The Week Ahead

287 Comments

10:18PM

And now the slow wind-down of a long, drawn-out, complex weekend storm system comes as snow gradually tapers off from northwest to southeast as of the writing of this blog late Sunday evening. After all of it, not a whole lot of snow fell in much of the forecast area, but amounts did build up to greater than 6 inches in parts of north central MA into southern NH, with some double-digit snowfall amounts further north in east central NH into Maine.

During the overnight hours as the final flakes end and the clouds break, watch for some freezing of newly fallen wet snow and slush. Icy spots on untreated surfaces will develop overnight and last through much of Monday morning. Monday itself will be a nice day with sun & some clouds as low pressure moves away and high pressure builds in. This high will hold on into Tuesday before giving way to approaching low pressure late  Tuesday into Wednesday. Enough cold air will be in place so that some snow falls in north central MA, interior northeastern MA, and southern NH  Tuesday night into Wednesday. But eventually milder air will take over so that rain falling elsewhere will overtake the snow areas as well. The problem is that cold enough air may be trapped at the surface over inland areas, resulting in a set up for icing. This storm system will lead into a long period of unsettled weather as February ends and March begins. It’s hard to time precipitation and specifics on movement and strength of disturbances this far away. That will be fine tuned as the week goes on.

Forecast for southeastern New England…

OVERNIGHT: Snow ends, clouds break, icy areas develop. Lows upper 20s to lower 30s. Wind light N to NW.

MONDAY: Mostly sunny to partly cloudy. Highs around 40. Wind NW 10-20 MPH.

MONDAY NIGHT: Mostly clear. Lows 20-25. Wind light variable.

TUESDAY: Sunshine followed by increasing clouds. Highs around 40. Wind light variable to E.

WEDNESDAY: Cloudy. Mix/snow interior northeastern MA into southern NH away from coast eventually changing to rain but possibly freezing rain if cold air remains trapped, with rain elsewhere. Low 28. High 42.

THURSDAY: Mostly cloudy. Chance of rain and snow showers. Low 33. High 38.

FRIDAY: Mostly cloudy. Chance of snow showers. Low 29. High 37.

SATURDAY: Mostly cloudy. Chance of rain and snow showers. Low 31. High 38.

SUNDAY: Cloudy. Chance of rain and snow. Low 30. High 37.

287 thoughts on “The Week Ahead”

    1. You’re welcome. What a long weekend in regards to forecasting and watching this all play out. In some ways it was far more stressful than the blizzard, and even last weekend’s storm.

        1. Thanks! Can’t say I was completely satisfied with my own forecast but in general I think it worked out.

          Noticed an issue again with people (not here on the blog, just comments I read elsewhere) not fully understanding how this particular event was a maze of a forecast even during its occurrence (nowcast) and not really understanding the information. But I already editorialized about this so I won’t get into it again. Hopefully the next event will run more smoothly all around. 🙂

      2. It was certainly stessful for the TV mets due to their bosses putting even more pressure on them to put up snowfall maps so many days in advance.

        2. So right and the problem with doing that REALLY showed on this one. Unlike the blizzard where it was pretty much a lock a few days away.

  5. Regarding the unsettled weather for the Wednesday-next Sunday timeframe, since there will likely not be a cold high to our north, I suspect much more wet than white.

    Would you agree at this early stage TK?

    1. The CPC supports the lack of a high to our north with above normal temps for ME and parts of NNE this week while SNE normal to slightly below.

    2. We’re getting into the time of year where you don’t need the cold high so much, but you get cold air aloft that can help to make snow, but even so you still need it to set up just right. I think the midweek system brings the heaviest QP and snow happens inland for a while due to lingering cold air aloft that will be dragged down, then warm air takes over. I flip flopped it later in the week basically with an educated guess that we’d have the coldest air over us about Friday.

      It’s WAY out and I don’t want to plant any seeds yet but I could see Sunday ending up as mostly snow for parts of the region, IF it were to play out similar to what is shown on the Euro.

      1. Thank you Charlie. As always I enjoy your contribution here. We poke fun at each other but it’s all in good taste.

  7. snowed on and off last night, snowed all day today up in stratton. Fresh powder. up to my knees in some of the glades.

    Roads west of fitchburgh are bad. rt 2,i91 are snow covered and visabilities must of been less than a quarter mile.

    when i got home i was met with a heavy wet snow to shovel out of the driveway. of 4 inches.
    tuesday through thursday looks unsettled with it mainly being rain for the coastal plain. icy mix through the rest of mass. snows up north.

    1. We have about 4 inches or so from the entire weekend here but never that much at once since the Saturday night snow melted in the overnight and morning rain, and I shoveled another inch layer off late this afternoon before the final layer was put down…

  11. Over the weekend.

    Logan=1.8″
    Boylston, MA=10.1″

    Official forecast from NWS for Weds/Thurs this week=yucky!

  12. Thanks TK !

    Looking into early March, I’m thinking last March’s +8.4F temp anomaly is safe. 🙂 I just hope its not going to reverse itself this year. 🙁

    Got about 1 inch of snow last night.

  14. TK you worried about icing because looking at euro thermal profile I could see some potential icing if we don’t warm up fast enough in the interior.

  15. Got that 8″ Hadi.

    Not surprised at that Boylston number which is only two towns east of me. There was a good echo that sat just east of Holden a little longer.

    Have to dig deeper into the Euro still but it looks like we have a shot at adding to the snowcover out here this week along with some rain and other junk.

  17. I think, as we get closer, day be day the EURO will incrementally trend a bit colder with the mid week event as the block becomes even stronger.

    1. The drive in was spectacular this morning Hadi. There’s a section of road where I have a clear panoramic view of Wachusett Mountain to the north. Today’s view was especially brilliant because the east face was lit up from the sun hitting the snow that was stuck to everything. I wish I had a zoom camera with me – it would have been worthy of a frame.

