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Sept 11-12 Wednesday, Thursday Storm Threat


free_man

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It's rare we see an EML signaled so far out. And if we do it seems like models weaken or lose it as we get closer. I'd like to see it still there on Monday afternoon to think its real

Actually I feel like the models do a pretty good job sniffing out the potential a few days out.

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Looks as though the "last, best, final offer" for severe next week.  Thoughts?

Is that based on a low amplitude Euro wave and a cold front in 10 days?  GEFS don't support widespread severe.

 

There is a quick look I use on the ECMWF site for severe, and one of the ingredients is at least 15 m/s (30 knot) 850 mb flow.  You have that over the Lakes and even NY day 8 and 9, it looks gone before Day 10 and New England.

 

I could be missing what you're seeing.  Can you explain?

post-138-0-45869700-1378586620_thumb.gif

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I think you mean the 11th-12th

Anyway an unusual time for EML advection... Especially with monsoon season well underway but it can happen. Maybe a 2013 severe outbreak is delayed but not denied.

 

That I can see, in the Plains, however, I usually want more directional shear between 850 mb and 500 mb.  Of course, I approach it from the supercell angle, not the potential derecho angle.

 

msl_uv850_z500!Geopotential%20500%20hPa%

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Ed, I don't care so much for supercells and they (from a violent POV) are extremely rare in NE.   

 

It looks like a multicell type day, perhaps a lewp/bow in there.  Honestly, I haven't looked deeply into shear or any model data concerning wind profiles (ala bufkit) because it's still a ways out.

 

The overall setup would look like easily a wind threat, and possibly hail.

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Like Ryan said, the signal has been fairly consistent for several runs now. It will likely come down to timing and just how much clearing we get just out ahead of the front. Remember the length of daylight is getting shorter fast and the sun angle is as low as April. We'll have to thread the needle just right for a widespread event, but it is possible.

I'm surprised Wiz hasn't posted yet...

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If there was any kind of instability at all, Tuesday could be intriguing for CNE/NNE with the warm front. It's just not favored in this setup. Still long very long, looping hodographs coming out from the NAM and GFS to our north thanks to good shear and crazy helicity.

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I think you mean the 11th-12th

Anyway an unusual time for EML advection... Especially with monsoon season well underway but it can happen. Maybe a 2013 severe outbreak is delayed but not denied.

Quite unusual...but not completely unprecedented. Setup is looking nearly textbook. Go from a frost in northern VT monday morning to hail Tuesday morning on the leading edge of the EML? I say yesss.

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Quite unusual...but not completely unprecedented. Setup is looking nearly textbook. Go from a frost in northern VT monday morning to hail Tuesday morning on the leading edge of the EML? I say yesss.

Welcome back.

 

Euro says Thursday all hell breaks loose..Hopefully we can hold this for a few more cycles to feel like it's legit

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How do the lase rates look on the euro for Thursday? It looks like the flow becomes a little more SWrly and lapse rates decrease a bit from Wednesday. Tuesday Night could have a heck of a complex traverse CNE/NNE.

using 7-5h...the euro has a very good plume come through on wednesday but that shifts eastward and we are left with <6c/km for thursday afternoon. 

yesterday's 12z was a bit slower with the departure but was still only like ~6.5c after 18z. 

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using 7-5h...the euro has a very good plume come through on wednesday but that shifts eastward and we are left with <6c/km for thursday afternoon. 

yesterday's 12z was a bit slower with the departure but was still only like ~6.5c after 18z. 

 

Thanks, that's what it looked like to me. I'm almost more interesting in later Tuesday/Tuesday night. That's a mega theta-e push coming in. Although Thursday could be a good day too with that strong trough digging on. 90s Wednesday, 60s next weekend with frost. Gotta love it.

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Thanks, that's what it looked like to me. I'm almost more interesting in later Tuesday/Tuesday night. That's a mega theta-e push coming in. Although Thursday could be a good day too with that strong trough digging on. 90s Wednesday, 60s next weekend with frost. Gotta love it.

it's a serious punch over NNE. atmosphere essentially goes from autumn to mid-summer in a few hours. 

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I think you mean the 11th-12th

Anyway an unusual time for EML advection... Especially with monsoon season well underway but it can happen. Maybe a 2013 severe outbreak is delayed but not denied.

 

As Ekster said, it's not totally unprecedented.

 

1998090700.72518.skewt.gif

 

And almost certainly the New England outbreak on September 9th, 1821 included some EML involvement.

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Does SNE miss out on the Tues nite deal? It looked Euro was the most aggressive with that

 

Well I kind of like seeing the complex modeled across NNE. Heights to build north so the traditional thinking of these complexes peeling to the right and ending up further south may not totally apply...but worth watching.

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Well I kind of like seeing the complex modeled across NNE. Heights to build north so the traditional thinking of these complexes peeling to the right and ending up further south may not totally apply...but worth watching.

 

I kind of like the time around Tuesday early when the steep lapse rates really try and build in. On that leading edge you'll have pretty strong theta-e advection. Get a little LLJ in there, and you can force some early day severe hailers.

 

Here is the Ukie depiction at 12z Tue. A lot going on in the image, but fill is H7 RH, cyan is divergence, salmon is theta-e advection. You can see a broad area of high theta-e advection (bullseye over SW Quebec), as well as some weak divergence extending down into NNE. The fact that the model is spitting out high RH across NNE also points towards some sort of convective initiation.

 

post-44-0-05747600-1378649893_thumb.jpg

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