Thursday April 15 2021 Forecast (7:18AM)

113 Comments

DAYS 1-5 (APRIL 15-19)

All week we’ve been eyeing the possibility of some mid April snowflakes. Nothing new for us at this time of year. In fact, just last year on April 17-18 there was a storm system that produced measurable snow right to the coast and a general 1-3 inches across much of eastern MA and 3-6 inches in higher elevations of RI and central MA. These systems happen. They are not easy to forecast since quite often the rain vs. snow can be and often is even more needle-threading than a winter system to nail down in terms of a forecast. But I have not over analyzed this one. Here’s my best shot. In general, we will be seeing low pressure moving eastward off the northern Middle Atlantic Coast later today and intensifying as it is captured by its upper low pressure partner pulling it northeastward and making it do a bit of a cyclone loop. This system will be at its maximum intensity as it is making its closest pass. The various computer guidance, as is typical, display some differences but in general most of them bring the low center right in over southeastern New England while it does its loop. One model (the NAM) has been forecasting this loop to be a little further southeast, offshore or barely to Cape Cod, on its last couple runs, and the result has been its snowfall forecast has been to bring the rain/snow line further east, producing more snow into eastern MA than is depicted by other guidance. A springtime setup like this can be one that produces substantial amounts of snowfall in higher elevation while just a few miles away you see all rain. Snowfall can occur in lower elevations if you keep the warmest air away, which could happen with a low center a little further offshore. So you see the forecasting dilemma. Believe the outlier model that has pretty much no support from any other model, or lean toward the solution shown by pretty much all other available guidance? For now, this forecast will look similar to yesterday’s with added detail since the event starts soon. I’m not biting on the dramatic solution the NAM offers. But as there have been times that it, as an outlier, has been correct, it’s obviously wise to monitor closely. Does it do this again on its next run? Does it come back to the other models’ ideas? Or do they join it? It plays out like a meteorological soap opera! Stay tuned……….. Whatever happens with precipitation details, the heaviest of it ends Friday morning and as the low matures (“fills”, or “stacks”, basically becoming vertical low pressure tube underneath and with its upper low), it will start to pull away but will still be close enough to keep Friday overcast with occasional rain/mix/snow eventually tapering to drizzle before ending. This process may take until early Saturday to be completed, and with the low still offshore, Saturday will be day with a gusty breeze and a fair amount of cloudiness before enough dry air works in for more sun later. The Sunday-Monday outlook is still OK, but high pressure’s center is likely to be a little further southwest, which allows it to turn milder, but also leaves the door open for a couple low pressure troughs to move along in a more zonal (west to east) flow, so we would have at least some cloudiness around at times, and possibly a couple shower chances as these disturbances pass by.

TODAY: Clouding over. Rain arriving in central MA & RI mid to late afternoon. Highs 50-57, coolest coast. Wind SE 5-15 MPH.

TONIGHT: Overcast. Rain, possibly heavy at times, changing to snow in higher elevations of southwestern NH, central MA, and mixing with or changing to snow in higher elevations of northern RI where some accumulation is possible. Rain may mix with or change to snow eastward toward the I-95 belt toward dawn. Lows 34-41. Wind E 5-15 MPH but gusting over 20 MPH coastal areas.

FRIDAY: Cloudy with snow/mix inland areas, rain/mix coastal areas, tapering to snow/rain showers and areas of drizzle. Total snowfall accumulation for the event expected to be 3-6 inches in highest elevations of southwestern NH to around the MA border, 1-3 inches on mainly unpaved surfaces to about I-495 and mostly near and north of I-90, and less than 1 inch as far east as the I-95 region from I-90 northward. Highs 38-45. Wind E to NE 15-25 MPH, strongest coast with gusts 30-40 MPH possible.

FRIDAY NIGHT: Mostly cloudy with rain showers and areas of drizzle. Temperatures steady 38-45. Wind NE to N 10-20 MPH with higher gusts, especially coastal areas.

SATURDAY: Cloudy start with lingering rain showers and/or drizzle eastern coastal areas, then mostly cloudy to partly sunny with a slight chance of a passing light rain shower. Highs 45-52. Wind N to NW 10-20 MPH with higher gusts possible.

SATURDAY NIGHT: Variably cloudy. Lows 37-44. Wind NW 10-20 MPH.

SUNDAY: Partly sunny. Slight chance of a passing rain shower. Highs 55-62. Wind W 5-15 MPH.

SUNDAY NIGHT: Variably cloudy. Lows 40-47. Wind W 5-15 MPH.

