Saturday Forecast Update

214 Comments

8:01PM

This is just a quick update on how I think the storm Sunday and Monday will play out…

Some light snow/freezing drizzle Sunday morning over the NH Seacoast down to the eastern MA coast including Boston and its immediate suburbs will be a result of an onshore wind and not directly related to the coming storm.

The precipitation from the storm overspreads southern New England from west to east during the morning and midday, reaching the Boston area by 1PM.

A rain/snow line should be somewhere in southeastern MA and may move north toward Boston for a while, but by late in the day this line will start heading back to the southeast as the colder air wins out. It may take most of the night to make it all the way across the South Coast and Cape Cod so a good portion of the storm there may be in the form of rain. Elsewhere, snow will take over and be dominant.

The wildcard portion of this storm is how much back-lash snow occurs on Monday as the low center gets into the ocean water just to the east of New England and very rapidly intensifies. Right now the greatest chance of moderate to heavy snow lingering through the morning will be across southern NH and northeastern to east central MA, extending down through the South Shore and Cape Cod.

Blizzard conditions are possible along the coast during Monday morning. Blizzard conditions are defined by 3 or more consecutive hours of 1/4 mile or lower visibility caused by falling and/or blowing snow with winds sustained or frequently gusting over 35 MPH.

Ok, so about those snow amounts? This is tricky, but here’s my best guess, and highly depended on both a rain/snow line to the southeast and the amount of back-lash early Monday…

1-3 inches outer Cape Cod & Nantucket at the end, 3-6 inches remainder of the South Coast of New England, 6-10 inches interior southern MA to northern RI northward to about the Mass Pike including Boston, 10-15 inches over central and northern MA into southwestern NH, and 15-18 inches due to extra back-lash snow over northeastern MA and southeastern NH on Monday.

Please understand that these snow amounts are still subject to change and I will update this when needed!

The remainder of this post is from earlier today but has been edited slightly.

DAYS 1-5 (FEBRUARY 11-15)
TONIGHT: Mostly cloudy. Lows 20-30 north to south. Wind light variable becoming NE.
SUNDAY: Cloudy. Spotty very light snow or freezing drizzle near the MA/NH East Coast in the morning. Snow develops west to east midday and afternoon except mix/rain southeastern MA and southern RI. Highs 25-40 north to south. Wind NE 10-20 MPH, higher gusts near the coast.
SUNDAY NIGHT: Overcast. Rain/snow line moves southeastward, crossing Cape Cod lastly overnight. Snow elsewhere. Temperatures 20s north, 30s south, but falling slowly. Wind NE 15-30 MPH, higher gusts especially coast.
MONDAY: Mainly cloudy. Periods of snow favoring eastern areas with heaviest most likely northeastern MA and southeastern NH. See above for accumulations. Temperatures falling to 20s. Wind NE to N 25-35 MPH gusts above 50 MPH interior and above 60 MPH coast.
TUESDAY: Mostly sunny. Lows 5-15. Highs 25-35.
WEDNESDAY: Mostly cloudy. Chance of snow showers. Lows 10-20. Highs 20-30.

DAYS 6-10 (FEBRUARY 16-20)
Snow showers possible to start the period then fair and cold weather dominating, moderating late in the period.

DAYS 11-15 (FEBRUARY 21-25)
Pattern transition underway here but there may be another storm threat during this.

214 thoughts on “Saturday Forecast Update”

  1. Hi all!

    There are a lot of new readers out there as of today thanks to a very well known news photographer in the area promoting Woods Hill Weather. I’m grateful for the boost!

    A message to anyone that wants to comment that has not done so before. You’ll need to add an email address and a username. Make sure these are the ones you are planning on using if you want to comment regularly. The first post will go into moderation. Once I approve it, you will be free to post so long as you make no changes to your email or username. If you change either, you’ll need to be re-approved.

    Be patient if you comment and are waiting approval. I’m doing this solo most of the time and can’t always check the blog right away. I will check as frequently as possible. Thanks! 🙂

    1. I sorta left CT and western MA out but I’ll fix that later…

      I must head out to check on friend’s kitties now. 🙂

      2. Maybe make another tab like you did with contests that lists our handles and locations? So there is a central place to look?

