Sept 11-12 Wednesday, Thursday Storm Threat

[TalcottWx]

  On 9/10/2013 at 6:28 PM, Arnold214 said:

Hard to believe all of New England would light up as per 12z spc wrf. But if it's right and the strong sfc heating combined with a subtle short wave to light it off right in the EML, then holy moses watch out.

 

 

  On 9/10/2013 at 6:36 PM, Wx Hype said:

Just a massive outbreak as depicted on the WRF

Could you guys link it?

[weatherwiz]

  On 9/10/2013 at 6:28 PM, Arnold214 said:

Hard to believe all of New England would light up as per 12z spc wrf. But if it's right and the strong sfc heating combined with a subtle short wave to light it off right in the EML, then holy moses watch out.

 

Holy crap you're right.  This makes me want to skip my math class tomorrow.  

[Quincy]

  On 9/10/2013 at 6:39 PM, sbos_wx said:

Could you guys link it?

http://www.atmos.albany.edu/student/silviott/models/deterministic/wrf_spc.php?runtime=12

[CoastalWx]

  On 9/10/2013 at 6:28 PM, Arnold214 said:

Hard to believe all of New England would light up as per 12z spc wrf. But if it's right and the strong sfc heating combined with a subtle short wave to light it off right in the EML, then holy moses watch out.

 

All models in some shape or form show QPF and similar features so would think it has the right idea, but perhaps too aggressive? I've seen the WRF do this, but given the environment..a few cold pools might really light it up. Supposed to go camping up at Pawtuckaway state forest west of PSM tomorrow night. Debating if it's worth a pine tree falling on my tent.

[TalcottWx]

  On 9/10/2013 at 6:40 PM, Quincy said:

http://www.atmos.albany.edu/student/silviott/models/deterministic/wrf_spc.php?runtime=12

That page is sweet thanks

[Quincy]

  On 9/10/2013 at 6:43 PM, CoastalWx said:

All models in some shape or form show QPF and similar features so would think it has the right idea, but perhaps too aggressive? I've seen the WRF do this, but given the environment..a few cold pools might really light it up. Supposed to go camping up at Pawtuckaway state forest west of PSM tomorrow night. Debating if it's worth a pine tree falling on my tent.

Seeing it on the Euro as well is encouraging. Will be closely watching the trends from the RAP and HRRR tonight to get a better idea as we close on in. GFS LI values lower than -11C in western Mass. tomorrow aren't shabby and as many have said, we still have some pretty good lapse rates at that point.

[weatherwiz]

  On 9/10/2013 at 6:43 PM, CoastalWx said:

All models in some shape or form show QPF and similar features so would think it has the right idea, but perhaps too aggressive? I've seen the WRF do this, but given the environment..a few cold pools might really light it up. Supposed to go camping up at Pawtuckaway state forest west of PSM tomorrow night. Debating if it's worth a pine tree falling on my tent.

 

That s/w coming out of PA actually is pretty decent looking, not overly strong but it may very well be enough to weaken the cap

[Quincy]

It's kind of amusing to see some high res model solutions with the air-mass we're in. NMM has a goofy complex dropping south into Connecticut later tonight. 

 

  On 9/10/2013 at 6:45 PM, weatherwiz said:

That s/w coming out of PA actually is pretty decent looking, not overly strong but it may very well be enough to weaken the cap

That and we're actually seeing some height falls during the second half of the day. At least somewhat encouraging.

[CT Rain]

  On 9/10/2013 at 6:28 PM, Arnold214 said:

Hard to believe all of New England would light up as per 12z spc wrf. But if it's right and the strong sfc heating combined with a subtle short wave to light it off right in the EML, then holy moses watch out.

 

 

  On 9/10/2013 at 6:25 PM, CoastalWx said:

True EML cap too. H5 temps are like-10.5C or so. Not bad, but H7 temps are like +10C as you mentioned.  We will need some help to bust the cap.

 

Just a beautiful EML. I have noticed the 12z runs have weakened CIN a bit. You can see on the GFS 700 mb temperatures falling during the late afternoon/evening. That shortwave to the west is very weak - I don't think it's enough to do it. 

