Friday December 4 2020 Forecast (7:37AM)

213 Comments

DAYS 1-5 (DECEMBER 4-8)

A cold front slips by today and low pressure develops on this front to our southwest, quickly organizing and strengthening as it tracks northeastward through Saturday, the center of a rapidly deepening low likely passing just southeast of Cape Cod Saturday night. For us, this will be a quick-hitting but fairly potent late autumn / early winter storm, starting as rain for all, from the South Coast this evening northward overnight into Saturday morning. As the storm center deepens and makes its closest pass then starts to pull away toward the Gulf of Maine, colder air will be drawn in from the north, and additional cold air will be generated aloft by the deepening process and brought toward the surface by the process of dynamic cooling (in which moderate to heavy precipitation drags the cold air down with it). This will change the rain over to snow, first during the midday hours of Saturday in the hills of southwestern NH and north central MA, then toward lower elevations and southeastward so that most areas with the exception of Cape Cod, the Islands, and the immediate South Coast will see snow before the precipitation exits in the early hours of Sunday. The highest snowfall amounts are likely to occur in areas that changed over first, as well as a band of more intense snowfall where the right combination of “just cold enough” and heaviest precipitation occurs. As the storm exits and moves away during Sunday, we’ll see windy and cold weather with a few snow showers possible in an otherwise blustery sun/cloud mix kind of day. Winds will quickly drop off Sunday night and early Monday as we get into a very weak ridge of high pressure between the departed storm and an evolving storm south of New England, which may graze the region Monday night and early Tuesday with some precipitation, although most indications are that this system will remain largely offshore. Still, we should keep an eye on it as it would not take much to “happen” in the atmosphere to draw it closer to this area. Later Tuesday, that storm will also be pulling away, leaving us with dry and chilly weather.

TODAY: Partial sun through lots of clouds morning. Cloudy this afternoon. Highs 48-55. Wind SW 5-15 MPH, gusts 20-25 MPH.

TONIGHT: Cloudy. Rain South Coast evening, spreading north overnight. Lows 40-47. Wind SW 5-15 MPH with higher gusts, shifting to N.

SATURDAY: Overcast. Rain all areas morning, changing to snow from northwest to southeast in all but the South Coast region during the afternoon. Temperatures falling to 28-35, coldest in southern NH and central MA, by the end of the day. Wind NE to N 10-20 MPH except 15-30 MPH Cape Cod with higher gusts possible in all areas, but especially coastal areas and higher elevations.

SATURDAY NIGHT: Overcast evening with snow, possibly heavy at times, except just rain mixing with snow South Coast, ending from southwest to northeast late evening and overnight followed by partial clearing. Accumulation of snow – slushy coatings South Coast, 1-3 inches Cape Ann southward along the immediate shoreline through Boston to the South Shore westward to Providence, 3-6 inches from the NH Seacoast down the northern portion of the I-95 belt to I-90 then westward from there into south central MA and eastern CT as well as northwestern RI, and 6-9 inches from the Merrimack Valley and interior southern NH through north central MA. Lows 25-32. Wind N to NW 10-20 MPH with gusts 25-35 MPH.

SUNDAY: Cloud/sun mix. Passing light snow showers possible. Highs 33-40. Wind NW 15-25 MPH, higher gusts.

SUNDAY NIGHT: Mostly clear. Lows 18-25. Wind NW diminishing to under 10 MPH.

MONDAY: Partly to mostly cloudy. Highs 31-38. Wind variable up to 10 MPH.

MONDAY NIGHT: Cloudy. Chance of snow/mix/rain favoring the South Coast. Temperatures steady in the 30s. Wind NE 5-15 MPH.

TUESDAY: Cloudy start with a chance of snow/mix/rain favoring Cape Cod, then clearing. Highs 35-42. Wind N 10-20 MPH.

DAYS 6-10 (DECEMBER 9-13)

High pressure brings dry but seasonably chilly weather for December 9. Disturbance from the northwest brings a rain/snow shower risk December 10 with a brief shot of milder air then a shot of colder air with dry weather December 11. A frontal boundary and possible low pressure system brings the threat of unsettled weather back for late in the period, December 12-13, but this is low confidence based on questionable performance of guidance.

DAYS 11-15 (DECEMBER 14-18)

Keep this a low confidence general outlook for a somewhat active pattern with 1 or 2 precipitation threats and variable temperatures averaging near to below normal.

213 thoughts on “Friday December 4 2020 Forecast (7:37AM)”

  2. Thanks TK!

    Red sky this morning… 😉

    I don’t recall any of the tv mets this morning even mentioned any storm system south of us Monday night.

    TK, as always you are on the ball! 🙂

    1. I’ve been watching the period through December 8 for a while, but Pete mentioned it yesterday and that we should keep an eye on it.

      1. 12/5 – 12/25 has been an open watch period for any reader of this blog ….The more you know.

        I see 9″ in your forecast. So to be clear – everyone is getting 9″!

  3. Good morning and thank you TK.
    Your snow totals are about where I expected they would. We shall see how it shakes out. Not a prediction, but sometimes these chageovers, especially with dynamic cooling involved, can happen much sooner than forecast with dramatic results. I’ll be watching for that. Hey, even WxWatcher said watch for surprises.

  6. The difference I see for my area between 0z EURO and 6z EURO is it throws a little more snow my way. I am hoping for a little bit of westward trend.
    Bernie Rayno tweet for next week as he is keeping an eye on the period TK is. keep an eye out for upper low Monday

  8. 12Z NAM has the rain getting pretty heavy by 7-8 AM tomorrow.
    How soon/if it will changeover, that is the big question.

  9. at 13Z, 8AM, 850 mb 0C line is far to the NW across Far Southern vt and the berks. At 14Z, 9AM, it has collapsed to about the 495 belt, indicating to me that we “could” have a rapdi changeover. We shall see.

    1. Well perhaps I190. Sorry. It stays about there for a few hours
      with NO advancement Eastward. Crap. Looks like no
      advancement until the system starts to turn the corner, but
      then how much qpf is left. The system is loaded.

  10. 12z NAM you tease me as I miss accumulating snow by just a tad. It is closer to my area than 6z run so maybe it could inch back just a smidge more.

  12. Some ramblings on the upcoming event….

    1. The ocean temperature is 49.64 F. Any wind component from the East and kiss snow good-bye near the coast.

    https://imgur.com/a/yH3fbNg

    That being said, the wind is progged to back to the North between 18Z and 21Z, thus allowing snow, even at the coast

    2. The storm is deepening fairly quickly which means to me that there is a chance that dynamic cooling can overcome that 850 mb 0c line faster than forecast.

    3. warm ground means nothing to me. Look at the October snow. It accumulated 5 inches here in JP with no problem at all and the snow was never heavy, mostly a steady good light clip with occasional moderate bursts. Tomorrow any snow is likely to be pretty heavy.

    4. As the storm starts to pull away, it is deepening rapidly, thus
    expanding the precip shield Westward, prolonging the snow near the coast for a longer period of time.

    In short, shaping up to be an interesting day tomorrow with much now casting going on. It will be cool to watch the changeover reports coming in.

    Boston “could” get more than forecast. We shall see.

    Also, not for nothing, but this could be a case where Logan
    gets 2 inches and I could see 6 inches in JP. 🙂 🙂 Love it.

    1. The positive the storm has going for it is the intense dynamics which is a big plus for changing to snow.

      But, for comparison, the October event, we had low 20F dewpoints affecting into the area, and the airmass was much colder.

      The dynamic cooling is going to have so much more to counteract this go around. I hope it works out, but I’m skeptical to the degree of how much snow the models are spitting out.

    2. Could I see Worcester and other elevated areas getting a quick 3-5 and low elevation areas north and west getting a quick 1-3, yes and for an hour or 2, it could look like a blizzard. But, I can’t sign on to the Nam’s projections:

  14. With this snow being wet for those who have to shovel it is going to be like moving cement and I would not be surprised to see some power outages across interior SNE tomorrow.

  20. Thanks TK.

    Hard to emphasize enough how uncertain this forecast is. One thing TK mentioned that I like: the snowfall totals may not take on a typical distribution. Where it snows for longer will get more snow, but there will also likely be that area that changes over later but has very high rates for a few hours which piles up the snow.

    The NWS Boston probabilistic snow maps look off to me. The expected forecast is at or above the 90th percentile. To me it seems more an issue with the 90th percentile map than the “expected snow” map. Their expected snow map looks reasonable to me (maybe a little too high at the coast and a little too low inland) but the 90th percentile should be somewhere around double those values. The Gray, ME office maps look really good to me.

    1. Fun times as always around here. I think when it does changeover it get intense, just for how long is the question.

    2. Right, their high end map is exactly the same as the expected
      map. A little boo boo on their part. Get after them!

  21. One area that would really concern me for some higher totals would be from the Merrimack Valley down into the Worcester hills and northeast CT. I don’t think it’s at all unreasonable that there ends up being a stipe of 10″+ in that zone, but that’s obviously not the only possible outcome.

    Also, ski country will *love* this one. They’re gonna get blasted up there.

  25. Nice NWS write-up on the upcoming event.

    One thing they mention that I have not seen mentioned here, or if it was, I missed it:

    With a rapidly deepening cyclone, the latent heat release from the convection will likely lead to downstream ridging and if anything, reinforces the possibility of a more inland track (inside the70W/40N benchmark).

    https://forecast.weather.gov/product.php?site=BOX&issuedby=BOX&product=AFD&format=CI&version=1&glossary=1&highlight=off

  27. I’ll see what the Euro says, but I get the distinct
    feeling that this sucker will track farther N&W than originally
    thought. That would be a bummer.

    C’mon Euro….

  29. Is the HRDPS onto something???

    It shows the system deepen in Massachusetts bay and retrograde just tad. Look at these few frames:

    https://www.tropicaltidbits.com/analysis/models/hrdps/2020120412/hrdps_mslp_pcpn_frzn_neus_32.png

    https://www.tropicaltidbits.com/analysis/models/hrdps/2020120412/hrdps_mslp_pcpn_frzn_neus_33.png

    https://www.tropicaltidbits.com/analysis/models/hrdps/2020120412/hrdps_mslp_pcpn_frzn_neus_34.png

    https://www.tropicaltidbits.com/analysis/models/hrdps/2020120412/hrdps_mslp_pcpn_frzn_neus_35.png

    10:1 snow

    https://www.tropicaltidbits.com/analysis/models/hrdps/2020120412/hrdps_asnow_neus_48.png

  30. I wonder if this is something Ryan Hanrahan’s is looking at with this latest tweet. Mark you look to be in a great spot at the moment.
    Saturday’s nor’easter is quickly turning into a major snowstorm in the hills and some accumulation expected in the valley. Power outages possible given the heavy, wet nature of the snow. We’re analyzing the latest data and we’ll keep you posted today as things evolve.

  31. JpDave according to eweather on twitter the HRDPS did shift west from 6z run. I am noticing with that model along with the NAM and GFS accumulating snow is really close if not here for my area.

  32. I agree JJ, this storm is really blowing up on the latest model runs and with all the dynamics and my elevation, I think we are going to flip to snow fairly quickly and it should be ripping for awhile after the changeover with 1-2″ per hour snow rates from NE CT into Worcester County.

    I would not be surprised if we made a run at 10″. I think you may also be pleasantly surprised how well you do JJ. You typically see multiple bands set up shop in these coastal storms and there is often an outer snow band closer to the edge of the precipitation shield where good convergence sets up. I could see that happening across western New England, especially with the track of the storm tucked in close to the coast.

  33. Imagine if this storm were happening in mid January with a colder antecedent air mass and higher snow ratios? We would likely be seeing a widespread 1-2 feet across interior SNE.

  34. This storm is going to overproduce in areas that are not slated to get much. Keep calm it will snow a lot more! It’s 2020 anything can and will happen!

  35. Mark if this thing tracks inside the benchmark I should be in business. I am liking what I am seeing with the latest runs of the EURO, GFS, and NAM is it is shifting the accumulating snow real close to me or has me in it.

  38. Eric F has a tweet from about an hour ago that I think is important.

    It’s the 3K Nam’s projected surface temps during the snow part of the storm: most low lying areas: 34F, even projects 33F for Worcester.

    So, I think low lying areas are going to have to have very heavy precip to accumulate and anytime the intensity lightens some, it will snow, but might now accumulate and if it gets light, it could even mix with rain.

