Thursday PM Thunderstorm Update!

47 Comments

3:20PM

With the morning storms well out of the way, some sunshine has heated things up, and made the atmosphere ripe for more storms as a cold front slices into our short-lived burst of heat. These storms have already formed during the past couple hours over NY State & VT, and a solid squall line (as of 3:15PM) runs from west central NH across southern VT and into NY, including the northwest corner of MA. This line is expected to march east southeast, crossing eastern MA between 5PM & 7PM, a bit later toward far southeastern MA including Cape Cod & the Islands. This line has the potential to produce strong winds with some straight-line wind damage and an isolated downburst. Torrential rain, some hail, and of course, dangerous lightning can be expected with this line.

From experience, this setup often results in the strongest part of the line running along and south of the Mass Pike, with areas to the north of the Pike and into southern NH seeing less widespread powerful storms. This may occur today, but regardless of where you are, do NOT let your guard down until the storms has passed by.

I will update again as needed with any changes, and a full Boston area forecast will be posted this evening. A quick look ahead suggests a mild, dry Friday, and a cool and unsettled weekend.

Be safe everybody!

47 thoughts on “Thursday PM Thunderstorm Update!”

  2. The Doppler is pretty impressive! Such a strong, unbroken line of storms. Doesn’t look like much of anyone will be spared some stormy weather this afternoon/evening.

  3. Not expecting it to, considering the dynamics and the heating of the sun – but what are the chances the storms could weaken somewhat as they approach Central and Eastern MA?

    1. I think I read somewhere that they are getting stronger as they move east. Also that they will continue to develop over the ocean.

    2. This reminds me of many setups I have seen that the northern part of the line weakens, or starts to become downdraft-dominated, as it moves closer to the coast, while the southern part of the line holds strong and contains most of the severe weather, along and south of the Mass Pike. Let’s see if that is how this one plays out.

  4. I should add here that we may not be completely out of the woods in all areas after that squall line passes. That line is on a pre-frontal trough, meaning that the cold front itself sits back to the northwest still. I was looking at the visible satellite loop and you can see a nice slice of sun behind the squall line, and developing cumulus ahead of another frontal-induced cloud bank. This just tells me there are other mechanisms that may cause lift (the front itself and outflow boundaries from the squall line), so scattered showers and storms, and even possibly another line, cannot be ruled out as we go through the evening!

  7. Thanks TK. I use that site as well. I like all of the additional information available like Vortex signature, Hail Size, Cloud tops etc.

    Btw, Perhaps it is my old eyes, but to me it “appears” that part of the line is bowing
    out????

  8. Does anyone know if Portland ME will be north of this? My son is camping on an island up there. Thank you

    1. Vicki, there are severe tstorm warnings out for just west of there. The northern part of this line is going to clip them. Hopefully they will be weakening as they come through there… I’m sure your son’s good sense will keep him as safe as possible.

  9. TK, coastal – thanks for the reply. I have seen thunderstorms actually get stronger as they get near the coastal waters – someone told me that was due to a coastal front. TK, your explanation makes sense regarding the strengthing and location of the storms. In any case, I looked at the satellite loop and TK, you are right. After this line goes through there is a clear area and more clouds to the northwest. That makes sense as the Severe Thunderstorm Watch is until 10:00 anyway.

  10. Severe tstrom warning for Framingham just issued. I assume it’s for most if not all eastern MA

  11. wow just checked out the doppler radar, that line of storms looks vicious. it will be interesting to see what they do as they march eastward…most likely split up right over my area like most T’Storms do…

  12. That cell that popped up in advance of the line in NW CT has rotation in it, but the meso will weaken rapidly as it just becomes part of the squall line. That is an indication to me once again that the southern part of the line will be the bear, and the northern part will be more of a cub with time… We also did not get a chance to heat up as much in areas that the northern part of the line is going to move into. This has at least slightly diminished convective potential.

  13. I’m about to head out for a short local “chase”, safely of course. I will take pics and video if possible. So far the line is behaving as expected. Don’t see need for immediate changes to thinking.

    JJ if you are there, you can update in this section all you want to keep the readers up to date. I’ll chime in from the road if possible (I’ll probably be in a parking lot somewhere anyway).

    Everyone, please leave your comments about what you see! And be safe!

    1. Good luck and be careful, TK! It’s getting dark in Sudbury and I think I heard thunder.

  15. I can see the north edge of the front to the northwest. The clouds I’m the sky over our house are almost rippled like blown sand.

  16. Getting Dark in Boston.

    Btw, as predicted by TK, the Northern End of the squall line is WEAKENING.
    It “Appears” to be dying quite quickly. Unless there is some sort of regeneration,
    I think the Boston area will be spared. Of course we’ll still have to look to the
    West for possible additional storminess.

  17. Perhaps I spoke too soon??? There “appears” to be some new life in the Northern
    Section? Getting mighty dark in Boston.

  18. It is very dark in Sudbury now and the wind is picking up – about 30 m.p.h. and gusting.

  19. Gotten cloudy quickly down in the Pembroke/Marshfield area. I’m interested to see if the storms hold together all the way to the coast.

    1. Vicki – it is still very dark here in sudbury and thundering and just starting to rain. We are still getting gusts of wind. We went out awhile ago and the clouds were really something – looked like little funnel clouds (I know they weren’t) .

      It’s pouring now – lots of thunder and lightning.

  25. Rainshine I saw the little funnel type clouds hanging down too. Amazing. Seems more thunder your way. No more than run of the mill here. Wind quieted down after it blew grandsons blow up pool down the street

  28. It’s still dark here in Sudbury and started thundering and lightning again. On doppler radar looks like a heavy shower trying to build around Maynard, which is not far from here and to the north.

  33. It’s 66 here in Sudbury, too. Still dark and thundering and lightning and raining light to moderate. I am going to close down now – have a safe and good night all!

  34. Its kind of strange, there’s more lightning now with this area of rain than there was with the initial line of storms.

  36. We are still having lightening. I have no idea where it’s coming from. Uxbridge lost power after heavy lightening about 30 min ago

  37. The lingering lightning is all positive CC & some CG discharges, which is typical for elevated convection on the back side of squall lines or an MCS. This particular line had quite a bit.

  38. I took a few good pics of the clouds before the torrential rains came down, if only I could post them on here for you all to see.

  39. GAH! Wrote a new update that my phone killed literally one second before upload! At home, on the trusty desktop, writing a new blog…

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