  6. Thank you, TK. Your explanations are so wonderfully crafted. I have a quick question on the rather significant difference in weather this winter along the northeast corridor. While Boston hasn’t had a lot of winter to contend with, it’s definitely been wintry at times. And this current spell may push our snow amounts to the average yearly total (!) as well as bring our average temperature reading down to close to average for the season. Very different story just 300+ miles south of us where it’s been very mild all winter, including today. What’s causing this?

    For new WHW members: I’m in Boston. Well, my body is. My mind sometimes wanders off to faraway places like Quebec, Kimmirut, Amsterdam, and Prague, as readers of this blog know.

  7. My instinct tell me this will be more snow than rain for most areas in the immediate Boston area, north and west. GFS will not be correct.

  9. I find it interesting that the Blizzard Watch/Warning is in an area (Cape) that will be getting the most rain.

  10. Thanks TK.
    Will be looking forward to hear your thoughts on what you think I will be getting down here in CT.

  11. Logan “overachieved” today with 3.2″ 😀

    Most forecasts were for widespread 1-3″

    Total snowfall to date = 30.9″

    1. Good point Jimmy, I didn’t think of that!

      Unless we get really skunked this week, Boston should surpass last year’s total and maybe a shot at normal.

      Total 2016 = 36.1″
      Normal = 43.8″

    1. Probably can’t make it! Do me a favor though and let me know when you are going again…would love to meet up!

  14. Philip where are weather records are kept for inland CT at Bradley we have more snow right now 36.3 inches compared to last year where it was just 26.9 inches. Now were 5.2 inches from normal season. If we get more than that tomorrow will have above normal snowfall and this will mark the first time have an accumulating snow in October leading to above normal snowfall for the winter.

    1. Wow! Hopefully that low forms in just the right spot for your area Jimmy! 😀

      Of course not to put a damper on things but I am wondering if low placement is even more critical for CT than Boston??

      1. The low is tracking a little too close so after an initial burst of snow for the shoreline it will go over to mix and plain rain especially southeastern CT. For my area it always a close call to see if that mix line gets up here. If your north and west of I-84 with this track best shot to remain all snow.

  16. Newscasters (as I expected) are already comparing this to 2015. Of course I didn’t help matters I guess by posting those thoughts in the previous blog. 😉

    Still, fast forward to 2017…Pats win SB, we are heading into a snow blitz this week… 😉

    1. I knew the 2015 comparisons would pop up, but this is similar to about 20 other winters in the last 100 years and none of them are 2015.

      1. Let’s see. Was it 69 or 68. I know where I was but it spanned two years. But it is probably human nature to compare something to their most recent memory. Also there are not many dinosaurs like me around 🙂

  17. Pelham, NH just over the border up 93. Hopefully, we get some good snows in this one. The last two we under achieved. We got in the trough of one of those gravity waves on Thursday and didn’t end up with as much as everyone around us, and last night we got just under an inch, was expecting 2-4. I am hoping this is the one we overachieve. Bernie Rayno mentioned potential for dry slotting in this storm and he said it would happen from northern MA to very southern ME, potentially keeping down accumulations. Has anyone else heard that?

  18. Regardless of low placement (unless it doesn’t form at all or well OTS) NH and Maine are a sure bet for deep snows…16-24″.

  21. Thanks TK for the update, and for being so welcoming to newcomers.

    Would like to change my user name from oceanair NS to Oceanair – it’s just quicker to type. Really like this blog and all the great commenters here.

      1. Thank you South shore kid – I’m a North shore kid – it’s great to hear from different locations, especially when storms start up

      1. Thanks Vicki – I picked up that username a long time ago – I love being near ocean air anytime I can, whether winter storms or foggy summer nights or lashing rains – love the sound of fog horns, and rigging clanging against the masts – and rocks raking up and down on a cobble beach – have to tear myself away at times to get any work done

  22. To haterain I saw that you mentioned that you were under gravity waves on thursday, what is that exactly? Does that explain the lower snow accumulations in northeastern mass on Thursdays storm?

  23. Hello! Just saying hello. I lurk frequently. The last storm – you called it before everyone else! Enjoy this next storm. Hoping for dry fluffy stuff again in Shrewsbury.

  24. Have seen the 00z GFS ….. I’m thinking about 3 inches total for Marshfield, mostly Monday. Maybe we get a bit tomorrow, but we’ll get a change to a chilly rain for many hours.