  19. Thanks TK! As much of a bust this storm was, you did a great job keeping us informed. It was a very tricky forecast to say the least. I can’t believe I’m saying this but that GFS had the right idea all along! Go figure 😀

  20. Just dug a little deeper into the Euro. Generally pretty cold though the period. To Hadi’s point, concerned about icing this week as with some cold air at the surface.

    Looking forward to seeing how the King and GFS resolve a potential storm late week. NWS points to favoring Euro and more progressive. We’ll see.

  21. Good morning.

    I was awol all day yesterday due to a power outage that lasted from 6AM
    to 10:30PM. It sucked. Even made the channel 5 11PM news. The whole neighborhood is up and running now on a generator. I was going nuts without
    access to my “stuff”! 😀

    NSTAR sucks! They only care about the bottom line and absolutely REFUSE to
    allocate funds for dearly needed system-wide maintenance and improvements.

    Sorry about that, but that is how I feel.

    Re: Weather Related issues
    JP picked a solid 3 inches.
    Rained from about 10PMish or so Saturday night until around Noonish Yesterday, then it snowed with varying intensity until about Midnight.

    Regarding the rest of the week, have only a brief look at a couple of models.
    I really don’t have a take on it, except to comment briefly on the 0Z Euro.

    850mb temps look interesting on that run. I want to take a look at the Wundermap
    for closer time increments.

    Have a great day all.

    1. Awwww OS – I wish you’d called. I would have gone in and we could have had a party. Seriously, though, sorry you lost power. It isn’t the equipment that needs upgrading as much as the testing cut back. From a maintenance standpoint, all of the utilities have cut back on routine testing which is key to keeping the equipment running. It’s all part of the game big companies are playing. Money filters to the top (trickle up) and workforce is cut and tests are stretched to longer cycles

      1. I re-read and wish we had the ability to edit these. I should have added that you are absolutely 110% correct OS. I did check to see if any samples from your area are being tested but it’s too early to know.

        1. Vicki,

          The problem still isn’t fixed. AS I stated, we are running
          on a generator. The generator is about 300 feet from my house. As I drove by this morning, there was the generator purring like a cat, with several NSTAR trucks and an open man hole. They are still working to repair this problem, which means at some point they will have to kill the power to reconnect us.

          2. My guess is, in addition to fixing the problem, they have to either replace what was damaged and that would be a thorough test on it and any of its fluids or they have to test what was damaged. That takes a bit of time and it would make sense that there will be a disconnect and reconnect. Good luck. Are power outages common in your area? It seems to me Boston in general rarely has a problem considering the number of people.

            1. Vicki,

              From time to time there are a rash of outages. When we get them, they are extensive.

              The DPW crews have dumped SO MUCH SALT on the roads recently, Including Saturday night, that when it rained Saturday night, the SALT water
              seeped into the manholes and somehow
              caused damage. (this is what one NSTAR
              employee told my Son anway)

              Funny, we never lost power during
              blizzard of 78, Hurricane Irene, Sandy or the blizzard of 2013. Routine nothing event and power goes out. Life in the City. 😀

  22. Morning All-

    Did a final forecast for the Friday afternoon and then took the entire weekend off. I Certainly had significant concerns about how it would verify, as I only made slight tweaks down, but it worked out fine.

    I had originally a little to no accumulation to 1-3, 3-5, 5-8, 7-10, for the storm from southeast MA to the northwest into Worcester County and New Hampshire. I toned those down to 1-3 Boston, South West to 495/95 then 3-5 Northwest Boston suburbs, and 6-9 Worcester area into New Hampshire which was identified as the “jackpot” area. I extended the duration of the event from ending Sunday afternoon in the east to Sunday evening and for the most part it worked out well. I think from the beginning I called this a light to moderate winter weather event and snowfall rates would not exceed moderate intensity for much of the region and snowfall rates would be often light, so its impact would be negligible in most urban and suburban areas where most people live. I did blow the snowfall amounts west of Worcester, where I was 1-2 in valley locations and 4-8 in favored elevated areas. I had real concerns about the western extent of accumulating snow and that concern did come true, creating a significant forecast error.

    Why did I go into such detail of what had been forecast 60-72 hours ago? There were good forecasts out there and there was enough data out there for forecasters to create good forecasts and enough conflicting data that there should have been caution on going in too big, too early in the forecast cycle. Remember those 10-14″ + forecasts? However, the public hears what they want to hear, but don’t listen. There are forecast ranges and then there are ranges within small geographic regions, but people don’t pay attention to the detail and hear 12″ and that was not even for their area, but they say “I hear we are getting a foot of snow” and from there these things take on a life of their own.

    Now with the internet providing so much detailed weather content, you have all sorts of folks who can read model data, but really have little understanding of the physics, chemistry, climatology, and the associated algorithms and equations that go into that data product, but are convinced they know what is going to happen. Based on this and the anonymity of internet, they use their knew found knowledge to take pot-shots at meteorologists and forecasters when things don’t come together perfectly. Combine that with meteorologists’ now blind faith in the ECMWF and seeming paralyzation that ensues when it produces inconsistent data, you end up with a vicious cycle of bad forecasts, pressure to justify the forecast, pressure to respond to the ignorance and arrogance of the masses, constant forecast adjustments, and then finally disillusionment for both the public and professional forecasters alike, but for very different reasons.

    It is a science and most science involves a hypothesis, which is really what a forecast is. No one is infallible and no scientific tool, such as a model, is infallible. Take in all the information, and I say often there is almost too much information out there now, but also allow for the fact that caution is often better than recklessness, both in proactive forecasting and the reactions those forecasts generate in us towards forecasters.

    2. JMA,

      Outstanding. Very well stated.

      Tk and yourself should stand as examples of HOW it should be done!!

      Thank you both for being here. This small group is probably the most well
      informed weather-wise out there.

      I really don’t need the TV mets. I have all I need right here. Not that I don’t watch, as I certainly do. 😀

      We are all very fortunate to be part of this forum. Thank you again TK!

