Thursday Forecast

134 Comments

7:16AM

DAYS 1-5 (DECEMBER 8-12)
The approach today will be a little bit old school as I’m currently not really trusting any computer models that much. Risky perhaps, but here goes my best shot at what I think will take place in the coming days. The next 3 will feature a west to northwest flow and a colder trend, with the coldest air of the season arriving later Friday into Saturday. The dominant Pacific jet stream will send an area of moisture this way during Sunday, bringing a chance of snow, favoring late day. How this system evolves is uncertain, but Monday will likely be an unsettled day with a risk of rain/mix/snow depending on location. There is plenty of time to work out these details.
TODAY: Partly sunny. Highs 38-45. Wind light variable early, then W increasing to 10-20 MPH and gusty.
TONIGHT: Mostly clear. Lows 24-30. Wind W 10-20 MPH with higher gusts.
FRIDAY: Partly cloudy. Highs 35-42. Wind W 15-25 MPH with higher gusts.
FRIDAY NIGHT: Mostly clear. Lows 18-25. Wind NW 15-25 MPH with higher gusts. Wind chill below 10 at times.
SATURDAY: Mostly sunny. Highs 27-34. Wind NW 15-25 MPH with higher gusts, diminishing in the afternoon.
SUNDAY: Increasing clouds. Chance of snow by late day. Lows 13-21. Highs 30-38.
MONDAY: Cloudy. Risk of snow/mix/rain. Lows 26-34. Highs 34-42.

DAYS 6-10 (DECEMBER 13-17)
Low confidence on timing of systems. At this time it appears one Pacific jet stream system will depart early in the period, a second one will threaten snow/mix about mid period, and another may approach by the very end of the period. Will refine this in future posts. A significant cold shot is possible around December 15-16.

DAYS 11-15 (DECEMBER 18-22)
No major changes to the overall pattern. Will work on the timing of systems.

134 thoughts on “Thursday Forecast”

  6. Thanks Tk . When you say later Sunday is that later afternoon or night . Thank you . I will need to plan Sunday around that I guess .

  7. Good morning again and thank you TK.

    Watched the live performance of Hair Spray last night with my wife and I found
    it to be surprisingly good, save for the inordinate amount of commercials which made
    it almost impossible to watch. We’ll take a pass on any future live performances like
    that.

    As skiiers always say: THINK SNOW

    Models look interesting, however, as pointed out by TK and JMA, they do not believe
    they are handling things well, so we shall see. Regardless, it looks fairly active
    and with cold air around there are possibilities. We will just have to wait and see
    how everything lines up.

    Truthfully, to me anyway, the Sunday night/Monday system looks fairly promising
    with a possible “Moderate” snow event “should” it stay snow OR in the areas where
    it is all snow.

      1. Doesn’t look that way right now John. We shall see, but I think it comes in later. TK has said that in his forecast. 😀

  10. From Harvey…

    Harvey Leonard ‏@HarveyWCVB 12m12 minutes ago
    At this point, there appears to be the potential of anywhere from a dusting up to 2″ of snow Sunday #wcvb

    1. But he doesn’t go out on a limb and say anything about Sunday night into
      Monday where the “potential” is for more than that. hmmm

      Does he think it doesn’t happen? Does he think Rain?

      OR he just ain’t saying???? 😀

  12. The only caveat is that the ocean is still fairly warm and systems that would stay all or mostly snow in February tend to end up as rain Boston s/e…December can be frustrating in that regard but let’s see what happens.

    1. True. It depends on exact path and wind direction and strength of that wind.
      A stronger wind = more rain along the coast.

      It also depends upon how cold the air mass remains. If it get’s marginal at all,
      it will flip to rain along the coast. It also depends on the intensity.

      Many factors are involved to determine coastal snow/rain.

  17. Far western areas of SNE with that second system look to be all snow looking at the tropical tidbits site of 12z GFS then the rain tries to change over to snow.
    None of these systems look major.

  19. That system shows wintry mix down to parts of the Mid Atlantic and snow wintry mix up here before going to rain.
    No snowstorms with those three systems next week but three opportunities for at least some snow before a change over.

  20. 12Z GFS sets up a parade of lows coming at us. At least four (4) through hour
    288. How much of that will be snow is the big question. Looks like
    an extremely active month.

