Thursday Forecast

1:49AM

DAYS 1-5 (DECEMBER 21-25)
From Solstice to Christmas, this will be an action-packed 5-day period, so let’s get to the details. First, we had a cold and tranquil day as autumn bows out and winter takes its place as of 11:28AM today, but this cold high pressure area over the region is one ingredient and an upcoming complex precipitation event that will be generated by a warm front trying to cross the region later Friday into Saturday. As we often see here in New England, dense cold air will be trapped at the surface and even though it warms aloft, the cold air will hang tough near the ground, especially over interior sections. Before it warms aloft for the rain/ice situation, much of the region will have cold enough air above to start as snow, with the exception of coastal areas south of Boston through the South Coast, which may start as snow, mix, or rain and will have negligible accumulation of snow. A minor accumulation of snow is likely generally from a Boston to northeastern CT line northward, with some moderate amounts possible from near the MA/NH border northward. But snow is the lesser worry in comparison to the icing which may be significant in interior areas especially near and west of I-495 and mostly north of I-90. It may take until sometime around midday or afternoon Saturday to scour out the last of the cold air in much of the region, and it may never leave the deeper valleys. So the degree of icing will depend on how much rain falls once it is warm enough aloft to end the snow. It looks like 2 main surges of precipitation will occur, the Friday midday and afternoon portion which should be the snow (mix south) to ice (rain south) transition, and then another surge sometime Saturday. A developing low pressure wave may bring one final push of heavier rain to the region sometime Saturday night when temperatures should be their relative mildest. Surface temperatures will have to be closely monitored to determine where icing will occur and persist. By the time we get to Sunday, which is Christmas Eve, we’ll be in a slice of drier air but with some cold filtering in. This sets the stage for the next precipitation threat as a new low pressure area develops south of New England and likely passes just southeast of the region. This will be a position that allows snow to occur for at least interior areas, and rain or snow near the coast, for the overnight hours of late Christmas Eve and into Christmas Morning. Leaning toward a colder scenario with more snow than anything else. The details of this threat are yet to be fully determined but whatever happens should be winding down by the end of Christmas Day, based on current timing. So, lots to follow and here are the forecast details…
TODAY: Bright sun into afternoon, filtered by high clouds late. Highs 28-35. Wind NW 5-15 MPH.
TONIGHT: Clouds increase and thicken. Lows 16-24. Wind N under 10 MPH.
FRIDAY: Overcast. Precipitation arrives west to east late morning and midday as snow except snow/mix/rain South Shore to South Coast, continuing through afternoon with accumulation of 1-3 inches northwest of a Boston to northeastern CT line, 3-5 inches north central MA and southwestern NH, and under 1 inch to the southeast of the Boston to northeastern CT line. Highs 28-32 except 33-38 coast. Wind light N to NE.
FRIDAY NIGHT: Overcast. Areas of fog. Any snow changes to rain but freezing rain is likely many interior areas and especially I-495 belt northwestward, and possibly some icing extending to near the coast from Boston north, then precipitation may taper off for a while. Temperatures steady 28-32 interior, 33-38 coast but may rise slowly overnight especially coastal areas and southeastern MA/RI, but may briefly fall in coastal NH and northeastern MA to Boston. Wind light N to NE.
SATURDAY: Overcast. Areas of fog. Periods of rain which may still be freezing in central MA, interior eastern MA, and interior southern NH, especially valleys. One more period of mainly rain possible evening. Temperatures rise very slowly interior valleys to 32-39, 40-50 elsewhere. Wind light N interior areas, light E to SE elsewhere, shifting to W and increasing to 10-20 MPH overnight.
SUNDAY – CHRISTMAS EVE: Partly cloudy daytime. Clouding up at night with a chance of snow overnight. Temperatures 30s interior and 40s coast early, slowly falling later.
MONDAY – CHRISTMAS DAY: Mainly cloudy morning with a chance of snow, possibly mix/rain southern coastal areas. Partial clearing afternoon. Temperatures generally steady upper 20s to middle 30s.

DAYS 6-10 (DECEMBER 26-30)
Mainly dry and cold weather follows the active period and then another storm threat may occur before the end of the 6-10 day period.

DAYS 11-15 (DECEMBER 31-JANUARY 4)
Cold pattern continues and another storm threat presents itself in the very early days of 2018.

