Monday Forecast Update

253 Comments

5:30PM

DAYS 1-5 (MARCH 13-17)
Adjustment being made with this update for a slightly further west track of the center of low pressure for the Tuesday storm. This introduces a little more warning aloft especially from the Boston-Providence corridor southeastward. Some guidance has this even further west but not going with this scenario at this time. Regardless, the storm will be intensifying rapidly as it comes across far southeastern New England and will have a large impact, even where it is not all snow. Wind and coastal flooding concerns remain, along with blizzard conditions northwest and west of the storm track as it passes. This should be a very strong wind event for the entire area. The difference between yesterday’s thinking and today’s, in additional to more mix/change to sleet/rain close to Boston-Providence, is a period where the wind shifts to southerly over Cape Cod as the low center would track west of there. This more westerly track also introduces the probability of a dry slot, or precipitation-free area that moves up from the south during the evening Tuesday and basically shuts things down along and east of the track of the center of low pressure, while snow would continue to the west before everything tapered off later. Also still expecting some snow showers Wednesday with the upper low still, but not seeing this as an event with anything more than minor additional accumulation. Fair weather is back for Thursday and Friday but with below normal temperatures as the cold pattern continues.
TONIGHT: Thickening overcast. Snow South Coast before dawn. Lows 22-30. Wind light variable.
TUESDAY: Overcast. Snow area pushes north quickly in the early to mid morning and becomes heavy at times, first in RI and southern MA then the remainder of MA into NH, changes to sleet then rain Cape Cod and Islands, into southeastern MA and southern and eastern RI. Thunder is possible. Best guess on where the line gets to is about Boston and maybe immediate Metro West and southward down I-95 and possibly onto Cape Ann MA as well. Highs range from 25-30 interior MA and southern NH westward, ranging to 40-45 Cape Cod and Islands later in the day. Wind NE increasing to 20-35 MPH interior, 30-45 MPH coast, but much higher gusts at times.
TUESDAY NIGHT: Rain/sleet ends where the changeover occurred and possibly into interior eastern MA and southeastern NH, while lighter snow continues in areas to the west of the track of the low, tapering off later at night. Snow accumulations ranging widely from 1-3 inches outer Cape Cod and Nantucket to 3-6 inches remainder of Cape Cod and Martha’s Vineyard, 6-12 inches southeastern MA, southern and eastern RI including from Boston to Providence, 12-18 inches elsewhere except 18+ inches in pockets of interior MA and southern NH westward. Temperatures may rise slightly over southeastern MA briefly and remain nearly steady elsewhere before falling to lows of 22-30 all areas overnight. Wind N to NW 15-35 MPH with higher gusts except briefly SE to SW over parts of southeastern MA before shifting to NW there.
WEDNESDAY: Mostly cloudy. Snow showers. Additional minor accumulation possible. Highs 25-35. Coldest interior areas. Wind NW to W 10-20 MPH.
THURSDAY: Partly cloudy. Lows 10-20. Highs 25-35.
FRIDAY: Mostly sunny. Lows 15-25. Highs 30-40.

DAYS 6-10 (MARCH 18-22)
Watching possible storminess during the March 18-20 period. Dry March 21. More potential unsettled weather about March 22. Temperatures below normal.

DAYS 11-15 (MARCH 23-27)
Watching possible storminess again later period. Temperatures near to below normal.

253 thoughts on “Monday Forecast Update”

  10. Thank you, TK.

    Thank you, Dr. Stupid (Smart) for the weather map forecasts from around the dial. I think they’re all overdone. But, I hope I’m wrong again.

    I think Tim Kelley is onto something about tomorrow night as whatever falls tomorrow will freeze over, so even if you only have 6 inches of snow on your car it’s a good idea to remove it. Otherwise you’ll be scraping and chiseling for a long time on Wednesday.

    What’s remarkable to me is that we’ll be getting another Canadian High Wednesday which will drive nighttime temps into the teens in Boston, I think. That would make three consecutive Canadian Highs in March causing temps to plummet to at least the teens in the city. I really can’t remember this happening in March.