MONDAY: Partly sunny. Highs 56-63. Wind SW 5-15 MPH.

DAYS 6-10 (APRIL 20-24)

A shot of warmer air to start the period but an approaching trough from the west likely means a chance of rain showers to go along with that. Cooler air follows that as the shower threat gives way to fair weather for the middle of the period. Approaching low pressure may bring a rain chance late period.

DAYS 11-15 (APRIL 25-29)

Unsettled weather threats most likely early and again late in this period with fair weather in between. Temperatures near to possibly below normal.

113 thoughts on “Thursday April 15 2021 Forecast (7:18AM)”

  2. Good morning and thank you TK.
    Great discussion. Not only eas it full of information and details, but it was so well written.

    One thing that stood out to me, you did not deal in absolutes. You gave it your best shot, but explained the caveats. Great job. Love this in a forecaster

    Can’t wait for the 12z runs.

    1. Thank you Dave!
      I have a feeling that the NAM is going to have changed its tune for the 12z.

      1. You are probably correct, but one never knows. very curious to see if it does or not. Either way, should be an interesting night into morning.

  3. If I May, here is a re-post from earlier this morning.
    TK Mentioned that the NAM brings the snow to Eastern
    sections. Have a look at the 6Z NAM and 3KM NAM to see
    what he meant.

    HELLO NAM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    https://maps1.pivotalweather.com/maps/models/nam/2021041506/036/ref1km_ptype.us_ne.png

    https://maps1.pivotalweather.com/maps/models/nam/2021041506/084/snku_acc.us_ne.png

    https://maps1.pivotalweather.com/maps/models/nam/2021041506/084/snodpc_acc.us_ne.png

    3KM NAM

    https://maps1.pivotalweather.com/maps/models/nam4km/2021041506/060/snku_acc.us_ne.png

    I must say that ALL other models keep the snow much farther to the West of Boston. So, is the NAM onto something OR is it far more likely the NAM is OUT TO LUNCH?

    I will say this: At the 11PM Broadcast, Harvey seemed a bit nervous about a possible more Southern track that could bring the snow farther East. To me, more reasonable than the absolute that this will be a rain event.

  17. Thanks TK and excellent discussion
    Looks like I will be missing out on any meaningful snowfall. I am not disappointed as it is spring. If BOS could get 0.2 out of this it will win the snowfall race between NY. So far your winning on the diamond with a 9 game winning streak. I did not think BOS would be in first place at any point this season.

    1. Still early. Yankees have more talent and are a better club overall. Of course, we know that talent isn’t everything. Should be an interesting year. Frankly, that’s all I care about. I want meaningful baseball in September. We may indeed have that around here.

  19. Thankfully the areas that see the snow the trees are not full of leaves otherwise we could be looking at big time power issues due to the snow being wet.

  21. Joshua I did not see a 9 game winning streak for the Red Sox after the 0-3 start. The way they looked that series it looked like it was a long season ahead. As far as the Yankees the 3-6 hitters combined worst average in major league baseball. They are going to that bullpen an awfully lot so far as starters other than Gerrit Cole are not giving them length. You can’t expect the bullpen to be used that much and perform at the level they are doing so far which has the best ERA in baseball.

      1. I think it will be now casting at 3 or 4 in the morning. 🙂
        Or look out the window at 7AM and see what you have.

    1. No way we get snow to the coast with this track. Even if cold above, too much East to SE wind from the Ocean.

    2. Agreed. I do think eastern mass could see some pretty non accumulating flakes at the end still. That’s my favorite type of snow – all show no collection.

      1. We’ll know soon enough.
        If stays SE of us, there is a chance. If it moves up over SE MA, Fuggetta about it.

  29. Thanks TK.

    This was the 6z Euro snowmap at 10:1

    https://www.americanwx.com/bb/uploads/monthly_2021_04/1279076165_download(2).png.2687dbf16ba6a475ecb48f8b98f4a00a.png

    Even if we assume 5:1 ratios and half those totals, that is still a good dumping for interior MA, NE CT and northern RI.

    It’s got temps aloft several degrees below 0C and 0.5″ QPF in about 3 hours. That’s some intense snow and would add up during the overnight hours.

    We will see what the 12z has to say….

  31. JPD and others, has anyone watched the Netflix short series “This is a Robbery”? It’s about the Isabella Stewart Gardner museum heist. My guess is most here remember it.

