Tuesday Forecast

137 Comments

7:38AM

DAYS 1-5 (JANUARY 16-20)
We’re in the final days of the “cold” pattern and it will hold one more winter weather event before it changes. Does this mean no more winter weather threats for the season? If you think that’s the case, you have never lived here or you think it’s April 16, not January 16. So this upcoming event will be born of an approaching cold front from the west and a disturbance to the south and will come together rather quickly late tonight, or really during the early hours of Wednesday, and will be about a 12 to 16 hour event. It will be followed by high pressure bringing fair and chilly weather for Thursday and Friday and then a milder Saturday.
TODAY: Partly sunny morning. Mostly cloudy afternoon. A few snow showers possible South Shore of MA. Highs 28-35. Wind light NE to SE.
TONIGHT: Cloudy. Snow developing after midnight except mix/rain Cape Cod. Lows 25-34, mildest Cape Cod. Wind light S.
WEDNESDAY: Overcast with snow except mix/rain Cape Cod. Snow accumulation coating to 1 inch parts of Cape Cod, 1-3 inches New Bedford MA area to Plymouth MA area including coastal RI, 3-6 inches elsewhere except pockets of 6-8 inches from northwestern RI and northeastern CT through central and northeastern MA and southern NH. Highs 27-38, mildest Cape Cod. Wind light variable.
WEDNESDAY NIGHT: Mostly cloudy with a chance of light snow showers evening. Clearing overnight. Lows 17-25. Wind NW 5-15 MPH.
THURSDAY: Mostly sunny. Highs 28-35. Wind NW 5-15 MPH.
FRIDAY: Partly cloudy. Lows in the 10s. Highs in the 30s.
SATURDAY: Mostly sunny. Lows in the 20s. Highs in the 40s.

DAYS 6-10 (JANUARY 21-25)
Milder January 21-22 with fair weather January 21 then low pressure passing north of the region January 22 with an early-day light mix/rain threat and a late day rain shower threat. Fair and a little colder January 23-24 then a risk of more unsettled weather to end the period.

DAYS 11-15 (JANUARY 26-30)
Overall pattern on the quieter, milder side.

137 thoughts on “Tuesday Forecast”

  2. Thanks TK
    Very light snow falling where I am which to me is the appetizer before the main course comes overnight tonight into tomorrow.

  3. Thank you, TK.

    Is Sutton in the possible higher amount area? I’m selfishly hoping tomorrow night’s meeting is postponed. I don’t want to go and share my virus so it would give me time to get better.

  4. As to when the snow ends, some mets have it ending by 3-4 pm and others not until just after dinner time.

  5. Wonder how they will handle schools around here. Not a lot of snow but timing isn’t good. My oldest is hoping to reschedule a midterm tomorrow ha.

    1. 2 things:

      1. It wants to keep heaviest precip more to the N&W
      2. It wants to keep it mostly Rain Boston S & E. Not due to warming aloft, but
      rather boundary layer issues. #1 relates to this.

      Of course this is 1 model.

      This on again off again, yes, no, maybe crap is driving me nuts. The NAM did this just prior to the 1/4 storm as well and we know what happened then.

  7. Thanks TK.

    9z SREF foreshadowed the warmer trend in the 12z NAM. Still not totally on board with a warm solution. Pretty much agree with TK’s numbers right now, though may have to tighten the cutoff southeast if the warmer solution does become more likely. Will wait for the rest of the 12z guidance before making any big changes. Still think many northwest of I95 end up with 3-6.

      2. See my post below, didn’t see yours before I posted. Warm nose right around 925mb could lead to sleet/fzra issues.

  8. Also noting a decent warm nose at ~925mb on the NAM. That looks to be where the warmest temperatures in the column are tomorrow morning. That would not be good for snow, as it would mean either rain, or, if surface temperatures stay at or below freezing, an area of freezing rain/sleet.

  9. For those interesting in seeing/understanding what WxWatcher meant, please
    see the 925 mb (approx 2500 feet) chart and notice where the 0c (32F) isotherm is.

    https://imgur.com/a/6wEIg

    For you convenience here is an approximate Millibar to Altitude conversion:

    evel
    Standard Height
    1000 MB 364 ft 111 m
    925 MB 2498 ft 762 m
    850 MB 4781 ft 1458 m
    700 MB 9882 ft 3013 m
    500 MB 18289 ft 5576 m
    400 MB 23574 ft 7187 m
    300 MB 30065 ft 9166 m
    250 MB 33999 ft 10366 m
    200 MB 38662 ft 11787 m

        1. Yes, that line. That represents the freeing level
          at 2,500 feet or so. If there is melting at that level,
          then not much chance for snow at the ground, UNLESS
          that layer is thin and/or the Precipitation is HEAVY enough to overcome that layer. Either is case is NOT
          likely IF this verifies. Does not mean it will.

