Monday December 14 2020 Forecast (7:01AM)

290 Comments

DAYS 1-5 (DECEMBER 14-18)

Firstly, I don’t want to neglect to mention that today is a new moon, and the tides are astronomically high, and some minor coastal flooding is likely to occur near high tide times especially along east and north facing shores… For some time we’ve been anticipating a middle of December stretch of active weather that features some wintry weather opportunities, and 2 such opportunities are now pretty certain, one today and another at midweek. First today’s, which will be a minor event as a wave of low pressure approaches from the southwest and passes just south of New England by this evening. This will be occurring as cold air filters into the region, so with temperatures marginal for rain vs. snow, and on the milder side of the line in many areas, this event will likely start as rain or a mix of rain and snow for many areas later this morning. During the afternoon is when colder air will filter in from the north and some will be brought down from above adequately enough to flip the precipitation over to mostly snowfall, which will then exit from west to east by early evening as this progressive system exits the region. It will leave behind a minor snow accumulation, favoring areas near and south of I-90, but a burst of moderate snow can leave untreated roads slick for a while, and as temperatures fall tonight behind the system, any untreated wet surfaces will become icy. That cold air will be delivered with a little more force on Tuesday as what was our minor low pressure wave intensifies into quite the storm as it passes through the Canadian Maritime Provinces and creates a healthy northerly air flow out of eastern Canada between itself and high pressure north of the Great Lakes. While Tuesday will be a day with plenty of low angle December sun, it will be a cold one, and helps to set the stage for our next storm system. This low pressure area starts out as a rather innocuous looking system in Texas Tuesday, but travels steadily eastward through the lower Mississippi Valley, picking up moisture from the Gulf of Mexico, then heading northeastward toward the Tennessee and Ohio Valleys. A warm front extending eastward from this initial low will be the focal point for the development of a new low pressure area near the Carolina Coastline through Wednesday, which will then travel northeastward, passing southeast of New England Thursday. All the while, high pressure will sit over eastern Canada, supplying plenty of cold air. At this point, there are still some notable model guidance differences in how much snow will fall, but they are in general agreement that the odds favor the heaviest snowfall being in the southern half of Massachusetts southward. With the amount of cold air expected to be around and the track of low pressure offshore, this should be a straight snow event for pretty much the entire region, with the only possibility of mixing being on the outer part of Cape Cod and Nantucket, just due to the ocean water temperature still on the mild side. Going to hold off on putting snowfall numbers on this system until tomorrow morning’s update, but just know that an event requiring at least some snow removal is rather likely. As it departs and the sky clears Thursday night, we’re set up for a very cold night and a cold/dry Friday.

TODAY: Cloudy. Rain/mix arriving west to east by late morning and midday, transitioning to mix/snow through mid afternoon before ending by evening. Snow accumulation of a coating to 1 inch especially near and south of I-90, with an isolated 2 inch amount possible. Highs 33-40. Wind N 5-15 MPH.

TONIGHT: Clearing. Lows 21-28. Wind NW 5-15 MPH.

TUESDAY: Mostly sunny. Highs 31-38. Wind NW 10-15 MPH, gusts 20-25 MPH.

TUESDAY NIGHT: Mostly clear. Lows 17-24. Wind N under 10 MPH.

WEDNESDAY: Sun followed by increasing clouds. Highs 28-35 Wind N up to 10 MPH.

WEDNESDAY NIGHT: Thickening overcast. Snow arriving late evening and overnight. Lows 18-25. Wind N to NE 5-15 MPH.

THURSDAY: Overcast with snow (possible mix outer Cape Cod & Nantucket), ending late. Significant snow accumulation possible in southern NH and northern MA and probable southern MA southward. Highs 23-30. Wind NE to N 10-20 MPH, higher gusts possible.

THURSDAY NIGHT: Clearing. Blowing snow possible. Lows 10-18. Wind N to NW 10-20 MPH. Wind chill below 10.

FRIDAY: Sun and passing clouds. Highs 27-34. Wind NW 10-20 MPH.

DAYS 6-10 (DECEMBER 19-23)

Dry, cold weather expected behind storm with Canadian high pressure December 19. Next unsettled weather threat comes later on December 20 with rain/mix/snow possible, followed by a return to dry weather December 21 with a shot of seasonably chilly air. Have to watch for a minor system with snow/mix possible toward the end of this period.

DAYS 11-15 (DECEMBER 24-28)

Active pattern may continue with at least one and possible two precipitation threats to be fine-tuned as we get closer. Variable temperatures, averaging close to normal overall.