    1. Unfortunately this Canadian high will leave as soon as the storm arrives…if it hasn’t already.

      1. Yes, you’re right. But there is a replacement high pressure area behind it. Just too far away to force the low to the benchmark. The replacement high is a cold one, too. Not as bitterly cold as the previous two, but still.

  11. Total Logan snowfall to date = 39.2″

    Normal Logan snowfall = 43.8″

    My storm prediction @ Logan = 9.2″ (3/14/17)

  12. Listening to Governor Baker. I am a huge fan of his. After about six times saying clearly but in a different manner that he would like people to stay off road and use public if they need to be out he smiled and said……am I making this point clear enough

  13. Sutton superintendent just sent out a phone voice recording. He said he sees this as a wonderful opportunity for students to take the day and use it to help their parents clean the house from top to bottom including bathrooms. For extra credit he suggested doing a second bathroom

    I am incredibly impressed with this towns school system

  15. I am a disappointed Cape Cod snow lover–spirits sagging with every subsequent forecast (not here) 18-12-8-6-4 to nothing? Damn!

    2. that stinks but thats what ya get when living on the cape, just think, when we are swaltering in the tripple digit heat your usually in the 80s abd 90s and within a half hour of a beach.

    3. Welcome Tim. Just remember that in summer we are all disappointed daily to not be on the cape 🙂

      1. Oh snap! The drama……….

        But he didn’t commit to when so it could be next year. 🙂

  18. Thanks TK, and thank you for all the hard work and dedication on this storm! Events like these really reinforce what meteorology as a profession is all about. I very much enjoy finding the subtle beauty and nuances in everyday weather, but a storm like this is like the Super Bowl for a forecaster. It’s been great to look at all the different takes over the past few days from the many talented minds we have forecasting weather today, some of the best of which are right here. Hopefully tomorrow will be a fun (and safe) day!

    2. You’re right. And they also separate scientists from the rest of the pack. 😉

  19. Looking at the futurecast radars, it appears that NYC never even mixes and yet Boston changes totally to rain! The only similarity I can think of is the March 1888 Blizzard. NYC all snow while Boston was back and forth between rain/snow.

      1. You’re also looking at radar simulations from 18z model runs that may not be completely accurate.

        Be careful about falling into the “latest run is automatically better than the last run” trap.

  20. Can you weigh in 😉 on the weight of the snow in the Worcester area? Are you thinking light and fluffy or plaster of Paris? I’m in Shrewsbury. Oh and hello everyone! Still a voyeur on the blog.

    1. I think the snow in that area will be moderate to slightly dry consistency for most of it. IF the extreme west option does happen, they’d have a period of wetter snow.

    2. Hi Suzanne. Welcome. You are just about due north of me in Sutton….almost neighbors but not 🙂

  21. For example, the further west NAM and GFS actually warm the atmosphere 2 different ways. So they arrive at a similar solution but not the same way.

    NAM warms it faster above (700mb level) and more slowly at the surface (850mb and below).

    GFS…just the opposite. It warms the surface to 850mb much faster and never warms 700mb that much at all.

    2. So, if you combine the NAM surface with the GFS 700mb …. 🙂 🙂

      Excellent analysis, thanks TK !

        1. Cold column and snow 🙂

          The column gets “measured” at various heights that are located by pressure levels. Two of those levels are where the pressure equals 850mb and 700mb, where they measure to get a temperature of that height within the column. It helps to determine precip type in winter and potential high temps during the warm season.

  22. Waiting until 0z runs to freak out, don’t trust 18z runs(and 6z) to do anything more than nudge an existing forecast a little bit.

    1. https://www.americanwx.com/bb/topic/32149-gfs-12z-and-0z-runs-compared-to-6z-and-18z-runs/

      I read more on this here. Apparently the difference is a bit overblown, but I did see this…

      “I feel that the biggest differences between 06z/18z and 00z/12z can be seen for individual, high impact events….where better in-situ sampling can make a difference [example: some critical shortwave that is important for some downstream development or something entering the North American Raob network].”

  23. Thank you TK for the PM update.

    6-12 for boston. Well that about covers it. 😀

    I am not please by the whole course of events with the bugger of a storm. Not one bit.
    But then again, what can I/we do about it? Not a damn thing. Accept it for what it is.