      1. JMA. Excellent write up. I’m one of those people with little knowledge in comparison to you and TK in terms of meteorology. Afterall, I’m a medical person and fix people, not predict forecasts, lol. However, I have always had a special place in my heart for meteorology and have learned a lot from people like you over the years. I hope to continue to use this forum in an attempt to mingle with other meteorology goo-roos as well as broaden my ability to accurately predict forecasts through science. Thank you for everything you bring to this great forum.

        1. You are an excellent forecaster Arod. Your very educated when it comes to the weather, you understand it completely and I always learn something from your posts.

  23. Thanks JMA, good stuff as always!!

    Watching the comedy on twitter with the local mets cracks me up, they change the forecast based on each model run which I just don’t get. They should know better IMHO.

      1. I am for sure, although I am trying to learn from TK and JMA to blend Meteorology and common sense into each run. It takes time, but we are all learning so much.

        We are certainly better informed than the average public, no?
        😀

  25. I can’t tell you how much I have learned over the last two years from the Blog and JMA and TK you are invaluable resource.

  26. Good morning everyone, got a little under an inch partly cloudy, nice to see the sun out temps is up to 34.6 degrees already so that’s a sign of spring, it appears we’ve got a good dose of rain coming for the Foxboro Wrentham North Attleboro areas Tue night Wed, with the precip deficit keep it coming, enjoy the day 🙂

  27. It has been a spectacularly beautiful winter morning in New England. The trees and bushes are covered with snow. The sky has gone from a few spots of very light blue to icy grey clouds with the sun behind. New England at its finest!

    1. I agree. I love the look of fresh snow covered trees. After a good snow, I like to take my children out in the woods, build forts and experience the winter wonderland.

  28. That stinks O.S.

    We stood guard in your absence.

    I rarely watch TV weather. The resources here are all the inside information you need.

    1. Same here retrac I probably watch 1 maybe 2 times the local mets through the week, not a big local news person, I watch more national news, blog is great 🙂

    2. I usually ONLY see the weather broadcast as part of the 11PM news as
      I am watching with my wife. We watch channel 4, so in general I see Todd.
      However, when there is an “event”, we watch the news broadcast on channel
      5 so I can see Harvey. 😀

      2. Harvey is the best met on tv in my view of thing’s. His entire team is top notch. I could go on an on about jc as well, she is hot.

  29. Do my eyes deceive me or does it look like a storm-free weekend for a change? Yeah, I know it could change, but hope.

      1. Got to admit though, you can tell beyond doubt winter is on its last leg. With the sun and the birds out, you can tell change is a ‘comin. 🙂

  30. I agree Arod to an extent in regards to model watching. I think we are all becoming much better at taking them as a guidance vs. a forecast. And then using our knowledge to issue our opinion.

    90% of my weather comes from here vs. anywhere else.

    1. Remember watching the weather channel and relying on that as a good source of weather information? And how about accuweather and dialing 1-617-936-1234? Remember that? Then it was off to watch the local news and switch stations between 4, 5, 7 and try to catch all the forecasts. Watching the local news weather forecasts now has become equivalent to relying on TWC and accuweather for reliable weather forecasting. I, too, come here almost solely for up to date weather information.

      3. I remember calling the number too and had forgotten all about it. I will disagree that our local mets are like TWC but would agree that station management is trying their hardest to make they seem as if they are. Once they were allowed to actually do their thing rather than push out numbers far too early they did a good job.

        1. how about 617 787-7372. That’s the WBZ4 weather phone. Typically when Barry is on, it’s updated each day early in the morning. No other MET updates the weather forecast on the phone daily. Todd tries to in the evening but sometimes when you call, a weather forecast can be two days old. They should just stop doing it all together if they cannot get it done in a timely manner.

          1. Oh, didn’t know it was still in operation.
            I stopped calling that LONG ago after the first time I listened to an OLD forecast. 😀

    1. What concerns me is the 0Z Euro pretty much keeps the 850mb 0C line
      at or South of the immediate Boston area. If any runs trend colder, we
      could be in for more Wintry weather. (Snow/Mix/Sleet etc.)

      IF not, then the distinct possibility exists for a whole bunch of Warmth.

      12Z Euro will be telling. 😀

      1. 850 temps are all below zero in Boston throughout the storm, but 2 M temps are all above zero by 2 degrees through most of the QPF part of the storm. OS you would love accu pro!! So much info.

        1. I’m sure, but even at that nice price, not in the budget right now. Thanks

          Too many other places to allocate those funds. 😀

    2. Let’s see what the 12Z Euro says.

      Even the GFS looks interesting for 2/28,3/1. 850mb temps are AOK,
      but coastal boundary layer issues. Like last event, GFS is confining any snow
      to the interior. 😀

  39. Worcester starts to get much colder at 2 M temps and 850 temps as we get into Friday on the GFS. GFS also has tons of precip from Wed on….

  42. Look at this 0Z Canadian:

    http://raleighwx.americanwx.com/models/ggem/00zggem850mbTSLPp06066.gif

    Look at total qpf:

    http://raleighwx.americanwx.com/models/ggem/00zggemp72072.gif
    (some of this would include what fell last night from 7PM onward)

    And, 850mb temps are Below freezing the entire time, however, it
    does depict RAIN in the Boston area and snow far N&W.

    So there is some conflicting data on this event.

    Common wisdom would dictate a mostly rain event coming up.

    BUT, we do need to watch this.

  44. For the foreseeable future (at least the short term) there will not be an arctic high to our north which will make snow difficult to dominate the coastal plain. Yes this time of year a high to the north isn’t necessary but a gazillion things need to come together for a mostly snow situation for a widespread area.

    1. 850mb temperatures cold enough, precipitation intense enough, surface wind
      NE to N and finally, surface temperatures cannot be too mild. Need an airmass with surface temps no higher than 40s and preferrably 30s.

      Although, I have to share this.

      One time long ago, I believe it was in April (could have been late March), afternoon temperatures reached 64F. Precipitation started early in the evening and by 9 or 10 PM it was snowing. Ended up snowing 4 or 5 inches.

