Saturday Forecast

198 Comments

9:25AM

DAYS 1-5 (DECEMBER 17-21)
Wide area of overrunning snow this morning and midday brings several inches of accumulation before a combination of warming aloft from south to north and a tapering off of precipitation from west to east puts an end to that. After that, just areas of light rain/drizzle, which will freeze on snowcover and other surfaces over the interior as temperatures struggle to reach or exceed freezing during the day. Eventually, it warms up overnight and that means a round of rain showers will accompany a cold front that will cross the region Sunday. Behind this front, another shot of cold air will freeze anything up that is on the ground, so make sure all areas you want clear are done by midday on Sunday. The first few days of next week look dry, starting out cold then moderating to a more seasonable level.
TODAY: Overcast. Snow in the morning changing to rain/drizzle south to north except freezing rain away from the coast by midday before ending. Parts of the region may see the precipitation end before a change can take place, however. Snow accumulation before 1-3 inches South Coast and Cape Cod, 3-6 inches I-95 corridor to the I-495 belt, 5-8 inches north central MA and southwestern NH. Temperatures rise slowly to around 32 north and near 40 south by the end of the day. Wind S 5-15 MPH.
TONIGHT: Mostly cloudy. Spotty drizzle and a slight chance of rain showers. Patchy fog. Temperatures rise into the 40s. Wind S 5-15 MPH.
SUNDAY: Mostly cloudy. Patchy fog early. Rain showers likely morning and midday, may end as mix from northwest to southeast afternoon. Highs 48-55. Wind SW 10-20 MPH morning shifting to NW with higher gusts afternoon.
MONDAY: Mostly sunny. Lows 15-22. Highs 27-34.
TUESDAY: Partly sunny. Lows 12-20. Highs 30-38.
WEDNESDAY: Partly cloudy. Lows 14-22. Highs 34-42.

DAYS 6-10 (DECEMBER 22-26)
Risk of rain/mix/snow later December 22 to early December 23. Risk of a few rain/snow showers December 24 – not a major system. Fair December 25-26 based on current timing. Temperatures near to above normal. Will refine this forecast in the coming days.

DAYS 11-15 (DECEMBER 27-31)
A fairly active Pacific jet stream pattern continues with one or two storm threats possible during this period. As is expected this time of year, precipitation type would depend on track and overall set-up, but odds would favor rain as it looks like milder air will dominate with a northward-displaced jet stream in this area.

198 thoughts on “Saturday Forecast”

  2. Thanks TK !

    Tom says:
    December 17, 2016 at 9:27 AM
    Calm wind suddenly over to about a 10 mph E wind. Temp jump to 33F. Top layer of snow, 2 inches, is wet. Mix of rain and snow, visibility up to a few miles.

    We do live fairly close to the ocean, so this is for easternmost Marshfield.

    1. Hang in there, I’ll bet you get another inch or 2 on top of what you have.

      Noticed it’s 19F in Portland and 21F in Portsmouth. If the winds back to the N for a time this afternoon ……..

      1. And they will. Even if Boston passes the freezing mark, it will
        be short lived as temps will fall back below freezing. Classic.

  4. Thanks TK.

    Pretty well pounding snow here in Wrentham. We may mix within the next hour, although it hasn’t warmed much. As expected, heaviest snowfall rates near the mix line.

  5. Thank you, TK.

    More snow than I expected in downtown Boston. Coming down moderately. Temperature is up to 29 where I am.

    With respect to this storm the Euro model may prove to have been the most accurate. The warming is happening aloft, but the cold dome is stubbornly resistant.

    1. Joshua, do you have decent line of sight to get a handle on
      visibility. I have so many trees and houses around I can’t see too far to
      get a handle on it. My best guess is visibility is somewhere between
      3/8 and 1/2 mile or so.

      Thanks for the help.

  6. Re-post

    JPDave says:
    December 17, 2016 at 9:28 AM
    Growing up I would have been in 7th heaven to have all that I currently have at
    my disposal to watch storms evolve and monitor their progress. Computer models, Radar displays, Soundings, satellite images and loops, social media and of course
    WHW blog. Truly amazing times!