189 thoughts on “Thursday Forecast”

  1. Friday under performs in snow. Cloudy with scattered and light precipitation will be the predominant feature during the daytime hours. Friday night and Saturday AM a more icy / cold scenario than previously anticipated with greater Q during this time frame. 0.1 to 0.3 ice accreation. GFS/ECMWF will not be your model friend in the next 48 hours. For you modelogists go short-term here. Even more important go wind direction, temps – surface and upward, and dp’s and dry cold air battling with WAA.

    1. Thank you, but what are your feelings for Christmas Day?
      It “appears” to be trending snowier, but who knows. tx.

        1. Many Thanks again.

          If fast, then accumulations not so great? I know one can’t put a number out this far in advance, but is the thinking light like in 1-3 or 2-4 or a tad more moderate like 3-6 or 4-8. I don’t suspect major at this point.

          Many thanks again.

  2. Best areas for snow Friday will be MA RT 2 North and NE MA / SE NH.

    Merry Christmas and Happy New Year! I don’t post often anymore because often my thoughts are redundant, but I read most everyday. Simply, TK gets it.

  3. I would expect winter advisories to pop up later today for the interior of SNE with the icing potential tomorrow evening into Saturday morning.

    1. We need to monitor that wind direction. It is “possible” that some icing occurs even in Boston. We shall see. Any easterly component and the city is spared.
      It “looks” to have Easterly, but then go North later, so we’ll have to watch.

  4. I’m just thinking about all those, who might have a plan for after work ends Friday, to head west on the Mass Pike or any interstate north into northern New England or even a rte 84 down into interior Connecticut. Hopefully, folks can adjust their travel plans and still make it in time for Christmas.

    1. I had the same thought also. That route always sees heavy traffic for holidays.

      My son heads to very southern NH to pick up his son and head here for weekend. I’m thinking once out of Boston he will hopefully be ok.

  5. I was about to post (as my heart goes from a-fib back to normal hahaha I love my medication) that I’m leaning to the low ends of my snow ranges still for the reasons that were posted above by JMA.

    I also feel that the colder/faster scenario is the best one regarding a Christmas snow. We get the snow, minus the ice, but not too much snow to shut down travel. Still a few days out obviously but this is how it’s looking.

    1. TK,

      You seem to be having many episodes. Has your doc considered
      Cardiac Ablation? Each case is different, just wondering.

      Hope you are feeling better.

      1. The medication I take works so well when I have them that we don’t need to go the route of ablation at least for now. He also said that multiple episodes over a period of time is not out of the realm of normalcy for what I have. So for now, I just pop the extra pill. πŸ™‚

        1. Oh, great. That’s good news.

          The reason I asked is that a friend had so many
          episodes that just would not stop that it was
          debilitating, so he went through several ablations
          and is finally doing better.

  6. Thanks TK, great discussion. Thanks to JMA as well. I pretty much agree on all points. An active period but with very little snow for most of SNE through Saturday. You’ll have to get to far northern MA and especially NH/VT to see more than 2-3″ on Friday-Friday night. Icing is the real concern. Warm air aloft will not be denied. It’ll just come down to the surface temperatures. How quick does the low level cold get scoured out. Along and outside 495 looks to be the main threat area.

    As for the Christmas storm, I agree on fast movement, but I’m not convinced that means snow. I could see it hugging tighter to the coast. But we need at least another day to have a better idea of that.

    1. I do think the cold air delivery will be adequate both surface and aloft on Sunday, just ahead of the system. I do agree it may warm enough at least over Cape Cod for rain versus snow. Like the colder scenario all levels elsewhere, but certainly not a lock.

  7. Thank you, TK. Excellent post with all the information anyone could need to plan for their holiday weekend.

    1. Great song. Love Clapton. Thank you.

      And I really enjoy the instrument solos. Long tall woman…the long version…is one of my favorite. But my all time favorite is the drum solo in A Gadda da Vida

      I hope you and your family are well!!!

    2. I love everything Clapton has done. My favorite song by him though is “Forever Man” because it reminds me of 1) Being chased home by a thunderstorm from Bedford to Woburn on a summer day in the mid 1990s and 2) Chasing a thunderstorm from Woburn to the South Shore around the same time.

