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Sept 11-12 Wednesday, Thursday Storm Threat


free_man

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When it comes to convection, especially when talking about possible severe and high end/outbreak stuff, there are always alot of if, and's, or butt's...not just when it comes to SNE

Yep. Even tomorrow is not a done deal for upstate NY. So many things could go wrong. Latest HRRR brings a big MCS through during the morning that probably kills the atmosphere for most of the day out there. 18z NAM was further north and shows barely anything after the morning junk, that's also much further north. RAP actually looks good in contrast.

It will largely come down to nowcasting. The ingredients are there, but timing, placement and daytime heating will be critical. It could end up going one of several different ways. We'll see.

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I think that certainly factors in to some degree. It's not a major factor..but it certainly hurts

It doesn't hurt when you have 2SD 850s, steep lapse rates and extreme instability. The setup is something you'd typically expect out of August, if not July.

The limiting factors here are placement and CIN.

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Also, while the chances are extremely low on Wednesday you still need to pay close attention b/c of how volatile the environment will be.  Even if you only see one storm develop, the chances of that one storm producing sig severe is pretty high 

As it appears now there won't be one cloud anywhere in SNE. You can just picture how the sky is going to look. That miserable, hazy, light blue color with not even a high cirrus cloud

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I think that certainly factors in to some degree. It's not a major factor..but it certainly hurts

 

Actually, if anything, having this setup now benefits. If you look at the system, it's more of a mid-fall type system given the degree of forcing associated with it and the strength of the jet dynamics associated with it.  I doubt we would see something as dynamic say July, though it certainly would be possible.  

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Actually, if anything, having this setup now benefits. If you look at the system, it's more of a mid-fall type system given the degree of forcing associated with it and the strength of the jet dynamics associated with it.  I doubt we would see something as dynamic say July, though it certainly would be possible.  

 

Should say that we could see similar dynamics but the forcing wouldn't be the same...take a look at the temp gradient at 850mb...you wouldn't see that in July and that will be a huge boost for uplift and lead to a much more defined "sloped" front

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I think Kevin is talking about weaker solar insolation and the atmosphere having a summer hangover and this can be a factor...but CAPE is CAPE. 4000J is 4000J, but means nothing if we are capped.

 

Typically I would agree about the solar insolation being an issue but not this time.  Thank you EML and 850mb temps into the low +20'sC.  Hell, if we had those values in mid-July or early August we would make a run for 101-102F

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Typically I would agree about the solar insolation being an issue but not this time.  Thank you EML and 850mb temps into the low +20'sC.  Hell, if we had those values in mid-July or early August we would make a run for 101-102F

 

Yeah but the insolation is what helps generate strong low level updrafts. Anyways, it won't matter for some areas further north. Check out GRB sounding tonight for kicks.

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I think Kevin is talking about weaker solar insolation and the atmosphere having a summer hangover and this can be a factor...but CAPE is CAPE. 4000J is 4000J, but means nothing if we are capped.

 

Yeah when you're dry adiabatic from 550-700mb and you have a super anomalously warm airmass it really doesn't matter. It's nice having warm SSTs this time of year compared to late May or early June too. 

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Seems like a lot of if's, and's or but's...Never a good sign when talking about severe in SNE, Add the fact that it's mid September..and that should pretty much throw the last shovelful of dirt on us.

 

Painful to possibly see massive Tor's and wind damage rip across NNE..while it's sunny and 98 down here and cloudless..reading posts from Tip about summery appeals in the long range.

Fall thru early spring severe can often be surprising with high shear such as that which is forecast. IMO CAPE forecasts, even w/ EML look to soundings is overdone on Tuesday  X NEUS. 

 

When it comes to convection, especially when talking about possible severe and high end/outbreak stuff, there are always alot of if, and's, or butt's...not just when it comes to SNE

 

True but don't hinge your forecast 6on a CAPE forecast alone. A sage forecaster who I interned with when I was in college said no thunderstorms ever happened with a  Showlatwer index or Li of < 0 or a KI > 35. Yes everything looks impressive BUT will all elements actually come together in time and palce on Tuesday across the NEUS; especially after the morning MCS moves through  NY and NE.

The fact that it's September doesn't really matter either. The setup is unusual for September but isn't unprecedented. The window for convection appears to setup a couple hundred miles north. 

Totally agree.

 

Yep. Even tomorrow is not a done deal for upstate NY. So many things could go wrong. Latest HRRR brings a big MCS through during the morning that probably kills the atmosphere for most of the day out there. 18z NAM was further north and shows barely anything after the morning junk, that's also much further north. RAP actually looks good in contrast.

It will largely come down to nowcasting. The ingredients are there, but timing, placement and daytime heating will be critical. It could end up going one of several different ways. We'll see.

 

Absolutely agree

Seeing those on a severe day is like waking up on Christmas morning and seeing present galore under the tree

And then you plug-in the XBOX and it doesn't power up.

 

Yeah when you're dry adiabatic from 550-700mb and you have a super anomalously warm airmass it really doesn't matter. It's nice having warm SSTs this time of year compared to late May or early June too. 

As I said abovestrong  kinematics in Fall thru early spring tend to be the more influential factors in late season severe than CAPE value

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Fall thru early spring severe can often be surprising with high shear such as that which is forecast. IMO CAPE forecasts, even w/ EML look to soundings is overdone on Tuesday  X NEUS. 

 

As I said abovestrong  kinematics in Fall thru early spring tend to be the more influential factors in late season severe than CAPE value

 

I actually think... given upstream soundings... CAPE forecasts are probably underdone in some areas. 00z GRB sounding has MUCAPE >4000 j/kg. 

 

Agreed re: kinematics but EML presence argues for high end severe where convection can occur. That's a bit trickier to figure out. 

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Yes, Tuesday has major potential if things clear out fast enough. If not, it could be a lot of nothing.

Its a Catch-22 for tomorrow: If the skies don't clear out then the CAPE forecasts will bust; on the other hand if the warm front lifts fast to the north or northeast and we clear the CAP will rule. Best scenario for severe weather tomorrow is clearing but warm front slows across NNY/NNE so both best shear and CAPE are manifested.

 

Wild card for severe tomorrow is shear params are correct and even 1/3rd to 1/2 CAPE is materialized even w/ cloud cover. My personal experience is that even w/ only minor insolation/warming at least some isoalted to scattered severe is still possible.

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