Saturday January 30 2021 Forecast (8:38AM)

245 Comments

DAYS 1-5 (JANUARY 30- FEBRUARY 3)

Before we get into talking about the upcoming storm, let’s talk about the cold that still has hold of us. Another day today of well below normal temperatures, but this time less wind, so it won’t feel as harsh as yesterday. We’ll also have nearly 100% sunshine, which is now just starting to be noticeably a bit higher in the sky during the day than it was in the darkest days of late November through early January. It’s subtle, but it’s there, now being light well into the 5:00 p.m. hour. If you’re an early riser you’ve noticed the same on the other end of the day – that morning twilight starting a little earlier. In fact, Boston experienced its first sunrise before 7:00 a.m. today, 1 minute before. While the sunsets there are just a few days away from reaching the 5:00 p.m. or later threshold, we will probably only see the sun go down one of the next 4 days – today. Tomorrow is about a 50/50 shot and will depend on how quickly high cloudiness advance ahead of the coming storm, and how much they thicken up. But since they will be coming from the direction we’d be looking to see sunset, this is reducing our odds of seeing Sunday’s sunset. When we get to Monday we’ll be under a thickening blanket of altostratus clouds as our storm, a redevelopment of an Ohio Valley low, starts to make a northeastward movement to the south of New England. So definitely no sunset visible that day, nor will it be visible on Tuesday, the first day it occurs 5:00 p.m. or later at Boston, as we will still be under complete influence of that storm system, which will not be out of here until Wednesday, when we will actually visibly see our first post-5:00 p.m. sunset (at least in most of the region, pending any post-storm passing cloudiness). Hey, how did I get to Wednesday’s weather without talking in as much detail as I could about the storm? Don’t worry. I didn’t forget. I was just saving that until the last part of this discussion. You’re not getting snowfall amounts out of me yet, but you may start to see those in the comments section of the blog from me as we get deeper into the day and I get to look over another set of model guidance to get a better idea of how they are handling the evolution of this system. The energy for this system just came onshore on the West Coast yesterday, and it was with today’s 00z model guidance that we finally started to get better sampling for model initialization, and from here on in, in theory, the guidance should be performing the best it can under current reduced air travel circumstances. As always, the models are guidance, one set of tools in the meteorological process – one I hope leads me to a fairly accurate prognostication of upcoming events. And here is what I think so far, followed by a detailed forecast….

Storm timing: Snow arrives south to north Monday afternoon.

Storm peak (heaviest precipitation): Monday night to very early Tuesday.

Snow amounts: No numbers yet, but highest chance for the most significant accumulation currently expected in the I-95 belt and/or I-495 belt.

Rain vs. snow: A rain/snow line will probably be involved in this storm, most likely limiting snowfall near the coast especially southeastern MA.

Coastal impact: While not extremely strong, some significant and persistent onshore wind from the northeast & east will probably result in minor to possibly moderate coastal flooding focused on the high tide in the early hours of Tuesday morning. A more northerly wind may cause minor flooding on north-facing shores for the Tuesday afternoon high tide.

Duration of storm: While I’m leaning toward the heaviest precipitation being Monday night, it should be lighter and more spotty (still with a possible rain/snow line involved) through Tuesday, but that does not mean some areas cannot see additional snow accumulation.

TODAY: Sunny. Highs 18-25. Wind NW 5-15 MPH gusting 20-25 MPH morning, diminishing in the afternoon. Wind chill below 10 at times.

TONIGHT: Clear. Lows 0-7 except 8-15 urban centers. Wind NW under 10 MPH.

SUNDAY: Sunny start, variably cloudy finish. Highs 25-32. Wind N under 10 MPH.

SUNDAY NIGHT: High overcast. Lows 15-22. Wind NE up to 10 MPH.

MONDAY: Thickening overcast. Snow arriving south to north during the afternoon at least into the I-90 belt, may be mixed with rain South Coast / Cape Cod. Highs 26-33 except 33-40 South Coast / Cape Cod. Wind NE increasing to 10-20 MPH, higher gusts especially coastal areas by late-day.