    3. Always loved that song. I was just thinking the other day that a true rock sound is sorely missing in modern music and then someone linked me to this band called Greta Van Fleet… Give it a listen… They sound a lot like Led Zepplin:

      https://youtu.be/aJg4OJxp-co

      1. Pretty cool. Didn’t know of this band. I like their sound.
        My only complaint: I want that 3rd guitar!! I don’t like
        3-piece bands as the sound is clearly missing something.
        Never liked 3-piece, not even Green Day, until they added
        that additional guitar, then they were complete.

    1. There is one benefit of the upgrade of the GFS that I have noticed, and it is that it catches these features before other models quite often. At the moment, I buy it.

      1. Well, I suppose that is something.
        Funny, it has been advertising this for a couple of days.
        First just a hint of it and then gradually more and more so.

        So, you believe that the final outcome will be closer
        to the GFS solution than say to the EURO one?

        Thanks

  8. As Tk had mentioned in a post I wouldn’t trust anything the model shows for Christmas till the earliest tomorrow and obviously today’s runs for tomorrow. Christmas is still a complete up in the air forecast as we know that here . My gut instinct tells me tomorrow Boston/ south minimal impact .

    1. The city itself should end up with under 1 inch of snow Friday and very little icing, but we have to watch for a low level cold drain down the coast, so I can’t rule icing out entirely for the city.

      As for the Christmas threat, my feeling at the moment is snow for Boston, no mix, enough to have to clear, but not enough to prevent travel.

      1. Thanks if enough to clear even a couple of inches if it was that would keep us here for awhile . I guess the timing it Shuts off and amount is the key thing . Can you comment on the post from WX. Thanks Tk.

        1. 4 days away the only thing I’ll say about timing is I’d lean toward morning-midday event, regardless of p-type and intensity/coverage, at this point.

  9. Ok, The 12Z NAM is in. A couple of Observations.

    1. It pretty much is in agreement with TK and JMA assessment of the tomorrow
    event. Ie, most snow to the North, with a bit in Boston and next to Nothing South
    of the city.

    2. It strongly hints a NO storm per se on Christmas Day, however, at the same time
    it does suggest that it wants to develop a Norlun trough. Just does not got out
    far enough in time. Just what I perceive from looking at the charts near the
    end of the run.

    Take a look at the isobars on this 12Z NAM at 84 hours

    https://www.tropicaltidbits.com/analysis/models/nam/2017122112/nam_mslp_pcpn_frzn_us_28.png

    1. I have a feeling those totals will be a bit less and shifted S&E some.

      Dying to see what ye ole Euro shows with the 12Z run. πŸ˜€

  10. I will root for that to happen since that would be a White Christmas.
    Icing across the interior tomorrow night looking like a good bet.

  11. It’s too bad we can’t just get a couple inches of snow and be done with that system tomorrow night instead of having to deal with icing especially in the interior.

  12. Regarding the GFS surface temps, I would go back to something JMA said earlier; global models are not your friend here. Gotta go with the high res guidance, and even they sometimes miss the persistence of low level cold. The 95 corridor and even a little ways outside of it should go above freezing pretty easily. But 495 and outward has the potential for prolonged icing Friday-Saturday. I think we’ll see some places in northern MA exceed a quarter inch of ice, which can have significant impacts.

    1. That’s what I’m afraid of although I’m about 600 ft above sea level. Any idea at what elevation the temps are expected to be above freezing? Thought I saw earlier on a map that it was above 2500 feet?

  13. I just hope that Logan reaches normal snowfall for the month (9.0″). It would be a shame not to at least get that much with all the forecasts of a front loaded winter. Quite frankly I was anticipating a bonanza of snow by now “a la” 2015, at least close to double December norms.

    1. Not sure where you got the idea of a bonanza. I said expect an amount of lighter snow events in the area versus 1 or 2 huge ones.

      1. Sorry about that TK, I must have missed that part of your outlook. Having said that, I definitely must understand better the definition of “front loaded”. πŸ™‚

  14. Daylight gets longer after today, like Tom said.
    Best part about today,?
    90 days till spring!!!
    And yes I know there could be a foot of snow and 20 degrees on that day. BUT… more warm weather to come after that than cold. So all the blog readers who hate winter and snow, take the little things to get through to the other side.

