Thursday March 18 2021 Forecast (7:33AM)

79 Comments

DAYS 1-5 (MARCH 18-22)

A hint of spring, a taste of winter, that’s how we roll here in March, and it will be no different the next few days. We had a nice day yesterday, ending up with plenty of sun and relatively mild air for mid March (very late winter), and today will have its own relative mildness to it despite an overcast and eventual rain moving in. But cold air is not far from us and will be making its way steadily south as low pressure passes south of the region tonight and early Friday on its way to sea. This will flip the rain to snow from north to south, and allow for some generally minor accumulation before the system exits. The “worst” of the snow in the pre-dawn of Friday will be to impact visibility for anybody driving. Heavy enough snow may coat some secondary roadways and walkways for a short while, making them slushy/slippery, but main roads should stay just wet with this one, and most of the 1/2 to 2 inch accumulation should be on grassy surfaces and cold car tops, etc. Is it possible that a couple years may go over 2 inches? Yes, but it would make very little difference in overall impact. By later Friday, we’re dry, breezy, chilly, and clearing out. The vernal equinox at 5:37 a.m. Saturday marks the start of spring, although Saturday morning will definitely still have the chill of winter before the March sun makes the balance of the day quite tolerable despite a gusty breeze. Sunday and Monday will feature a decent temperature moderation, especially if you are away from the shoreline. The trademark “cooler coast” will be in effect as we develop sea breezes both days under the influence of springtime high pressure.

TODAY: Cloudy. Rain arrives west to east this afternoon. Highs 46-54. Wind SW to variable up to 10 MPH.

TONIGHT: Overcast. Rain evening, changing to snow overnight from north to south and accumulating 1/2 to 2 inches before tapering to snow showers. Lows 27-34. Wind variable shifting to N 5-15 MPH evening increasing to 10-20 MPH with higher gusts overnight, strongest near the coast.

FRIDAY: Mostly cloudy to partly sunny. Chance of snow showers early. Highs 36-43. Wind N 10-20 MPH, higher gusts.

FRIDAY NIGHT: Mostly clear. Lows 23-30. Wind NW 10-20 MPH, higher gusts, diminishing to 5-15 MPH.

SATURDAY: Sun and passing clouds. Highs 45-52. Wind NW 5-15 MPH.

SATURDAY NIGHT: Mostly clear. Lows 22-29. Wind N 5-15 MPH.

SUNDAY: Mostly sunny. Highs 52-59, but cooler eastern coastal areas. Wind NE up to 10 MPH.

SUNDAY NIGHT: Clear. Lows 32-39. Wind variable under 10 MPH.

MONDAY: Sunny. Highs 52-59 except cooler coast. Wind variable up to 10 MPH with coastal sea breezes.

DAYS 6-10 (MARCH 23-27)

March 23 … high pressure overhead, fair weather, mild inland, cool coast. March 24 … high pressure moves off and a frontal system approaches with a risk of rain showers. March 25-27 … Drier weather returns, cooler initially then moderating.

DAYS 11-15 (MARCH 28 – APRIL 1)

Overall pattern is dry but temperature forecast is uncertain as we will again be near a boundary between a warmer US Southeast and a colder eastern Canada, which is not unusual at all for early spring in the Northeast.

79 thoughts on “Thursday March 18 2021 Forecast (7:33AM)”

  2. Good morning and Thank you TK. Looks like most models have come back to reality. I guess the only way for increased snow totals is for an earlier change to snow.m, which is not likely.

  4. In general agreement. Not sure the models were ever that far off except maybe 12k Nam which got to juiced but to be expected with downstream convection. Now the 10:1 and Kuchera snow maps, they might have led people astray, but all the informed people here know not to be seduced by the power of the snow side.

    Coating to 2″ spot 3″ amounts possible accumulation and impact less on paved surfaces. Do watch out for some slippery surfaces at daybreak tomorrow:

    After that a warming trend commences on or about the 20th. Does not mean we are immune from temperature swings for a day or two and despite generally dry conditions, it also doesn’t mean a wave of precipitation along with a similarly timed cold shot leaves us immune from frozen precipitation. But given overall temperature trend, dry pattern, and time of year, impactful winter weather becomes less likely with each passing day.

    Enjoy what I think is going to be a great early spring weekend in terms of weather.
    .

  5. Thanks Tk . What time do you think it flips to snow around the Hospital before midnight or say around 3am . Asking for reporting time , many thanks .

          1. You meant extremely minor , none the less I’m sure we will be here but I’m usually here at 3am most of the time anyways . Thanks .

  8. 11Z HRRR has the rain never really flipping over, save for a bit of mixing at the very end. I presume this is a very possible solution.

    Did someone warn us about model fluctuations????? Hmmm

    2. And yes, someone did warn is about model fluctuations… WxW! One of the best “forecasts” I think I’ve have is saying how good he was going to be at anticipation of future events in meteorology. That forecast is verifying. 🙂

    1. Nobody’s getting 5.

      Dude on WBZ radio (anchor) misfired big time this morning essentially saying we’d all be dealing with 3 inches of snow on the roads for the commute.

      Nope…

        3. I have never listened to radio forecasts. Oddly, they have been off for as long as I remember. Never understood why. Exception may be Npr. It has Dave Epstein often and his forecasts tend to mirror yours.

        4. I can’t listen to the exaggeration anymore, I am wondering if it is the anchor adding her two cents.

      2. WBZ Mets have been driving me crazy for the longest time . They seem to always be dramatic . Avid listener for my commute but I never buy into what they say .