290 thoughts on “Monday December 14 2020 Forecast (7:01AM)”

  1. Good morning and thank you TK.

    Would I ever love to see ALL of the models be at least in somewhat agreement.

    It looks to me as if the Euro is beginning to come in line with the GFS.

    0Z Euro snow 10:1

    https://m3.pivotalweather.com/maps/models/ecmwf_full/2020121400/102/sn10_acc.us_ne.png

    6Z GFS snow 10:1 (I used 10:1 for a true comparison)

    https://m3.pivotalweather.com/maps/models/gfs/2020121400/096/sn10_acc.us_ne.png

    Both Maps show the little bit from today.

  2. Here is the 6Z RDPS Kuchera snow at 84 hours with it still snowing in all Eastern sections, so not complete.

    https://m2.pivotalweather.com/maps/models/rdps/2020121406/084/snku_acc.us_ne.png

    Now here is a change. The 6Z NAM now introduces rain!!

    https://m2.pivotalweather.com/maps/models/nam/2020121406/078/ref1km_ptype.us_ne.png

    Kuchera snow at 84 hours.

    https://www.pivotalweather.com/model.php?m=nam&p=snku_acc&rh=2020121406&fh=84&r=us_ne&dpdt=&mc=

    So how can we have 1 model almost completely suppress it while another comes so far North and tight to the coast that it introduces rain and everything in between these 2?????????

    How the hell does one make a forecast.

    Btw, I LOVED how AJ Burnett handled it on the 11PM Broadcast. He explained very nicely how today’s system is scheduled to blow up into a monster storm NE of NewFoundland headed for Greenland and how it could suppress the Wed/Thurs system South. He basically said it could snow a little or a lot and to stay tuned. Kudos to AJ.

    I like him a lot and I loved his presentation style. Channel 5 would do well to replace Harvey with him when Harvey retires.

    Buckle up and enjoy the ride no matter what happens.

    At this point I do not believe the GFS is the solution and I do not believe that the NAM is the solution. If I had to pick one
    model solution of all of them, it would be the Euro, although I would hope it would be a blend of the Euro, UKmet and GDPS.

    We shall find out soon.

    1. 12Z NAM is running and panels will be coming out starting
      around 8:40 or so. We’ll see what it spits out. 🙂
      Fun times! I love it, not matter how it turns out. Absolutely fascinating.

  4. 35 here with dp 31.
    I expect precip to start right off as snow.
    Will know very shortly as precip is knocking at my door.

  5. The 00z euro had less than the eps mean which has been consistent. The 06z euro went north with the mix line getting to the islands and trying to mix up to the cape.

  8. Something I’ve noticed with most maps posted, the low pressure for wed/thurs isn’t projected to be terribly strong, hovering around 1000mb. Most of our major east coast snows occur with much stronger systems. Am I missing something?

    1. No, you are not missing anything. That is what I have noticed as well. Not to worry as there is plenty of moisture that is available
      and that moisture over running the arctic cold will get the job done, “Hopefully”.

      1. Gotcha, I was thinking it must have something to do with the moisture interacting with the cold high to the north

    1. The real juice with today’s system will be staying South of our area, at least that is what is expected. 🙂

      1. Thanks JpDave! Hopefully the next system doesn’t follow suit. I remember a few storms in recent years that looked awesome on radar and appeared to be coming right for us but the precip shield just never makes it here

  10. At what point do the shorter term high res models become more valuable than the medium-long range globals in a situation like this?

    1. Good question, but I for one will look at all of them right along.

      The NAM’s wheel house is generally 48 hours in, so We are getting there. Same with RDPS. and HRRR’s wheel house
      is generally around 18 hours, even though it goes out 48 hours
      at 12z, 18z, 0z and 6Z.

  13. No cowabungas from dave yet means the solution for the next storm is still resolving. That’s my official metric.

    1. Wish I could shout it out. Just not warranted yet.
      This is a strange storm evolving and it “appears” to be slightly
      weaker with each passing run.

      We may end up with a rather routine 6-10 inches. 🙂 🙂 🙂

      I’d take it, but with some of these runs, one would have hoped for more.

      And btw, you will NEVER see a Kowabunga from me for a routine 6-10 inch event, unless it was October or May.
      Kowabungas are reserved for the big ones.

    1. What disappoints me about this run is the snow intensity.
      No great shakes. The real heavy intensity snows are now
      gone from most of the runs and the Storm weakens as
      it moves Eastward South of our area. Although it may snow
      for a reasonable period of time, it will be mostly a good steady light snow to occasionally moderate. Not sure we will ever
      see true HEAVY snow. That is hard to come by.