    1. Certainly remember. Have been there several times. My wife used to play there as a child. Have not seen it, but thanks for mentioning it. The Mrs. and I may tune in.

  37. 18z NAM coming back to Earth. It took 2 runs to happen. I gave it a bit more credit than it deserved, thinking maybe one run. 😉

    Some interesting things may still lie ahead for us in the weather department. Well of course they do because the weather is always interesting one way or another. But the hint of below normal temperatures in my extended forecast may be slightly underdone. Too early to be sure of that though. Will monitor…

    1. Timing is everything. Imagine that lobe of cold air (expected to be here next week) in place with tonight’s event. Would have made things very interesting.

      1. Sure thing!
        Well hey, it’s not impossible that a lobe of colder air can coincide with a set-up to produce significant snow later than this. It’s happened. It becomes increasingly more rare day by day, but it’s not impossible (especially away from coast & at elevation). References often made here: April 28-29 1987. And of course May 9-10 1977.

        1. I have photos somewhere of my daffodil heads just peaking above the April 29 snow. Resilient things that they are, they survived.

            1. They sure are. We are blooming a bit later than the last few years but still earlier than years gone by

              We’d drive to Charleston every April vacation and were well into NJ before seeing forsythia and dogwood.

  38. Another thing to keep an eye on in the longer range – there’s a tropical system developing in the Western Pacific. Models have it becoming a SuperTyphoon this weekend, and recurving just east of the Philippines. Once it does so, it could have a major impact on the upper-air pattern. This is more common in the Fall, but since tropical season in the Western Pacific is year-round, it happens in the Spring as well.

    1. That entire process has always fascinated me since I had to watch for that on a regular basis for the shipping and of course the energy forecasts in the longer range…

      1. Too bad Stratton already closed but Mount Snow is still open through this weekend and Killington has a long ways yet left to go. Wish I could get back up there Saturday with 12-18″ likely up the spine of southern/central VT but the softball schedule this weekend says otherwise 🙂

        1. I figured some must have closed and it is a shame but then when all is said and done, they know the business. I also wish you could get back up there

  42. Boy that is an interesting look in the long range 12z GFS. Any real springtime warmth is on hold till May if that is correct with a few additional snow chances coming, at least up in NNE. I see three coastal storm possibilities in that run. Where was that pattern in January and March?!

  44. Bring on the disruption!!

    John Bagioni
    @FaxAlertWeather
    4h

    While I am not dismissing meaningful snow amounts across the high terrain areas of Litchfield County (2 to 4 or 3 to 5″ across far northern parts of Lit cty). But all eyes are on Tolland and Windham counties where truly disruptive amounts could occur?

  45. Thanks TK. Been very busy lately so am not on here much but enjoy reading the discussion here whenever I can! Not much to add with this system. Classic springtime interior snow special. Going to be a pretty impressive show in the next 24 hours. Very wintry pattern the next 2 weeks. But as usual in April, look up and inland for snow chances 🙂

    I hesitate to use the term “drought buster”, but this storm may be pretty close to it in SNE. Will at least alleviate all our short term concerns.

  46. Mark I am rooting for your Islanders tonight to beat the Bruins and my Rangers to beat the Devils so the Rangers get within two points of that final playoff spot. Rangers off to a strong start up 3-0.

    1. Islanders are not! The Bruins are overdue to win this one though. They have lost every game to the islanders this season so far.

      1. will see if it holds or if temps bump up after really heavy precip lightens a tad. I’m glued to the radar

    1. Rangers looked very good last weekend against the Islanders despite the Islanders pulling off the win in OT. They’ve got a good shot.

      Islanders had a much better second period.

  51. Mark the Rangers are building something good. Final month of the regular season they are playing meaningful games. Igor Shesterkin is less than 10 minutes away from having back to back shutouts.

    1. Unfortunately the Islanders aren’t helping you out tonight. It was bound to happen eventually after the Islanders won the first 5 games against the Bruins.

        1. I expect maybe when this next batch heads in we flip. down to 35 now to we’re gonna be close with heavy stuff coming in. Still sleety mix right now.

          1. I believe the guy in Princeton with the snow was reporting 33F so might be at a slightly higher elevation than you.

    2. Wow. I keep checking but nothing. Retrac? Maybe Scotf77 and ofhers. Can you please send it this way

  55. A few flakes in there from time to time but still mostly rain. Temp steadily dropping though and down to 36 now.

  57. At 1:35. About a half inch on unpaved surfaces. A dusting on some of the road. Huge flakes. 35 degrees

Comments are closed.