    I shall try. Waiting on those 0Z runs.

  25. Thanks TK.
    I am hoping that good dumping for my area the weather models are showing happens.

    1. You’ll do pretty well, JJ. It’s the coastal areas inside I-95 I’m concerned about. Also, the snow that falls will stick around for a while as it’s not exactly going to warm up anytime soon.

  27. MobIle this evening.
    Just before heading out was looking ar rap model.
    As of 18z has 13.5 inches
    For boston at 10:1 with at least an hour perhaps 2 before changeover

  28. Not for nothing, but high resolution models are showing a period of intense
    Snowfall from about
    16z to 19z or so. Insane rates
    Up to 5 inches per hour.
    Even if it flips to rain, damage done with a foot or more snow. Do not give up
    On the snow.

      2. We’ll see, John. I’m almost always wrong when it comes to these storms. But, what I’m seeing from this storm is not a classic nor’easter set-up. For the coast it looks more like a snow to sleet to rain scenario, which spells kitchen sink in my book. With the potential for east/southeast winds, it would not surprise me if Boston hit 38F tomorrow at a certain point mid to late afternoon, only to come crashing down when the storm exits for the Gulf of Maine.

  29. I noticed that intense band on HRR model coming into my area late morning. For those who do change over I think your still get a good amount of accumulating snow.

  30. Let’s REEL IT IN for a moment.

    18z runs don’t change everything. People need to stop focusing on snow accumulations only. Final #’s, while significant and important, are NOT the whole story here. Please pay attention to this!

    Boston may get 8 inches of snow, 12 inches of snow, 5 inches of snow, 14 inches of snow. Here’s what matters: There is going to be a period of time in the city where snowfall rates are 1-4 inches an hour and travel is extremely hazardous. It’s about time we realize that storms are not all about the final snowfall numbers. It’s an event, a process, and it takes time. And there are more aspects to this than snow accumulation for goodness sakes. There are conditions ongoing during various stages of the event.

    Don’t lose site of the fact that even places that flip to rain are going to get pounded with snow for at least a little while before that happens. And the winds are also going to surprise a lot of people with this, so get ready. This going to be anything but a non-event – trust me on this.

  31. Well said TK!! Whatever falls will be what it is. I think people are too focused on snow as well and the wind will be ferocious. Hurricane force gusts are within the realm of possibility.

    Amazing view of storm developing off the NC coast, looks like a hurricane starting up. Transfer has taken place so let’s sit back and enjoy.

  32. Now that the energy transfer has taken place, how are models verifying? Tom, this is usually one of your exercises 😉

    1. Pretty well, I believe.

      For instance at 8z on the 18z nam, there’s a projected 40 mph wind gust contour touching cape hatteras and sure enough, they were gusting to 39.

  33. I’m very interested in what the short range guidance shows during the next several hours…

  34. Let’s watch and see how it unfolds over the next 3-6 hours and watch for placement. I think it ends up east. We shall see.

  35. Interesting note from our Canadian friends. I looked up forecasts for Nova Scotia. The province will be on the eastern side of the low for the most part. They’re expecting mostly heavy rain after a brief burst of snow in the southwestern part of the province. Note, they expect the low to track through Maine, which implies a track that would likely be west of CCC.

    From Environment Canada:

    Rain, heavy at times is expected. The frozen ground has a reduced ability to absorb this rainfall. An intense low pressure system will approach the Maritimes from New England on Tuesday and track through Maine on Wednesday. Snow will develop over southwestern Nova Scotia Tuesday afternoon and change over to heavy rain Tuesday evening. Rain will spread northward reaching eastern Nova Scotia near midnight. Rainfall amounts of 30 to 40 millimetres are expected with this storm and the possibility of flooding exists due to frozen ground conditions.

  36. A friend who lives in NYC emailed earlier and said they were all getting ready to have things close down. Will be interested to hear her reports tomorrow

  37. It doesn’t run through the whole storm yet, but the HRRR gives me no reason to doubt my 12″ number for Boston. Vast majority of precip will fall as snow on the front end along I95, Boston to Providence. Probably 9-10″ in Providence where they mix a bit sooner.