      It is getting into a very tricky time of year for forecasting snow or a rain/snow line. 😀

        1. No. That one delivered something like 13 inches to Boston and was a snow event from the start. Temps were
          in the upper 20s throughout.

      2. There were a couple of March storms in 1984 – one March 13 and the other maybe the 28th or 29th. The later caused significant damage as it was very wet, heavy snow and the trees couldn’t handle the weight. We were out of power for 4-5 days.

  45. GFS shows 1.75 QPF through Sat for Boston, again most of it as rain except as you get into Friday.

    Worcester is a different story as it gets much colder sooner.

  46. Models tend to have a real difficult times during these transitional times as we approach the change of seasons. ECMWF certainly has its trouble here, the GFS/NAM has well documented significant issues each for different reasons during this time. Don’t obsess over 850 lines and 2m temps. Look for general trends with the models in regards to position, duration, etc. and the climatic set up at the time of the event. Then apply knowledge you already know and have learned from past events. Elevation, urban vs rural areas, sun-angle, daylight precip vs nighttime precip, intensity of the precip, surface temps, daytime / nighttime temps in the days leading up to the event, accumulation on paved vs non-paved surfaces and how that relates to potential lower or higher impact.

    1. And isn’t it reasonable to at least look at 850mb temps to see model
      trends towards a colder/warmer solution. Of course don’t obsess over it.
      And it is only guidance, it rarely ever pans out exactly as depicted on a model.

      We’re slowly getting it.

      Many thanks for your patience. 😀

      1. I didn’t say not to look at the data, just don’t obsess on it 48-96 hours out and try to pinpoint rain snow lines and such. Of course watching what the modeled 850 lines and tracking where the model is placing it and what direction it is moving are important. But does the line make sense with where the low placement is, where a high is positioned? 2m temps are a little different. Look at things like wind direction and wind speed. 2m temps can be critical with these types events, but again trying to nail down what they are going to be for a 3 hour period on a Thursday morning, when it is Monday, is real tough. What you can determine is they are going to be marginal and then try to use the other factors we discussed to trend a forecast to what happens with marginal 2m temps, as opposed to hard and fast rule of 2m temp 31.8 snow, 2m temp 34.1 rain.

        2. Thanks JMA. Of course pinning down temps 3 days before is nearly impossible, but temps sure will help with figuring out how real the potential is.

          1. So is having experience with similar situations in the past. 😀

            In the past, some mets and the NWS have had
            their fair share of problems with Precipitation types when we get into these situations, especially from this time of year on. Honestly, in the past anyway, they have underestimated the potential of dynamic cooling.

            With today’s write up, they ARE factoring
            that in. 😀

            We shall see.

  49. From the NWS this morning:

    IT APPEARS THIS FRONT WILL STALL AS IT MEETS COOLER
    BLOCKING HIGH PRES IN THE CANADIAN MARITIMES. THEREFORE…IT
    LOOKS AS THOUGH SRN NEW ENGLAND MAY STAY ON THE COOL SIDE OF THIS WARM FRONT FROM TUE NIGHT WELL INTO WED MORNING. THERE IS DECENT ISENTROPIC LIFT IN THE FAVORABLE SNOW GROWTH REGION APPARENT ON SOUNDINGS…WHICH SUGGESTS SOME DYNAMIC COOLING AT PRECIP ONSET…PARTICULARLY INLAND OF THE S COAST. COMBINE THIS
    SUPPORTIVE PWAT VALUES IN THE 0.75-1.0 INCH RANGE…AND A PERIOD
    OF HEAVY SNOW…PARTICULARLY N OF THE MASS PIKE

  50. First snowfall map for Wednesday by JR…C-2″ Boston, 2-4″ just NW. It could be a few hours of snow for Boston before change to rain. Merrimack Valley may never see a change.

  51. Terry from channel 4 posted a map already. It said 0-1 in Boston south, 1-3 just north of the city and 3-6 Southern NH Maine.

  52. One map goes up, they all go up.

    It reminds me of the “Twelve Days of Christmas Song,” where one light goes out, they all go out!

    1. I noticed, too, that Channel 7 likes the 2-4 and Channel 4 likes the 1-3…I think JR and crew has something against prime numbers. 🙂

  53. One model on wcvb web site has lawrence at 9.3 inches by late thurs/early am Friday?
    Did I miss something? Lol

  54. Let me guess, the mets are getting pressure yet again from the TV bigwigs? LOL. 😀

    Maybe I am living in a fantasy world, but I wish the mets would stand up to their bosses if they don’t feel comfortable forecasting specifics too early.

    1. I agree but give them credit. We are 48 hours out from an event, so it’s not that inappropriate to post an early estimate. It’s better than 96 hours! 😀

      1. True alisonarod, but it was not uncommon back in the day for a Don Kent to first post a snow map 24 hours (and sometimes even less) and the general public and local officials were quite satisfied with that…of course times were much different then.

    2. I bet TK is thrilled not working in TV. He is definitely much better off here with this blog…for his sanity if nothing else. 🙂

    1. The King wasn’t so King in our last non-storm, lol. I can’t believe that the GFS was pretty spot on in terms of precip type/amounts. We all thought the GFS was out to lunch.

  56. i aint saying nothin about this next storm until tomorrow evening. right now rain/snow basically a given. 😉

  57. marshland… has 2 feet of water. + .5 to 1 inch thick of ice in areas. plust alot of water runiing into it. I hope to god we do not get 1.5 inches of rain here in billerica.

  58. If you take the 12z GFS’s snowtool verbatim it delivers 6-12″ of snow on a line from Springfield, Worcester, to Lawrence on Wednesday. NAM is generally less than a 1/3 of that.

  60. I may be totally off base, but I can’t recall a forecast of sleet/freezing rain so far this winter. It seems that it has either been rain or snow. Usually February is known for its ice storms. Of course given our power companies lately, that is not a bad thing either…keep the ice storms away.

  61. The high temperature in Boston is projected to be 40 degrees on Wednesday. It may be possible that Boston could grab a quick coating first thing Wednesday morning before the switch over to rain. We saw this weekend in boston nothing was sticking on roads until that tempature went down.