      1. Sorry…..no idea how that posted

        When my father in law was alive. Your enthusiasm reminds me of his, Dave.

  8. Heavier snow should keep it an all snow event north of the pike. In Boston, there may be some sleet to finish off.

  9. Dave, My guess would be less than a half mile visibility. It’s coming down moderately still and accumulating. A gentle snow storm, but definitely more than just a dusting. It’s nice to be surprised by more snow than expected. It’s often the opposite as storms get overhyped and we wind up with little or nothing.

  12. Just over 4″ and pounding snow in Coventry Ct. Up only a degree in the last hour to 19. I think the back edge of the precip will get here first before any changeover.

  13. I measured 5.5 inches just after 9am and the way the snow is coming down its got be over a half a foot now.

  17. 22.1 here with what I would call light to moderate snow. It is quite fine which I would guess would limit visibility

    We have just a hair over 3 inches. Still no wind. I don’t have the new weather equipment set up yet so no anemometer. There is a great flag across the street that seems to work just as well. It was straight out for the past two days but is not moving at all so far today.

  18. Southern RI is now flipped to freezing rain.
    Friend in Bristol recorded 2.4 inches before the change.

  19. Ok, I now know what I did wrong in estimating the snow from my window.
    I did not account for the snow falling off the sides of the vehicles and adding to
    what “appeared” to be depth.

    I just took an accurate measurement.

    2.8 inches here and pounding SNOW.

    Should easily make the 4 inch threshold and hopefully more. We shall see.

    btw, the temperature is up to 29 here. It doesn’t feel cold out, but then I was
    shoveling the walks and stairs. 😀

  22. Don’t get why all the main roads aren’t plowed at all. When we got that inch a few days ago the plows were out in full force pushing nothing.

    1. East Woburn is being plowed regularly. I guess maybe the DPW finally realized that the east side is just better than the west. 😀

      1. Haha nothing here. Just getting pushed down as cars go over it. TK what’s your thought on cleaning roofs? Wasn’t sure if the temp warmth will negate it? Thanks.

        1. Tomorrow morning’s milder air should take care of a lot and much of the rest will melt or sublimate early in the week. A north-facing slope will be a bit more of an issue in terms of getting it to melt/dry.

  23. That yellow and orange on the radar is creeping up this way.
    When it arrives will it be massive sleet or heavy snow or even worse Heavy Rain????

    1. I don’t think it will make it to you. Not as heavy precip anyways. The progress of that line has slowed, and it’s now a race between the mix line and the back edge of the steady precip. It’s still pounding snow here, 26F. Measured 3.4″ a few minutes back.

  24. Not a fan at all of NWS’s wording. They make it sound like precipitation is essentially steady all day, all night, and all of tomorrow.

    Nope.

    1. A general 2-4 inch snowfall in eastern massachusetts with higher amounts in central and western MA of 4-6 inches thus far. I did not expect some places in barstable county to achieve 3 inches.

  35. Arod, Dave, your numbers will likely verify. Good job. It’s snowing hard right now. A beautiful sight, I must say. I really expected a changeover to rain early after only an inch or 2 and a washout later in the day. While much will melt tomorrow, we will have some snow on the ground and certainly some piles early next week. Who knows, perhaps we will wind up with a `white’ Christmas in Boston.

    1. Indeed, and if it was January (lower ocean temperature) I don’t think the rain would penetrate the coast as much as it is.

  42. JJ, that’s a nice amount of snow. The way it’s snowing right now in Boston we could reach 6 inches. Probably not, but who knows.

  46. In a couple hours, early afternoon, probably need to start watching the surface winds and temps in Beverly and Lawrence and eventually Logan. (Not that it’s exactly warm up there now) But, I am interested to see if and how far south there’s yet an additional small temperature drop.