  15. I’m so confused by that NAM run. Why are the higher totals now to the north?? Mix/rain being introduced??

      1. I hear u, but weren’t we talking about there being a fluff factor and temps wouldn’t be an issue? Kuchera ratios were supposed to be higher than 10:1, at least for Boston.

  16. this whole thing seems just sketchy. I’ll set my expectations low and just plan for hazy, cloud filtered sun with light very granular snow.

    1. I agree 100%. I smell a rat or if you will, something fishy about all of this. Just not your classic Nor’easter for sure.

  17. take a look at the 500 & 700 vort signatures on the models. There is a lot of lift going on which is what I believe is the reason for so much moisture for such a weaker system. The placement of that Upper level low is so important with this system which will determine position.

    1. I would think that the placement of the high to our north is key as well. We don’t want it “too” close to NNE…or too strong.

    1. Yea, still takes that right hand turn! run after run after run.
      Watch it be stubbornly correct. 🙂 🙂 🙂

  31. At this point, < 3 days to the start of the event, the GFS has to be thrown out as the outlier. Even with it thrown out though, there's still a lot of uncertainty.

    1. Well, that is what we would like to do with it, but both
      TK and WxWatcher cautioned NOT to do so, because in their
      mind the GFS solution is on the table.

    2. I am hesitant to do so as the GFS was more correct about the last storm so I am hesitant to throw it out but its very hard not too as the ensembles are a mess while the EURO ensembles are pretty much in sync

  33. The GFS seeing that high stronger and deeper. That’s the biggest difference I see so far. Watching that very closely as soon as today’s system explodes.

  36. No matter which model snow output, I think there´s general agreement of the low moving mostly eastward, once it exits the Jersey/Delaware coast.

    So, I can kind of lean less towards the higher snowfall projections because, if you just look at those snow projections, the heavy precip would have to move NE and would have to survive well into what is going to be low level dry air.

    I´d lean more towards the GFS and hopefully, the truth lies a bit further north than the GFS projects.

    1. I understand what you are hinting at here, but I am afraid
      I am not in agreement.

      Yes, the system will turn to the East, the question is at what
      latitude does it put on its blinker and take the right hand turn.
      ALL modes, except the GFS say it will wait until a higher latitude to take the turn. Stays on track for a few more exits before leaving the throughway.

      All models agree that the system slowly weakens on its Eastward trek.

      Regarding dry air, sure, that will be a factor, however, with a NE and NNE wind, there will be some Atlantic moisture being injected into the system. In short for SNE, could still get a big snow out of this.

      Could the GFS be correct? Sure, but I am hopeful it is NOT!

      Now, I am waiting on the UKMET and then the EURO and we start all over again.

      I must be a SICKO to enjoy this!!!!

      1. It sure is. We’re at it again 🙂

        Every model has the East turn farther North than the GFS.
        I sure hope that the GFS is an OUTLIER. We’ll find out.

        Euro is up next to dash our hopes. It will probably send the system to Bermuda!!!

  45. As I said earlier it’s going to be a tremendous victory for the GFS if the other models cave. So far with the 12z runs were not seeing a cave toward the GFS. With that still time for a change.

    2. Still, not a single one north of say Atlantic City, NJ. That’s not usually a big snow producer position here in SNE.

  47. Mark you would think later on today or early tomorrow CT would be placed under a winter storm watch based on what were seeing in the 12z runs. I had to laugh with 30 inches the CMC was showing for Hartford.

    1. Norton NWS hinted at watches coming. My guess is later this PM after they digest all of the 12Z data, including the EUro.

      1. This is what they said this morning:

        Confidence is not high enough to consider Winter Storm Watches
        just yet – there is enough uncertainty based upon all of the
        above factors to play this more conservatively since we are
        still 72+ hours out.

  48. Perfect, we’re getting anywhere between 2″ or 24″ in the center of Central MA.

    I realize it is what it is, but it is funny to put things in that perspective.

    Keep the models flowing JP!

  51. I posted this near the end of the last blog and will say it again here…One thing to be leery of with all these models spitting out big snow totals is that this system looks to be hauling. The bulk of the accumulating snows are in and out in 12-15 hours. Going to be tough to pull out many 20″+ snows in that timeframe unless the snow rates are extremely intense. More likely we are going to see a max swath of 12-18″ in the “jackpot” zone with maybe a few isolated 20″ amounts.

    I would expect the first NWS map to probably go 8-15″ from the Pike south and then they can adjust up from there. I’d probably start 5-10″ in northern MA.