    Logan itself, 4 to 5 total (so maybe an inch or 2 tomorrow before a changeover, the NE wind in this case doing the trick) with 3 more on Monday. The suburbs of Boston, 5 to 10 miles inland may squeeze out an extra inch tomorrow, for a storm total of 5 to 6 inches.

    And then by the time you get to northern Mass, 6 – 10, except Essex county that might total more with a better chance at heavier wrap around amounts Monday.

    I do think the NE wind tomorrow, usually good in February, is not the coldest NE wind we’ve ever seen and that will have an effect by late afternoon through early evening.

  27. My thinking on the rain/snow line…

    When the storm’s precip comes in, the line will be somewhere from the South Shore (possibly right up to about Logan) down to the Canal then across to extreme southern RI. It will oscillate in this area for hours, with Cape Cod being mainly rain well into the night. There will be a period somewhere between 10PM and 2AM in which Boston may mix or briefly change, but probably right at the airport. This could be a situation where Logan rains and the bulk of the city itself is still snowing.

    After 2AM the line heads southeast and eventually crosses Cape Cod by 5AM. Most of the snow in that area falls after 5AM.

    So, for Boston, I think 90% of the storm comes in the form of snow with 3-5 inches before the mix time and 3-5 inches after it, accounting for a 6-10 inch storm total.

  29. TK – Will Boston have a much wetter snow overall compared to the last one and do you still feel that it will start around 1 pm as you earlier stated above?

    2. Steady stuff should be in around 1. Right at Logan I figure wet snow to start, maybe a touch of rain/mix, then snow, then a mix zone late night gets close, then back to snow for the remainder.

      Yes there is a chance they never mix.

    1. I concur. Very light though. 30 degrees here.

      Just looked at the Euro. Down more than 20% on snow for Boston, from
      10.6 to 8.0 inches, but still a hit and that is for Logan and as TK mentioned,
      it could be a situation where logan goes to rain while most of the city is snow.

      We shall see tomorrow. Onto the 12Z runs.

      Oh btw, 0Z RGEM is a pretty big hit. 😀

  32. Answer to yesterday’s AccuWeather Trivia Quiz … although the answer is sort of right and sort of wrong.

    Following the famous blizzard, what else happened in the Boston area in February 1978?

    A. No more snow
    B. Another snow storm
    C. Flooding rains
    D. A solar eclipse

    The AccuWeather answer is A, no more snow.

  33. NWS 437 AM EST Sun Feb 12 2017 Update –
    …As for the city of Boston, always a tricky forecast with marginal temps and
    onshore flow. However temps are fairly cold aloft and even by
    00z tonight it`s about -4C at 850 over Boston. This combined
    with low pressure intensifying south of Long Island should
    result in pressure falls turning the wind in Boston to NNE. Thus
    leaning toward mostly all snow for much of the day.

  34. I’m thinking I might get my generator out of the storage container in my front yard. I have a feeling I maybe needing it.

    Beautiful snow falling now in Hanover.

    1. I certainly took note of that, however, radar echoes are looking impressive, so don’t give up just yet. 6Z 3km NAM looking as good as ever. perhaps it is picking up on something others are not?

      Watch the temperatures and radar.

  37. Light snow out my window now. Too bad its going to change over to mix and maybe rain in my area later today which will prevent this from delivering a lot of snow.

  38. I remain very wary of the higher numbers on the ranges. I’ll say 4-8″ for Boston. My concern: backlash not performing. I think most of the total snow for the Boston area comes today and early tonight. Then we get the lull, at which time light rain will mix in for many. Cold air will filter back in, so most or all of the backlash precip will be snow, but I have serious doubts the heavy stuff gets much beyond Cape Ann. This has been a challenging forecast though, we’ll be nowcasting.

  40. NWS snowfall map has 14″ for Boston. They obviously are counting on absolutely no mixing or changeover. Early this morning TK did mention the possibility of that but I suspect on the lower side of probability.

  41. I don’t think Boston gets 14 inches. I do believe they will surpass last winters snowfall after this storm. If we don’t get that mid week storm its not looking good for snowlovers for a while.

