean rain or sleet where models have snow, so I’m working on that.

  42. Jpd dave. I saw that snow Map you posted the 3k nam ferrier snow map, what is that exactly and I am curious why it has higher amounts to the west. I did see it in tropicaltidbits features. I am still confused what it Is exactly and how it calculates snow

    1. TK can elaborate, but I found this:

      Levi Cowan‏
      @TropicalTidbits

      I’ve added a new snowfall product for the 3km NAM utilizing a rime-based snow/liquid ratio correction from Brad Ferrier. This greatly reduces bogus “snow” accumulations due to sleet, thus most relevant in warm regimes. SLR capped at 10:1. Comparison example from today’s 18Z run:

  45. I think about this every winter – It is so hard as a business owner to get a sane, rational weather forecast for the weekend? The hype train seems to have left the station already – “half a foot in Boston” etc. I have to make staffing and inventory decisions that effect quite a few people – really hard when employees and customers Are calling about “the big snowstorm” coming this weekend …..

    1. Tell me about it I’m calling & messaging customers now .I have 4 jobs going this weekend & estimates to give . But if it snows I’ll be dealing with that in the city instead .

  46. TK mentioned above what is causing the rather rapid changes in modeling we are seeing. The secondary southern wave is going to dominate, and it will drag its heels enough to amplify considerably before getting to our latitude as the Arctic shortwave digs in as well. I’ve felt for awhile we would see something from this setup.

    There are still real concerns with the ratios in terms of accumulation. Less than 10:1 is likely in eastern MA. If it shifts much further west, the changeover line will move past I95. Watching the timing as well; Sun angle isn’t much of a factor this time of year, but nighttime is always better. If the heaviest holds off until after dark Saturday, that will help a little. Still a couple days out, need to see the 0z guidance tonight, and as the NWS discussion mentioned, the 12z guidance tomorrow may really be when we can lock things in. My early number for Boston Logan would be 3″. A general 3-6″ for most of the area. Less southeast MA/Cape/Islands. If it goes further west, numbers would be cut to the east, but risks could increase for higher (5-8″) totals further inland with higher ratios.

  47. Its not too often you see winter storm warnings issued in parts of Mississippi and Alabama. Same system that will affect us Saturday.

  49. Accumulating snow in parts of southern Texas is not something you see too often.
    Great tweet from meteorologist Ryan Hanrahan with regards to this system.
    This storm is another great reminder why should should use ensembles and not op runs bouncing back and forth. No surprise to wake up to a wobble back west… has always been in envelope of possible solutions.

  50. Captain. I just watched the coverage of your team. What an amazing tribute to Scott Nelson just hearing their words of admiration for him. I truly believe the young man who said he was watching from above is right. Awesome young men

    2. Thank you, Dr. Your maps are awesome. But even if you don’t have time to put them together, please just pop in to say hi.

      Thank you

  53. Will be interested to see the 0z runs. First up NAM. I am not staying up for the EURO.
    We maybe tracking another snow threat Tues Wed time frame next week.

        1. The 12z Euro has a general 6-12” across SNE with the clipper diving south and spawning a developing coastal storm. Looks nothing like the GFS which keeps the clipper passing to our north and is basically a complete miss for us.

  56. I think it’s going to rain mid event, for some time, at Logan and downtown Boston.

    NNE wind at even just 10 mph should do the trick when the water temp is 49F

    1. If the airmass was just a bit colder or we had a polar high to the north. Even inland, the projected sfc temp is around 0C during the event.

  60. 0z GFS total snow at 10:1 ratio:
    https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=neus&pkg=asnow&runtime=2017120800&fh=78&xpos=0&ypos=217

    Pretty similar to the NAM and showing the potential for 6″ across a good portion of interior SNE away from the immediate coastline.

    0z GFS still a whiff for Tuesday with the clipper passing to the north and not much of anything here. Looks nothing like the Euro…interested to see if the 0z Euro holds serve with the more amplified/snowier solution.

      1. I think way down here by rexhame, we’ll end up with a coating to 1/2 inch at the end. Out towards your area, an extremely wet snow of 1 to maybe 3 inches and you may rain for some middle portion of the event. This idea is predicated on the ocean playing a big role in the boundary layer and also that the column, above the boundary layer, may not stay cold enough throughout the entire event.

        1. Exactly Tom . Way less down are way. It remains to be seen how much the back bay ends up with but I think it should be plowable.

          2. Yes. Quite the snowfall amount dropoff in eastern mass. The question is whether that quick drop off is near the immediate coastline or 10 miles inland.

        2. I agree to an extent but I think I would add at least a inch to your totals. If I am reading this map properly it appears the 6z NAM is showing more of a northerly wind. This will keep the ocean influence closer to the beaches.

          2. Yes, if the sfc wind stays due north or 360, then we’ll see more than I’m thinking. But, if its even 020 or 030 for a while, then I think it might be a different story. I guess that will be a nowcasting part of the event.

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