  52. Repeat caution: don’t blindly discount the GFS, even now.

    BTW, is the Chilean model out yet? 😉

    1. I think this will be a big disappointment for many. Many times when large amount of snow is showing days ahead of time it rarely pans out. I would rather see smaller amounts and build up but that’s just my unscientific opinion.

      1. I think you are right & I have a hunch the GFS is going to Nail this . Let’s watch the tv Mets hype it up

        1. I don’t think the meteorologists have really been hyping it up at all.

          some of the news stories have but that’s to be expected. The ratings game…

    3. Having trouble locating it, else I would have posted it?

      Let’s see we
      Had a couple of American,
      A couple of Canadian
      A British
      A German
      A French
      and a Japanese.

      Fun

  53. So, at hr 72 on the EURO, the best 850 mb flow off the ocean is along the south coast.

    Still, there is 30-40 knot east-northeast 850 mb flow up to the Mass/NH border.

    I think the heaviest synoptic snow from the storm will be along the south coast.

    I think a general 3-6 south of the Pike and 2-4 north of the Pike to a dozen or so miles north of the Mass/NH Border.

    I think there´ll be a 4-7 or 4-8 inch contour in that favored Boston to its southwest suburbs zone that gets extra with a little help from the flow off of the ocean.

    The big 10 – 15 inch amounts, I think, skirt the south coast and are headed for Long Island, MV and maybe Nantucket.

      1. Something like that.

        I like it as a starting point because if the storm ends up further suppressed, then, your not having to make a drastic reduction from a higher starting point.

        If it works out better, your already at 3-6. I dont think, even with a big hit, this will be 20, more like 8-12, so, we´re not terribly far away from that range starting at 3-6.

        Still feeling uncertainty for sure.

        1. The idea being, when there´s uncertainty, like I think there is in this situation, I think you kind of aim for the middle in projecting snow amounts.

          When certainty increases, go for it, trying to come really, really close to what will be the final amounts.

    1. Still a significant 6″+ snow region wide but continuing to tick south with the northern fringe of that heavy snow band.

    1. If you look at the 12z EURO it is showing a 10-15 inch snowstorm for CT. Where I am in CT if this solution holds I will be very happy.

    2. Yeah, not looking too bad here in the New Haven area.

      That mixing and sharp gradient over Long Island in some of the models gives me pause, though.

  63. It’s rather important to note that I have not indicated that we would be expecting anything like a blockbuster snowstorm from this. Look carefully at the way my wording has been, very cautious given the uncertainties, bringing it into focus without reacting to single model runs, like the one that gave Boston 25.1 inches of snow the other day, for example. When the time is right then numbers will be put on it. I still expect to have them ready to go by tomorrow morning’s update although I may be able to comment on it this evening here.

    1. People looking at storms ahead and wanting numbers while a current storm, albeit small, is overhead is a bit of counting your chickens before they hatch I’ve always felt. Or maybe I’m the crazy one.

  64. This is a Mark and JJ storm. The rest of us can watch the dry air crush this one. Would love for it to change but been burnet too many times with this exact set up.

    1. Well that puts Tom & i in the 8-12 but I’m just not getting excited yet . And for the record I’d be excited with six or seven inches I don’t need the high end

  66. The GFS has been holding serve for days and has not backed off. Meanwhile, the EURO continues to slowly sink toward the American solution as WxWatcher wisely predicted it would. I’m in camp Tom with this one until proven otherwise. I never had a great feeling about this one even 24-48 hours ago which is why I have not chimed in. If you review yesterday’s model data more closely, the highest snow totals were predicted to our distant southwest i.e PA, NJ and while snowfall projections still remained impressive throughout southern New England, accumulations dropped off significantly in yesterday’s runs. That gave me pause as the models suggested a weakening system with an abundance of dry air to overcome. Today, it becomes a bit more clear that those obstacles “may”ultimately lead to the demise of our Wed/Thurs special. Let’s hope today’s system can move along a little faster upstream to allow the full potential of the midweek event to be realized here in the Boston area.

    2. The GFS has not been holding serve for days. Less than 48 hours ago it had 25″ for Boston. The Euro EPS over that same time frame has been equally consistent and and made subtle adjustments south.

      I agree southeast New England is not in the sweet spot for this storm and this wont be a “blockbuster” but south of the Pike still looking good for significant snow IMO.