  42. Coastal front back west of the Boston harbor buoy and has arrived in eastern Marshfield.

    36.7 at the buoy, with an ENE wind (070) and 36F in Marshfield with an east wind.

  45. What I am not seeing on the latest runs is the Backlash as alluded to by WxWatcher.
    Whatever Boston gets will have to come from the front end snows, Unless there is a surprise and the backlash gets in here in a big way. What I see so far on the back end
    is a period of light stuff not amounting to a whole lot at all. And if we mix or change, then even those totals go down.

    4-8 or TK’s 6-10, seem much more in line than the totals the NWS are throwing out there. I believe they will have to adjust downward.

    We’ll see how things actually play out.

    We picked up a coating overnight, perhaps upwards of 1/4 inch.
    I do NOT see it snowing as of this moment.

    1. NWS is aware of this, but apparently, they are incorporating backlash in their numbers.

      Models in good agreement on the overall evolution of developing
      winter storm and especially snowfall potential on the front end
      today but then some uncertainty on how quickly and close storm
      intensifies to the region. This greatly impacts magnitude of strong
      winds Mon along with comma-head snows.

  48. I’m going to rain on the party this morning ….

    The wind is 070 on the east side of the coastal front. There’s a low center that’s going to be coming off of the NJ coastline and a small retreating high in New Brunswick. All 3 are going to give maritime boundary layer air momentum into eastern Mass, unless the wind goes ageostrophic early.

    I believe Logan’s going to pop to 36 or 37F btwn 10 and noon and its suburbs will pop to 32 to 35 not long after.

    The chill at 850 will help the column in heavy precip, but with the marginal temps and February brightness, I think there’ll be periods when it struggles to accumulate.

    I guess I’m throwing out there that I believe from 128 south and east, the front end may not deliver as well as being anticipated.

  49. It’s going to have to come down in a hurry. Dry slitting is already in central PA and hauling east. Backlash snow again is not classic for these parts. Down east Maine? Not so. I think Boston misses out but north and east is a different story.

  50. Nws seems to think that the models are over doing the rain.
    ” However, models continue to struggle with isallobaric drainage
    flow connected to an inverted ridge apparent within mass fields.
    This has, and will likely continue to keep cold air with low
    dwpts in place as the SN overspreads. Therefore, not liking the
    mesoscale guidance bringing in as much rain as they currently
    prog, low lvl airmass is likely to be colder than BL temps
    currently progged. Therefore, have increased (spatially) the
    snow across the region. Will just need to continue to monitor
    onshore flow as or if it develops later today, as this would be
    the trigger for the warmer influence.
    Maybe that’s why they have higher totals, they also mentioned that a lull of activity tonight and a dry slot for SE mass

  51. The NWS amounts are probably too high in general, but that’s typical.

    That said, I should copy/paste the message from the other day about being careful not to verify a forecast before the event actually takes place. Seems we’re heading in that direction again. Not that it surprises me. 😉

    I’ll be updating the blog soon. Don’t expect any huge changes. Just had a brief moderate ocean-effect snow shower go through Woburn.

    1. Hi TK, I am wondering about the thinking that goes into NWS amounts in general. I’ve noticed that they’re frequently quite higher than other outlets, especially compared to local networks; do you have an idea of why that might be? Is there some systematic bias in their approach? Thanks!

  52. 12Z GFS Instant Weather Snow Map (Kuchera Method)

    http://www.instantweathermaps.com/GFS-php/showmap-conussfc.php?run=2017021212&time=PER&var=ASNOWI&hour=036

    It has snow accumulating with surface temperatures mainly in the mid 30’s.
    Shows a semi-decent backlash, yet still only manages about 7 inches or so
    for Boston. It looks to be cement, unless it is flat out wrong about the surface
    temperatures, which it may be. Interesting ahead.

    OH here is how it depicts the backlash.

    http://www.instantweathermaps.com/GFS-php/showmap-conusncep.php?run=2017021212&var=PCPPRSTMP_2m&hour=027

    Som other site maps might look prettier. not sure.