  25. One generality I feel certain on ….. This is a great sign for ski country. This pattern actually will get precip into northern New England and I’d guess that a majority of the precip will be snow. Additionally, the weather between and after these systems will support snow making conditions. I think there will be some good conditions for the end of month school vacation on the slopes.

        1. I think the lack of snow hit a couple of decades ago before snow making was perfected. At that point, lots of places (slopes and hotels, etc) went out of business. The saving grace is snow making but many forget that there is a lot of attraction for reasons other than downhill skiing. To compensate, prices skyrocketed. That makes it impossible for the average person, and certainly family, to afford to ski as we did when I was a youngun’ It is truly a vicious cycle and not one I expect to swing in the other direction any time soon….if at all.

  26. There is a bit of mugginess in the air today which I do not expect when temps in the 30s. We have a solid overcast but it seems almost as if the heavy fog we had mid-morning just lifted and is now sitting above us. Temp is 39 with a 34 DP

  27. Big earthquake near the Solomon Islands. Preliminary magnitude of 8.0 appears to have been downgraded to 7.7 by the USGS. Buoy data indicates a tsunami was generated, and products have been issued to account for this, including a Tsunami Watch for Hawaii.

    Magnitude 7.7 is very big, but combined with a depth over 40km, my gut instinct is that it’s a little small to produce a destructive basin-wide event across the Pacific. Locally destructive impacts closer to the source region are definitely possible though.

  31. 12z Euro is as good as it will get for SNE snowfall early next week. As this Euro run shows it, the system remains intact enough to maintain a solid precip shield, but doesn’t dig so much that it cuts to the west. For Monday-Tuesday, it shows 6-10″ region-wide (10:1 ratio) save for the South Shore/Cape. Very unlikely.

  32. So far there has been ZERO consistency from run to run and until that happens it’s really anyone’s guess what will pan out. I’ll take TKs experience and old school meteorology at this point

  33. That 120 hr panel on the EURO though is very interesting ….

    Look at the isobars and you can see the kinks in them that indicate a trof of low pressure and/or an extension of low pressure back to the west from the main offshore system.

    Then at 850mb, you can definitely see convergence, with an easterly flow at 850mb in northern Mass and westerly flow in southern Mass. And its plenty cold at 850 mb.

    I think the EURO is usually pretty good picking up on these kind of quirky weather situations. Maybe something is brewing in the 120 hr time frame.

    1. And I very much buy this because what is driving it ? ….. a massive ridge it projects to develop out just west of the US, building all the way into Alaska, which pushes the arctic air and (polar vortex, or a weak one anyway) further eastward into Canada which would give an opportunity for eastern and southeastern Canada to really chill off.

    2. Tom very astute observation. We get a bit of a Norlun at this hour as you suggested. have a look

      http://imgur.com/a/ezAdD

      On this run the 1 foot level reaches just about to Boston or at least the
      Western Neighborhoods or very close by suburbs.

  34. Similarly at 216 hrs …. you can see the isobars again, this time in southern Canada, hinting at a piece of the arctic/polar high in central Canada trying to build and bridge to the north of New England. In turn, it would be more difficult for systems to just charge to our west. Overall, an interesting run …. a colder solution run all around for sure.

    1. Thanks for that image JpDave, easy to read !!!

      I could see the EURO picking up 5 days out on an inverted trof or some extension of low pressure back to the west and I agree that the resulting precip would mostly be snow given the projected 850 mb temps.

      Based on prior experience, climatology and the EURO’s past track record on snow projections, I don’t buy into this idea of widespread, heavy snow.

      But a few to several inches around and near the convergence area, yes, I could open my mind to that as a possibility.

      1. Norluns can be prolific. Don’t discount a period of heavier snow.
        Not yet anyway.
        We’ll have to keep an eye on it. When all is said and done,
        it will probably blast through the Lakes! 😀

        1. Ha ! So true !!

          To your point, I remember a Norlan trof back in the early 90s that dumped feet of snow in coastal SE Maine (kennebunkport, ogunquit area I think it was).

  36. Get those higher totals down a little south my way.
    Tweet from meteorologist Ryan Hanrahan
    Becoming more confident in a winter storm Sunday PM/Monday. How much snow, ice, and rain still to be figured out.