  68. Here is a comparison of the 6z GFS run vs the 12z GFS run at about 1AM Thursday. Keep your eye on CT and you can see a distinct shift northward with the extent of the heavier snow band on the latest 12z run…

    6z:

    https://www.pivotalweather.com/model.php?m=gfs&p=prateptype_cat&rh=2020121406&fh=72&r=us_ne&dpdt=&mc=

    12z:

    https://www.pivotalweather.com/model.php?rh=2020121412&fh=66&dpdt=&mc=&r=us_ne&p=prateptype_cat&m=gfs

    The following frame in each looks about the same in Eastern MA as the storm maxes out and then starts to weaken. So not much of a notable change for Eastern MA but the higher totals did come north here in CT on that latest GFS.

    I do think it will tick north more some as the Euro has ticked south and they will meet in the middle. This still would equate to widespread significant snow south of the Pike but really a tough call as you head further north. Higher bust potential there.

    GFS ticking north and Euro

    1. That is actually as of 9AM this AM. Note how they pushed the 8-12″ range into Boston with the latest update I posted above.

    2. That met. at WeatherTrends 360 is excellent. He reminds me of my mentor in the private sector.

  71. 18Z NAM almost out far enough. At 60 hours I see signs
    of a right turn, 500mb flattening and system weakening.
    Hmmm Where have we seen that before????

  73. 18Z NAM is great! It moves the heavy snow South some from
    the 12Z run and leave a dramatic cutoff in snow at the MA/NH border. South of there 12-20 inches all over!!

        1. What does the Nam see that the GFS doesn’t? Trying to understand what underlies the divergence. Is it that the NAM expects a juicer system?

          1. TK could answer this better, but I believe that the GFS thinks that today’s system when it intensifies in Atlantic Canada into a powerful storm NE of NewFoundland, that it will influence our Thursday System and shunt
            it Eastward well South of SNE. Meantime the NAM
            thinks it will have less influence, allowing the storm to travel farther North before moving Eastward.

            My 2 cents, anyway.

    2. Quick look says they were all fairly reasonable if you take the run right before the precip arrived (12z today). NAM may have been a tad overdone on the precip itself. I don’t think this has much influence on how they do for the upcoming system…

  77. I’m sitting here scratching my head….. ?????????????

    18Z RDPS and then the 18Z GFS next up before moving onto
    the 0Z suite.

    2. Yup, cuts off at bristol and plymouth counties in MA, nothing north of there. Interesting. Looks like enough of uncertainty for NWS not to pull the trigger, even though their snowmap shows the same amount in those areas, lol

      1. Agree. Funny as hell if you ask me.
        Either they should issue the watch all through the 8-12 inch zone or lower amounts North of the watch.

        Just plain NO consistency or logic.

        1. I would post it here for all the areas it shows but I do not know how to do that . My location in pembroke is considered western Plymouth county throw a rock from my house & I could be In Hanson , Duxbury,, Hallifax, , marshfield etc

  79. Ok. I agree with the winter storm watch. I am not sure if they meant to send that for a larger area or are going to just expand it later…
    I agree with NWS’s first call snow map.
    I like the NAM’s general storm track (18z run, 12z was too far north). The NAM’s precipitation is probably a bit overcooked but that’s nothing new. One thing that needs to be taken into account: Very cold air mass travelling at least partly over water. There is probably going to be some ocean enhancement in coastal areas and for some distance inland (based on land set-up and its relationship to wind direction) until the winds back around to NW during Thursday.

  80. A note on current conditions, it just flipped to all snow here in Sharon for the first time today. Temps quickly dropping as the sun begins to set. Careful on the roads, I can imagine they will deteriorate.

    1. Same in Westwood Ace. According to the latest radar trends, I think precip shuts off before there is any meaningful accumulation but you’re right, with declining temps, wet roads could turn icy and treacherous.

  81. On and off light rain and snow here in Manchester CT today with no accumulation.

    Gotta love the NAM with those 18-30″ totals for all! Of course we know those totals are overdone. Perhaps some convective feedback here? NAM used to be notorious for that (I am recalling those 60″ totals it was spewing out before Nemo).

    But even cut those totals in half and we are doing pretty good.

    1. NAM is also holding onto the precip longer through the day Thursday on the back side. It’s also notorious for that. Likely also contributing to the higher totals.

  90. I don’t have much too offer since my Thursday – Saturday thoughts when those 24-30″ snow total maps started appearing.

    Best snowfall accumulation is south. I am not overly concerned about mixing. It’s going to be cold.

    The NAM is trying to close off the low and bring it too far north / northeast, too close to the coast. There is a lack of ridging to our west to deepen the east coast trough enough to make this system
    evolve as it depicts.