    2. I think that shows both where the cold air will be and where the heaviest precip will be. (I say that by seeing slightly darker shades in se mass vs CT. for heavier precip amts)

  13. Nws tweet

    [Tech] 12z NAM trending warmer Wed w/low track over Cape Cod Canal. This means milder air into I-95 w/psbl change to rain by 10 am. Need to assess more but may lower snow totals PVD-BOS w/PM forecast. Highest totals N CT into W MA. Main impact to AM commute, PM commute less so.

      1. Then I guess those “plowable” amounts will end up down the drain, if that much snow even falls tomorrow. 🙁

    1. This has been a tough winter for forecasting imho.

      I say again, this on again/off again, Yes/No, Maybe crap is driving me
      nuts!!

      I sure would NOT want to be responsible for putting our a public forecast.

  18. Don’t be fooled . Plowable event still on 3-5 Boston looks like the range , way less south of Boston . Mild air cones in after for 50s this weekend

    1. RGEM 10:1 snow totals:

      https://www.tropicaltidbits.com/analysis/models/rgem/2018011612/rgem_asnow_neus_34.png

      RGEM brings RAIN into the Boston Area as well and then some!!

      https://www.tropicaltidbits.com/analysis/models/rgem/2018011612/rgem_mslp_pcpn_frzn_neus_30.png

      Ok, another model to support the NAM.

      It is looking more and more that there will be considerable rain with this event. Most snow up front, then rain and perhaps a touch on back end.
      Net snow on the ground likely to be minimal.

      At this point, I think this is a more likely scenario than not.

      Now we see what the Euro says. My guess, on board with the snow
      to rain scenario. We shall see.

      1. Looks like your area gets gipped with this one. Waiting to see what the EURO shows for my area. Its been showing around 5 6 inches of snow for my area for a few runs now.

  20. Some of these models are showing to much warm air aloft but I also think models are being a bit to robust, sure some areas are likely to see more but I still like the general 2 to 5 inches of snow leaning towards the lower end, with those that find themselves in the heavier bands, seeing a bit more.

    1. In fact the HRDPS is a RAIN storm for boston with just a touch of front end
      snow.

      If the Euro comes in the same, KISS IT GOOD-BYE

      1. It’s too late, the public already has planned for a winter storm. Was just driving on Rt. 1 from Foxboro to Dedham and electronic signs saying Winer Storm Warning, prepare.

  22. The noon tv mets now have rain for Boston and out to 128 as well. Totals falling off for the entire coastline and mostly rain for SE MA. Nothing but SLOP for Boston tomorrow.

  23. Here is the 12Z Euro data. Surface temperatures for 1PM tomorrow, 925 MB temps (2,500 feet) and total snow amounts:

    https://imgur.com/a/tRZ0m

    It’s official, BACK OFF the snow totals.

    More wasted cold and another disappointing storm system, however typical it
    may be. 😀 😀 😀

    You’d think this system had GULF origins,.

    1. It calls for 1.7 inches for Boston.
      Woburn; 3.2
      Billerica: 3.7
      Sutton: 4.5
      Holden: 5.1
      Princeton: 5.7
      FitsBurg: 5.8
      Manchester, NH 5.4
      Machester, ct: 4.5
      Waterbury, ct: 5.1
      Pittsfield, MA: 7.7
      Albany, NY: 5.2

      There ya go. A MONSTER STORM. Get the bread and milk. head for the storm shelter!!!!

  26. So how long does the NWS wait to take down the Winter Storm Warnings?

    In my humble opinion this event was never more than a Winter Weather Adivsory
    event. Now it may be even less for some locations.

    I wonder IF there is room for an Eastward change? Probably not as we are very close.
    We shall see. If anything, it moves even more West.

    1. Nothing would surprise me. From straight up rain to a foot of snow. I think our problem is too much info, too sensitive models, and too much reliance on model output.

      1. I think we are pretty much assured it starts as snow, so it’s just a question of soon the changeover is, IF there is a changeover.

        Watching the HRRR. 925 MB temps are solidly good through 6AM, but it is the 10AM to 2PM time frame we are looking at.

        Wish it went out 24 hours.

        1. Man you act like we aren’t getting anything . Could possibly be a good few inches before the morning . The key I suspect is what time it starts in the city . The word around here is 1am .

                1. Love the exchange.

                  As it stands right now, Boston will be LUCKY
                  to see 2 inches.

                  As always, time will tell.
                  Perhaps we’ll have a shift with the 0Z runs tonight.

                  FWIW, the HRRR has it starting in BOSTON in the 3AM to 4AM timeframe.

    2. Don’t worry, the WSW will be taken down for the late afternoon updates. They have to evaluate how far west needs chopping off. I suspect that Worcester is still ok for snow certainly.

      Boston to 128 is most certainly done for sure. 🙁

  27. I was a bit surprised waking up this morning Boston was put under a winter storm warning. I think Worcester county west in MA will have a winter storm warning when this gets updated and in CT the warnings will stay for Hartford and Litchfield counties and the winter weather advisory will be taken down for immediate shoreline.

    1. I would be curious as to how much snow a Winter Storm Warning warrants these days. I “think” back in the day it had to be at least 6 inches and a Winter Weather Advisory (formerly Travelers Advisory) at least 4 inches.

      1. I think the criteria is 6 or more inches in a 12 hour period or 8 or more inches in a 24 hour period

        2. That is what it used to be anyway.

          I love them using Winter Storm Warning with
          accumulations 4-7 inches. GIVE ME A BREAK.

          Accumulations should be 6 inches or MORE
          to use Winter Storm Warning. IF there is a low end
          amount less than 6 then it should be WINTER WEATHER ADVISORY. But then I am a pain in the ass prick and a stickler for proper details. It seems like we
          live in DC now.

  29. If the storm develops further offshore a westward track probably wouldn’t matter. I believe the problem is that it is going to develop a bit too close to the coastline along with a sharp trough.

    Does that make sense JPD?

    1. If it developed more off shore, by definition the track would not be farther
      West. However, as it stands now it does look like it will develop too close to the coast.

      Watching the HRRR. I see a slight hint that it wants to take it a tad farther
      East than the other models. Not far enough out yet.

      I have seen tracks this close as all snow.

      Just wondering what is driving the warmer air.

  31. I have seen in past events Taunton in their discussion state that they put a WSW out, even though they thought the totals were less than 6″, due to the expected impact/timing of an event, i.e. morning/evening rush hour. Didn’t sound like an official criteria, but a judgement call.

    1. Then they should use other wording.
      Hey no one is going to listen to this grumpy old man, but to me
      this is NOT a Winter Storm Warning event.

  33. I’d throw out there one thing arguing for more snow …

    The low’s pressure at 12z tomorrow is 1,020 mb.

    Shouldn’t be a strong sfc wind.

    At 7am tomorrow, looks like 850mb temp at Boston is btwn-2 and -5C

    Put all this together and if there’s mod to heavy precip ahead of the low, I think it would fall as snow in Boston, maybe even marshfield. A couple hrs of mod or heavy snow can dump 3 to 4 inches of wet snow easily.

    1. If the 18Z NAM is correct, then you are most likely correct.
      This back and forth is killing me.

      At least the QPF is so low, it doesn’t make a whole lot of difference one way
      or the other. 😀

  39. Snow amounts, in my opinion, on the NWS are now somewhat low. Not underdone by a ton.

    Again, this is not a rapidly intensifying low or a low with a pressure near 1000 mb.

    It’s almost tough to call it a low with its projected pressure.

    It feels much more like a wave with a blob of precipitation.

    I like 4″ for Boston, 5 for Jamaica Plain and 2-3 for marshfield.

    Yes, all 3 locations will end as rain and temps may get to 34F or 35F tomorrow. But, assuming there’s a shot of mod to heavy precip from 6 to 10 am, I think that’s mostly going to fall as snow. Again, 1,020 ish mb lows aren’t scary for flooding the column with mild air too quickly.

  40. For now, no changes to snow amounts in my forecast. May very slightly trim southeastern areas, but not by much.

    The 12z suite was a bit too warm.

    Just to clarify, by definition, if there is a forecast that includes anything in excess of 6 inches in the range, the NWS must issue a Winter Storm Warning for that zone. I think we worry a little too much about that line between advisory and warning. There is not a great deal of different in impact between 5.8 inches of snow and 6.2 inches of snow.