  38. Come on EURO shift those big totals a tad further south to me.
    Last good norlun trough here in CT was back on January 7th, 2011 and the I-84 corridor from Danbury to Waterbury got a foot or in some places just over a foot in 6-7 hour time period. The timing of course was an afternoon on Friday and made for a horrible commute in that part of CT.

  39. Compare and contrast the 18Z surface at 54 hours with the 12Z GFS surface at 60 hours.
    Conditions for the same time period only run 6 hours apart.

    18Z NAM

    http://www.instantweathermaps.com/NAM-php/showmap-conusncep.php?run=2016120818&var=PCPPRSTMP_2m&hour=054

    12Z GFS

    http://www.instantweathermaps.com/GFS-php/showmap-conusncep.php?run=2016120812&var=PCPPRSTMP_2m&hour=060

    GFS has the system centered over SE Colorado while the NAM has the system
    centered over North Central Nebraska. Hmmm, that is quite a difference.

    I SMELL A RAT! Or perhaps it’s a CARP?

  40. HMMM, the NAM takes the system through the great Lakes and then it DIES
    with more action much farther South. Not sure how the NAM would develop this
    situation after 84 hours. I can look at the DGEX later, but the Nam’s wheel house
    is 48 hours in, so probably just not worth it. 😀

    18Z GFS is cranking and should start to come out a bit more than 1/2 hour
    from now.

  43. Finally seeing multiple chances of at least some snow starting early next week. I am not getting excited. The way these forecast models have been next run we could be looking at a rainorama.

  44. See-saw is trying to tip to the cold/more snow. But I’m not completely biting this yet…

    Just need a little more info.

      1. Yes, but ALL of us are well aware of this model business. 😀

        Just showing the output. I don’t think that any of us
        made a forecast.

        It is Thursday afternoon. This event isn’t until later Sunday into Monday. Time for some fine tuning.

        It just seems to me that the systems just want to punch through
        the Lakes.

        I surely do hope that the Euro is correct, but I am beginning
        to think it is smoking some crack cocaine. 😀

      1. Just the overall pattern. I just don’t know how much and how long the jet stream gets pushed to the south. That’s always been a concern. It has to be just right to get a snow event down in southern New England.

        1. I’m still rooting for it. Clearly the GFS and EURO
          are seeing things differently. If it mean anything (probably not as they are both American models) the NAM seems to be similar to the GFS out at 84 hours or so. (I know they didn’t start off the same, but they appear to get there or nearly so. More similar than the Euro anyway)

  47. 18Z GFS pretty much the same as the 12Z.
    Has about 2-3 inches of front end snow then a RAINORAMA for Boston
    and surrounding area. 4-6 or 7 inches WELL inland.

    Seems MUCH more realistic than what the Euro is pitching.

  48. John Glenn passed away. Very very sad but what an incredible man and phenomenal life.

    He was a Christian Scientist. The basis of my faith being rooted in Christian Science, I remember often hearing one of the key hymns as he took his trip around earth. If I may post here as a tribute to him.

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

    1. Yes, indeed a great man and American. Wish we had more like John Glenn in politics these days. Alas, that’s just too much to ask for.

      Thanks for posting the tribute.

      1. Well, on further thought, I was absolutely wrong. My old memory failed me.

        It was Alan Shepherd who was a Christian Scientist which of course makes the hymn have a whole lot more sense. Otherwise, it is a lovely hymn and I suspect fitting for all astronauts. I also wish we had more like John Glenn.

  49. Thanks, TK.

    If I am reading the general trend correctly it would appear that SNE will get waves or impulses of wintry weather over the next two to weeks, and perhaps longer into the future. Always hard to pinpoint precisely where snow/rain lines establish themselves. SNE appears to be where many of the lows will track, which isn’t always favorable for snow here, but IS favorable for snow in central and northern NE. Whatever happens here, it appears southern Quebec will be under the influence of fairly strong cold high pressure areas with occasional moisture-starved clippers passing through. I’ll need my long-johns as QC will likely have daytime highs below 10F during the middle part of the month.