    I like Eric’s map. Maybe bring the high end of the 6-12 further south.

  91. From NWS Boston:

    DUE TO UNCERTAINTY, THE FORECAST WILL BE BASED ON A BLEND OF THE
    ECMWF AND GFS WITH MORE WEIGHT GIVEN TO THE ECMWF. THIS HAS RESULTED
    IN MINIMAL CHANGES FROM PRECIOUS FORECAST. WE HAVE ISSUED A WINTER
    STORM WATCH FOR N CT, RI AND SE MA WHERE CONFIDENCE IS GREATEST IN
    ACCUMS OF 6-12 INCHES. HEAVIEST SNOW FALLS WED NIGHT LINGERING INTO
    THU MORNING ACROSS EASTERN MA BEFORE TAPERING OFF BY THU AFTERNOON.
    LESS CONFIDENCE FURTHER NORTH DUE TO THE PRESENCE OF A SHARP QPF
    GRADIENT WHICH MAY LIE ACROSS SNE. THESE ARE ALWAYS AREAS OF HIGH
    BUST POTENTIAL IF STORM TRACK SHIFTS N OR S. CURRENTLY HAVE ACCUMS
    OF 4-8″ NORTH OF THE PIKE. IF CONFIDENCE INCREASES, WATCHES WILL BE
    EXPANDED NORTHWARD EARLY TUE MORNING. THE OTHER CONCERN IS THERE
    COULD BE ENOUGH BOUNDARY LAYER WARMING FOR A MIX OR EVEN CHANGEOVER
    TO RAIN FOR NANTUCKET AND THE OUTER CAPE. GUSTY WINDS EXPECTED ALONG
    THE COAST, ESPECIALLY CAPE AND ISLANDS AND WIND ADVISORIES MAY BE
    NEEDED.

    THE IMPORTANT POINT TO REITERATE IS WE ARE STILL 60-72H FROM THE
    EVENT BASED FROM THE 12Z GUIDANCE. FURTHER CHANGES ARE POSSIBLE.

    1. I’m guessing their precious forecast was actually supposed to be there previous forecast. Haha!

    1. Still not great, but the GFS has ticked north again.

      2″ more snow in Hartford, 3″ more snow in Worcester, and 1-2″ more snow in Boston vs. the 12z run.

      1. As we get closer. the GFS may start picking up on the ocean effect snows in southern New England.

        My instinct says this increase is for that and not really from the storm´s synoptic snow shield.

  93. The GFS at 6z is so menacing looking and then poof, just dries right up. If this is the right solution I’ll be fascinated watching that play out on the radar. Not thrilled as a snow lover but The thing just totally craps out.

    1. Not at all, just a little uncertainty. This year had certainly put out sad faces but whether we get a storm or not isn’t going to cause people to be that sad.

  95. As long as there’s still snow on the ground for xmas I couldn’t care less how much we get from this storm

    1. I would like to see something at least 6 inches so I can enjoy being home & not at the Hospital removing it

  99. Saturday morning could be on the cold side with lows in the single digits if we have a good snow pack and clear skies.

  100. I saw references on Twitter to March 22, 2018. I didn’t remember that storm so I went to the blog archives to remind myself–a disappointing one for snow lovers. I’m wondering if anyone remembers that set-up and sees this as a good analog to it?

    1. I don’t recall the setup but in my log from that year, I recorded 2.2″ in Coventry and I made a note “bust storm”

      The storm I have seen going around as an analog is Jan 23, 2016…

      https://www.americanwx.com/bb/uploads/monthly_2020_12/149D16C6-9275-473B-8B14-8EE282EFCC78.png.0c43da1b0d131bd8ac83d1320a5ae0e6.png

      Big Mid Atlantic storm but a sharp cutoff in New England due to blocking. Maybe shift that whole accumulation map north 75 miles and that is what we will end up with here?

  102. I remember that of the four Nor’easter’s that March that did not materialize. Even though that storm did not pan out March 2018 ended up quite snowy.

  104. Sizable jump south on the 18z Euro, after the GFS has shifted very slightly north the past couple runs. In other words, moving towards a consensus but heavier weighted to the GFS. Still plenty of time for change but that’s the way I continue to lean. Boston on the edge.

    1. Thank you as always WxWatcher! That’s how I am leaning as well. GFS has been remarkably consistent. I believe Boston will be spared from a blockbuster event. I can envision the northern extent of the heaviest shield trying to invade southern New England and not quite making it. At first glance the envelope of snow will appear impressive on radar as it makes a B line toward us only to suddenly hit a brick wall and then be squeezed out underneath us. Some of us will be frustrated and disappointed as the precipitation shield becomes compressed like an accordion as the area of low pressure slides eastward. I’m not sure if that made any sense to anyone but I’ve seen this too many times historically speaking.