  38. Heading south over the bourne bridge tomorrow no matter what at 7:00am, will keep track of the snow/ rain change over as long as my work computer will work like home computer , no appointments so will try and id work computer with tk in am. Yes I am a computer moron, but i can lift heavy things.

    1. 🙂

      Banner night. Not just a major storm but three new family members. Doesn’t get much better

  41. I have to travel down from concord nh tomorrow morning. What time should i leave by in the am ?

    2. Depends on destination, but I’d recommend having all travel complete by 9AM north of Boston and 8AM to the south, even 7AM further south.

      1. And I meant to copy a loop of it. That offshore moisture is moving NNW onshore, while the band lifts N.

        This is one of those systems that has tapped the pacific south of Central America, the Gulf and eventually the Atlantic.

  43. Thanks for the warm welcome everybody…I still hope the storm takes a miraculous jog east and the Cape gets buried or at least a good from-end wallop of snow!

    1. Welcome ! Good luck with the wind !!

      Perhaps there’ll be a few hrs late morning tomorrow where you can get a quick 3-5 inches before a changeover.

    2. You might be one of the lucky ones who loses power. I’d take that over two feet of snow…..but then it is possible I’m in the minority. As unbelievable as that may seem

    4. i think you see a good burst of snow to start. maybe 1-3 inches 2-4… something to watch for is a extremely heavy band moving through before the change over.

  44. What time do you think the heaviest snow will begin to taper? My husband works at Beverly Hospital and is hoping to get back to Westford tomorrow night and avoid sleeping over if possible – and we (my son Sammy and I) are at his mercy to get dug out. Although per my norm I’ll be hiding under the bed…

    Be safe tomorrow everybody!!

    1. I was literally reading to the end and then going to ask where you are. Good to see you here too. Been too long. Wishing your husband safe travels.

  46. Looking at those potential snow rates of 3-4 inches per hour could throw a forecast into ruins. Maybe Matt Noyes was right all along.

  48. Statewide travel ban in CT has been issued for tomorrow effective 5AM and “until further notice”

    1. Just as fun as the bread shelves I posted yesterday! It really is crazy how baked in our psyche going to the store for bread, milk and eggs is. Started in some regions in the 50’s when there was a milk shortage. Grew even bigger in new England with blizzards like the one in 78 obviously. But now we have ten day forecasts, very few surprise storms and even for huge storms we have better snow removal equipment, preparedness and alerts. You would think the panic shopping would diminish yet it does not. I find it intriguing.

      1. I would agree. I see a good reason to have food in the house, especially if there is the possibility of widespread power outage. But we have known about this, as you said, for a while. Just do your weekly food shopping. And it is intriguing.

        I don’t recall it before 1978 but then I was mostly living at home so didn’t worry about who got the food as long as I had some 😉

        1. During Nemo we lost two fridges of foods and I put in a claim for $500. We have spotless record but it came back to us in a negative way . We don’t stock up at all anymore for that reason .

          1. That storm really affected us down here, didn’t it? I’m concerned a lot of areas are going to experience this tomorrow.

  51. A funny little thing to share: I post the map collages I make on another site and someone suggested an app called “Dark Sky” for accurate forecasts. I plunked down 3.99 for it because it looked kind of neat. Plus the person said Dark Sky reported Boston was only getting one inch. Sure enough I open the app and take a screen shot. Then after fiddling around with it for a bit (25mins) I had a sensible chuckle as I observed the forecast had changed somewhat considerably. I present the side by side time-stamped screenshots: http://i.imgur.com/NRg2mGRh.jpg

  52. @NWSNewYorkNY: It should be noted both the 12 & 18Z GFS operational runs are ~90 miles west of GFS ensemble mean.

  54. What a cool “briefing” presentation NWS put out. Agree or disagree with the content, directionally it’s a great “exec summary” if you will. Very cool.

  59. NAM track is dreadful. Over CT and into eastern MA. Flips to rain most of CT, Worcester County and into SE NH.

    3. I don’t think I’ve ever seen the RAP so bullish with a snow event around here. I tend to not rely on it as much because it’s analogous to just an antiquated/lower resolution version of the HRRR, but to see it showing the amount of QPF that it is, is impressive. I think this thing is going to be pretty juiced up. 2″+ liquid equivalent in some places is in the cards.