    That brings up another issue I mention but is often un-grasped by the general public. It is not always about the total snowfall, but the conditions at certain times. We have had 15 inch snowfalls over 2 day’s time cause less disruption than a 3 inch snowfall in 2 hours coinciding with a commute.

    1. Thank you for your clarification. I guess I have a problem with
      their definition and as I said previously, no one is gong to change that just
      for me. 😀 😀 😀

  42. My number for Boston Logan tomorrow is 3.5″. I think the new NWS “most likely” range map looks pretty good now, although they may have cut back too much right along I95. I also continue to wonder if areas northwest of Worcester are able to get the QPF to generate widespread 6″+ totals. I like the 18z NAM.

      1. I think you jumped ship to early on this old salty . This will be a few solid inches in Boston’s & plowable.

    1. Thanks Senior.

      Well, I think they are all around the correct numbers.

      Now let’s see if there are additional surprises with the 0Z runs. 😀

      I think my hair would turn gray if I had to make public forecasts. Oh wait
      my hair is gray. Well then it would fall out. Wait a fair amount already has.
      Oh well, you get the idea. 😀

      2. How about daily forecasts to 250,000 people, many of which are making investment decisions on your information that has to be clearly written enough to be translated into a bunch of languages? 😉

        1. That’s a tall order. Yet you still make the time to keep us informed here on the blog. It’s very much appreciated!

    2. Thank you, sir!!! Being able to the maps from all of the media outlets is huge. And I know it is no small effort on your part.

      Much appreciated!!!

      1. Yes. Rate of deepening is enough to drop the pressure in the Boston area for about 12 hours as it is moving away.

    1. Pembroke sent email saying decision will be made in the morning . I think here they may have it .

  50. Looking at latest hi-res trends and regional observations… I definitely think more snow than rain even for Boston and much of the 95 corridor tomorrow. I don’t think the 925mb level is much of an issue in terms of warm air aloft. Looks close to isothermal to me up to that level and plenty cold at 850. The HRRR is showing snow even for areas at 33-34 degrees at the surface. I think that’s reasonable as long as the precip intensity is decent. However, given those marginal temperatures from 925mb downward, it should be a very wet, pasty snow for the 95 corridor. Ultimately, as it has looked for awhile now, I think many places see 3-6″, with more in the way of 5-8″ numbers farther west due to a little more QPF and better ratios. Could see a nasty freeze-up tomorrow night as well after we get into the mid 30s for the afternoon.

    As usual, watch HRRR trends, and watch surface temperature observations as well as the radar.

    1. By mid morning though say 10 I think it’s a lot wetter type snow maybe . I think it’s done by noon time in my opinion.

      1. It’ll be wet snow pretty much the whole way. Temperatures are already around 30 and won’t go down much tonight. But yes, the further through the day we go, the wetter the snow will be especially as the air aloft warms as well.

        As for end time, expect at least light precip to continue well into the afternoon and possibly early evening, though accumulating snow in the Boston area should wrap up between noon and 2PM.

    1. NWS in an earlier discussion awhile back did mention a possible coastal for Thursday but soon blew it off and never mentioned it again. Could that be it?

  54. Some schools in northern MA closing. Makes sense to me. I like that they let parents know as soon as possible. It is far different than it was back in the day. Others …in the areas expected to receive less snow…are waiting which also seems wise.

  55. Just drove almost 6 hours to the Poconos… hit the snow in NY, pretty hairy in PA… 25 mph for last hour. Looks like it’s going to jump out to the redeveloping coastal though… left the wife and kids home to shovel, not good!

  56. 0z NAM Snow:
    https://www.tropicaltidbits.com/analysis/models/?model=namconus&region=neus&pkg=asnow&runtime=2018011700&fh=36

    0Z GFS Snow:
    https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=neus&pkg=asnow&runtime=2018011700&fh=36

    3z HRRR Snow:
    https://www.tropicaltidbits.com/analysis/models/?model=hrrr&region=neus&pkg=asnow&runtime=2018011703&fh=18

    They look a little colder than earlier runs today. Looks like most places are going to end up in the 3-5″ range based on this guidance with spot 6″ amounts NW areas.

    Second storm that tries to develop south of us shoots straight east and out to sea on the GFS and CMC with no threat to SNE.

    1. Progressive, positive tilt trough not connected to the one preceding it. The wave never gets close.

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