      1. I actually don’t think we see any snow, just a cold rain. Higher elevation will see snow. Just a guess. I wish for no snow.

  62. It quite possible that places in west of 495 could be in for quite an ice event, that low level cold air does not want to retreat, I think there will not be a problem removing that cold air hence why 90% rain in the Boston and Providence corridor, temp is 39.5 and it’s gotten cloudy, hadi what r the steps to getting accu pro? And if anyone has it how is it?

  63. EURO looks a little colder with upper level temps but still marginal for surface in Boston. Still not much on that run for Boston. Worcester looks better than the ooz run for temps as well. Again for this time of year this will be an interior storm and elevation storm.

    1. If upper levels are cold enough, Just because a model says rain, doesn’t
      mean it will be rain. Still “could” be snow. 😀

  65. It still looks to me that we will see some snow in Boston (more interior), then
    a change to Rain in coastal areas (Sleet perhaps some freezing rain then rain Interior).

    It is a question of HOW MUCH before any changeover.

    UKMET keeps it pretty cool. Canadian warms up as does GFS. Euro warms, but
    has a more prolonged period of cold enough for snow.

    Need more time for models to sort this one out.

    For most of this year, forecasts have not been easy or routine. Always a certain
    degree of difficulty. 😀

      1. “could” be. We do have Blocking with a strongly negative AO
        and NAO.

        2013022512z ECMWF RUN NAO Values
        NAO value for forecast hour 000: -212.120544
        NAO value for forecast hour 024: -172.285889
        NAO value for forecast hour 048: -251.666428
        NAO value for forecast hour 072: -332.275208
        NAO value for forecast hour 096: -399.70697
        NAO value for forecast hour 120: -432.26062
        NAO value for forecast hour 144: -385.533783
        NAO value for forecast hour 168: -364.38208
        NAO value for forecast hour 192: -363.733521
        NAO value for forecast hour 216: -331.935059
        NAO value for forecast hour 240: -277.478821
        NAO value for Day 1-5: -317.639038
        NAO value for Day 6-10: -344.61264

        Even if it goes “underneath” us, thermal profiles could be an
        issue in the Boston area, perhaps not so much farther North.

        “Could” be some boundary layer issues as well along the coast.

        In short, another difficult forecast. Not cut and dry at all.

  66. During this week, 2m temps, 850 temps, and the 500 mb upper level flow. To help those who do not know what we mean when we throw these terms around, here are a few definitions.

    When we speak of 2m temps, it is the temperature that we measure at 2 meters above the surface. It may be cold enough to support snow in the upper levels, however if the 2m temps are much above freezing, frozen precipitation turns to plain rain. So 2m temps often can be looked at as surface temps.

    In terms of the temperature at 850 mb. This is the determination of temperature at a height where the pressure is at 850 mb. This heigh typically is around 5,000 feet which is still considered the low levels of the atmosphere. Typically, when temps at the altitude of 850 mb are 0 degrees celcius (32 degrees F) or less, snow is what falls. When temps exceed o degrees C at 850, rain is often the result. But, remember those 2m temps (surface temps). Even if the 850 temps are below freezing, rain can still result of the 2m temps are above freezing.

    Finally, you may hear about the 500 mb chart or even the 300 mb chart. Consider this the steering currents that are occuring in the mid and upper levels of the atmosphere (18,000 ft and 30,000 ft, respectively). What occurs at 500mb (steering flow at the mid-levels) and 300 mb (the jet stream) often is what determines the all important track of storms. At 300 mb, you will find the jet stream. This is responsible for turbulence when flying (especially when flying against the jet stream) because airplanes fly at an altitude of 30,000-40,000 ft. So in essence, you’re flying in the upper levels of the atmosphere.

    850 mb line = lower levels (critical temps favoring snow/rain)
    500 mb line = mid levels (steering pattern)
    300 mb line = upper levels (jet stream)

    I hope I didn’t confuse anyone! 😀

    3. Nice job Arod. That is a very nice summary.

      You “may” want to throw in a little something about the 1000-500mb thickness as well. 😀

      1. Although that “might” be getting a bit advanced for some????

        I have a nice link somewhere on the whole thing about rain/snow.
        Let me see IF I can find it. 😀

          1. Thanks OS. I left out 1000-500mb thickness discussion due to its complexity as it pertains to the 540 line. But I will do so the best I can in its simplest terms below.

            1. Yes, I figured that. The reason why I commented: “Although that “might” be getting a bit advanced for some????”

              😀

  68. Anyone notice the storm at the end of the EURO run, that has a chance of coming up the coast. Lot’s of blocking etc… just something to keep thinking about.

      1. Originates in the Gulf as well so it will have juice to work with. I would for sure keep an eye on this one. Have a feeling it could be a big one for a lot of areas.

  70. Maybe with this storm the trend is reverse of this past weekend, calling for low totals now and increasing as we get closer 🙂

  72. In Austin, Texas for work. Very windy here (from the plains storm to the north), and very, very dry. I mean completely parched. They’re desperate for rain here and seem to be in between systems all the time.

    Still think it will snow in Boston Thursday night into Friday. Not a lot, but at least some.

    Miss Boston already.

  73. Anyone also notice how the EURO brings in some real cold to Florida. It would suck to be on vacation there over the next two weeks!!

  74. Hi, everybody, I have a simplistic question, but it has been bothering me. Many of the forecasts for this coming mid-week storminess refer to colder-type precipitation “North of the Mass Pike.” Exactly where is this? I live in Woburn, which is certainly north of Newton, but do they mean further inland? Woburn is usually more snowy than rainy in most scenarios, but when meterologists show their maps with predicted precipitation amounts, I’m usually uncertain of where “I” am. Thanks for your help!

    1. I think they tend to use landmarks, or in this case, a highway that is well known to all for possible rain/snow lines.

      It depends on the weather scenario. Sometimes, if the only thing in question for rain/snow is mild air from the ocean, then its more likely they would use inside I95 or 128.

