Friday Forecast

182 Comments

7:34AM

DAYS 1-5 (MARCH 17-21)
Hello and Happy St. Patrick’s Day to all! Apologizes for the post that left you a bit info-deprived yesterday. Back on track today! High pressure provides what will be the nicest day of the week today, albeit starting with some cloudiness over parts of eastern MA due to a weak inversion (a thin layer of warmer air just above colder air) in the lower atmosphere this morning. Low pressure will approach Saturday and wobble its way south of New England Sunday, intensifying as it does so. An area of mix/snow will occur Saturday night into Sunday for at least portions of southern New England (CT, RI, southern MA) and the questions remain of how heavy does it get and how far north and west does it expand. Will attempt to answer these by tomorrow, but for now the further south and east you are the better chance of accumulating snow exists. There may be a fairly narrow swath of significant snow along an inverted trough (basically a line of lower pressure and air convergence that extends back from a departing low pressure center). Spring arrives, well the Vernal Equinox occurs, on Monday, and some nicer weather is expected then as well as Tuesday. But we know that the arrival of official spring does not always mean the winter switch is shut off…
TODAY: Variably cloudy start over eastern MA then increasing sun. A few clouds may drift into RI. Mostly sunny otherwise. Highs 35-42. Wind light variable.
TONIGHT: Mostly clear. Lows 10-15 interior snow-covered areas, 16-22 elsewhere. Wind light variable.
SATURDAY: Sunshine fading behind increasing clouds. Highs 33-40. Wind light variable.
SATURDAY NIGHT: Cloudy. Snow developing overnight especially southern MA, CT, RI. Lows 20-27. Wind light N to NE.
SUNDAY: Cloudy. Periods of snow, especially southern areas, with some accumulation. Highs 30-37. Wind light NE to N.
MONDAY: Partly cloudy. Lows 15-22. Highs 40-47.
TUESDAY: Mostly sunny. Lows 20-27. Highs 45-53.

DAYS 6-10 (MARCH 22-26)
Unsettled weather is possible both early and again late in the period. Temperatures near to below normal.

DAYS 11-15 (MARCH 27-31)
Another episode of unsettled weather is most likely during the middle of the period. Temperatures near to above normal.

182 thoughts on “Friday Forecast”

  2. Thank you TK. Now that I just finished typing and posting on the other blog.

    I will re-post here:

    JpDave says:
    March 17, 2017 at 7:35 AM
    6Z GFS SNOW Kuchera

    http://maps1.pivotalweather.com/maps/models/gfs/2017031706/084/snku_acc.us_ne.png

    10:1

    http://maps1.pivotalweather.com/maps/models/gfs/2017031706/084/sn10_acc.us_ne.png

    NAM Kuchera

    http://maps1.pivotalweather.com/maps/models/nam/2017031706/084/snku_acc.us_ne.png

    10:1

    http://maps1.pivotalweather.com/maps/models/nam/2017031706/084/sn10_acc.us_ne.png
    Reply

  3. JpDave says:
    March 17, 2017 at 7:45 AM
    The 3KM Does not go far enough to get the totals, but here is a partial.

    Surface at 18Z Sunday

    http://www.tropicaltidbits.com/analysis/models/nam3km/2017031706/nam3km_ref_frzn_neus_60.png

    10;1 snow at that point

    http://www.tropicaltidbits.com/analysis/models/nam3km/2017031706/nam3km_asnow_neus_61.png

    Please note: as with the last storm, have to be careful with 10:1 maps as ratio
    may be lower than that. Alos, that surface is 18Z which would have nearly maximum
    sun angle. Both could affect totals.

    Here is the latest SREF

    12 Hour Snow ending 15Z Sunday

    http://www.spc.noaa.gov/exper/sref/gifs/latest/SREF_SNOWFALL_MEAN12HR_f060.gif

    Ensemble Members. Mean Snow for Boston: 5.41 inches

    http://imgur.com/a/K7fBp
    Reply
    JpDave says:
    March 17, 2017 at 7:48 AM
    It should be noted that the 0Z Euro, now has system closer than yesterday and not
    a complete swing and a miss, but still only delivers a coating to 1/2 to boston and
    only an inch or 2 well to the Southeast of Boston. BUT it has moved closer.
    Reply

  4. Here is the 1st official word from NWS re: Inverted trough

    an inverted trough extending back towards Lake Erie from the surface
    low center emerging off the Delmarva.