      1. Thanks arod, good to see you here. Yep, there will definitely be some haves and have nots. Even within the heavier precipitation there will likely be at least one significant zone of subsidence south of the “death band” where the highest totals will be. First flakes for SNE still some 48 hours away so we’re by no means locked!

      1. The south shore is still likely to remain within the heaviest axis of heavy snow while several miles to the north is spared. The sharp cut off will be that close. I’d still expect to see some impressive totals your way at this time.

        1. I guess at this time that’s good but long way to go. Appreciate the response Arod always a pleasure seeing you here .

  105. I am still liking where I am at the moment in CT. I am hoping CT won’t be on the edge as is the case with Boston.
    WxWatcher down your way does Philadelphia end the streak of over 650 days without having an inch or more of snow?

    1. Ha, I think they do, but while Boston may teeter on the snow/dry line, Philly will likely deal with the snow/rain line. Should be several inches in the city before any changeover but lots of uncertainty down this way too. It’s gonna be a stressful but fun couple of days 🙂

      1. The drop off in snow totals the models are spitting out across your forecast area is incredible….from 16″ to 2″ in about 20 miles. And Philadelphia right in the middle of it. Such high bust potential with the snow forecast depending on your exact location.

  106. 18z Euro Kuchera Snow:

    https://imgur.com/lZp8tXw

    Another tick south from 12z as WxW noted but still significant snow regionwide:

    6″ North Shore
    8″ Worcester to Boston
    12″ South Shore
    10-15″ RI, most south
    10-18″ CT, most south

    Important to note though the 18z EPS (Euro Ensemble Mean) held steady and did not move south. EPS Mean remains NORTH of the operational.

    2. I believe we are just one more tick away from what we likely see region wide. Getting closer to what might be reality but boy I sure hope I’m wrong and that we end up with what the NAM has been advertising.

      1. It sure would be nice if pembroke stays in that foot potential as that would be an awesome event to watch from home , he’ll maybe pull an all nighter lol

      2. Note the 52 member Euro EPS mean did not bite and shift south with the operational at 18z. Ensemble mean has higher totals farther north. I don’t think the Euro is going to come south much further, if at all.

  108. From Norton NWS office

    The uncertainty revolves around the amplitude of the southern stream
    shortwave and extent of downstream ridging over the Maritimes.
    Confluent flow leftover from intense storm over Newfoundland limits
    the extent of downstream ridging and this is a de-amplifying wave as
    it tracks south of New Eng. Max low level easterly wind anomalies
    pretty much remain south of New Eng and the low level jet weakens a
    bit as it lifts north into SNE. These are limiting factors to a
    blockbuster snowstorm for SNE as heaviest snowfall may remain to the
    south. However, there are other considerations that do favor heavy
    snowfall in SNE. This is a southern stream system with abundant
    moisture and while the storm will not be very deep, we have a strong
    high to the north which will supply plenty of cold air and also
    result in a moderate easterly inflow for a period of potentially
    heavy snow. Higher SLR are possible if we can get into a period of
    favorable snow growth but details of snow growth and mesoscale
    banding can not be resolved at this time range. Convection and
    resulting latest heat release could result in further north storm
    track but this is unknown at this time.

  112. I´m looking at the 00Z NAM´s 850 mb wind flow.

    At hr 57, there is no doubt the best of the easterly low level jet is near the south coast/Long Island.

    In theory, that´s where the heaviest precip should be or just north of it.

    Its really far south of our local area.

    But, there´s still decent easterly flow up to the Mass/NH border and I think the NAM moistens the lower levels enough to bring the snow to the ground by this time frame.

    Its definitely over-amped in our local area, but I think the easterly 850 mb flow very, very late Wednesday night into early Thursday is our best time frame for steady snows that can pile up due to the cold temps and high snow ratios.

    Several inches, yes, but what the NAM is probably going to spit out again, I can´t buy it.

    1. yeah and that last part is another reason I can´t take it serious.

      Southern NH, except the immediate seacoast, usually doesn´t get ocean enhancement because on a northeast wind, for most of NH, thats a land breeze off of southwestern ME

      That would then imply that those southern NH totals have to come from just the storm.

      I cant see a low that is decently south of the benchmark´s latitude throwing its moisture all the way that far north.