  12. Thanks TK, and thank you for the kind words above!

    I would say we did indeed see the influence of the Southeast convection in the models. The NAM especially fell victim, which makes sense since it tends to be the most vulnerable to that sort of thing. Basically from a 4-8+” event over most of SNE to nothing over a couple of runs. That’s a change!

    It’s easier to predict change though than to predict exactly what the changes will be. I think the biggest lesson is just to recognize that forecast uncertainty is higher when widespread convection is involved upstream the day or two before.

  13. Apologize if this was previously mentioned.

    Read about retired hurricane names Dorian, Laura, Eta, and Iota … as always it’s about deadly hurricanes.

    I must have missed this earlier … no Greek alphabet names will be used. It seems that names like beta, theta, and eta are too confusing for some.

    1. I think it’s time to abandon the name lists altogether.

      Tropical Wave
      Tropical Disturbance
      Tropical Depression (Year) A (B,C, Etc)
      Tropical Storm (Year) A (B,C, Etc)
      Hurricane (Year) A (B,C, Etc)

      Example: Hurricane 2021-E for the 5th system of the calendar year. Go by CALENDAR year, no set season. Use 26 letters (no skipping Q and Z). If you go beyond 26 storms which will be rare, then go to AA, BB, etc.

      1. Noooooo. I love the names. A name with last two digits of year works for me but names are fun. That said, in the scale of things to worry about, this is about as low as it gets, so whatever the final decision is works.

        1. This idea probably isn’t remotely being considered by anyone official anyway. I came up with it this morning on the way to work. 🙂

    1. Back up to over an inch for Boston. No big deal, but an inch
      is considerably more than none. 🙂

  18. 15Z SREF has a mean of 3.61 inches for Boston with a high of 8.46 and a low of 0.00

    A rather large range, no? 🙂 🙂

  21. Going to hang with the 1/2 to 2 forecast, lean toward the half inch side of the range. Best chance of 1-2 is going to be toward the South Coast which changes over last but also snows with the greatest rate. Again, grass & car tops, decks & tables, maybe a walkway or two if it’s cold enough. Streets just wet – maybe some slush on the side roads.

    Is this the last chance for “the season”? You know better than to just say “yes”. Many of our late March & April snowfalls have come with very little ability to see them more than a few days in advance. Never, ever, EVER count snowstorm chances out until we get to May, because they we know how exceedingly rare it becomes.

      1. It could be. We just won’t know for sure for … about 6 weeks. That’s just simply how it works ’round here. 🙂

  22. April Fools Storm of 1997. The only April snow day I ever had. I believe it was quite mild a few days prior to that storm.

    2. Very mild. Took my children to Walden Pond a day before the storm – which began as very heavy rain, by the way (imagine if it had all been snow!) – and it was in the 60s. I may have told this story to you all at WHW before. In any case, an old man sitting on the beach told my son and daughter “it’s nice and mild now, but you’re in for a big surprise tomorrow.” I had followed the forecasts and had heard several mets say plowable snow was possible. But only on the morning of the storm, when it was raining cats and dogs, did the forecasters really have a better handle on how this storm would unfold at night. The temperature where I was in Brookline never got below 31F, but that was just cold enough for incredible accumulation in the wee hours of the morning. Will this happen again in my lifetime? I doubt it. But maybe in my children’s lifetime, or their kids, should they decide to have any.

      1. Love your story, Joshua. Waldon pond was always a go to place for Mac and me and then with our children. What a wonderful memory for you.

        I suspect the forecast was different inland. I kept kids home or maybe school was cancelled ahead. Either way we headed to the barn in Hopkinton very early where horses were because we knew it would be bad enough that we wouldn’t make it back later that day or next day. Daughter exercised horses and while she cooked them down and settled them in, I stood outside the barn door and watched as fiesta flakes began to fall. I still remember the feeling of anticipation that something big was in its way.

  23. Vicki I don’t remember April 29, 1987 and the other late March storm mentioned on this blog from time time occurred a few weeks prior to my birth.

    1. The later March storm occurred when my son was a couple of weeks old. Son doesn’t remember April 29 either but then you were both just three

  25. First time on here in ages (new job is keeping me hopping!) but just wanted to say thanks for the Walden love!
    Signed,
    A Concord townie (I don’t live there anymore but as chair of the class of ‘94 who works mainly with Concordians I eek into honorary townie status.)

    Missed you guys – although was happy that we didn’t have too crazy a winter during covid.

  28. Snowing now in Coventry CT. 35 degrees and dropping. Should pull out several hours of light snow. Not expecting much accumulation though as it looks like the heaviest precipitation has shifted south.

  30. Hard to call any forecast that calls for a coating to 2″ amounts on non paved surfaces a bust, but I did think most of the region would at least some snow, but many places saw not even a flake. A bit too warm and the faster cutoff off of precip than anticipated left most with no measurable snow.

    For parts of SNE during the month of February the atmosphere just wanted it to snow, we kind of flipped to the reverse of that idiom during March.

    Anyone got those 5-10″ Kuchera maps from 12z Tue 12K NAM that were floating around the internet as forecasts? A rite of spring – the useless model generated snowfall map.

    1. I do snow removal for a Boston Hospital JMA & I was watching those projected temps & I was thinking to myself no way & sure enough it was no way. We had No snow & the wind dried a lot of the pavement which was a bonus .

    2. I had people questioning my “1/2 to 2 inches” as too low based on those NAM maps a couple days ago. It’s still meteorology not modelology, but even sometimes the best application of meteorology is still not going to get you the exact outcome – we needed some last minute adjustment for that, and even then it still wasn’t enough.

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