      1. Been doing it for years but only recently started posting them here. Wish I had done it sooner. lol

    3. To add to this: NWS seems to be hedging their bets on this one. They’ve been tweeting stuff like “If storm intensifies and/or shifts N, could be dealing w/ +6″ snows” and telling people to view the worst case scenario map which currently looks like this: http://i.imgur.com/LGSP0v5h.jpg

    4. Thanks Dr. S! I happened to catch Fox 25 News last night at 11:00 and Kevin said one of the models was projecting up to 12 inches. He never mentioned which one but did up his amounts after seeing that data, but obviously not as high as he mentioned.

      1. Yeah a few meteorologists seem to be jumpy right now with giving out numbers that might be viewed as too high. That last storm seemed to get them a lot of hate. People want them to have exact totals and nothing less will suffice.

        2. unfortunately, it’s not an exact science. This one will be
          equally tricky and in a sense worse. Worse? Well
          most people are not/were not expecting a storm
          for this weekend. With the “blizzard” there was much
          anticipation.

          What worrisome this weekend is IF it turns out to be a foot of snow and no one expects it. I am NOT saying we will get a foot of snow, just that this one is very tricky.
          Could be a miss, an inch or 2 or a foot. Who knows.

          1. I think I said in this very blog a couple days ago there’s a chance this storm could randomly drop 12 inches unexpectedly as an FU to meteorologists so that they look unprepared to the public.

            By the way: let’s say the totals DO increase and they get that data even later tonight. Guaranteed people will still be angry because most people don’t pay attention to the news after Friday morning. lol. Mother nature why dost thou forsake thy forecasters?!

            1. Because she can! 😀

              For that very reason I hope Boston gets
              12-16 inches!!! I know, not going to happen, but it would be cool.

              Here’s my forecast for Boston:

              0-8 inches. Virtually a lock. 😀

              1. I’m going to play it safe and say 0-12 inches. You’re playing it too close to the hip with such precise numbers. 😉

                1. I’m playing it even saferior and saying 0-20

                  Dr. Stupid….I know I’ve said it before but do not believe it can be said often enough. Your compilation of them maps is AWESOME

  7. Here is a tweet from Ryan Hanrahan yesterday. I thought it was interesting.

    Ryan Hanrahan‏Verified account @ryanhanrahan 21h21 hours ago

    After a pain of a blizzard to forecast now we get a weekend Norlun trough to forecast. Awesome

          1. You may still get your wish. Nothing etched in stone at this point. However, it looks more and more likely there will be something. 😀

            1. I think some anounts out there for Boston seem high gas maybe it’s the uncertainty of it . South shore and more Plymouth south looking plowable if it pans out .

                1. As I said not etched in stone. Southern areas more likely, but Boston not
                  completely out of it yet.

  13. Given the air mass slated to be in place, this would be a …. what can accumulate between 6pm Saturday and 8 am Sunday.

    2. To some extent, however, it depends on the intensity during the day Sunday.
      Even with you scenario, I’d got to like 10AM or so and not 8. If it is banging
      During the day Sunday, it WILL accumulate. If it is light then you are 100% correct. It will come down, but not much will accumulate.

  14. I see signs that the coastal will develop much farther South. Not sure what the implications are. probably more likely OTS, but then the upper low could capture it
    and bring it up closer to the coast.

    2. Hmmm, the upper flow is flatter down the coast. Hmmmm

      So far no coastal. Something is up this run.

  15. watch that high angle sun eat away at the snow especially for those not on the cape. It be a wet snow that does not accumulate well

    1. We have a very solid (in measurement and in type) snow down here. Wouldn’t that make accumulations easier.

      The still footish of snow is frozen so solid the kids were walking on the top at the bus stop.

  18. They are not complete but it looks like the higher res 4k and 3k nams are more bullish than the regular nam

  21. Not sure if I said thank you, TK. Was out doing food shopping early before the big wave of milk shoppers arrived so arrived to the party here late.