      1. I think looking at the NAM it’s pretty much on a benchmark track, maybe a tad outside. But with that high placement the fetch is going tj be intense.

  114. Back in March 2013 I remember the storm that was 700 miles away and eastern half of SNE got crushed. I wish I could remember the synoptic setup but it is probably different than the one forecasted for this storm system.

    1. I remember that one as well. I don´t remember the synoptic set-up clearly, but I´m going to guess that somehow, there was quite a 850 mb easterly jet into our area.

  115. Not for nothing, but since it’s come into range, the NAM has been uncharacteristically consistent with its handling of this system

    1. Yeah how many times over the years have we said don’t trust the NAM and boom we get what it spits out.

    2. Eric Fisher
      @ericfisher
      11m

      NAM has been the extreme northern outlier and it’s starting to adjust. Stronger with the HP to the north, farther south with the low. Less amped and more open-wave in the mid-levels. Coming into line slowly but surely.

      1. hadik
        @hadik1974
        Replying to
        @ericfisher

        There are always those times where we discount the NAM and then it gets us.

        Eric Fisher
        @ericfisher
        4m
        Replying to
        @hadik1974

        Trueeeee

        hadik
        @hadik1974
        3m

        Tough call for you all. Feeling for you to make a decision. Watching that high very carefully, curious what it shows tomorrow once this storm today explodes.

      1. Today’s system will be an absolute bomb in the Eastern Maritimes, up through Newfoundland. There isn’t as much cold air up there right now for heavy snow. But the system may crank out hurricane force gusts in St. John’s, along with lashing cold rains.

  118. Looking at the 18z GFS vs the 00Z NAM, it is really a difference of about 60-70 miles in the location of the High in eastern Canada and where the low starts heading east. GFS has it shunted east at about Ocean City MD while the NAM takes the low 65 miles north to Atlantic City before shunting it east.

    That 60-70 miles north or south obviously has a huge impact on our snow amounts here in New England.

  123. Looking at 00z NAM the high is about 3MB weaker than 18z. I think the low is further north but starts to shear out as it gets closer. Biggest snows will be in NEPA area.

    1. Slowly but surely it’s inching up those totals. 6″+ snow area in SNE has expanded for the third run in a row.

      1. Respectfully, it really illustrates that this is a PA/NJ special. While I appreciate the uptick in snowfall amounts successively offered by the GFS, I think it’s inching real close to what is most likely to occur in SNE. Both the EURO and GFS are simply adjusting to model consensus IMHO.

        1. It’s inching closer but it has got more adjusting to do. There is still overwhelming model consensus against a solution that suppressed.

  126. The GFS has a small, secondary area of moist east 850 mb winds in our area.

    I think the GFS has this sniffed out. A snow event up here that’s born indirectly between onshore flow btwn the high to north and the low to the south.

    The big amounts southwest of New England are the synoptic shows from the low.

    What looks like 4-7 inches in our area is the 850 mb jet and a cold airmass over a relatively mild ocean. I like the gfs snow projections.

    1. I do too, Tom. A moderate to borderline heavy event for Boston with a more significant impact south and west. Synoptically speaking, I don’t see Boston getting into the real action with a track outside the BM. The GFS likely depicts a much more realistic outcome than that of the NAM. I’m very interested in seeing the latest guidance from the EURO.

    1. Looks good Matt! And the snow map looks similar to the 18z Euro projections.

      The short range models appear way overdone and the GFS still a bit underdone but it is coming around. I think the Euro is a reasonable compromise right now.

    1. ROTFL! I just don’t see this solution verifying unless the H is displaced or weaker than projected which would be nice:)

        1. I don’t know what worse: snow changing to rain or being dry slotted? I think the latter is most frustrating.

  130. Right now it feels like for this storm minimum would be around 6 inches and maximum just over 12 inches. I am not buying those 18 plus amounts.

  133. 0z Euro is WAY NW as well.

    Surface Map at 1AM Thursday….

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=prateptype_cat_ecmwf&rh=2020121500&fh=54&r=us_ne&dpdt=&mc=

    Surface Map at 7AM Thursday with low just south of NYC….

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=prateptype_cat_ecmwf&rh=2020121500&fh=60&r=us_ne&dpdt=&mc=

    10:1 Snow:

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sn10_acc&rh=2020121500&fh=84&r=us_ne&dpdt=&mc=

    That’s solid double digit totals for most with Kuchera ratios and about a foot for the MA Pike corridor. 12-18″ across CT and RI.

    I think this is a reasonable compromise between the GFS and the over-juiced Canadian and short range models. Should be a nice storm for everyone!

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