[OceanStWx]

  On 9/10/2013 at 6:28 PM, Arnold214 said:

Hard to believe all of New England would light up as per 12z spc wrf. But if it's right and the strong sfc heating combined with a subtle short wave to light it off right in the EML, then holy moses watch out.

 

[Quincy]

  On 9/10/2013 at 6:51 PM, CT Rain said:

Just a beautiful EML. I have noticed the 12z runs have weakened CIN a bit. You can see on the GFS 700 mb temperatures falling during the late afternoon/evening. That shortwave to the west is very weak - I don't think it's enough to do it. 

I'm inclined to agree here. While a few isolated storms can't be ruled out, I just don't see the forcing necessary for an organized line of storms, let alone an outbreak. Local terrain influences, any outflow or boundaries and any kind of upper level forcing (even if it's weak) could capitalize on steep lapse rates, but not in a widespread way.

[OceanStWx]

  On 9/10/2013 at 6:43 PM, CoastalWx said:

All models in some shape or form show QPF and similar features so would think it has the right idea, but perhaps too aggressive? I've seen the WRF do this, but given the environment..a few cold pools might really light it up. Supposed to go camping up at Pawtuckaway state forest west of PSM tomorrow night. Debating if it's worth a pine tree falling on my tent.

 

Don't forget to call that storm damage in.

 

I'm actually impressed as to how well modeling handled this MCS as of a couple days ago. If you go back to the first page and look at some of the images I posted, the forcing was progged to arrive later Tue morning/afternoon rather than overnight and clearing early.

 

I've taken a peek at some of the progs for tomorrow there is some subtle forcing that works through during the day. If you look at the trop pressure, you can see some higher values drifting across New England during the day. Sometimes that's all you need in a capped environment.

[CT Rain]

You can see the subtle s/w and height falls on the Euro as well. But boy that's pretty weak. 

[CT Rain]

  On 9/10/2013 at 6:54 PM, OceanStWx said:

Don't forget to call that storm damage in.

 

I'm actually impressed as to how well modeling handled this MCS as of a couple days ago. If you go back to the first page and look at some of the images I posted, the forcing was progged to arrive later Tue morning/afternoon rather than overnight and clearing early.

 

I've taken a peek at some of the progs for tomorrow there is some subtle forcing that works through during the day. If you look at the trop pressure, you can see some higher values drifting across New England during the day. Sometimes that's all you need in a capped environment.

 

On the maps I'm looking at (which are fairly low resolution) I didn't see anything on the dynamic tropopause (1.5 PVU sfc) that jumped out at me on either the NAM or GFS. You might be able to shed more light with better maps. 

[ORH_wxman]

That EML is something we haven't really seen in a long time. It wasn't even that good looking in the 6/1/11 outbreak (we had a less defined EML in that one)...but unfortunately, the other ingredients look like they might lead to another frustrating setup.

[Quincy]

  On 9/10/2013 at 6:59 PM, CT Rain said:

On the maps I'm looking at (which are fairly low resolution) I didn't see anything on the dynamic tropopause (1.5 PVU sfc) that jumped out at me on either the NAM or GFS. You might be able to shed more light with better maps. 

For those wondering about this sort of map:

[weatherwiz]

  On 9/10/2013 at 7:01 PM, ORH_wxman said:

That EML is something we haven't really seen in a long time. It wasn't even that good looking in the 6/1/11 outbreak (we had a less defined EML in that one)...but unfortunately, the other ingredients look like they might lead to another frustrating setup.

 

This is probably the best EML we've had since 5/31/98.  Too think though, even the EML during the superderecho was better than this

[CoastalWx]

Well if models are right, it's 7-7.5C/KM tomorrow aftn. I thnk that's about what 6/11 had in the aftn, but with much less shear this time around.

[CT Rain]

  On 9/10/2013 at 7:08 PM, weatherwiz said:

This is probably the best EML we've had since 5/31/98.  Too think though, even the EML during the superderecho was better than this

 

I don't know... there have been several "null cases" where we've had very steep mid level lapse rates that were poorly timed or other ingredients didn't add up. 

[CT Rain]

  On 9/10/2013 at 7:11 PM, CoastalWx said:

Well if models are right, it's 7-7.5C/KM tomorrow aftn. I thnk that's about what 6/11 had in the aftn, but with much less shear this time around.