      But in this case, since potential mild air is coming in from the south, the Mass Pike is a better landmark to use.

      TK can probably speak better to Woburn specifically, however, it is definitely far enough north of the Mass Pike to fit that criteria when describing the rain/snow line in those terms.

      1. Good explanation Tom and great question Linda. The problem is that if they say rain south of the pike and snow north and I live right on (along) the pike, it gets a bit unclear for me. I do notice this year far more than other years the pike is being used as a point of reference.

        1. I agree, Vicki. I am used to seeing “north of 128.” And I’m in the same boat that you are — Woburn is at the junction of 93 and 128. So I always take the “worst case” scenario and call myself north, which is usually what happens — more precipitation rather than less.

  75. OS has requested I discuss the critical thickness at 1000-500 mb as that term is thrown around a lot as well although its quite complex. The 1000-500 mb thickness is just one tool to help one determine rain vs. snow but should not be used as the sole determinance of precipitation type.

    At times you hear us talk about the 540 line. The 540 line happens to critical in terms of the 1000-500 mb thickness discussion and in terms of determining precipitation type.

    The ‘thickness’ is the vertical distance between pressures at 1000 mb (lower in the atmosphere) and pressures at 500 mb ( a bit higher in the atmosphere). Remember, pressures drop as we go further up into the earth’s atmosphere.

    There are two things to consider when referring to the 1000-500 mb thickness:

    1) the temperature of the air between these two pressures (between 1000 mb and 500 mb)

    2) and the moisture content in the air.

    These two properties (air temp + moisture content of the air between these two pressures) is what is computed to determine the ‘virtual temperature.’ The higher the virtual temperature, the less likely it will snow. If the air temp between 1000 mb and 500 mb rises OR if moisture is added to the air between 1000 mb and 500 mb, the thickness will rise and therefore the virtual temperature will rise.

    The greater the thickness, the higher the virtual temp, and thus the greater likelihood of rain.

    Thickness below 540 = snow
    Thickness above 540 = rain

    This is why the 540 line is also important in determining rain vs. snow along with 2m temps (surface temps) and 850 mb temps (temps at the altitude of 850 mb) alike.

      1. This was the most difficult part of meteorology for me to understand. Fortunately, it’s rarely used as the sole parameter to determine precip type but I agree it is as important as the others.

  76. Tweet from NWS

    @NWSBoston: For Tue night – Wed night, potentially heavy snow north of MA rte 2 corridor and transition zone south to MassPike. More to come soon.

  77. Very well said Arod, it took a while for me to learn this stuff so it’s good to show to people what it all really means.

    1. To be truthful, I didn’t understand it at all, until a met I knew online from
      New Jersey (on Air Radio Met in NYC Metro area) explained it to me
      beautifully. Now I’ve got it. 😀

    1. I think the combination of the strengthening negative NAO and some pretty decent dynamics with heavy precip is going to result in snow occuring further south in Southern New England than currently being modeled.

      Perhaps a couple to many inch front end dump in Boston and maybe even a thick coating to few inches all the way to the Cape Cod bridges.

      2. You “could” be correct. As Hadi said earlier, Maybe this will
        be the one where all initial amounts were NONE or LOW, only to have them be continually UPPED! 😀

  79. Here is the 18Z NAM. Looks very interesting, however, even though 850mb temps
    are OK, NAM still has rain in coastal areas with snow inland.

    http://www.instantweathermaps.com/NAM-php/showmap-conusncep.php?run=2013022518&var=PCPPRSTMP_850mb&hour=045

    Here is the 1000-500mb thickness chart for the same time:

    http://www.instantweathermaps.com/NAM-php/showmap-conusncep.php?run=2013022518&var=PCPTHKPRS_1000-500mb&hour=045

    Notice how far North that is. Even so, NAM has Snow to the South of this line.

    Here is precip type:

    http://www.instantweathermaps.com/NAM-php/showmap-conussfc.php?run=2013022518&time=INSTANT&var=PTYPE&hour=042

    Here is snowfall total at 72 hours:

    http://www.instantweathermaps.com/NAM-php/showmap-conussfc.php?run=2013022518&time=PER&var=ASNOWI&hour=072

    This is an 18Z NAM with all of its pitfalls, but couple this with a colder
    EURO, Canadian and Ukmet, inland areas just “may” be in for a surprise.

    Coastal areas, boundary layer issues abound with an East to ESE wind direction.
    Going to be CLOSE. 😀
    Could be another situation where Hadi and I pick up 4 or 5 inches (before change), while Logan gets skunked. 😀 😀 😀

    1. Agreed totally. A colder trend. How much it will end up is the question.

      This situation is getting more interesting by the second. 😀

    1. I do, mainly because this negative NAO seems to be the strongest of the winter and I’m banking on the idea that though its not at its lowest value by mid week, it is transitioning towards a deeper NAO and guessing models dont have the implication of that quite yet on a slightly further south track.

      Also, the intensity of the precip looks pretty good and banking that it might be good for cooling off the column a bit for the first 3 to 5 hrs of the event to get snow.

  82. Pete B tweet.

    @pbouchardon7: If there’s anything I’ve learned from the past storm…we’re in spring mode now. Get ready for MAINLY rain in the next storm (Wed).

    1. Huh??

      Spring Mode? To me, Spring mode means BE FOREVER on your guard
      for surprise Snow!!

      At this point, I really don’t think it was appropriate to say get ready for mainly rain (even IF that is what eventually does occur). There is enough model
      evidence to, at the very least, pause and consider the possibilities.

      Clearly models are pointing to a warm boundary layer near the coast, Likely preventing snow. But what about the 495 region? As Hadi aptly pointed out,
      residents in those areas are certainly WELL within channel 7’s broadcast area.

      Even with the Boundary layer issues, current trends are colder, so I don’t think we can rule out Snow totally on the coast, although snow is not likely at this point. We’ll see what the 0Z runs have to say.