MONDAY NIGHT: Overcast. Snow, possibly heavy at times, with significant accumulation possible, except rain/mix South Coast and possibly South Shore of MA. Temperatures steady 26-33 interior areas and North Shore of MA to NH Seacoast, steady or rising slightly 34-41 coastal areas to the south. Wind NE to E 10-20 MPH except 15-25 MPH coastal areas with higher gusts.

TUESDAY: Overcast. Periods of snow northwest of Boston, snow/mix/rain Boston south. Temperatures generally steady 26–33 interior locations, NH Seacoast, and North Shore of MA and 34-41 coastal areas Boston southward. Wind E backing to N 10-20 MPH inland and 15-30 MPH coast with higher gusts.

TUESDAY NIGHT: Mostly cloudy. Additional mix/snow showers evening. Lows 25-32. Wind N 10-20 MPH, higher gusts.

WEDNESDAY: Partly sunny. Highs 33-40. Wind NW 10-20 MPH, higher gusts.

DAYS 6-10 (FEBRUARY 4-8)

A shift in the large scale pattern as a plunge of arctic air enters the west central US and the East Coast moderates, meaning a milder trend for our area February 4-5. Next low pressure area travels well northwest of New England and its warm front / cold front combo brings a chance of some brief snow/mix/rain followed by rain showers sometime those two days. The February 6-8 period may see some additional unsettled weather with an active jet stream between very cold air to our northwest and milder air across the southeastern US.

DAYS 11-15 (FEBRUARY 9-13)

The cold air that moves into areas to our west and north will probably find its way to the Northeast with time, so expect colder weather for this period, probably starting out dry, but eventually ending up with a threat of unsettled weather by later in the period.

245 thoughts on “Saturday January 30 2021 Forecast (8:38AM)”

  1. Good morning and thank you TK. Too bad this storm wasn’t approaching closer to the rain/snow webinar last Wednesday as it appears to be setting up as a classic rain/snow line situation. Where does it set up and how long does any rain last will factor greatly into the accumulations.

    I fear substantial rain in Boston. Hope that fear is unfounded.

    Waiting for 12z runs

  2. For those on FB (and probably Twitter too), there is at least one false map going around regarding the upcoming storm. Somebody found an old TWC map from a previous blockbuster storm that happened to occur on the same days of the week and are passing it off as a map for the upcoming event (which shows 2 feet or more for Boston). It’s NOT the right map. And personally I’d like to give whoever decided to put it out there, as my mother would say “a boot-in-the-ahhssss”. Disgusting.

  4. Thanks Tk should be an interesting couple of days at work as I’m guessing I’ll get in on Monday & leave more than likely on Wednesday, welcome back right . At work now I left the house just after 3am this morning i think yesterday same time felt a tad colder In my opinion but either way it’s brutal outside & I hate it .

    1. Well comparatively speaking, it’s going to feel quite mild during the upcoming storm. We’re not keeping much cold air around for this one…

  8. Thanks TK!

    Some thoughts before I head off “into battle” here…

    This will not be a day to hug every model run. There are certainly still multiple failure mechanisms on the table, but a major snowstorm for nearly all of SNE is the most likely outcome at this point. I really wouldn’t be too worried about mixing save for far southeast MA and maybe the immediate coast. I think we’ll see the NAM and some other guidance correct colder and less amplified, although with these type of systems there does seem to be an air of inevitability about late trends north.

    I don’t think SNE will see the very highest totals from this storm. I expect those will be further west, anywhere from around my location in south-central NJ/near Philly up to around Binghamton, NY, depending on the track. Similar to the December 16-17 storm this past year, with the maximum totals being found in the pivoting axis of the dominant deformation band. That’s where you’ll probably see a (narrow) band of 2-4 foot totals. But like with Dec 16-17, there will probably be plenty to go around for SNE as well, and maybe a little less in the way of banding which could make the distribution a bit more uniform.

    If I had to broadbrush a range at this point, I’d say most in the WHW area are looking at about a 10-16″ event, possibly less at the coast, possibly some higher “jackpot” areas, but with a lot of wiggle room still in the forecast.