 

Yeah... it seems to me like it's not that rare... but getting that kind of EML plume in here when other ingredients are lining up is a lot harder to do.

 

FWIW down this way on BUFKIT I'm seeing some 8-8.5 C/km kinda lapse rates.

[weatherwiz]

  On 9/10/2013 at 7:12 PM, CT Rain said:

I don't know... there have been several "null cases" where we've had very steep mid level lapse rates that were poorly timed or other ingredients didn't add up. 

 

it's certainly probably we have had better EML's but tough to remember them when they come with nothing.  

[ORH_wxman]

 

  On 9/10/2013 at 7:11 PM, CoastalWx said:

Well if models are right, it's 7-7.5C/KM tomorrow aftn. I thnk that's about what 6/11 had in the aftn, but with much less shear this time around.

 

I thought 6/1/11 was slightly less than that...more like 7C. Though I'd have to go back and look at the post-mortem thread we had on it. It was obviously a very good setup though due to the extreme shear and the prefrontal trough focusing discrete convection in the warm sector out ahead of the main front.

[weatherwiz]

  On 9/10/2013 at 7:14 PM, CT Rain said:

Yeah... it seems to me like it's not that rare... but getting that kind of EML plume in here when other ingredients are lining up is a lot harder to do.

 

FWIW down this way on BUFKIT I'm seeing some 8-8.5 C/km kinda lapse rates.

 

Absolutely!

[CoastalWx]

  On 9/10/2013 at 7:14 PM, CT Rain said:

Yeah... it seems to me like it's not that rare... but getting that kind of EML plume in here when other ingredients are lining up is a lot harder to do.

 

FWIW down this way on BUFKIT I'm seeing some 8-8.5 C/km kinda lapse rates.

 

It could be. The H7-H5 product I had has a pocket of 7.8C or so overhead at 00z Thursday on the GFS, but the soundings at the actual terminals probably have it locally higher. I just use it for a general overview.

[CT Rain]

  On 9/10/2013 at 7:17 PM, CoastalWx said:

It could be. The H7-H5 product I had has a pocket of 7.8C or so overhead at 00z Thursday on the GFS, but the soundings at the actual terminals probably have it locally higher. I just use it for a general overview.

 

IIRC on the Springfield tornado day the steepest mid level lapse rates were departing that morning but were still quite steep when tornadogenesis occurred.

 

The Washington DC derecho case was a good one last year and I think there was another EML day that produced some severe around Memorial Day? I'll have to dig through the soundings.

[CoastalWx]

  On 9/10/2013 at 7:16 PM, ORH_wxman said:

 

 

I thought 6/1/11 was slightly less than that...more like 7C. Though I'd have to go back and look at the post-mortem thread we had on it. It was obviously a very good setup though due to the extreme shear and the prefrontal trough focusing discrete convection in the warm sector out ahead of the main front.

 

The morning EML was actually more intense. IIRC, it was close to -8C/KM that fired up the elevated stuff. The aftn weakened ever so slightly.  It could be closer to 7, I thought I remember earlier in the aftn it was somewhere around 7-7.5C/KM.

[CoastalWx]

  On 9/10/2013 at 7:20 PM, CT Rain said:

IIRC on the Springfield tornado day the steepest mid level lapse rates were departing that morning but were still quite steep when tornadogenesis occurred.

 

The Washington DC derecho case was a good one last year and I think there was another EML day that produced some severe around Memorial Day? I'll have to dig through the soundings.

 

I have the meso analysis saved somewhere at home, but yeah the morning EML was classic.

[TalcottWx]

  On 9/10/2013 at 7:20 PM, CoastalWx said:

The morning EML was actually more intense. IIRC, it was close to -8C/KM that fired up the elevated stuff. The aftn weakened ever so slightly.  It could be closer to 7, I thought I remember earlier in the aftn it was somewhere around 7-7.5C/KM.

That elevated stuff rocked 

[Tropopause_Fold]

that is some pretty serious heat over the southern lakes / northern ohio valley. 95-98 in a lot of areas. but, completely void of any convective activity thus far too until you get down to the ohio river. 

[Quincy]

Here is the SPC analysis 700-500mb lapse rates for 6/1/11, for what they're worth: