Wednesday April 21 2021 Forecast (7:13AM)

72 Comments

DAYS 1-5 (APRIL 21-25)

The changeability of New England’s spring weather can be showcased in many ways. Yesterday in speaking with a friend on social media, I noted that one such example of the upcoming swings will be that some locations that reached or exceeded 70 yesterday may see a snow shower Thursday evening with wind chill in the 20s, only to be back near 70 again Saturday. When the first bubblings of the coming summer’s heat start to build in the South, and winter’s lingering cold and snow cover try to hang on in Canada, they often meet somewhere between, and our region is definitely somewhere in between. We live in a meteorological battleground, and while this can be seen numerous times throughout the year, it’s often most vividly displayed in the springtime. And here we are now. This next showcase of variability will be started as a frontal boundary, the one that entered from the west as a cold front that promptly came to a halt over the region and slid back to the north as a warm front, becomes the atmospheric running board for a low pressure wave today. This low will track just northwest of the WHW forecast area, across northern New England. On our side of the boundary resides mild air, for now, and the low pressure areas and the contrast across the front from our mild side to a much colder air mass on the other side, will result in a more widespread ribbon of showery rainfall that will be preceded by isolated rain showers. Once the main shower area gets here it may have a thunderstorm or two embedded in it, but mainly this will just be a gusty rain shower episode later today into this evening. The snow that has been falling across much of the Midwest behind the front is going to head across northern New England, giving the mountains a bit of snow for a little more spring skiing, and while that area will miss our area, the cold air behind the front will not miss. We’ll see a significant temperature tumble from today’s mild readings to air that feels more like February or March on Thursday, which is ironically Earth Day. Not a great day for an Earth Day picnic – sorry! Blustery, chilly, sun to start then lots of clouds. Some of those clouds may even produce a rain or snow shower, favoring the hilly terrain west and north of Boston, by later Thursday. The gusty wind will be the result of the air pressure difference between departing low pressure in eastern Canada and a high pressure area sliding southeastward from the Ohio Valley to the Middle Atlantic States. This high will move across the Middle Atlantic and offshore during Friday and Saturday. During that time we will see the wind relax and shift to the west Friday and southwest Saturday, resulting in a warming trend with dry weather. Another low pressure area will be trekking eastward in a now zonal (west to east) flow pattern, and it’s destined to bring our next shot at much needed rainfall for the second half of the upcoming weekend. More details on this system as we get a little bit closer to the event…

TODAY: Partly sunny through early afternoon with isolated rain showers. Mostly cloudy mid through late afternoon with widespread rain showers and possibly a thunderstorm arriving from west to east. Highs 55-62 South Coast, 63-70 elsewhere. Wind S increasing to 10-20 MPH, gusts to 30 MPH.

TONIGHT: Cloudy with numerous rain showers evening. Clearing west to east overnight. Lows 32-39. Wind shifting to NW 15-25 MPH, gusts 30-40 MPH.

THURSDAY: Sunny start, then lots of clouds. A rain or snow shower possible mainly hills north and west of Boston by mid to late afternoon. Highs 43-50. Wind NW 15-25 MPH, gusts 30-40 MPH.

THURSDAY NIGHT: Variably cloudy. Slight chance of a rain or snow shower early. Lows 31-38. Wind W 10-20 MPH and gusty.

FRIDAY: Partly sunny. Highs 50-57. Wind W 10-20 MPH, gusts up to 30 MPH.

FRIDAY NIGHT: Mostly clear. Lows 40-47. Wind SW 5-15 MPH.

SATURDAY: Sun and high clouds. Highs 65-72, cooler South Coast. Wind SW 5-15 MPH.

SATURDAY NIGHT: Clouding up. Lows 47-54. Wind S to SE 5-15 MPH.

SUNDAY: Cloudy. Rain likely. Highs 50-57. Wind E 10-20 MPH and gusty.

DAYS 6-10 (APRIL 26-30)

Zonal (west to east) flow pattern starts to transition to blocking again… Drier/breezy/cool April 26 as low pressure departs and high pressure builds toward the region from the west. High pressure may sit over the area for several days thereafter ending April with a dry stretch, temperatures trending milder but coolest along the coast much of the time.

DAYS 11-15 (MAY 1-5)

Favoring continued blocking with the region staying mostly dry with near seasonable temperatures, but it won’t take much to completely change this outlook, so it’s low confidence.

72 thoughts on “Wednesday April 21 2021 Forecast (7:13AM)”

  3. Good morning and thank you TK. I echo Tom’s sentiments.
    Not only a great discussion, but so well written. Very colorful descriptors used.

  6. Tk for 3am at the hospital tomorrow would you guess it’s closer to 32 or 39 . Thank you

    1. Upper.
      But even if it was 30 or 31 the ground temp would be at least 5 to 10 above freezing.

      1. I am thinking were going to see a line of storms weakening entering western parts of SNE as we typically see in the spring. The severe weather reports will be in the Hudson River Valley Northern NJ today

  10. Wow. Some awesome gusts out here. I don’t think I’m in Kansas any more.

    Oh wait….I wasn’t in Kansas to begin with.

  14. I am surprised eastern CT is under this severe thunderstorm watch. With the wind direction coming off the Long Island Sound that would stabilize the atmosphere and a stable atmosphere is a thunderstorms kryptonite.

    1. SPC always overforecasts severe weather up here. They try to apply the same ideas they use in the Midwest and the Plains to here, and just don’t seem to get that it’s different here.

      1. You would think they could learn this, but I guess not.
        Oh well, we know and I suppose that is all that counts.

  15. I agreed with the outlook yesterday of the marginal risk in extreme western CT. I was surprised to see a good chunk of CT in the slight risk today. I have seen this so many times in the spring where you have a strong line of thunderstorms west of SNE and as they enter western areas the weakening begins.

  16. Thanks TK.

    Had a good squall line come through earlier with heavy downpours and very gusty winds. Partial sun back out here now in Manchester CT and 60 degrees. We’ll see what if anything later this afternoon brings…

  17. A line went through here as well. Two of the grandkids were out playing and I sat on deck …until rain got too heavy. Temp dropped from 66 to 57 and now is back up to 59

  19. Waiting to see if they extended the severe thunderstorm warning in the Hudson River Valley to my area. Fast motion with these thunderstorms.

  22. This was showing signs of rotation just over the boarder. It is entering Kent CT right now and moving fast to the northeast.

    1. It seems to be moving toward Springfield or even South Central direction. If I’m not mistaken.

  23. This storm when it was in eastern NY had a funnel cloud with it reported by a trained weather spotter.

  24. Sun breaking through in a few spots here. There are some pretty funky clouds south of here toward Mark land moving very fast with the the tops elongated. No idea I’d that means anything but just looked interesting

  25. Vicki you are correct about the direction of that storm. It now has a severe thunderstorm warning with and not a torando warning.

    1. Thanks JJ. I saw that the tornado warning was allowed to expire. That is great news. Right now, it seems Sutton will split the two lines with the one further to the east the closest.

      I can’t tell If the tstorm area to your south is headed for you.

  26. Mid 60s with a tornado warning in NW CT right now.
    Mid 30s and snowing in Albany right now, just 50 miles to the NW.

  29. Vicki I have had rumbles of thunder briefly heavy rain and the winds were not all that strong. North of me in Kent Goshen Falls Village seeing pics of hail and damage.

  30. SPC’s over-forecasting of New England severe weather goes back as far as I can remember paying attention (circa 1985), and probably before that. In fact, it goes back to before a time they were called “SPC”. 😉

  31. Overall this stuff should be weakening once it gets east of the CT River & starts to feel significant influence from the south wind off the water south of New England. This is typical for springtime, especially at this point in the spring when the waters are still “cold” in comparison to the land. You need some pretty substantial dynamics in place to overcome that influence, and we don’t really have that today.

  32. A wimporama came through here in 2 batches dropping
    0.11 inch of rain and dropping temperature from 72 down to
    58.

  33. Nice little bow with that line approaching my area. Can hear thunder not too far away. I would suspect some gusty winds with this line.

  34. The second squall line just moved through here in Coventry CT with heavy wind blown rain, lightning and thunder. Wild for a few minutes but definitely not “severe”. Big temp drop from 62 to 49.

    My mother in Amsterdam NY just texted me a picture from her house…white ground and snowing heavily.

  37. Freeze Warnings up for tonight/tomorrow AM for interior CT and RI.

    Freeze Watches up for interior SE MA for tomorrow night/Fri AM.

  39. Well now ….poof. There were a few tiny pieces of hail and one clap of thunder and that was all she wrote

  40. As of 5PM, the showers/storms are behaving as expected. Feeling the stability, struggling, trying to redevelop ahead of themselves on outflow, each cluster a little smaller and weaker than before.

    Areas of CG lightning decreasing…

    This trend will continue, though some nice photogenic approaches and possibly aftermath skies depending on how quickly we get into some partial clearing (location dependent of course).

  42. Basically the odd cloud formations seen ahead of this were a form of asperatus. They did not have great wave action in them. Another thing seen was an elevated roll or partial shelf cloud. Similar to what you get in many t-storms but occurring at about 7,500 to 10,000 feet above the ground due to the higher bases of the storms.

    1. I’m really excited with the photos I got since I just learned the sort of new classification a few days ago

  45. It thundered pretty good late this afternoon, enough to get me to turn off my tv. I guess most people do not do this but I do. I was taught by my mother and grandmother that lightning can literally blow out a tv, maybe even cause a fire. “When thunder roars, shut off the tv while indoors”. Not a good pun, I know.

    2. It is a myth that just turning it off will protect it. A surge coming through the electric outlets has the potential to damage or fry anything plugged into it, whether it is “on” or “off”.

      Surge protectors SOMETIMES help, but can be easily overwhelmed by a surge that strong, depending on where the strike occurs. The safest bet is to unplug whatever you want protected.

  46. Snowing now here in Coventry Ct and down to 34 degrees. There is a light coating out on the grill cover. What a change from 7 hours ago.

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