    1. AS soon as that wave gets to the coast or otherwise passes our longitude,
      the temperature WILL crash. I can feel it. I have seen it so many times before,
      even when NOT forecast. 😀

  47. Vickie – Happy happy very belated anniversary! I love that you had the rehearsal dinner at the Lexington Sheraton! As for today – I really think the WHW enthusiasm must be contagious. The snow is pounding here in Westford and I think I’m actually enjoying it! I would guess about three inches now here.

    1. Thank you, GettingBetter. See what this blog does…..it sucks you right in. You gotta love it here

      I’m about to go out and feed birds. Although, somehow there is seed in the feeder that I have not filled since late summer. Either the elves or a neighbor took pity on my poor birds 🙂

  50. MIX line,

    I “think” on this radar screen shot, the bright Orange line represents the SLEET line
    and right behind it, the changeover to RAIN. The yellow ahead of it represents the big
    snow flakes just prior to the change to sleet.

    Click on image to enlarge

    http://imgur.com/a/HOq9V

      1. Watching the loop it was making steady progress towards my area, BUT on the last few frames it retreated. Perhaps it NEVER makes it here. 😀

    2. I think that’s accurate. I’m in North Smithfield which is located in northern most RI. Flakes are large and becoming less numerous. I have not officially gone outside but to me it’s possible it’s beginning to mix. The end of the accumulating snowfall is near. However, I think this storm overachieved a bit in a few locations.

  51. Very close to 4 inches here or perhaps a bit more as at least an inch, perhaps more
    has fallen since I shoveled and measured. 😀

  52. I’m pretty impressed by this storm. I haven’t measured but i wouldn’t be shocked if we end up going over 6″ from this

    1. That little development on the Warm front saved the bacon, else it would have
      been a quick inch or 2 and over to rain.

      1. Well, it measures 2, but it’s a bit settled. I guess I’ll go with 2, but one could reasonable argue 3 if not for the last hour or snow of either very wet snow or rain/snow mix that compacted everything.

        This seems like a true changeover. Don’t see a hint of a wet snowflake falling anymore.

  58. Still snowing moderately to heavy, but temperature has reached 32.
    Not good. Bad sign. I suspect that mix line is fast approaching.

  60. The back edge of the Precipitation is moving Eastward rapidly. The mix line is
    moving Northward fairly quickly. If I had to guess, right now I’d say we change
    over here, prior to the precip shutting off. It will be close.

  61. Mix line approaching the I95, Rt. 24 interchanges on 93/128.
    That means it’s only 8-10 miles from me, while back edge of precip is about 100 miles.

    Guess which will win out?

  63. I was nervous yesterday putting an 8 in my forecast amounts…
    Seeing at least on 7-inch amount so far makes me feel better about that gamble.

  64. There is quite a surface boundary (temp gradient) setting up with, SE Mass and the immediate coastline up through Logan at or above 32F. Accompanying that is a light E or SE wind.

    On the other side of the front, low to mid 20s, with a very light northerly surface flow.

  65. Just shy of 5 here

    We have a very fine snizzle in Sutton. Not sure if that is correct term but I like saying it

    Some flakes tossed in

    Temp still 24.6

    1. As I type that, looking out window, seems snow and snizzle are having a battle with snow trying to make a comeback

    1. Same here. Just came out of Patriot Place 20 min ago and was snowing, got 1 mile down route 1 and the switch occurred.

  67. Just shoveled again and took a measurement.

    Funny but exact same total as WxWatcher, 4.3 inches, BUT still SNOWING
    moderate to heavy. However, bigger flakes now, so that is usually the kiss of death!
    We shall see.

    11:35AM and still SNOW

  71. That is exactly what happened here, huge flakes before the changeover to sleet. Always the kiss of death! Out to shovel now before this stuff gets any heavier. Now light freezing rain and 24.

  77. Mix just about to get to me as the precipitation tapers off. Time to measure and do snow removal. I have a crew of 3 so this should be quick.

    Check in later!

  78. Nice little snowstorm. Can’t complain. This is what December `should’ be like. What a difference a year makes. I know it’s going to `warm’ up tomorrow and by Wednesday, but at least it won’t be weirdly mild next week. Seeing bees and blossoms on Christmas Day last year was just not fun.

  79. Glad I bumped my snow amounts up a tad on the forecasts I wrote early this morning. Here at StormHQ World Headquarters I awoke at the crack of Noon to a 33-degree rain. (If you got home from work at 5:30am, you’d sleep until Noon too).

    Final snow tally was 3.7 inches.

  82. 16Z HRRR show Boston down to 31 by 20Z (3PM) and 27 by 0Z (7PM)

    Be CAREFUL out there this afternoon and evening. Cracks freezing again by 9PM
    and up to 44 by 3AM.

  84. So, I have a question or two. Here in Chelmsford, at 11am, it was 24* and snowing. Now, at nearly 1pm, it’s gone down to 21*, and for a little while, it was a mix/sleet/snow. Oh and now, it’s snowing again! Is the brief changeover due to different temperatures at different layers in the atmosphere? What would make this happen?

    1. Yes to question 1. Question 2 : I think we all saw that as well at some point further south of you earlier in the day. Having the column warm above 32F isn’t always a smooth process and it can have a thin slice of mild air move in, then cool off just enough again due to factors such as heavier precip or lifting of the air. Eventually, had the precip continued, even there would probably be freezing rain by now, as enough mild air above would have overcome those factors.

  86. Thanks, TK.

    We got a little over 5 inches of snow here in Sudbury. It was a light freezing rain about 1/2 an hr. ago. Also, it’s 26 degrees at the Willow Hill School here in Sudbury.

  87. My weather station has not shown the temperature getting above freezing so far in Wrentham even though snow ended a couple hours ago. A walk around outside revealed a pretty solid crust of ice on the driveway and on top of the snow.

  88. 3.5-4 inches here in Quincy. I timed shovelling to just before we went above freezing. It was raining by the time I finished. Hoping the ice-up isn’t too bad later. We’re heading out to have some fun.

  89. I would say that the rain/snow line just barely made it to Boston and it only produced a very light rain thankfully didn’t make the snow any heavier. It was fairly easy to shovel, but the snow stuck to the shovel much of the time. Could have been worse had it been pouring.

    Logan 1:00 pm obs. = 33F N 5

  93. Unfortunately these boards will quickly become quiet for potentially a couple of weeks. It’s so much more fun when we all have a snow event to get excited about. Will need to watch for the 12/22-12/23 period although not looking very impressive at this time.

  95. So my forecast seemed to have vertified nicely which I had for a bit. I have a feeling most that have 4 or 5 inches and less will see most of it gone by the end of tomorrow if not Monday and tuesday. There is hope though, Chance of that system TK has been mentioning to through some precip around the 23. As long as its not the 22nd I am good. I just want this semester to end.
    this is what the Canadian is showing. GFS is not showing it but the euro show something. with what I have I am not sure if it tracks to the north or if it does something similar to the canadian.
    http://www.tropicaltidbits.com/analysis/models/gem/2016121712/gem_asnow_neus_31.png (subract 3 inches its showing for this system) so about 8+ for Thursday night into Friday) Its a chance. Again not sure how the euro sends the system as it skips in 24 hour increments.

    1. This one unfortunately looks to be a lakes cutter. We need a secondary low to bomb out to the south of use for the Canadian model to verify. There could be a lot of qpf with this one however.

  96. A general 3-7″ region wide snowfall. My thought around Thanksgiving was this would happen around the 20th-22nd and TK I think was thinking around the 15th-17th. Maybe the evolution of system was slightly different than what either of us thought for our first region wide moderate snowfall, but I would say nailing the timeframe like TK did is why he is one of the best to forecast anytime, any region.

  97. Hello again.

    Just cleaned off the car and scrapped the walks one more time and applied salt.

    32 with FREEZING DRIZZLE here. No sooner had I cleaned the windshield when
    there was a thin coating of ICE on it.