    I think this event will display the importance of a 1-2F difference around the freezing mark.

    It worked to our advantage in late October, but I think it works against us this go around.

    1. If it is snowing hard, 34 degrees is nothing. It WILL accumulate,
      guaranteed. Intensity is key. If we had a base of the heavier stuff and it lightened up, still would accumulate at 34.

      I have seen this enough times.

      If it snows hard, the accumulations will come!

    2. Yes, I might agree, cause that implies pavement, which is even harder to accumulate on.

      Now, could an area around 495 or even 128 get stuck under a heavy band and get 1, 2 or even 3 inches on the grass and slush up the roads briefly, I suppose. I’d favor the 1 or 2. I think elevated areas above 500ft or so are plowing and shoveling.

      1. If it snows hard, believe me, it will NOT take long for the pavements to become covered. Intensity is your friend!

  43. hey gang. I know, I almost hopped on in October but was busy remodeling the kids’ bath while they were off at college. Anyway, I’m back to talk a bunch of nonsense with ya’ll. BTW, hope you and all of yours have been well and safe.

    Looking like I should be looking forward to tomorrow. I gotta get the snow board dusted off.

    1. Wow …… I just don’t buy the EURO on this, but I suppose it would be unwise to completely discount it.

      1. I think the Euro may be under doing it.

        I am wavering all over the place. If the track is SE of Cape in anyway, the dynamic cooling WILL do the job. IF track is
        over SE MA, FUGGETTABOUTIT!!!

        1. I think the dynamic cooling will do a lot too !

          I hope I´m not coming across that I think it will be all rain.

          I just think these boundary layer temps of 33F to 35F can really impact accumulations significantly.

          If the projections were cooling to 31F to 33F or 30 to 32F under the heavy snow bands, then, I´d be more likely to agree with those amounts.

          I think it may look like a blizzard for an hour or 2 in the 128 to 495 area, but, when it lightens up, its going to be like, ¨for how hard it snowed, thats all we got¨ ?????

          1. Well, time will tell. Don’t be surprised if it ends
            up being more than you thought. All depends on
            that track. I am concerned that it might end
            up tracking over SE MA. Then all bets are off.

  45. Thanks TK
    Wx Watcher it’s ok you can say Sturbridge for a jackpot area. 😉
    I do think that mark and I and I’ll add Vicki too are looking to be in good locations for this one. At least from the latest projections. I know I’m at 730’ in elevation. Mark you and I seem to have relatively the same conditions during these storms. What is your elevation?

    2. SC – I am right about the same elevation as you….~700′

      I’m going 6-10″ for my area up to you and Vicki.

      Retrac, welcome back! Agree, with Dave – you should hit the WHW jackpot on this one – 12″+ ?? Dust off the snow board!!

  46. Welcome back Retrac. I thought that you may have been gone for good. Happy that is not the case.

    You should be pretty much in the zone tomorrow.

    1. That WSW is AWFULLY close to Boston. Interesting.
      How much snow will fall after the winds back to N?????
      How much column cooling will happen prior to that????

      I found that in my location, it doesn’t have to go to North, NNE
      will do it here. May need full North at Logan, but not here.

      I will be watching intently tomorrow. Should be a fascinating day.

      IF it does snow, I suspect my location will top Logan by a minimum of 2 inches and perhaps by many more inches. We shall see what develops.

  50. Understanding that it is the very strong dynamics and intense precip that will bring the cold air down to cool the column enough ……

    looked at sfc temps and the 32F isotherm seems to be a couple hundred miles NW of Montreal and Quebec City.

    Its 45F in Burlington and Caribou is similar. I do understand we are in a warm sector and there´ll be some cooling.

    I´d feel better about these significant snow projections if the cold air behind the ¨cool front¨ in SE Canada was a little colder.

    The dynamic cooling is literally on its own this go around.

  53. i don’t know how well the HRRR is performing or will perform,
    but it has the rain mixing with snow in the 2-4 PM time frame
    tomorrow for Boston.

    Waiting on some frames to see what it thinks it wants to deliver.

  54. HRRR keeps a mix near the coast for a long long time.
    Not sure I buy that, except within a mile or so of the coast.
    Wind will be North, so I do not understand this.

  56. To these old and weary eyes, the 18Z NAM “Appears” to be a COLDER solution to me. We shall see. Mix beginning in Boston
    around 10 AM ish give or take.

    1. Too good to be true. 850 0c line backs NW about 20 miles from
      the coast. Insert Dynamic cooling do your thing here!

    1. I, for one, actually like that map.

      3-4 inches for my area. Hmmm I still think I come in higher, but we shall see.

      And they left the door open for higher amounts with the
      shift East caveat. 🙂 🙂

  64. Snow totals near the coast will come down to when it changes
    and how intense the snow is. Model consensus is changeover
    sometime in the 2-4 PM time frame. If this can get cranking good, I do believe there is a chance that the mix/change can happen
    2-4 hours earlier. If that is the case, then 6+ inches is not
    out of the question near the coast (Perhaps not Logan).

    BUT, if that does not happen, then the lower totals will be
    achieved.

    My gut says it happens earlier. I’ll be watching tomorrow
    and will probably go nuts when it’s still raining at 4 or 5 PM. 🙂 🙂 🙂

  65. I’m laughing out loud here… It’s funny, and I very much enjoy watching this comments section go a bit crazy with the what-if’s and this and that. Gee, you’d think we have snow in the forecast or something. 😉 Haha what a great way to end my busy 4-day work week. Yup, just 4 days after a long break, so who’s complaining? Not I. Welcome back to those just coming out of their warm season hibernation. 😉

    A couple of quick thoughts…

    ECMWF snow too high in the “jackpot” areas. Dial that back somewhat. New updated snow map by NWS is decent, IMO. A lot of this depends on where the 1-2 inch band(s) set(s) up and how long it hangs there. So while it’s hard to draw a map that has uneven distribution, that is very much still a probability.

    No need to do anything to my amounts yet, but I’m leaning to the higher end of each range at this time and may add a tiny bit for the next update, especially central MA hills.

  66. Central MA is gonna get croaked. I generally like the new NWS Boston map in terms of spatial distribution. I’d extend the higher totals further towards northeast MA also, and down into northeast CT in line with what I mentioned earlier. It’s still a “high error bar” forecast, but as of right now:

    Boston (Logan): 2-4″
    Boston (JP Dave’s area): 4-6″
    Providence: 3-5″
    Worcester (ORH): 12-18″… which should be about the “jackpot” area in SNE, but I could see a pretty sizable 10-15″ band through the areas I’ve been highlighting.

      1. I’d say around 4-6″ there as well. Will be tougher for you guys to get as big of an “upside surprise” as areas further west. If it were to come together just right you could see 6-10, but that would be a less likely outcome (and conversely, there’s potential for it to go the other way as well).

  68. The way my forecast could bust would be a further east storm track. If that happens, you risk losing the type of rates that I’m counting on. But these bomb lows do tend to get dragged northwest during the rapid intensification phase for reasons mentioned earlier. The snow near Boston should come mainly on the back end in the last couple of hours. The colder air should start to rush in pretty good as it pulls away. I figure a couple lingering heavier bands should do the trick for a couple/few inches in the city.

    1. I agree with everything you’ve said this afternoon. A little more time to tweak if necessary before things get going.

        1. Kind of a tough storm to pin ratios to in a traditional sense since there will be a rain component beforehand. Using Worcester as an example, I think they probably come in around 13 or 14″ with a liquid total around 2.25″. So that would be 6:1, but probably about 1.50″ of that liquid will fall as snow, so I think the ratios probably end up close to 10:1 out there.

      2. I’d feel better if the cold air was a little more robust, but I do like this one a lot. Good track, hitting SNE right during the rapid deepening phase, high snow rates, high QPF, decent duration. I think it delivers, but there’s a lot that has to go just right.

        1. I like your enthusiasm.

          I am hopeful that the dynamic cooling does it’s thing
          faster than anticipated. We shall see.

  69. Funny thing. It is 58 degrees here in JP and my wife told me countless times that there is no way it’s going to snow tomorrow.

    I countered with, I don’t care if it were 70 now, it’s what the temperature is tomorrow that counts. 🙂 🙂 🙂

  70. I don’t like this one as much as some of you because of the lack of cold air, but also the surface DP’s. I think SW/ W of Boston into NE CT is jackpot area.