    1. I have better news for you ….its only 89 days to the vernal equinox. πŸ™‚ πŸ™‚

      We are ‘lucky’ in the northern hemisphere.

      Because aphelion (earth is furthest from the sun on July 4th and thus earth is cruising a bit slower in its orbit around the sun), summer is 93 and 3/4 days long.

      So, while it always doesn’t seem so in New England, currently, summer is 4 and 3/4 days longer than winter.

      In 10,000 to 20,000 years, it will be reversed as aphelion will happen during the northern hemisphere winter.

  15. Daylight does get longer overall but when we switch back to DST in early March, my mornings only get dark again until about mid-late April. πŸ™

    1. I get up at 4:30 am to get ready for work. I leave the house st 5:15 am, so unless it’s late June/early July, I always go to work in the dark. I’d much rather it be light when I get home in the evening.

      1. Blackstone, totally feel ya on the daylight, I rather have more day light when I get home than wake up to day light, I can do more with daylight after work/classes. I rather not have shining sun in my face in the morning. Evening night makes me sleepy earlier lol

    1. Interesting ….. fairly similar to the 12z GFS with respect to amounts, placement and features that are causing the snowfall.

    1. Unless you are the snow plower away from their family Christmas morning. Not trying to be a scrooge, but there is always a different side to the equation. πŸ˜‰

      1. Sure is looking that way . I’ve been working 7 straight busting my ass and was so looking forward to a 4 day weekend . I don’t want the money ( which would be jackpot money for me ) I want to be with my family.

  16. Winter Weather Advisory just up for the county I live in in CT. I would expect more areas in SNE to have a winter weather advisory.

  17. I usually would have maps up on my blog, but I just been to busy to do it.
    Predictions
    snowfall.
    Less than 1 inch south of the mass pike, East of I95. southern new england. Snow to rain.
    1-3 between the mass pike up to rt 2, east to I95. Snow to A period of Ice, freezing mark slowly makes its way north changing all precip to rain besides for usual cooler locations and valleys where the cold air sits in like TK alluded to up above. I think some could see near a quarter inch. of Ice out of this thing.

    3-6 with isolated higher amounts north of rt 2 up into VT and NH. Down east maine. Mixing with/ changing to freezing rain.

    highest threats of greater than .15 of an inch of Ice accreation. merrimack Valley, CT valley and usual cooler locations of the interior.

    Christmas day storm Not sure how fast it will be going, I think Sunday night through X-Mas day instead of just a evening/morning thing. ) I am leaning towards a light/marginally moderate event. We won’t know until Saturday.

  18. Winter Weather Advisories now up for a good chunk of SNE which is no surprise given the potential for icing.

    1. All of the global models will have difficulty with timing of energy beyond the Christmas Day event for a few more days before any real idea is had.

  19. I’m watching for the possibility of some enhanced ocean effect snow along the MA east coast tomorrow, Boston northward but Cape Ann especially. If it plays out right, it could add a couple inches to snow totals there. Some of the hi-res guidance hinting at it.

  20. I’m going to end the debate once and for all.

    It is not wrong to want snow.

    It is not wrong to not want snow.

    The bottom line is this: Mother Nature doesn’t give a rat’s patoot what you want and don’t want. So the best thing to do is accept what happens and make the most of it. That’s life. I’m not unsympathetic to anybody. I’m a realist.

    Moving on… πŸ™‚

      1. Snow is never good. Snow sucks. Snow stinks, snow blows.

        πŸ™‚
        And yes, the weather does what it does. Or doesn’t care what anybody wants, although sometimes I wish it would.
        πŸ˜‰

        1. If I could offer a word of advice…old ladies are known to do that

          Breathe

          Nothing we do will change a thing. Worrying about it will, however. It will certainly impact the anticipation of a very special day…..or days if plan b is needed. And as my mom wisely said….anticipation is half the joy

          In the meantime, i plan to enjoy TKs discussion, his words of wisdom, the links by JPD and others and the discussion around those

          I guess that was more than one word.

      2. It wasn’t about agreeing about disagreeing. We’ve already done that. I said it was not wrong to like or dislike snow (or any type of weather).

  21. Nice NWS discussion re: Christmas and they do mention an inverted trough.

    Christmas Eve into Christmas Day…

    Ensembles and 12z models are showing fairly decent potential for
    accumulating snowfall, mainly from later at night on Christmas Eve
    into Christmas morning. Models are keying on short wave energy
    rounding base of broad upper trough, which are highly subject to
    timing differences and errors at 3+ days out in time. What we have
    been seeing over past few model runs is an open wave at 700 mb that
    eventually closes off to our east, with a range of surface low
    tracks from just off SNE coast (12z GFS) to well outside 40/70
    benchmark. Even if more offshore track (12z ECMWF) verifies presence
    of an inverted trough extending back toward coast would still bring
    accumulating snow to much of SNE, especially to RI and eastern MA.

    These inverted troughs can easily “overperform” and bring more snow
    than one would normally expect with a more offshore track. That
    said, overall pattern with an open wave aloft which is progressive
    would suggest most likely snowfall accumulations somewhere in Winter
    Weather Advisory range (perhaps 2-5″) and not an extreme event,
    although a few spots could come in with slightly higher totals.
    Certainly something we will fine tune in next day or so, especially
    once models are able to determine this short wave`s interaction with
    what occurs Fri-Sat. Certainly enough to provide some holiday cheer,
    however.

        1. Right. Someone is going to fly over with a giant copter and tip a horse trough full of ice crystals. That’s how it’s done. πŸ˜›

  22. According to Harvey, the snow will occur from midnight Christmas Eve through midday Christmas Day with several inches expected.

    1. Agree with Harv at this point.

      If this forecast verifies the lesson about models will still not be learned. Everyone will go right back to being sure about how things are going to go days in advance.

  23. TK – What are your thoughts about the possibility of ocean enhanced snow for eastern sections tomorrow? Wx Watcher mentioned it above.

        1. The way Harvey is talking 12-12 with possibly moderate snow . Lots of folks will be late for dinner .

            1. That all depends on the amount that falls and the timing Tk and the obstacles the snow professionals will face with cars on the road especially the highways that always get gridlocked on the holidays and that’s dry conditions.

              1. Yes I know all of this. We have snow threats every year. Holiday or not, the approach is the same…

                There is heavier traffic on Thanksgiving than there is on Christmas, so volume should not be a big issue that day. We’re also not talking about a blockbuster storm here, but more likely a light to moderate snowfall over a 12 hour period.

                1. Indeed. We’re New Englanders and 4 or 5 or 6 inches of snow is not going to cause major problems. It’s just not.

                  I once drove from Stowe Vermont to Waterville Valley New Hampshire in a blinding blizzard. I had no business being on the road, but I was. Made it with no problems whatsoever.

                  The point is, we can handle 6 inches of snow.

                2. I can’t count the times I did the same. And we drove home from Stowe in an ice storm and that time we had no busimess being on the road.

                  Our friends to the north, however, were never stopped by snow. It just was a part of life. Not sure if it has changed. Folks don’t seem as accepting nowadays.

    1. A little is possible but I don’t think it will be significant. Initially the air will be a touch dry at lower levels with not much of a moisture feed off the ocean.

  24. GFS for a few runs now has been showing a big dump of snow late next week into next weekend. We shall see as its way to early to buy into that solution.

  25. There is a lot to read here. TK are your thoughts the same for tomorrow as they were this am? Starting late am? Daughter trying to decide whether to send son to school tomorrow. They have a full day and his bus ride home is an hour on mostly narrow, winding streets.

    Thank you, sir!

    1. For the most part yes. I think there may be a few insignificant flakes around in the morning, and then the steadier snow develops north to south while moving eastward during the midday-afternoon.

      There are some indications to me it may not warm aloft quickly enough to go over to freezing rain until sometime in the evening, and then it will be a race between that and a lull in the precipitation.

      1. Thank you very much. Daughter thanks you also. Grandson particularly thanks you. He is not a fan of missing school.

  26. Schools and districts well to the north into NH already closed for tomorrow. An extended vacation for some. Maybe more by morning?

  27. 00z gfs looks robust for Xmas day. 3-6 or 4-8 seem like a good bet to open on this bidding. See what other models overnight are showing.

  28. Good morning. Some early flakes here in Boston.

    Latest model trends “appear” to have upped the snow for Boston today just a tad.
    We shall see.

    Re: Christms
    Still some variation. Will post a few maps soon. Still have not looked t Euro

    GFS still advertising a major snow event now 12/30 into 12/31. This is at least 3 successive runs.