      1. With all due respect to Pete, you don’t just flip to spring mode. There is no such thing as a sudden switch of seasons. It flickers on and off. One eventually fades and the other gradually takes over. We could get a powder blizzard in April for all we know. Not likely from a climate standpoint but.. you know, 1982. We’ve been here before. 😛

    2. While I agree with PB that Wednesday looks mostly like a rain event, I’m not sure if I’d say we’re in “spring mode.” It looks like winter is going away, and it most definitely is in retreat, but beware of winter’s formidable counter-attacks in March and early April. It’s when we allow ourselves to think we’re in spring mode that we often get surprised. Hasn’t happened in recent years, but that doesn’t mean it won’t this year. The winters of 56, 69, 82, 96, 97 come to mind.

      1. Mainly rain for Worcester? I’m not so sure of that; hence, his tweet should have been more specific to Boston and coastal areas–not to include inland areas.

        1. Agree, Alisonrod. I meant rain at the coast (likely). I did not mean rain in the interior. I was also referring to the numerous possibilities that still exist in March and early April for snow and even cold outbreaks.

  83. 850mb 0 line good for snow making but critical thickness much too high. Trending colder which could be an important trend. Still looking like mostly liquid precipitation east of 495.

    1. According to the runs, absolutely. BIG spread between the 850mb 0C line
      and the 1000-500mb thickness 540 line. Usually they are not too far apart, certainly not this far apart. This is cause for concern if you like snow.

      However, this is New England and it is essentially Spring, so I wouldn’t rule out
      anything at this point. It bears watching for sure.

      Even the GFS has snow for inland areas. That 540 line runs more or less
      West to East and not SW to NE far to the North, yet both the GFS and NAM have snow Far to the South of that 540 Line, but West of Boston.

      Therefore, on these 2 models anyway, the issue for Snow at the coast is not
      the 1000-500mb thickness, but rather the boundary layer.

      That’s how I read it, anyway.

      Cheers

      1. Great interpretation OS. Perhaps you should explain the difference between the critical thickness and the boundary layer. I forgot to get into the discussion regarding the boundary/marine layer. People should note that the boundary layer is also within the lower levels of the atmosphere but higher than the 2m temps (surface temps) we speak of.

        1. Can’t do right now, but would be happy to do so.
          Perhaps a little later this evening under the new blog.

          Only hope I can do 1/2 as well as you did! 😀

    1. Funny, Even up there, with the same 0C line and 540 line, NO WSW in coastal
      areas. Obviously there are or expected to be boundary layer issues. 😀

  85. I agree Arod but that type of tweet will mislead so many people into thinking rain for everyone in his viewing area.

    1. Totally agree. And, I know Vicki doesn’t want to admit it, but he has proven irresponsible at times–not necessarily with his forecasting, rather with his informing of the public.

  86. wow it seems like everytime bilerica is right on that edge of big snow storm based on the latest nam im right on the southeastern edge of the red colors 😉 i aint buying it.

  87. Matt Noyes tweet

    @MattNoyesNECN: Tue night/Wed event not going to bring high impact Boston/Providence corridor, but 6-12″ snow possible Northern NewEng

  88. Good afternoon all…

    A bit under the weather (maybe battling a small bug). I haven’t read all the comments yet but will be doing that this hour and then formulating a new blog post during the next hour so that it is posted by 6PM (hopefully). I did see a few of the messages including JMA’s great post and A-rod’s fantastic met. 101 tutorial. Nice job to both of you and thanks! Also O.S. glad you have power again and can resume your daily duty of hanging print outs of the models on the map wall. 😉 (reference to what we used to do with the old difax printouts in the weather lab at U Lowell in the late 1980s) 😀

    2. During the Early 90s I had signed up for a fax service.
      At that time I basically had a printed menu of the charts I wanted.
      Then I would call a phone number, give a list of the charts I wanted along’
      with my fax number and in a few minutes, the charts arrived.

      I was in heaven.

      Now look at what we have?? NICE!!!

      Curious to see your thoughts regarding late tomorrow into Wednesday.
      I do hope you discuss some of the snow/rain parameters and boundary layer.

      😀 😀 😀

  89. I think this is the grey area that JMA alluded to this morning. Don’t just look at the models; rather, look at positioning of the surface low, critical thickness, surface temps, temps at 850 and the orientation of such relative to climatology. In other words, let’s see if the positioning of the 540 and 850 lines as depicted from the various models make climatologic sense. This will allow us to fine tune where the rain/snow line is most likely to set up rather than believing a model at its word 😀

  90. Winter Storm Watch just popped up for here. I haven’t really any time to model hug today or goof around on the blog…..so sad!

    Going to fawn over accupro and check in later peeps.

  91. Accumulations…snow accumulation of 4 to 8 inches…along with
    light amounts of ice. Total storm accumulations may locally
    reach 10 inches above 1500 feet in western Franklin County.
    * Timing…snow will spread into the watch area after midnight
    Tuesday night. The precipitation will end Thursday morning.
    * Impacts…the Wednesday morning commute will likely be impacted
    by snow. Wintry precipitation may also impact the Wednesday
    evening and Thursday morning commutes as well. In
    addition…heavy wet snow may cause some tree damage and
    scattered power losses across the watch area Wednesday and
    Wednesday night.

    1. This is likely due to the fact that you are further up in the boundary layer and therefore you’re in a location where the boundary layer is less of an issue.

  93. And OS. I concur with you. Even if 1000-500mb thickness values are too high in some locations, evaporational cooling in this case can overwhelm the column enough to produce snow. However, when 2m temps, 850 temps, thickness values and boundary layer issues concurrently present themselves, it makes it a nearly impossible job for dynamic cooling to overcome all of these obstacles. Unfortunately for the coast, unfavorable 2m temps, thickness values and the boundary layer will be battling against the dynamic cooling effect as well as the 850 mb temps and the warmth wins out–not to be the case inland.

    1. Yes, it will be tricky, and as I said, right now it looks like mostly rain near
      the coast, but that could change. We’ll see.