    I think coastal / urban/ deep valleys underperform, while elevation over performs.

    In my opinion this does get pulled a bit east, that is why I really like the areas of elevation SW of Boston for accumulations.

    1. Just have to be careful with the rapid deepening which sometimes induces a ridge downstream and bends the track left a bit. So I’m leery about the getting pulled east aspect.

  71. Not surprisingly, Ryan Hanrahan has updated his totals to 6-10″ for my area in NE CT:

    Ryan Hanrahan
    @ryanhanrahan
    ·
    25m
    Updated snow forecast with heavy, wet snow expected. The highest numbers will be in the higher elevations. The snow will be heavy so power outages are possible. Worst will be tomorrow late morning/midday/early afternoon. Details next at 4. #nbcct

    https://twitter.com/ryanhanrahan/status/1334962447258677249?s=20

    Unfortunately we are under his “widespread” risk for power outages now as well…

    https://twitter.com/ryanhanrahan/status/1334940584910393344?s=20

  73. The afternoon NWS discussion re: storm is outstanding, in my opinion. It has it broken down by region, what they think is going to happen, what could work against their forecast, etc …….

  74. If those amounts of 6-12″plus verify, I feel for those folks in those areas.

    Trees and that much wet snow do not mix well.

    And, when its a significant outage of power because of so many lines in need of repair, it just takes a long time to get power restored.

    At first, its a little adventurous, but it does not take too long, say after about 12 hrs without power, to become less fun.

  75. I think these snow projections are going to BUST !

    Oh, it will snow ……. pancake size flakes when an area gets under that intense band.

    But, the futurecast features temps at 34F, 35F, 36F, even 37F.

    Low-elevated areas will underachieve and because elevated areas are forecast to get so much snow, they might underachieve some too.

    1. The surface temps will end up lower than modeled at most locations. They don’t handle cooling from overhead very well. Low sun angle plays a roll. Another big key, as we get the dynamic cooling, keep an eye on the surface wind direction too. And also keep in mind what happened on October 30. This may be very similar.

  76. I find it interesting that this snow is going to be considerably wetter than the October event. While that snow wasn’t “fluffy” by any means was relatively easy to move, considering it was middle of the fall, no less. The lowest Logan temp iirc was around 28-29F? We are currently at our darkest days, and yet temps (even inland) probably won’t get much lower than 32-34F??

    1. The Oct event was with anomalous cold just to the north. This event does not have anomalous cold to the north (while it will be generating plenty of cold from above), but climatology plays a roll. We’re talking 5 weeks later, so the situation, number-wise, is quite similar. You have to take this into account.

      1. Pembroke probably sees a trace coating on the grass Tk is that your thinking . Rain & wind will be the issue here & hoping no winds like last Monday .

  79. So does anyone remember when “the models” had this system as a Great Lakes cutter? 😉

  81. Not to be a Scrooge the city’s and tows are really strapped for cash right now so we really don’t need a hit to the snow removal budgets. I really do enjoy a good old fashioned blizzard but not now.

    2. Very nice Matt. Thanks

      Darn I go away the day and we have gone from 3-6 to 12-18. Or did I make that up too

  84. I’m getting nervous about that NNW wind on the immediate backside of the low for coastal SE MA and Cape Cod.

  85. A lot of work went into that. Thanks Matt!
    I saw you sign onto periscope the other day when I was watching Bernie Rayno live yesterday. I like to watch Bernies take on storms, he like TK and others on this blog take complex weather prognostications and put them into terms the average person can both understand and learn from.

    1. thanks everyone for the kind words. I was thinking of starting a video thing but decided against it after I listened to the recording (PS I hate the sound of my voice)
      South Central I very much like watching his video’s and I learn things from his talks all the time. I highly suggest anyone that wants to learn the science behind winter storms to follow him. I follow several meteorologists on twitter that goes into the science behind weather/climate who other than just saying the forecast. I learned so much just by interacting of course here but also on twitter with meteorologists. I will admit I learned alot about hurricane forecasting over the past year and a half through different mets on twitter. Its an amazing resource if used correctly.

  92. Thought I heard some ice hitting the bedroom window like at 5:30. Got up and it’s starting to mix already at 40 degree surface. Looks like it might be a quicker flip I don’t know.

  93. Not an easy forecast and the recency bias of our October event pollutes the thinking a bit, even though the events are not synonymous.

    If we could make hyper local snow maps today would be the day.

    If you could imagine a wide U or V shape that is how I would describe the visual of best snowfall accumulations. The bottom of the U or V being NE CT into NW RI and then widening upward to left at the western edge of Worcester County up and through south central New Hampshire and then on the right side eastern Middlesex County and western Essex County. These areas will see 6″-8″ in the lower elevations 12″-16″ in their high elevations. (I think you will see snowfall totals where an area of a town that sits low could report 6″ while an area that is just a few miles away but 500 feet higher could report 12″. The higher the elevation the quicker the turnover to not just snow, but impactful snow as the DP’s will be the lowest there and accumulations easier to pile up as the snow density will be less. There will be difference in accumulation from 300 feet to 700 feet and anyplace over 1000 feet would be pushing the top end of the range. Subtle note-the higher the elevation the drier the snow, which means less tree / power impacts.

    Deep Valleys will be some of the slowest to turn over to impactful snowfall, even if the radar says it is snow. I believe the winter storm warning in the CT River Valley of Mass will be a bust. The cold and drier air will have a tougher time reaching the surface of deep valleys.

    Immediate coastal areas – Say within 3 miles of the coast, I believe remain on the lower end of the guidance with a general 1-3″ trending upward to 3″-6″ after you make it those few miles inland and then toward then upwards of 6″ as you move west. Coastal locations may pick up their greater share of accumulating snow from the departing fetch of the storm that will be lingering for a while into the early morning hours of tomorrow.

    Winds will gust along the coast to 40-50mph and seas once you get outside the protected harbors will grow to over 5 feet.

    1. Thank you JMA. Nice detail.

      What about that shift East you talked about? Do you think
      that happens? I didn’t like some of the 6Z Guidance, however, the 0Z Euro was quite robust.

      1. The shift east was termed by me as a “bit east” and is reflected in the lower totals in Berkshires Western MA and wider portions of CT with higher amounts east of Worcester, particularly to its northeast.

        1. Thank for the explanation.

          Should be an interesting day to say the least.

          So is your location in one of the valley’s or are you elevated?

  97. I see that WBZ upped their totals putting Boston in the 3-6″ range including north shore. As a north shore resident, I am thinking more like 2.”

    Some of these snow map cutoffs are sharp. I feel like I could take a few mile drive and suddenly be in some 6-12″ area.

    1. Tim Kelley on NBC10 has 6-9” for Boston, the highest of all.

      Can Logan realistically make a half foot?

  99. From what I can tell, Snow ratios are 3:1 to 5:1 at the outset and ends up being 7:1 to 8:1. Pretty damn wet snow!

  103. This might be one where Now Casting will be difficult. Though I am no model expert, I feel like I am seeing wide variations.

    1. The models are all over the place. The GFS wants to give us
      NO snow at all.

      The most consistent models have been
      Euro
      Nams
      Hrrr

      Cheers

  104. Here in JP, we have picked up 0.53 inch of rain already. Snow down the drain and there will be so much more rain.

    1. Thanks for the report Retrac. According to the models
      you are about 1-2 hours ahead of schedule. Now to see what your accumulations start looking like. 🙂 🙂 🙂

    1. 🙂

      This is what I was mentioning yesterday.

      btw, for the record it is 19 atop Mt. Washington, so the air
      is colder above for sure and as that air is drawn in it will
      aide in addition to the dynamic cooling to flip it over.
      And the Wind is generally North, also helping.

  116. Most of you look to be in a great spot with this one. One of our meteorologist here in CT said this morning if we had the cold in place this could have been 12-24 inches.

  117. Sitting under that heavy band for a while here and now in the process of changeover. About 50/50 rain snow mix. If that band stays where it is we are going to get crushed here in southern Worcester county.

  121. Not sure if it means anything, but Logan’s temperature dropped
    2 degrees in the last 10 minutes from 43 to 41.

    1. That means that the rain is dragging cooler air down from above, as was expected to happen. 🙂

Comments are closed.