    1. fwiw, the Euro is not so bullish for Christmas Day, perhaps 3 inches for Boston.
      Euro is on board with GFS for a whopper on 12/30 with 12-18 inches for Boston.
      We will really have to watch this time frame. Still out there, so it could go poof or pass harmlessly off shore.

      1. Here are some storm total snow accumulations for few cities;

        Boston
        today: 0.6 inch
        12/25: 1.3 inch
        2/30: 16.1 inches

        Sutton
        today: 0.9 inch with 0.33 inch ice later
        12/25: 3.6 inches
        12/30: 11.4 inches

        Holden:
        today: 2.1 inches wiht 0.66 inch ice acreation later
        12/15: 4.1 inches
        12/30: 9.5 inches

        Woburn
        today: 1.5 inch with 0.2 inch of ice later
        12/25: 4.9 inches
        12/30: 13.6 inches

        Marshfield:
        today: 0.0
        12/25: 0.1 inch
        12/30: 19.8 inches

        I can’t keep adding towns. I spread it around some for a representation.

      2. Euro has basically nothing on Xmas southeast of a Boston to PVD line. 1-4” for for most but ramping up to 5-6” near the NH border.

        The 12/30 storm jackpot however is centered more right along the i95 corridor and points southeast while the GFS pretty much hammers the entire northeast.

        Plenty to track in the upcoming holiday week….

          1. I see poor Tom gets a lump of coal for Christmas morning, not even a morsel. At least Boston will receive the true definition of a white Christmas…albeit just barely. πŸ™

            But I also see that he makes up for it big time come the New Year! We shall see. πŸ˜€

  29. snow has picked up in intensity here in JP from about 20 mile vis all the way down to perhaps 10 miles. πŸ˜€ πŸ˜€ πŸ˜€

  30. just looking at radar trends, it looks as thought boston may sneak into the southern extent of today’s snow.

  31. The dp depressions are large ….. Interior surface temps may struggle to get above 20F today, because the temps will drop this morning, while the Dp’s rise ….

    So ….. watch out this evening in towns near the coast that edge above 32F today. It may go from drizzle and not slippery conditions to freezing drizzle and icy conditions in a short period of time.

  32. The fact the EURO is on board at the moment for next weekend makes me pay a little more attention to the snow threat next weekend. Of course its over a week away and a lot change. GFS has had this snow threat for a few runs now.

  33. Steady light snow up here in Groveland, with a coating of snow on the ground….very much feels like Christmas!

  34. Good morning…
    I’m going to reboot my computer then update the blog.

    Before I do that a couple quick headlines:

    Yes I did talk about this finger of snow early (somewhere in the blog comments). The “main event” is still later this morning on.

    My forecast amounts for this event will be adjusted VERY little but essentially remain the same.

    The precipitation will essentially shut off for several hours tonight when the atmosphere is ready to produce sleet/freezing rain in much of the region – this will cut down on ice accretion.

    Most of the freezing rain will fall back from the coast from near I-95 westward through central MA and into southern NH during the pre-dawn to daylight hours of Saturday, but this may lull too and further cut down on ice accretion. That would be a good thing.

    Only pockets of freezing rain should exist as the final batch moves through Saturday night as we should have a very short-lived push of milder air taking the remainder of the region above freezing save for the deepest valleys.

    If someone misses out on Monday’s snow, it’s probably Cape Cod only.

    1. Thank you, TK, for the update while you are preparing today’s blog. Very much appreciate your going the extra mile!!! As always πŸ™‚

    2. Your efforts always appreciated.

      I’d be interested to know what’s in store for metro Boston – the urban heat island. Ice isn’t great for driving, but roads get salted. Sidewalks become treacherous. I’m glad this ice isn’t going to last.

  35. Just arrived at the office. ZIPPO snow on the way in and ZIPPO walking to the office front door. I couldn’t find a single flake drifting down. πŸ˜€

    Anxiously awaiting the 12Z NAM which should start spitting data within 10 minutes
    or so.

    Interested in seeing the NAM placement of the Christmas low and the attendant
    snow shield and where it sets up.

  36. New post!

    And if you have any questions about your specific area please ask me in the comments section of the new post and I’ll do my best to answer them as promptly as possible. I’ll be running some errands with mom today. πŸ™‚

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