    1. That’s been the idea all along, but the p-type with systems is going to be highly dependent on the exact configuration of things at the time. Not that this is never the case, but the Pacific jet dominated pattern is a fun one to try to time features in. And then you have the issue of temperature profile to determine p-type with each system.

      The general pattern is a piece of cake to forecast. Getting the details is a tedious task.

  50. 18z GFS similar to the 12z GFS with the follow up system Wed into Thursday with rain ending as some snow.

  51. I see the EURO has take some HGH this afternoon. I believe I read that Eric F and others are actually buying the GFS bc the euro is oversimplifying. Anyway fun to start tracking.

  52. I wrote the “be weary” warning last night because I could see the short wave placement that ECMWF was starting to trend towards. The issues in these zonal flows is generally the models can’t refine the speed of the waves of energy and thus end up with erroneous placement of the lows in relation to the trough and ridge axis (dips and rises) that exist but are continuously influx within these split flows and they have enormous impact on sensible weather outcomes-timing, progressiveness, temp profiles, and of course Ptype. Both the GFS and EMCWF have struggled with fine details here, but one consistency has been the ECMWF having significant issues with timing and erroneously creating less progressive scenarios.

  55. Pacific origins are typically warm. Yet, I am growing more confident of a light to moderate snowfall prior to changing over to rain.

  57. Kiss of death right there.
    I am just focusing on beating the Giants and winning the NFC East Sunday night. The next to lock up home field in playoffs.

    1. IF the 18z has it right then we have confirmation that this is a pattern that is for sure not behaving as it should…Ha!

      1. Which was always a valid possibility. There were a few details on the run I didn’t quite buy. The general pattern looked ok to me.

      1. I embrace better living thru chemistry for February and March. January doesn’t bother me much. The NFL distracts me. But from say February thru the end of March, I could just play Rip Van Winkle and skip it. The first couple weeks of April isnt a favorite either, but at least I can see the end of it on April 1.

  60. 2 more well known people gone in the year 2016…

    Yesterday, Greg Lake, of Emerson Lake & Palmer.
    Today, John Glenn, a true hero and pioneer.

  61. Tonight, Harvey is leaning colder for Monday with accumulating snow for Boston and any snow to rain limited to extreme SE MA/Cape.

  63. Yes, the placement of surface features changed some from the 12z run to the 00z run and of course, that is important to sensible weather, but I believe the big picture details of a colder pattern didn’t. I’d suspect the projected placement of the surface features will continue to change.

    What caught my attention on the 00z runs ….. Signs of a huge temperature contrast setting up, running northeastward from the western Gulf of Mexico to the central mid-Atlantic. Another big picture signal of a southern New England wintry weather event(s) in the upcoming few weeks.

  64. Do I recall in Dr Cohen’s most recent blog a paragraph or 2 where he says that instead of the autumnal above average Siberian snow cover and accompanying frigid temps “affecting” the hemispheric pattern in Jan and Feb, he suggested it might begin and maximize in December instead …… IF I have recalled that correctly and IF I understand it correctly, then that’s pretty impressive from Dr Cohen given what’s being projected on the models over the next few weeks.

    1. I’ll believe it when I see it, but it “appears” to be trending colder so there’s a shot.
      time will tell.

    2. maybe for you but I want snow where I live points north and west. Cloud care less if people inside of i95 get rain. Just make it snow here and up north for skiing.

  66. 6Z Nam showing a pretty WARM solution for Monday with barely an inch or so
    up front. Euro shows about 2 inches. GFS about 2-3 inches. CMC about 4 inches.

    Wonder what the 12Z runs will show?

  67. From NWS service this morning:

    Expect the models to start coming into better agreement
    later today as the energy responsible for the system moves onshore
    and is better sampled.

    The track of the primary low and any secondary low development will
    affect thermal profiles. So this is leading to a bit of uncertainty
    with the p-type through the event. At this time, believe it will be
    a mainly snow or rain scenario, but there is a low probability of a
    period of ice during the transition as the warmer air moves in
    aloft. While it is still a bit too early to detail exact snow
    amounts, confidence is high that a portion of the area could have
    accumulations in the 3 to 6 inch range. Most of the area should see
    at least a dusting of snow, with the possible exception being the
    Islands.

  68. with my link to the euro, I can not tell how it crosses New England, can someone post the snowfall map of the euro.

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