  98. Matt, you certainly said it re: CMC for 12/23.
    Pretty sizable system, although as depicted would crunch areas just back from the coast
    and leave the coast largely unscathed. But that is 6 days off and can change.
    Of course the GFS does not have it. 😀 Checking Euro now.

    1. Nope, Euro has a warm system for that time frame.
      Honestly, I think we are done with SNOW until sometime after the
      1st or perhaps even the 2nd week of January. I hope that is NOT the case.
      We shall see.

  100. Was up to 29.3 a couple of minutes ago. While I was catching up on comments dropped to 28.9. Not sure if that trend will continue. As WxWatcher said, it has not gone above freezing here today either. Son in law about to head out to clean up. We have a snow blower in the garage and he shoveled by hand. But then we have gloves and hats also and he didn’t use those either.

  101. Well I can confirm that my rain gauge does not have a heater.
    Reading 0.00 inches for today. Goes to show you nothing had melted here.
    I suspect I’ll start getting a reading overnight when the snow starts melting. 😀

  102. I know the CMC is unreliable but tis the season for miracles so hoping the solution that model shows happens.

  103. If I’m reading obs correctly, Logan had 0.5 melted for this event.

    Plymouth, 0.51 melted. Beverly, MA : 0.57 melted. Worcester, MA : 0.62 melted

    Fairly consistent amount region wide.

    1. It’s a real shallow push of cold air though ….

      Worcester Airport at 1,000 ft is already feeling the effects perhaps of the next milder system going to our west tomorrow morning.

      They are reporting a light SW wind and their temp went UP 2F during the last hour.

  105. 4.5 inches was my total here in Woburn.
    It quit as a mix of sleet/snow at 12:15PM, then after a break, we had light freezing rain about 1PM for a while, then just patchy freezing drizzle since.

  107. The draining of low level cold back to the south behind the precipitation is no surprise. It’s a result of the weak wave of the boundary. Temps will stay pretty chilly for several hours and not really go up until much later tonight into early Sunday, pre cold front. Even eyeing the risk of thunder with tomorrow morning’s rain showers.

      1. I’d rather be in Florida. 80 and sunny today in Orlando. I’d much rather have played golf today than break my back shoveling snow.

  110. Here in Northern CT we ended up with 7″ of powdery snow. As far as I know there wasn’t any rain, freezing or otherwise. The temp never went over +15 yesterday and it’s only like 22 right now.

    1. The difference between an overrunning event and one associated with a fully developed mid latitude synoptic scale cyclone. 🙂

  112. Looking at the 21z HRRR, it shows the potential for heavy downpours and possible thunderstorms in the 5-9AM window tomorrow morning, as the temperature rises close to 50. I’m with Hadi and Vicki; how could any weather geek not find weather like this exciting?

  113. 18z GFS starting to catch on to something on thurs-fri…as it is now it’s too warm, but it now has something in the vicinity

  114. I’m not even close to being convinced that something Thursday/Friday doesn’t carry a snow threat for at least part of the region.

  116. jP this is one step
    http://www.tropicaltidbits.com/analysis/models/ecmwf/2016121712/ecmwf_T850_neus_6.png
    then second frame is
    http://www.tropicaltidbits.com/analysis/models/ecmwf/2016121712/ecmwf_T850_neus_7.png
    look at the canadian (tad further south)
    http://www.tropicaltidbits.com/analysis/models/gem/2016121712/gem_T850_neus_21.png
    then it moves
    at same time as second frame posted by euro
    http://www.tropicaltidbits.com/analysis/models/gem/2016121712/gem_T850_neus_25.png

    exactly how does the euro move through does it travel across NY state or does it travel over us or does it take a similar route as the Canadian

    JP I know you said it was a warm storm but what is its track

  118. Thunder in Wrentham (and a way too early wakeup call). Great call TK, and picked up very nicely by the HRRR.

  119. 51 degrees with a 50 degree dew point and rain overnight. My 5 inches of snow is down to 2 inches is spots and bare ground in a lot of places.

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