    Enjoy the day all 🙂

    2. Thanks WxW. I agree with your overall idea here. I’m not really going to go with any #’s yet myself. I will say I hesitate to put anywhere in SNE in double-digit totals at this point though if I have to give that much away, although I’m not going to say it can’t happen either. Door is open. We’ll probably also be missing the synoptic mega band that nailed areas northwest of Boston in the December event, focusing more on the areas that you outlined for the “jackpot” zone. SNE has to rely on the evolution of that low pressure area and I’ve seen this set-up do different things to us before, enough to keep me at a low level of confidence as to how the details play out, snow-wise. 😉

  10. Nam is getting juiced up. 850MB temps looking good, so IF
    rain is involved, it will be due to boundary layer issues and the 41 degree ocean.

    1. So far looking at 3 hour increments, the kuchera snow is going up by an average of 1 inch per hour. Given it would be a heavy wet snow, that is pretty impressive. So far NAM is NOT showing any rain for Boston.

      1. It does show 850 0C line moving up towards Boston and settling in around a line from Cohasset/Scituate to Brockton to Providence.

  14. JPD, compare the precipitation (radar depiction) and snowfall (10:1) projection at 60 hours between the NAM 12km and the NAM 3km and let me know your reaction to that.

    1. TK – Sometimes I have to laugh. I was just about to post what you wrote about he 3k at 60. Last night I had written a post about a potential later start of the precip and then erased it, as you had posted the same thing minutes earlier.

    2. I’ll probably fail your test.

      2 things I notice:

      1. The NAM has the precipitation Farther North than the 3KM, so I presume onset is earlier. Looks like at least 3 hours earlier.
      2. The NAM has more snow on the 10:1 than the 3KM, some due to the earlier on set, but some due to lighter precipitation being portrayed by the 3KM NAM.

      Something more subtle than that? I am curious

      1. Yes basically. I think that at least partially illustrates one of the points that WxW made above.

  18. SO FAR (as of 12z suite that is completed through the storm’s time frame), if you want a hint from me, the 12z operational GFS is my favorite depiction of the storm at this point…………

    Please do not even remotely think about this being my final call. 😉

  20. Yeah 12z GFS IMO has the right track but very spotty precip depiction. Doesn’t add up, part of the puzzle though.

    My general forecast is 8-12 with a few pockets of 12-16 depending on any banding that set up.

    1. You’re making the assumption that everyone from DC to Maine wants it to snow that much. 😉 Probably more realistically about 15% of the population would be “happy” with that. 😉

    1. Yeah see that and don’t agree with the rain line that far north. We will be tracking it through the south shore and that’s as far as it makes it.

      1. I’m glad you can be that sure of it at this point. WAY too much model disagreement with 60 hours to go for me, as a long-time meteorologist, to be that confident on a rain/snow line. 😉

        1. I am with you 100%. I can’t stand the model divergence we are seeing. I wouldn’t want to have to make a forecast at this point.

          I have NEVER been excited about this event. Hope I end up that way, but certainly not yet. I want to see the models converge some on a solution. Perhaps with the 0Z run tonight, or certainly the 12z runs tomorrow.

  26. I think BL temps are garbage right now. A BM track this time of year is a snow maker for 90% of the region. I am watching the surface track at this point.

    1. A BM track is only part of the equation. We’ve had storms track INSIDE the BM that have dumped on Boston, and storms track OUTSIDE the BM that have delivered rain to Boston. It’s all about the complete synoptic set-up. Minute details right down to meso and even micro scales. We can’t even be close to confident on a r/s line because low pressure goes over or near 40/70. Weather doesn’t work that way.

      1. I agree but not often this time of year. I do agree plenty have gone either way but generally speaking Feb 1at BM track equals snow. I guess we have to keep an eye on that ULL. Saw Bernie this morning call for rain everywhere near the coast expect far interior places.

        1. It’s happened at any time of winter. Climatology plays some role, but the date is not magic. It’s still about the synoptics in play at the time.

          Climatology says that storms passing by us in late October where that one did produce rain here. Well, the synoptics of that particular situation said otherwise.

          Weather doesn’t fit neatly into seasonal envelopes like that. Forecasting would be much easier if it did. 😉

  28. Some of the short-range models have a little bit of OES sneaking into eastern MA pre-dawn Monday. Another meso-scale thing to take into account as we get closer to the event.

    2. Boundary Layer

      In meteorology, the planetary boundary layer (PBL), also known as the atmospheric boundary layer (ABL) or peplosphere, is the lowest part of the atmosphere and its behaviour is directly influenced by its contact with a planetary surface.[1] On Earth it usually responds to changes in surface radiative forcing in an hour or less. In this layer physical quantities such as flow velocity, temperature, and moisture display rapid fluctuations (turbulence) and vertical mixing is strong. Above the PBL is the “free atmosphere”,[2] where the wind is approximately geostrophic (parallel to the isobars),[3] while within the PBL the wind is affected by surface drag and turns across the isobars.

  32. Yes, yes…

    OES = ocean-effect snow.
    BL = boundary layer.

    Not a “classic” Miller B. The track of the primary low is a little left of the classic track, and the track of the secondary is a little right of the classic track. But it kind of fits into the category nevertheless as a low that is west or southwest of New England that redevelops near or off the coast somewhere south of New England. But that alone is not an indicator of a good performer. That puts the storm there, but other things come into play as well.

  33. Regarding boundary layer…

    In my humble opinion, it will not be a boundary layer issue
    that causes any rain, if any at all. (yes I know I said that earlier because the NAM was depicting that). I believe it will be a warm nose at or near the 850 mb level or “about” 5,000 feet give or take. The ocean is 40.6 degrees and I think snow would hold with any kind of intensity at all. We’ll have to watch that warm layer above.

    Euro is up next…

  35. Here is a nice SNOW video, courtesy of Arizona Snow Bowl in Flagstaff Arizon where they picked up a cool 68 inches of snow in the last 7 days. Who says it doesn’t snow in Arizona? 🙂 🙂

    https://www.snowbowl.ski/

    Of course the video is a sales promotion, but it looks awfully nice just the same.

    1. The city of Flagstaff, at 7,000 feet receives on average right around 100 inches of snow per year. The ski area, base at 9,500 feet, receives 260 inches per year on average, 111 inches so far this year.

      Phoenix is a 2 hour drive South of Flagstaff and it is an entirely different world.

  36. Anyone notice that the CMC and ICON now have a much different solution for late next week? Much weaker and colder solution with some rain and snow showers and no big rain event or warm up. Would be nice if that came to fruition and we could retain whatever we receive from this storm for awhile.

    1. Well, they are the worst 2 medium range models we have readily available. That may be part of the reason. 😉

    2. Nope, have not looked past the upcoming event.

      Still not feeling it Mark? Too much conflicted info for my taste.
      This thing could go either way or a mess in between.

  37. FWIW, the RGEM likes a lot of rain involved right into the I-95 belt and a healthy 8-15 inch snowfall outside of there, going by its 10:1 map. Just model data. I provide no analysis of that run on this particular comment.

    2. Do you think that model is also one of the worst?
      I thought that it was at least reasonable and much better
      than it’s cousin, the CMC or GDPS.

  39. Phew took me about 20 minutes to get through the posts and it is not even 1:00. You’d think we were expecting a storm 😉

    Because I would have been two hours reading all in depth, I didn’t see anything re wind. Can I assume typical nor’easter type wind.

    Most of all THANK YOU, TK!

    1. NWS said 40-45 mph.

      This would support wind gusts of 35-40 kt/40-45 mph along the
      coast, especially the eastern MA coast.

    2. your typical nor-easter winds. At one point I was thinking we could be talking the B word several days ago but the winds have fallen more in line with your typical winter storm.

  42. Thanks TK !

    I see a 500 mb feature deepening slowly with time and corresponding surface low strengthening with time.

    I think, dependent on evolution and track, this can set up eastern areas for a decent punch of snow on the back half of the system.

    I don´t know about an initial thump near the coast and seems reasonable with not the strongest or coldest high to the north, that the middle third of the event is most susceptible to be too mild for snow at the coast and maybe some distance inland.