      1. Tom at the bottom of that there is a save image button. Click on that and it opens the LOOP in another window. Then cut and paste that url like so:

        https://radblast.wunderground.com/cgi-bin/radar/WUNIDS_map?station=BOX&brand=wui&num=10&delay=15&type=N0R&frame=0&scale=0.33260869565217394&noclutter=0&showstorms=0&mapx=400&mapy=240&centerx=515.7516339869283&centery=316.66666666666663&transx=115.75163398692825&transy=76.66666666666663&showlabels=1&severe=0&rainsnow=1&lightning=Hide&smooth=0&rand=24781908&lat=0&lon=0&label=you

  54. AccuWeather trivia Quiz.

    Boston’s biggest snowstorm on record is …

    A. Blizzard, Jan 26-27th, 2015
    B. President’s Day Blizzard, 2003
    C. April Fool’s Blizzard, 1997
    D. Blizzard of 1978

    Answer later today.

  55. Just woke up and preparing for back-to-back 12-14 days (with a stay in a hotel tonight). Based on my quick look at the 12z stuff so far, I’m not really going to change my forecast much from yesterday:

    Cape Cod: 1-3″, mainly Monday from the backlash behind the storm.
    South Shore/Boston/Providence: 4-8″, possibly a little more, especially the further inland you get
    MetroWest/Central MA: 5-10″
    Merrimack Valley: 8-12″
    Southern NH/MA North Shore: 10-14″
    NH Seacoast/Southern Maine: 12-16″

    I likely won’t have much time to comment today or tomorrow, as I might be a tad busy at work both days.

    2. Sak I love how you add the south shore as we have a few of us down here . Reporting to work at 1pn and I didn’t get home till 1 am this morning ugh .

      1. Well, I live on the South Shore and have lots of friends and family here. Since my forecasts are written with friends and family in mind, I always have the South Shore on there.

  56. Snowing moderately in Coventry, CT and has been for the past hour or so. Roads are covered and we have about a half inch accumulation already. 24 degrees.

  58. Been snowing moderately for the past couple hours. Be curious to see if that mix line gets into my area. If it doesn’t I’ll be at the higher end of the 4-8 inches predicted.

  59. This morning’s RGEM snow map (10:1)

    http://www.tropicaltidbits.com/analysis/models/rgem/2017021212/rgem_asnow_neus_12.png

    UP from the 6Z run here

    http://www.tropicaltidbits.com/analysis/models/rgem/2017021206/rgem_asnow_neus_14.png

    This run shows little or no back end end snows and shows a change to rain in Eastern Sections tonight. Therefore, this is almost all front end and pretty potent.

    This is 10:1 so the real ratio likely to be more in the range of 6-8:1 IF and I say IF
    as wet as depicted. We shall see. 😀

  61. Watching what the final number is at BDL because if they record more than 4.2 inches it will be the first time ever having an accumulating snow in October leading to above normal snowfall for the winter. BDL recorded 1.5 inches of snow back on October 27th.

  62. In the 128 zone from Mass PIke up to Rt 3/rt. 93 aread, echoes from the synoptic snow
    are meeting echoes from ocean snow. Pretty cool. Have a look

    https://radblast.wunderground.com/cgi-bin/radar/WUNIDS_map?station=BOX&brand=wui&num=10&delay=15&type=N0R&frame=0&scale=0.33260869565217394&noclutter=0&showstorms=0&mapx=400&mapy=240&centerx=515.7516339869283&centery=316.66666666666663&transx=115.75163398692825&transy=76.66666666666663&showlabels=1&severe=0&rainsnow=1&lightning=Hide&smooth=0&rand=24781925&lat=0&lon=0&label=you

  63. So is there a consensus of no back end snow? If so when does the snow actually end in our area? Curious if cleanup is tonight or tomorrow…thanks!

    1. Who said a consensus?
      A couple of models downplayed the back end. The GFS has a fairly
      pronounced back end. I for one, haven’t a clue.
      Frankly, I don’t think we know until when/if it happens or doesn’t happen. 😀

        1. I’ve seen it before. Many times it snows here and rains
          at the airport. One time years ago, Logan got zilch and we got 5 inches. One never knows.

          But if Logan is up, I suspect we’ll go up soon.
          I am hoping the steady synoptic snow gets in here first
          to help keep the temperature 32 or below. We shall see.

  65. These ocean effect snow showers coming in from the ocean are non-stop and pretty
    decent at that. I don’t mean continuous snow just that the showers keep coming.
    It snows for 5 minutes and stops and 5 minutes later another one blows through.
    Repeat…

    3. Not a fan of packers….is that what you were going for 😉

      I don’t tweet so sadly cannot see more than that

  70. Visibility here UNDER 1/2 mile and getting close to 1/4 mile in the heaviest
    of the ocean Snow Showers this morning. 😀

    1. I think I may be getting a finger of the synoptic snow merging with the ocean
      snow. It looks amazing out there.

  72. Enough snow in Sutton to coat all surfaces. Again, for new folks, I am on a side road with no view of Main Street. Although I was out this am and surprised to find some streets in neighboring towns have a light snow pack. Felt like I was in ski country

  73. When Boston was 21-22 degrees and Marshfield was 37 degrees early this morning I knew that Boston was doomed and sure enough…happens every time.

    11:00 am obs. = 35F 🙁

        1. I know that. That is why I was wondering what it was where you are? Dorchester? Would give a feel for where
          that coastal front is exactly.

  75. Going to attempt snowblower repair this afternoon with the help of you tube :). Wish me luck. 3 years old and stalls right away after starting. Going to clean the carburetor in hopes that’s it!

    2. Clean carb, drain all old gas out of the unit and put new gas high octane with some stable . Also check spark plug. Good luck

  76. I’ve had steady Snow here for about 20 minutes. For all intents and purposes, the
    storm has begun here. 😀

    2. Here in Dorchester the snow is off and on. It snows pretty good for a couple minutes then abruptly diminishes. I wish it would make up its mind.

  78. Both RGEM and CMC showing half foot for my area. If that half foot happens by the time I wake up tomorrow will have a foot and half of snow on the ground most of which fell on Thursday. I am hoping that mix rain line stays south of me and it turns out to be all snow.

    1. Crazy cold up here with all that warmth to the south and west. Spring fever everywhere else. Old man winter must be a really good friend of yours OS :).

    2. Notice that little extension right down almost to MA?
      I believe this whole set up is what NWS was calling the Inverted Ridge
      draing cold air down into SNE. Perfect set up IF you want snow.
      It “should” be a mostly snow event.

  81. Wonder if we could get those snow totals to tick up just a bit.
    Tweet from Ryan Hanrahan
    1.0″ new snow in West Hartford. Snow growth is surprisingly good.

  82. The buoy temp, even with an E wind (it’s 10 minute wind direction measurements are btwn 082 and 086) reports a surface temp out over the ocean holding at 36.9F. It’s not like it has jumped to 41 or 42F. With the chilly enough air at 850mb, that probably can be overcome very close to the coast. Quite a wet snow though, be curious to hear reports on the trees later this afternoon.

    2. Note COLD High to the North. That is preventing it from Warming too much
      even out over the Water. Love it.

      As I said, I believe this to be a mostly Snow event, at least from the Boston
      Area northward.

      The big question is Backlash or not? That could make the difference from
      7-9 inches to 12-16 inches. We shall see.

      Even without the backlash, this front end is pretty impressive in its own right.

  83. Hi all! Updating very soon…

    Making very few tweaks and my #’s will look nearly identical to SAK’s, which is not really a surprise. Will let you know when the new post is up.

        1. Oh yuk. Mine heading to south shore RI in a few then back to MA 10:00 pm. Not as bad as Phily to Portland. Hope they and all travelers are safe

  88. I think today’s system means business.

    Intensity has been variable. Sometimes vis below 1/2 mile and sometimes closer
    to 1 mile, but overall very steady serious light to occasionally moderate snow.

    Watching for heavier snow yet.

  89. Backlash or not, a pretty good thumping is on the way for the afternoon and evening today. Complex forecast. But I too agree with SAK’s numbers.

  94. Here in Boston it is going to be an ongoing all day/evening battle with that dreaded east wind. Too bad water temps are well above normal.

  95. Just cleaned off my car and moved it from on the street in front of the house into
    the driveway so the plows/sanders can get to the end of the street (We’re at the end of a dead-end street).

    Measured 1/2 inch and noticed for 29 Degrees, the snow seemed heavy and wet. Interesting.

  97. 27 here in Sharon and temp creep this AM seems to have slowed. Synoptic snow just reached here from the west and coming down at a moderate clip already. We were in the mix zone on radar when the precip was coming in off the ocean but now showing solid snow. Air has an ocean feel to it though.

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