    Thank you and I think I can smell your mom’s Irish dinner cooking 🙂

  22. Look at WHEN the NAM shows most of the snowfall occurring …. Daytime.

    Take those nam totals and divide by 3 🙂 🙂 🙂

    2. The proof on this is to examine the sfc temp projections at hrs 54 and 57.

      While southeast New England is near the 0c contour, you’ll see northern New England milder where there may be sunshine. No polar or arctic air feeding into this, just enough cold air above in the column with heavier precip to create just enough cooling for snow.

  23. I do not think the snow will have a hard time sticking if it comes down hard enough plus the current snow pack gives it a great start.

  24. Tom, I don’t disagree with you entirely but there is definitely a trend happening here and worth watching. 12z GFS has also trended west

    1. You’re not the only one. All the meteorologists I follow keep saying how tricky this is. They also keep revising over and over.

      This is channel 7’s from this morning vs noon: http://i.imgur.com/MtEGrmoh.jpg

      And they are still saying they’re watching it develop.

      Thankful this is still mainly an overnight weekend event and even if it gets bigger there won’t be as much of a travel issue I think.

    2. As in being something more significant than is being modeled? Are the models starting to pick up on it or do u feel there is still a ways to go to what you think the final outcome might be?

  27. For sure our trend is out friend on this one. I usually always agree with you Tom but I do believe it can accumulate due to recent cold as well as snow pack. Intensity will also be strong if it’s benchmark track.

    1. Sun angle in March on black tops. It may accumulate on snow packs but it may not accumulate as much on black tops than if this were a January event.

        1. Yes. Yet, with a system with sustained heavy QPF out of reach, no more than a couple of inches may accumulate on roads in areas where several inches are modeled for example. Likely a small scale event but still enough to cause dangerous travel.

  29. Kudos to our resident expert should this matrliaze as he’s been calling for a storm around the 20th for a while now.

  31. Here are a few snow maps:

    GFS Kuchera (with sun angle and ratio, I feel the kuchera maps would be better
    for this event. At least more realistic than the 10:1 maps)

    http://maps1.pivotalweather.com/maps/models/gfs/2017031712/084/snku_acc.us_ne.png

    Nam Kuchera

    http://maps1.pivotalweather.com/maps/models/nam/2017031712/084/snku_acc.us_ne.png

    4KM NAM kuchera

    http://maps3.pivotalweather.com/maps/models/nam4km/2017031712/060/snku_acc.us_ne.png

    3KM NAM kuchera

    http://maps4.pivotalweather.com/maps/models/nam3km/2017031712/060/snku_acc.us_ne.png

    CMC Kuhcera

    http://maps3.pivotalweather.com/maps/models/ggem/2017031712/084/snku_acc.us_ne.png

  34. Currently, Subject to additional data, it looks like About 3 or 4 inches for Boston.
    Just my estimate at the moment. This is still evolving and there appears to be an upward trend in the snow, so we shall see what the 18Z and then more importantly, the 0z runs
    have to say.

  35. The irony in this event is while the column just above the boundary layer will be chillier than the last storm, the boundary layer will be borderline and the sun’s radiation during the day will be strong.

    1-3 inches on existing snowpack in lower elevations, 2-5 inches in any area above 500 feet in Worcester county if the precip makes it that far north and west.

    If you had the Sears tower in SE Mass, then the top of that might accumulate 4-8 inches. 🙂 🙂 🙂 🙂

    Had this been a nighttime event, it could have been a widespread 3-6 or 4-7 inches. Too bad. Or maybe good. 🙂 🙂

        1. Did you see my estimate for Boston?
          I am factoring in all of this and I came up with 3 or 4 inches for boston. When you really look at it, we are not that far apart. You factor sun angle a little more than I do and that is about all. 😀

          However, I do think it is trending higher. So more than
          4 inches in Boston is not out of the question. We shall see.

          1. That’s the other funny part of this. Last storm because of track changes, it was slowly downward on impact in SE areas, this time, its the opposite seemingly.

            1. I agree with that. In away this way is worse, especially over the weekend.
              It was mentioned above, but the last thing people hear is nothing or a nuisance coating to 2 inches and they go about their business for the weekend and then all of a sudden there is major snow storm.
              They’ll bitch like crazy that they weren’t told about it.

              Add to this and I am sorry but this frosts my behind, for the most part (Barry excepted) INFERIOR Mets are on duty over the weekend and they NEVER get it right,

    2. Was engaged (pre-Mac who swooped in and captured my heart) to the son of the family who sold the tower to Sears 🙂

      And on a weather note……..Can we drop that to above 480 feet please?

  36. Not so patiently waiting on the Euro. Initialization charts not far off now.
    15Z SREF should be out around the 3 O’clock hour and about 3:45 the 18Z NAM
    will start to appear. I wish there were a medium range run EVERY hour.
    I know the RAP is every 3 hours and the HRRR is every hour, but they go out 21 and 18 hours respectively.

      1. Well, IF it weren’t for STUPID time, it would be fully available by now. Unfortunately, I think there may be a delay as the initial panel (hour 0) should be out by now.

        1. Yes, something is clearly wrong on the technical side with the 12z Euro run, it doesn’t seem to be available anywhere.

          1. True Dat.

            Sorry, my Brother lives in Lafayette, LA.
            That’s the kind of talk I hear from him. 😀

  37. It’s a tricky forecast, but for now I lean towards lower snow totals for most of us, but share TK’s concern of a localized maximum band, which would probably be close to the South Coast or over the Cape. I also share other’s concerns about marginal temperatures and the Sun angle, not to mention the possibility that the storm is simply too far away to really impact us. For numbers, I very much like the NWS map at this point. 2-5″ Cape and South Coast, a coating to 2″ elsewhere. Maybe an inch in Boston would be my best guess, with about equal chances that turns into nothing or into 2-5″.

  38. So surprised to hear the low numbers 🙂

    I would say a general 3-5 inches from Boston south and maybe higher track dependent.

    1. I said 3 or 4 for boston, so what you say sounds good to me and reasonable.
      You are not going out on a limb and you have reasonably considered ratio and sun angle, but not overblown it.

      Actually, there may be more qpf well to the SE, but the ratio will be lower, keeping accumulations somewhat similar. There may be higher pockets.

      I’m good with that. 😀

  39. OK, now I am pretty certain. There must be some sort of delay/issue with the Euro.
    There should be data available by now and there is not. Something is up.

    Anyone have info?

    1. A weather page I follow on facrook mentioned same thing as well. Although when I looked at tropicalbits at every 24 hour incrementals the euro shows the low sliding way south if I’m reading it correctly

      1. 0Z Euro was more on board. Not nearly as much as the others, but it was a complete miss before and now not.

        DAMN, I want to see that Euro. OF course there are technical difficulties now.

        1. Maybe the euro will come with a big surprise with a low pressure sub 1000 delivering a foot ig snow. Wishful thinking!

          1. Wouldn’t that be nice. Doubt that. I’d be happy with it on board for 4 inches. That would mean
            room for more.

            Right now I just wish we could see some data from it! This SUCKS!

            1. Sucks for me and for you my friend. Because if you can’t see it then you can’t post it, therefore I can’t see it either . Let’s hope the trend continues with tonight models, after all tk mentioned this storm a while back and that can’t be ignored

              1. There was suppose to be a smiley face emoji after the word “either”. Lol I guess WordPress doesn’t like my emojies

  40. Technical failures on the ECMWF’s end causing a worldwide lack of data for the 12z Euro. I haven’t seen any ETA for the data; it’s possible we’ll never get this run.

    I’m not sure what we’re to do now. We all know there’s no way to make a forecast without the full blessing of the Euro 😉

    1. In this I’ll make an exception since we are so close, I’ll rely on the 4KM and 3KM NAM along with the RGEM and soon the RAP and HRRR. SCREW the Euro!
      Who needed ya anyway. SCREW THE EURO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    2. Thanks for the update on this. Much appreciated. Now I will STOP looking for it.

      FWIW, the 15Z SREF data is slowing cranking out. But then, no one likes the SREF anyway. Btw, why do they bother running it IF it is so subject to ridicule?

      1. Not for Nothing, BUT since this system has been in range at all, the SREF, like the NAM, has been all over it.

  42. I was just snooping around. It’s 87 in Phoenix and 88 in Yuma, AZ. Some pretty good heat there. 64 in Flagstaff at 7,000 feet.

  44. Well at least it wasn’t a whole network issue as the NAM is cranking right on schedule. 😀

  45. For what it’s worth I predict a mostly South Coast, CC and Island event with little accumulation. It’ll snow for hours and hours and not much will stick. Boston and Metro <1 inch; South Coast, CC 2-3 inches which will melt fast; Islands <2 inches.

    Longer range looking better for spring lovers. Old Man winter's been dancing in the ring, landing a couple of blows, but he's running out of gas and spring knows it. Spring's waiting for an opportune moment to deliver the knock-out in the coming 7-10 days.

    1. Hmmm, note: wind gusts to 60 MPH

      …WINTER STORM WATCH IN EFFECT FROM SATURDAY EVENING THROUGH
      SUNDAY EVENING…

      The National Weather Service in Taunton has issued a Winter Storm
      Watch, which is in effect from Saturday evening through Sunday
      evening.

      * LOCATIONS…Cape Cod and Marthas Vineyard.

      * HAZARD TYPES…SNOW.

      * ACCUMULATIONS…Snow accumulation of 5 to 8 inches.

      * TIMING…Snow will begin to overspread the area late Saturday
      night into Sunday evening with the heaviest snowfall occurring
      Sunday morning.

      * IMPACTS…Heavy wet snow could result in down tree limbs and
      isolated power outages. Visibilities will also be low due to
      near blizzard like conditions resulting in hazardous travel.

      * WINDS…Northeast 25 to 35 mph with gusts up to 60 mph.

      * VISIBILITIES…One half mile or less at times.

    1. Also appears to have a very very Sharp Gradient ending just South of Boston.
      This 18Z run is basically a swing and a Miss for boston.
      It also looks like NYC, North Jersey and Long Island get the inverted trough
      snow and Cape Cod and the Islands get the Synoptic storm snow.

      Figures. BUT it is the 18Z run. IF the 0Z run shows the same, then perhaps it’s all over. Still the GFS to come.

      AND still no Euro.

    1. Please accept my apologies. the 4KM Nam was not quite complete so pivotal
      weather defaulted to 12Z and I didn’t catch it. Those 2 maps above are 12Z.

  51. Tweet about euro

    ECMWF is pleased to announce their data issues have been fixed — and the Earth is again spinning on its proper axis. Data arriving now.

    1. due to the issue they had today i would not trust it. usually when models have an issue, something is up with that run.

      1. Could be, but we don’t know enough about it to make that
        judgement. Look for tweets from Those in the know.

  56. With all data out there still think it moves up near benchmark but precip shield isn’t massive so I still like the 3-5 from earlier. Nothing here has changed my thoughts.

  57. So what do we take from all of this mean?

    Well the experts can tell you far far better than I and I’m sure they might have a different opinion.

    We are nearing 48 hours from onset. This is a tricky situation perhaps better handled
    by the higher resolution models.

    I personally think that we should be looking at the #Km and 4KM NAM, the RGEM and then later the HRRR and the RAP. I know some don’t think much of the SREF, but all the members ARE High Resolution, So I look at that as well.

    Call me insane, but I think the HR models have a better handle on what’s going down here.

  58. The EURO is adjusting toward a likely scenerio. The other models IMHO are overdoing the precip. Look for a broad swath of 1-3 inches along and south of the pike with more to the south.

    1. Absolutely agree. Boston will not see much . I suspect I’ll be called in but thinking it may be a minor event for the city.

      1. Agree. I don’t think this will be a plowable event in Boston mainly due to temps, and barely plowable on the South Coast and CC. Timing is everything. Had the storm `waited’ until Tuesday night next week could be a different story as the last of the season’s arctic highs settles in to our north.

  59. I generally agree with what the overall media says, but there is a caveat. An inverted trough may get stuck right in eastern MA Sunday night and prolong snow. If that happens, it will accumulate in the city to some degree. It would not entirely surprise me to see flakes linger in eastern MA until sometime Monday morning.

  62. Don’t like 0Z NAM. I’m afraid this may be the new trend. Waiting on the HRs and the GFS. We shall see. Bad day for model watching. 😀

  65. Not looking good. Something happened that all of the models picked up on.
    Oh boy, what a turn of events. Oh well, that the way she goes.

    I’m even writing this thing off as much as it pains me. 😀

    good night and may things change overnight. Huh! Yeah right.