  46. Latest SREF ensemble mean snow for Boston: 8.86 inches
    Low of: 3.49 inches
    High of: 15.26 inches

    If ones takes the values closer to the mean, a 6-12 inch
    forecast from this would be good. But, the SREF is polluted with the NAM.

  47. Tk are you thinking early afternoon now vs later in the evening. Just trying to get a sense as I’m off Monday day for a doctors appointment regarding my knee but will be going in later when it starts .

  48. My dad and my mother and father-in-law have scheduled vaccine shots this Wednesday.

    I´m sure there are thousands, if not tens of thousands of over 75 year old people with appointments set up for this coming Monday and Tuesday.

    The weather is the weather, but this event is going to add to a lot of people´s angst.

  50. Super arctic air, parked over Siberia all winter, may finally be ready to cross the north pole and head onto our side of the northern Hemisphere.

    Medium to long range hints at it coming south thru Canada. Meanwhile, also signals of southeast ridge making appearance(s).

    Perhaps a more stormy February with significant temperature contrasts to work on in the continental US.

      1. Perhaps.

        Medium and long range models don´t pick up southeast Canada high pressure areas well. So, all it would take is a small bubble of high pressure in eastern Canada and 50s turns into upper 30s with a raw northeast breeze and we never warm sector ahead of what looks like a system going to our west.

      2. Not necessarily, a few of the models are backing off on that (albeit not the two most accurate ones as TK noted). Even on the GFS/Euro, there is a cold air damming signal ahead of the late week system, and the warmup is fairly brief. I dont see a repeat of the Christmas deluge/inferno where the snow was just incinerated from Long Island to Quebec City.

  51. Boston’s four high tides from Monday night through Wednesday morning are all greater than 10′.

  52. Matt… I don’t specifically recall the last Miller B. Probably 2 years ago. Maybe somebody can chime in with a more definitive answer.

  53. Ok. We’re just over 48 hours out from when I think the snow (mix South Coast) will arrive, so here’s my first guess on snowfall etc…and it’s a pretty simplified “imaginary” map.

    Draw a line from Boston to Providence southwestward to the South Coast. From there north and west, 6+ inches mostly Monday evening & night. Southeast of that line, 3-6 inches except 3 inches or less immediate South Coast especially Cape Cod. There’s going to be wiggle room here. Also, as far as the 6+ area. Why am I not putting a top # on the range yet? Because I have no great feel for what the maximum potential snowfall is. 8? 9? 12? 16? One can make a case for any or all. That will be part of the refining process to come. A rain/snow line will be involved. Certainly rain involved in southeastern MA. Probably mix/rain involved right into Metro Boston, and of course less likely the further west and north of the city you go. As always, don’t count this as the first and only word of mine. I’ll be adjusting as needed.

    1. For me, its probably going to be a heavy wet type of snow regardless. Always difficult to get the fluffy snows in the city. Oh well.

      Thanks TK! Looks like the usual potpourri SNE nor’easter. Yuuuuck!!!

  54. Dave, to answer your question above, no I am still not feeling it, not for my area anyway. We are dealing with three issues….dry slotting after the initial precip shield/thump comes through, warm air intrusion with a R/S line, and low snow ratios. Seems central CT is a prime spot for some shadowing as well which is showing up on most of the models. I’d be surprised if we pulled out more than 4-8″ here. I think interior eastern MA stands a better shot at double digit totals.

  55. Wow, 12z Euro joins the CMC and ICON and has completely lost that big warmup/rain storm late next week. Now depicting a few rain/snow showers Friday with another snow threat next Saturday…

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=prateptype_cat_ecmwf&rh=2021013012&fh=174&r=conus&dpdt=&mc=

    And another snow threat next Monday 2/8…

    https://www.pivotalweather.com/model.php?m=ecmwf_full&p=prateptype_cat_ecmwf&rh=2021013012&fh=222&r=conus&dpdt=&mc=

    Our storm Monday could be just the start of a more interesting pattern ahead…

    2. Still some pretty solid positive temperature anomalies on the ensembles for Feb 5-7. Some of them are double-digit positive anomalies. We will have to keep an eye on that cold air mass that enters the west central US though for just after that, as noted in my discussion today.