      To be honest, I am a bit skeptical of the absolute “NO SNOW” near the
      coast. Of course I could be dead wrong, but I am feeling a front end dump
      of snow, even in Boston. I’ll have more later on that.

      I need to look at some of Retrac’s column data from the cool website. That really tells the story (again, it is ONLY modeled results. It is not an actual sounding)

      😀

        1. I’ve lived here for 25 years and this is usually the time of year where we can really do well with marginal events.

          1. That is likely due to the fact that evaporational cooling can overcome B.L issues since you’re further up within the boundary layer. TK may be able to give you a better explanation.

  95. Interesting…Harvey has a far colder scenario for Boston compared to Pete’s. Brief rain to start but fairly quick change to snow. More shortly when his complete forecast comes out around 5:15 or so.

  96. This looks to be a burst of snow for areas at or near the coast going over to rain. Inland it will take longer for the changeover and a light to possibly moderate snowfall is possible and that area is where I think could have a tough Wednesday morning commute.

  97. sweet..

    AT THIS TIME IT APPEARS LOCATIONS
    ABOVE 750 FEET MSL WILL BE THE MOST LIKELY TO STAY PURE SNOW
    LONGER. THIS WOULD MEAN AREAS SUCH AS THE WORCESTER HILLS…
    MONADNOCKS AND EAST SLOPES OF THE BERKSHIRES ARE MOST AT RISK FOR
    SIGNIFICANT SNOWFALL.

      1. No, the county is split in two. The City itself is considered southern Worcester county. Holden is on the very southern edge of “Northern Worcester County”. There’s no WSW 5 miles away where I work yet which is also about 300′ lower.

  98. Snowfall for Boston on Wednesday:

    Todd = 1-3″
    Havey = no snow map yet, but probably in Todd’s range
    Pete = all rain and maybe 1-2″ from 495 to Berkshires

        1. One thing A-Rod is WAA like this can be real tricky. My experience with this is if you pick up more than 2″ around here with that, you did well.

          I’m not convinced yet about the higher totals but the NWS write-up makes me feel like a surprise is possible.

          Also, I want to dig into the 18z GFS some to see what that sit and spin thing is all about.

    1. Well at 850 mb, altitude is around 5,000 feet, so at 900 feet, pressures would be much lower 850 mb. The column looks cold enough to support mainly snow in Worcester until the tail end of the event around the 1st of March.

        1. atmospheric pressure at sea leval is 1013 mb so at 900 ft, pressure is roughly 950-1000 mb as you said.

      2. Yeah, I figure it’s about 985 mb’s here +-.

        I’ll post the GFS stuff later when it come out. Maybe I’ll do wind barb’s too.

        Interesting on the NAM, there isn’t a layer of warm air between the surface cold and upper cold as you would normally see with sleet events. This tells me there’s some cooling in the entire column.

        We’ll see what other model have to say

  101. There will be problems to keep frozen precip in Boston, it appears through the entire event it will be above freezing, I think in downtown Boston just a coating, id be suprised if Logan got more than a coating out to the 128 area a quick inch all of this being washed away by rain, could be a few slick spots west of 495,, beyond 495 2-3 inches 🙂

  102. wbz… their timeline precip map and channel 5’s as well shows the rain/snow line not making it past the mass pike and staying south of 128. i think the rain line makes it up to rt 2 at least with this system.

        1. east wind will go right over billerica which is a hill changing the precipitation to rain from the billerica center down. the sides.

        2. I agree I think north and west of 128 especially could get a quick inch of snow and west of 495 2-3 inches, there will be brief cooling of the column to get that but quickly by late morning the mild push off ocean even though is only 40 degrees still won’t be enough and changes to rain in Boston after possibly getting a coating IMO

  104. Watching Harvey, I noticed an interesting contrast ……

    This past weekend storm, when he would show the various models, it was the NAM that would project the highest snowfall potential and I believe the EURO was the lowest …..

    However, for the upcoming storm, guess which model was the most aggressive ? The EURO, I believe it gave Boston 4.3 inches.

  105. I know many here want the snow, but I’m done. I’m so physically exhausted from another all nighter last night. Although I did not arrive at work till 11 lastnight, I have not been to bed since Saturday night. Just ready for the next season.

    1. I hear you John. I’d just as assume this coming event were rain, get through the atmospheric block unscathed and in mid March, have the 40s and low 50s arrive and head into Spring. Hope you are able to catch up on some rest soon !

  108. Here’s the two sides of the southern Plains storm ….

    Gage, OK : Moderate snow, 32F, North wind 32, gusting to 40 knots

    New Orleans, LA : Thunderstorm, 64F, dewpoint : 63F

      1. Yes. I complain, particularly louder and louder in March and April about how long it can take to get a little bit milder weather in here. But, I’ll take this stable chill anytime over the severe weather threat and actual severe weather that seems to really devestate some area in the south every spring.

  109. latest nam run has me right on the 3-6 inch range with 6-12 just north. while the gfs gives me 1-4 inch areas with the 6+ well north and west of my town

      1. i hope im wrong about what i think is gonna happen and i end up with 3+ inches of the white stuff 😀 i rather have snow than 1 to 2 inches of rain

  110. Retrac I am right in your neck of the woods in Sterling sitting a few feet below 900′. Just moved here in May from Blackstone and getting used to the elevation. Much different from what I experienced in Blackstone and where I lived as a kid on the south shore. Snowblower wasn’t doing too well with the 9 inches of sloppy wet snow. Had to bite the bullet and got a bigger snowblower(Ariens). Don’t think my Craftsman would last too much longer up here.

    1. Cool. It really is different. I’ve mentioned before too that accumulation can be very different even on the other end of the city near Auburn. And Blackstone….I’ve seen 12″ here and sterling and grass there many times.

  111. Yeah it’s a nice little town. Much different than the hustle and bustle of the south shore, but getting used to the quietness. I’ve driven through Holden and that is a very nice town as well.

  113. I think that the 18Z GFS is crap warmed over. I can smell it from here! 😀

    We’ll see what the real runs show at 0Z. 😀

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