    1. So it sounds like that weather advisory for the cape goes bye bye? Here forecasters are saying “hey watch out maybe 6+” and now nothing? Woooooooo good thing it wasn’t a weekday event because more people pay attention to that and this would have drawn much ire after what people percieved to be a poorly called first storm this week.

  66. What is usually the result when one changes their forecasts based on 1 run of the NAM model?

  67. JP Dave said it- last night was one of those cases where the whole suite of models saw something that caused an across the board shift offshore for this next event. I wouldn’t knee jerk the forecast at this point since it could still wobble back- my numbers were low to start so I’ll stick with the potential for 2-4″ on the Cape but likely little more than a coating elsewhere, and it’s possible many of us don’t see a single flake.

      1. We don’t look at the GEM 😛

        And hey, even it looked a bit to the east, the global one at least 🙂

    1. Not particularly. This was never going to amount to much. Yesterday’s models were overcooking the QPF.

  69. I don’t feel any differently this morning than I did last night.
    It would take a big surprise to get any decent snow up to Boston.
    Probably a big surprise to get it on the Cape even.

    The 4KM and 3KM NAM appear to be trying as well as the RGEM.

    On another note, the snow was assaulted yesterday by the brilliant March sunshine
    and warming temperatures. I could visually see the snow piles melting. By the end
    of the day, there was a huge difference and large puddles. I suspect we’ll see a repeat
    performance today at least until any clouds move in IF any clouds move in. 😀

    So, I am ready for Spring. Will we see any Spring weather? Who knows.

    Looking down the road, I don’t like what I see from the GFS for April 1st. Of course that is waaaaaaay out there, so no need to worry just yet. AND the Euro has a significant event on the 26th into the 27th. Showing near a foot of snow for Boston.
    Again, when it comes to this kind of prognostication, 8-9 days out is an insane amount of time. Let’s see if Either of these events still exist on the 12Z runs.

  70. NWS still has the Winter Storm Watch up for the Cape and Islands. Funny thing though, in the text it says accumulations of 3-5 inches. Since when was that Winter Storm
    Criteria????? So this is another crappy example of a place holder? They don’t issue
    a Winter Weather Advisory Watch, so they issue a facuckta Winter Storm Watch
    and either take it down totally or replace it with an advisory.

    1. I haven’t had much faith in the NWS in a long time. Their credibility is diminishing. They just don’t make sense and their forecasts lag. Before long, they’ll be like the TWC.

  71. TK, is that Inverted Trough still possible?

    Usually we can see it showing up on at least some of the models.
    These eyes can’t see it now. There were signs previously.

    Thanks

  73. May I play the What IF Game?

    Here is the latest 11Z RAP Surface map with radar reflectivity valid 8Z Sunday:

    http://maps3.pivotalweather.com/maps/models/rap/2017031811/021/refcmp_ptype.conus.png

    Notice what appears to be an inverted trough hanging back there???

    Here is the 500MB chart

    http://www.pivotalweather.com/model.php?m=rap&p=500wh&rh=2017031811&fh=21&r=conus&dpdt=

    300 mb

    http://www.pivotalweather.com/model.php?m=rap&p=300wh&rh=2017031811&fh=21&r=conus&dpdt=

    200 mb

    http://www.pivotalweather.com/model.php?m=rap&p=200wh&rh=2017031811&fh=21&r=conus&dpdt=

    The only thing that keeps that from coming up here is the 200 mb flow.
    So the mean movement would some combination of 500, 300 and 200mb flow.
    Close.

    Even so, what about the trough. TK kept saying it could set up in Eastern MA.
    If you look at the current location and even if the movement is more ENE,
    the trough could clip Eastern MA, assuming it’s still there when it gets up here.

    So, my current question is: Is it premature to complete write this thing off???

    WATCH the HRRR and RAP for trends and let’s see what happens.

    Still likely off shore but WHAT IF?????

    1. You can clearly see the development of an inverted trough on the 500 mb chart. Inverted troughs as it pertains to their strength and especially location are features that often even the HR models have a difficult time picking up on. That could be the dark horse and our only hope for meaningful accumulations somewhere in eastern MA especially to our south and east.

    2. There’s actually nothing wrong with that. Clearly labeled “likely” and “chance”.

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