        1. “Todd’s Rule: Best chance of a snowstorm, Feb 6-10.” If you look at climatology, that may be kind-of-true over a very long period of time, but the difference is so small between that block of days and the week before and week after it that it’s pretty much negligible. But it was fun, nonetheless. 🙂

    1. I keeping chuckling at the maps here in the New Haven area. CT feels singled out for lower totals

    2. I agree, right now my early call would be 4-8″ for CT. Too many issues at play here….best QPF/forcing to our NE and SW, dry slotting, snow shadowing, warm air intrusion, etc. Unless we can get a tighter/stronger system and a more SE track, we are screwed. I guess that is better is nothing though!

  60. Looks to me that there could be many outcomes for Connecticut. Models still showing a large range of possibilities.

      1. NOT always. Sometimes it is spot on. The problem is, how does one know when it will be spot on? Ah, that is the question.

  66. 15Z SREF
    Ensemble mean snow for Boston: 7.71 inches
    High: 18.46
    Low: 2.85

    Take the extreme highs and lows out and you come up with
    6-10 inches.

  69. Re: NWS snow map.

    Here in JP we are almost on the line between 6-8 and 8-12, so looking like about 8 or 9 inches here. But Logan is in the 2-3/3-4 inch Zone. I could see JP getting 8 inches while Logan gets 3 or 4 inches. 🙂 🙂

  70. My mid afternoon opinions…

    The NAM is too high in pockets.
    The NWS mid afternoon update map is something I generally agree with.

    Remember what WxW said about trusting each model run too much. He’s right. Observe with care. 🙂

    1. I’m a blog lurker, not a poster. But I always come looking for these Dr. Stupid posts. They’re so convenient. Thank you!

  73. Once again at 18z the snowfall amounts are vastly different through 60 hours on the 3km NAM vs the 12km NAM.

    2. Why you do this to yourself man lol . Wait till tomorrow & model watch , you will be getting your snow .

      1. I have been telling you that RAIN will be involved, even if you didn’t want to hear it. I hope it is ALL snow. We shall see.

        1. Old salty it doesn’t matter to me it’s you that does not want rain involved . You want 100 inches & more lol . What would you do ??

          1. You do realize that telling JP Dave not to model watch is a fruitless effort. It’s his hobby, or at least one of them. 🙂 I think it’s fun to watch. 🙂

            Thanks Dave! 😀

            2. I love love love Old Salty’s posts when a storm is on a horizon. Takes the fun to a whole different level

      1. I’d like to see that hear.

        Do you remember several years ago, the NAM was spitting out 60-72 inches even for Boston! Of course, it never happened. I think Boston ended up with 10 inches or so. 🙂 🙂

  77. Model watching fun: I didn’t really look that far ahead on the 12z GFS today with any great detail beyond the Northeast, but I just looked at the entire N American loop. Today’s 12z run depicts a classic clipper type system moving at incredible speed and passing through New England on the second weekend of February. I love those systems. Not sure it will actually be right, but it would be fun to follow.

  78. I am not buying that 18 inches the 18z NAM showed for my area. I am preparing myself for a 4-8 5-10 inch storm and hoping for more. Anything less than that I will be disappointed.

  79. 18z GFS is not bad (again) in my opinion. The snow hole in CT is representative of the energy shift to the new low. The narrow strip of heaviest snow somewhere over interior MA is representative of where it snows heaviest longest. There is a rain/snow line involved. Still some tweaking to be done, for sure.

    1. We don’t have snow days any more….except if a significant amount of the area is out of power. It is why I asked earlier about wind 😉

      Thanks for the responses to that. Although, I’m hearing my grandkids will have a snow day regardless. !!!!!

  81. Clippers – god I miss those.

    Not sure any model has it right but. If you just have to find a model solution for the upcoming storm
    you could do worse than a GFS / ECMWF blend and then toss the rest.

