Jump to content

  • Member Statistics

    17,859
    Total Members
    7,904
    Most Online
    Malkir008
    Newest Member
    Malkir008
    Joined

Northeast Severe/Convective/Thunder thread II

Baroclinic Zone

By Baroclinic Zone,
in New England

Recommended Posts

  • Replies 1.1k
  • Created
  • Last Reply
Typhoon Tip

Typhoon Tip

Posted
Posted
  On 5/29/2012 at 7:59 PM, CT Rain said:

lol I don't think so

There's a wind shift that moved through with the sea breeze front but HFD is still 31/22. We're fine.

Cu development abated abruptly when the wind shift came through. That's stability.

I've seen this many times growing up in this part of the country with these S arriving stablizers. It doesn't reflect on the thermometer very well. Otherwise you wouldn't have lost your Cu.

But ... large scale ascent would overcome that if it can arrive from the W.

Link to comment
Share on other sites
CoastalWx

CoastalWx

Posted
Posted
  On 5/29/2012 at 8:09 PM, moneypitmike said:

What is EHI?

The basic premise behind the EHI (Energy-Helicity Index) is that storm rotation should be maximized when CAPE is large and SRH is large. 0-1-km EHI values greater than 1-2 have been associated with significant tornadoes in supercells.

Link to comment
Share on other sites
Allenson

Allenson

Posted
Posted
  On 5/29/2012 at 8:03 PM, ct_yankee said:

I have close relatives in Bradford and Corinth VT... Sure wish I was up there now.

Actually hasn't been too bad here so far. Last night was a lot worse.

Cool murky air here as taken the severe punch out of things.

I wonder if I know your relatives?

Link to comment
Share on other sites
moneypitmike

moneypitmike

Posted
Posted
  On 5/29/2012 at 8:11 PM, SquatchinNY said:

Energy Helicity Index. If I remember correctly, CapexHelicity/12000?

Thanks--now I'll just have to figure out how to interpret it.

Moving into overcast again, though no thunder like the last time this happened (I think that was from the SVTcell that skirted by at about 2:00p.m.).

84.1/72

Link to comment
Share on other sites
Typhoon Tip

Typhoon Tip

Posted
Posted
  On 5/29/2012 at 8:07 PM, ChrisM said:

3500 SB CAPE. 3k+ MU Cape. Li -9. Sounds unstable no?

You have to understand something... Atmosphere thermodynamics has rather discrete tolerances. A fraction of a degree can prevent activation.

It doesn't matter if CAPE is high. If the trigger point were say, 32C, and it's 31.5C, and there is no other forcing present at that time, you can say it is hot and humid with bloated CAPE until your blue in the face, it ain't going to make it happen!

When the wind shifted S it transported some stablizing influence, otherwise your Cu field would still be activated. That's not really open to debate.

Link to comment
Share on other sites
wxsniss

wxsniss

Posted
Posted

Thanks TT

  On 5/29/2012 at 8:09 PM, moneypitmike said:

What is EHI?

EHI = energy helicity index = (CAPE x H) / 160,000

tool for factoring in both instability and helicity to produce rotating supercells

not in itself sufficient or complete to predict tornadoes, but 0-3 km EHI > 2 or 3 or 1-2km EHI > 1 or 2 at least is thought a necessary parameter for tornadogenesis

i'm far from an expert... here's more reading:

http://www.spc.noaa....p/help_ehi.html

http://www.stormtrac...orecast/ehi.htm

Link to comment
Share on other sites
moneypitmike

moneypitmike

Posted
Posted
  On 5/29/2012 at 8:04 PM, Happy Valley said:

Scorching and humid, can just feel the moisture convecting out of the ground.

Cumulonimbus towering all around the valley, gonna' take a ride with the baby and snap some photos. Looks like we don't get in on the action until evening.

Don't say that too quickly, Chris. Just had a couple rumbles (thought the sun's back out)..

83.8/72

Link to comment
Share on other sites
OceanStWx

OceanStWx

Posted
Posted

The storms that are getting the tornado warnings are really maximizing helicity on the low level boundaries. In NY they are feeding off the old OFB, which is extending eastward into central VT where the latest TOR went out. In southwestern NH they are using the warm front to spin up as the cross the boundary.

Link to comment
Share on other sites
TalcottWx

TalcottWx

Posted
Posted
  On 5/29/2012 at 8:16 PM, Typhoon Tip said:

You have to understand something... Atmosphere thermodynamics has rather discrete tolerances. A fraction of a degree can prevent activation.

It doesn't matter if CAPE is high. If the trigger point were say, 32C, and it's 31.5C, and there is no other forcing present at that time, you can say it is hot and humid with bloated CAPE until your blue in the face, it ain't going to make it happen!

When the wind shifted S it transported some stablizing influence, otherwise your Cu field would still be activated. That's not really open to debate.

I really doubt this 'stabilizing influence' will have any more than a minuscule impact on the line that will and has always been progged to move through hours from now. The damage has already been done and the instability is still in the atmosphere. This isn't a fog bank dropping Logan down 30F in an hour in July.

Link to comment
Share on other sites
CT Rain

CT Rain

Posted
Posted
  On 5/29/2012 at 8:11 PM, Typhoon Tip said:

Cu development abated abruptly when the wind shift came through. That's stability.

I've seen this many times growing up in this part of the country with these S arriving stablizers. It doesn't reflect on the thermometer very well. Otherwise you wouldn't have lost your Cu.

But ... large scale ascent would overcome that if it can arrive from the W.

Yes we have a very minor amount of CIN. we've gone from 33-32C. Whenever there is a burp in the atmosphere (outflow boundary, etc) we'll overcome that CIN. It's not really an issue most of our big svr days in CT start with a cu field, go to no cu, and then the real stuff moves in.

Link to comment
Share on other sites
Typhoon Tip

Typhoon Tip

Posted
Posted
  On 5/29/2012 at 8:23 PM, CT Rain said:

Yes we have a very minor amount of CIN. we've gone from 33-32C. Whenever there is a burp in the atmosphere (outflow boundary, etc) we'll overcome that CIN. It's not really an issue most of our big svr days in CT start with a cu field, go to no cu, and then the real stuff moves in.

It'll be interesting to track... The stuff in NYS appears to be weakening slightly. How smoked is central NE over the last 12 hours though!

wow

Link to comment
Share on other sites
CT Rain

CT Rain

Posted
Posted
  On 5/29/2012 at 8:25 PM, CT Blizz said:

And HFD is? LOL

Yeah lol

It was just comical because it the winter you claim to be in central NE.

Anyways an interesting threat. Some isolated stuff starting to pop up in the Hudson Valley. May be a threat to Litchfield County.

Link to comment
Share on other sites
moneypitmike

moneypitmike

Posted
Posted
  On 5/29/2012 at 8:17 PM, CoastalWx said:

Mike, treat it as a combo that combined CAPE and helicity. Helicity is a measure of rotation, so you want those two to really hook up.

Thanks, Scott.

Do you expect we'll have watches put up in the BOX zones at some point? Nice to see things beginning to pop right on I-87. Those could have the potential to work their way into the BOX CWA--at least the western zones.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...