  61. The projected wind gusts on the 00z nam are worrisome …….

    Low track ….. Looks to me like the low is moving NNE until it gets to about Long Island. On that motion, it looks like it should go west of Concord, NH.

    But then, it keeps making that NE or ENE slide and you can see on the isobars how they kind of extend out ENE from the low center.

    I still believe that is symbolic of the system finally feeling some resistance from the decent cold dome to our north in Canada. The 00z NAM doesn’t change much for me, except for the wind, where it really makes me nervous.

  62. The Nam is being consistent but it’s not what you like so there is no possibility that it’s right correct . You never know

      1. I think the rain will come in quicker or mix to rain . I’m going with Nam runs . But I think like Tk said other things as well to focus on the wind is going to be a big problem . The ground is unbelievable soft .

    4. You have to consider its past performance during the cold season and it’s shown itself to be too warm and too far northwest in some instances.

      That doesn’t mean it will snow a foot all the way to Nantucket, but if it’s a 25 mile error, that will make a huge difference in Boston.

        1. I think you consider it and blend it into what you think my happen. So, certainly, I would say that Boston points SE are no longer going to see 100% snow or the huge amounts that have shifted west. But, a large amount of snow could still fall in Boston and a moderate amount in our south shore area before a changeover. And it won’t take many hours for it to happen 🙂 🙂 be safe out there tomorrow with the weight of the snow !!

    5. * No consistency other than a westward shift on successive runs.

      * With that track actually puts Boston into some of the heaviest snow, rate-wise, pre-change.

      * All short-range guidance is further east than the NAM position.

        1. I’m not rooting for one outcome over another. I’m just trying to get my forecast right. 😉

  64. 24 and dp of 15 in NE mass….this storm is going to be loaded and it will snow a lot before it flips to rain assuming it ever does in boston

    3. 40.5F out at the harbor buoy, 16 NM out in the harbor. Probably even a bit chillier closer to shore. Climatology wise, the ocean should have the least effect of the cold season warming the boundary layer at this time of the cold season.

    4. Relatively `warm’ as has been the case all winter, despite some impressively cold nights recently.

      TK will be right, as will the others who say there will be plenty of accumulating snow in Boston. They’re the professionals. I am not. But, I’m just not seeing it. If: a. the low tracks over Boston, which I believe it will (even west of Boston); b. surface temps are marginal at best throughout most of the event; c. ocean temps are relatively `warm’ with winds shifting to a east/southeasterly, I can’t imagine this scenario being conducive to more than a decent front-end thump of, say, 5 or 6 inches, followed by loads of sleet and rain.

  66. Reasons not to trust the nam in this situation just have to look at all versions to see how off it can be all of them somewhat different.

  67. Lower resolution NAM’s (32 and 12) are notorious for hooking too far left in rapidly-deepening storm situations. The 4km can be guilty of this at times. The relatively new 3km has been the NAM family’s best performer so far and this version has the low center considerably further east (near Plymouth MA) and the changeover line much closer to Boston versus inland, and rotates it in a little bit only briefly, AFTER the heaviest is over. This to me represents a more likely outcome.

  71. The only thing though about those 3K snow maps is that it looks like it projects 11 inches for Washington, DC.

    1. I agree they are overdone slightly, but still within the foot + plus range.

      Just west of D.C. is within that range. The city itself probably around 6-8 inches.

  74. Good evening. HRRR, RAP and 3KM NAM All project big snow totals for Boston.

    Here’s a good one.

    Harvey ended the Broadcast by saying he was looking at new information
    and he said on air: “You may be seeing it SNOW harder than you EVER have been
    before” I bleep you not! That is pretty scary crap!!

    1. And his wind gust map had 69 mph gust in Marshfield and 80 on Nantucket.

      I think we’re going to see a lot of things tomorrow we haven’t seen in a while.

      1. Agreed and I am worried sick about it. He had 64 for Boston.
        That coupled with heavy wet snow spells disaster.

        1. Headed to get some rest.

          Leaving heat up a bit higher than usual tonight, then plan to crank it in the morning.

  77. Snowing in NYC. Harvey says he thinks it will start sooner that previously
    thought.

    Good night all. I need to be up early.

  78. Dry slotting concern for long island which thinks NY does not see those totals in the city./ southeast mass could be included in dry slotting but I think it would be in the form of rain so no big deal lol….

    1. That first batch will be fighting some extremely dry air but the real meat will still be getting underway about dawn far south, mid morning Boston area.

    2. From what I can tell looking at radar, snow is breaking out in most of CT and western MA and the leading edge approaching Worcester.

      This appears to be happening a few hours early. Does this mean more accumulation and the storm ending earlier than expected?

      1. Just about none of it is reaching the ground. The air is insanely dry under that snow area. As noted above a few flakes in CT, and NYC. That’s it so far.

        It’s a touch early but no impact on the overall outcome.

    1. As the storm develops, I am wondering if cold air will get pulled down from the north. Not what I want, but I am wondering.

  89. check out the radar out of sterling, va. There’s a crazy band. “wicked high” DBZ. I’m sure its rain but holy crap.

  90. check out mt. holly radar too. gotta love being able to see the actual radar location because the echos are so intense

    1. Street/urban/basement flooding as well. I will certainly be checking mine periodically later today.

  92. Good moring. The Charlie Hole has enveloped Boston.

    Not liking latest Short range either. Oh well, I’ll enjoy whatever comes down. 😀

    1. Was snowing here pretty good shortly after 5AM, but it stopped. Not doing anything now. It’s all around but not here.

      1. Gives you 1 hr to enjoy a relaxing breakfast. 🙂 🙂

        A wall of moderate to heavy precip entering Martha’s Vineyard/Nantucket charging northward.

    2. Charlie…lol.

      I bet he limed and seeded a bunch of lawns on Saturday. I’m figuring it was 75 around the bubble that traveled with him while 70 degrees colder 20′ beyond his truck door.

  93. Well, I have my fingers crossed that, here in Marshfield, we change to rain as quickly as possible, and go through whatever winds come between s10 am and 5 pm without much snow on the trees.

  94. The snow hole over eastern MA this morning has been well modeled by the HRRR. However, the HRRR has been continuing to shift to warmer, joining some of the other warmer guidance. The big surprise of the morning so far seems to be an earlier than expected shift to rain/mix in DC, Baltimore, Philly, and just outside of NYC, implying a warmer than expected storm. We’ll see how that translates to the Boston area, presumably we’d see a similar result. Lower numbers may end up being the way to go, but we have to see how long we can crank out 2-4″/hr later on today.

    1. Precisely my concern when I awoke. I retired thinking we still had a decent shot,
      but now not so much. But it’s not over until it’s over, so we shall see.

      Nothing we can do about it either way.

  96. 7Am Wind has gone from East to Northeast at Logan. I like that, but is likely
    meaningless. Wind at 13.8 mph

  97. At work in Bourne now about 1 mile south of the canal. 32 degrees and a little wind
    I would be surprised to see much snow at all here

    1. secure snow in Boston just until even noon or 1 pm and you’ll probably accumulate 6 to 8 inches ….. Anything after that is bonus snow.

      1. If these short range HR models are correct, Boston should snow
        until between 3 and 4 PM. I realize that is a big if. I’ll be watching and watching the wind as well.

          1. 🙂 🙂

            I’ll never forget Coastal describing it a few winters back in that storm.

            The wind and the wet snow at some point reach that critical point and then it happens seemingly altogether where you can here the snapping of branches, falling of a few trees and there’s flickering not from lightning, but from exploding transformers. And because the power’s out, you hear and see most of it. Of course, just inland from the ocean, tons and tons of trees down here.

  102. I am actually on rt 28 at battles GMC, if we get waves here we have problems brother
    but the canal was calm

  104. 29 in the city now and it will be climbing as projected temp say between 11-12 will be 34 and climbs from there to the high 30’s ( 37 ) would not be surprised at 40 degree readings

    1. Good luck to you and your colleagues in the storm. I hope you’re correct to make the task easier. Go slow if there’s more snow than you expect, it would be quite waterlogged.

  106. We have been lucky down here with snow, hopefully you guys get a thumping with this one, your due

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