        1. To get a consistent train of these – A strong East Asian jet, +PNA, and cross flow over the western Rockies can help.

  83. I think as we get closer to Monday, we will se. the cold hang much tougher. I just don’t see a ton of rain. I think the models in general are just too warm.

    2. We’d need a stronger high to really lock that cold in. Not happening as much this time. The cold air is in exit mode as this low comes to us.

      1. Wankum has 5-9 for the city but said don’t focus on the higher number focus on the lower number .

        1. Sometime tomorrow I’ll see if there is a side of the range to lean on. The thing is is that there could be a very rapid buildup of snow over a very short period of time…

  84. Thank you, TK.

    Cement snow – 5 inches – in Boston with mixing and glop. Won’t be fun. But, I think this could be a whopper of a storm west of 495.

    I LOVE clipper systems, too, TK. Clippers, which my father used to call Alberta Clippers, were what got me interested in weather way back in the 1970s. My father used to talk about them, and how they’d sometimes redevelop off the coast and blow up into major snowstorms. I always thought that was really awesome, that a weak system – my father used to say “moisture-deprived” – could regenerate itself off the coast, gather ocean energy and become a major storm.

    2. Alberta clipper..
      Saskatchewan screamer..

      Those are two terms I have not used very much recently but we have not quite been in the right regime to receive those. Eventually we will.

  85. Most the accumulation will happen upfront when the cold is here. That’s how I see it happening.

  87. Probably around 7:1 on the ratio for Monday night.

    As far as model output goes, adjust the 10:1 snowfall maps accordingly.

    The 12 km NAM continues to appear as an outlier regarding the aerial coverage of heaviest snowfall. I have my doubts that this model is correct with that. Will be interesting to see what the rest of the 00z guidance indicates. they’re continues to be quite a difference between the 12 km and 3 km NAM.

  88. I was watching Mark Rosenthal on his Weatherblast site and he showed the Euro and pointed out a “breakaway” low south of Nantucket from the Delmarva parent low (8:00 am Tues.). Then fast forward to (8:00 pm Tues.) the breakaway low becomes the dominant (Delmarva low fizzles out) and brings down NNE winds to Boston southward.

    TK – Is this scenario possible?? If I understood Mark correctly this would be 3 lows involved. Primary-secondary-tertiary?? If that makes any sense.

    1. Sort of but not really. This is going to be a strung out area of low pressure and there can often be multiple centers. but in this case it’s really only two main ones but neither one of them ever gets all that powerful.

  89. And 00z GFS says what snow for eastern areas. Again just not seeing that happening but something to consider.

  91. Well the parallel GFS sure looks different than it’s cousin. Should be an interesting storm for sure.

  92. 00z GFS Kuchera Snow:

    https://www.pivotalweather.com/model.php?m=gfs&p=snku_acc&rh=2021013100&fh=102&r=us_ne&dpdt=&mc=

    00z GFS Para Snow:

    https://www.pivotalweather.com/model.php?m=gfs_para&p=snku_acc&rh=2021013100&fh=96&r=us_ne&dpdt=&mc=

    00z NAM Kuchera Snow:

    https://www.pivotalweather.com/model.php?m=nam&p=snku_acc&rh=2021013100&fh=84&r=us_ne&dpdt=&mc=

    00z 3km NAM Snow (not totally done yet in all areas):

    https://www.pivotalweather.com/model.php?m=nam4km&p=snku_acc&rh=2021013100&fh=60&r=us_ne&dpdt=&mc=

    1. That was a nice improvement on the 3km NAM. A little more robust in most areas. Both the NAM’s still look nice and cold. GFS Para pretty cold right towards the coast as well. GFS operational with R/S line issues and a big drop off in snow totals along the immediate coast

      1. The 3km NAM is a higher resolution model than the regular 12km NAM. These models all have different algorithms as to how the ingest the data and process the results, hence the differing outcomes in snow totals.

  95. Mark hopefully you could get into some of the higher totals in eastern CT. If you are a snow lover in western CT you are loving what you are seeing with the 0z runs so far.

    1. Still not looking great in eastern CT. If I could squeak out double digits, I’d be happy. You are looking better out there further west. You should hold onto the snow longer and be closer to the better deformation banding.

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