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Spring/ Summer 2014 Convection Discussion


weatherwiz

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The severe threat really isn't looking all that great early this week, ASOUT. Timing was just one factor, but too many things are going against any type of organized severe event.

Maybe something isolated can get going in eastern NY today and sneak into far western New England. There's some pretty good turning in the lowest levels of the wind field.

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Overnight model runs look impressive for Monday and Tuesday severe potential. Damaging winds and tornadoes possible both days with a sultan signal as well. 

Yeah..I thought things actually looked even better the next 2 days than they did at 12z yesterday. It's gonna be a fun and potentially wild next couple of days thru out the entire region. May even be chase material if it looks imminent

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Yeah..I thought things actually looked even better the next 2 days than they did at 12z yesterday. It's gonna be a fun and potentially wild next couple of days thru out the entire region. May even be chase material if it looks imminent

 

Don't think anything would be remotely chaseable... low topped supercells and heavy rainers. 

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If we can avoid cloud debris and crapvection, there could be some action west of the river Monday. The NAM has some good wind fields, but low-end instability. (GFS is less impressive)

Tuesday looks like more of a squall line/marginally damaging wind potential. If the front were to slow down some more, that would up-tickle the threat a bit.

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I think instability comes into question, but seems like your typical low LCL spin-up type deal and embedded segments that can cause wind damage..esp Tuesday. 

 

Yeah I think that's what most of us expected in the first place lol

 

Looks like a pretty classic setup for that. Not sure where the expectation for a high end outbreak was coming from?

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There are a few different "types" of severe weather events in this part of the world. 

 

The "high-end" NW flow with very strong instability aided by a remnant EML plume. Pretty much the only way to get widespread sig severe. 

 

The closed-low/southerly flow. We get 1 or 2 of these every summer and especially by July and August when SSTs are warm you can get some real nasty storms with low topped supercells. Juicy theta-e air in the boundary layer and anomalously strong wind fields ahead of the deep trough can do it. These setups are normally pretty "meh" prior to 6/15 but this time of year they can produce. Many examples and research (check out the CSTAR/SUNY Albany warm-season cutoff climo/case studies). 

 

And of course the more generic setup with modest instability/shear that can produce various storm modes depending on forcing and other mesoscale details. This is by far the most "typical".

 

So as long as everyone isn't looking for setup "1" and trying to compare setup "2" to other similar events prior we're in good shape. 

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There are a few different "types" of severe weather events in this part of the world. 

 

The "high-end" NW flow with very strong instability aided by a remnant EML plume. Pretty much the only way to get widespread sig severe. 

 

The closed-low/southerly flow. We get 1 or 2 of these every summer and especially by July and August when SSTs are warm you can get some real nasty storms with low topped supercells. Juicy theta-e air in the boundary layer and anomalously strong wind fields ahead of the deep trough can do it. These setups are normally pretty "meh" prior to 6/15 but this time of year they can produce. Many examples and research (check out the CSTAR/SUNY Albany warm-season cutoff climo/case studies). 

 

And of course the more generic setup with modest instability/shear that can produce various storm modes depending on forcing and other mesoscale details. This is by far the most "typical".

 

So as long as everyone isn't looking for setup "1" and trying to compare setup "2" to other similar events prior we're in good shape. 

 

Good post!

 

Which was the Windsor Locks storm BTW?  ;)

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Yeah I think that's what most of us expected in the first place lol

Looks like a pretty classic setup for that. Not sure where the expectation for a high end outbreak was coming from?

SPC day 6 convective outlook showing a 30% for the area. Its like winter storms: we get a weenie run with a mind blowing blizzard for day 7 or so which either subsequently goes offshore or weakens. Between the first glimpse and the actual event, we all (definitely myself included) try to see that big event again, even if the models are clearly against the idea. Its just mighty hard to let go of the idea that it may not be the big one, after we get all excited about it.

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Good post!

 

Which was the Windsor Locks storm BTW?  ;)

 

haha yes good point lol

 

I'd argue that acted more like a "scenario 2" - the ULL was progressive but we had the anomalously strong southerly LLJ and plenty of rich theta-e air channeled up the valley from the Sound. 

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SPC day 6 convective outlook showing a 30% for the area. Its like winter storms: we get a weenie run with a mind blowing blizzard for day 7 or so which either subsequently goes offshore or weakens. Between the first glimpse and the actual event, we all (definitely myself included) try to see that big event again, even if the models are clearly against the idea. Its just mighty hard to let go of the idea that it may not be the big one, after we get all excited about it.

 

Speaking of SPC, whereas the day 6 mention was :weenie: today's is overly negative for Tuesday.  We're barely in the convective contour at all.  Not criticizing them in general they do a good job, but there has been highly inconsistent handling of this one, which probably relates to how certain forecasters view severe in the NE.

 

I think Ryan hit this one on the head, specifically a high shear, low to moderate CAPE event with chance for low level mesos and supercell structures early before the primary threat, heavy, training rains takes over.

 

edit-

 

Speaking of the SPC, they're definitely on the rapid progression train. They think minimal thunder, if any, here Tuesday. Can you smell the rain yet?

 

maybe that's it, they just have the prefrontal trough clearing way early?

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SPC day 6 convective outlook showing a 30% for the area. Its like winter storms: we get a weenie run with a mind blowing blizzard for day 7 or so which either subsequently goes offshore or weakens. Between the first glimpse and the actual event, we all (definitely myself included) try to see that big event again, even if the models are clearly against the idea. Its just mighty hard to let go of the idea that it may not be the big one, after we get all excited about it.

 

Models really haven't changed though... I don't see any reason to get more or less excited based on how things look on NWP currently. 

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Tomorrow is probably the best as far as directional shear goes.

 

Agreed. I wouldn't be surprised though if we see some locally backed winds S or SSE on Tuesday with that front approaching. May be tough to get a good handle on that until we get closer to the day. 

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Does the setup and strength of ULL and depth of trough and anomolous cool in Midwest have any bearing on this as far as making closer to higher end or does that not have any effect on it?

 

These events just really aren't "high end"... you could get a freak storm like the 2008 New Hampshire F-2 but that takes a lot of stuff to go exactly "right" like small scale storm interactions etc. 

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Does the setup and strength of ULL and depth of trough and anomolous cool in Midwest have any bearing on this as far as making closer to higher end or does that not have any effect on it?

 

I don't think it will be high end...just a setup that Ryan mentioned as conducive to some spin-ups and pockets of wind damage. They don't always behave as planned either.

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I don't think it will be high end...just a setup that Ryan mentioned as conducive to some spin-ups and pockets of wind damage. They don't always behave as planned either.

 

We know the setups that are good for widespread significant severe and this just isn't that. You can get a couple tornadoes and microbursts though... and even some good winds associated with small bowing segments that are able to mix down some of that LLJ. 

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I don't think it will be high end...just a setup that Ryan mentioned as conducive to some spin-ups and pockets of wind damage. They don't always behave as planned either.

But I guess what I'm wondering is because this isn't your typical summer setup and it's more anomolous does that have bearing on potential outcomes or should we not even include that in our evaluations?
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