OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 Nice image. Tuesday does look good further north for some sort of warm front runner diving SE. Here's another procedure (stolen from my time at DVN). Basically showing divergence on a pressure surface. The idea is to pick a surface near the LCL so you can find forcing for convection. This happens to be 875 mb, and blue is negative value, so convergence (i.e. lift). Pretty easy to see the frontal boundary moving in aloft. And as you suggest, this max convergence moves ESE with time. Link to comment Share on other sites More sharing options...
weatherwiz Posted September 8, 2013 Share Posted September 8, 2013 Very impressed with overnight model runs! Hoping my friend can be able to come down Link to comment Share on other sites More sharing options...
SlantStickers Anonymous Posted September 8, 2013 Share Posted September 8, 2013 So we've got a pretty good connection between EML and real noteworthy severe in NE, is this the first time having the conditions present has looked possible this season? Link to comment Share on other sites More sharing options...
weatherwiz Posted September 8, 2013 Share Posted September 8, 2013 So we've got a pretty good connection between EML and real noteworthy severe in NE, is this the first time having the conditions present has looked possible this season? This is really the first time this year we've had a modeled EML work into the region. Link to comment Share on other sites More sharing options...
SlantStickers Anonymous Posted September 8, 2013 Share Posted September 8, 2013 This is really the first time this year we've had a modeled EML work into the region. Very nice, my interest is definitely piqued. Obviously there's still the standard up in the air factors one gets with convection, but not seeing a parade of "Mehs" yet is always a good sign. CAPE values on the NAM map from this morning looked pretty good, spinners possible? Link to comment Share on other sites More sharing options...
weatherwiz Posted September 8, 2013 Share Posted September 8, 2013 Very nice, my interest is definitely piqued. Obviously there's still the standard up in the air factors one gets with convection, but not seeing a parade of "Mehs" yet is always a good sign. CAPE values on the NAM map from this morning looked pretty good, spinners possible? Getting high Cape this time of year is a major, major plus. This setup should have more than adequate shear. As far as spinners go, all will really depend on strength of llvl winds and how large hodos are which we can pinpoint closer to the event. Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 Here's another procedure (stolen from my time at DVN). Basically showing divergence on a pressure surface. The idea is to pick a surface near the LCL so you can find forcing for convection. This happens to be 875 mb, and blue is negative value, so convergence (i.e. lift). Pretty easy to see the frontal boundary moving in aloft. And as you suggest, this max convergence moves ESE with time. WAWT_NAM.jpg What do those numbers represent? Link to comment Share on other sites More sharing options...
OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 What do those numbers represent? MSLP Link to comment Share on other sites More sharing options...
OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 Getting high Cape this time of year is a major, major plus. This setup should have more than adequate shear. As far as spinners go, all will really depend on strength of llvl winds and how large hodos are which we can pinpoint closer to the event. To emphasize that point, here is a procedure from Ekster. Basically, we're looking at the progression of the EML by Tuesday afternoon. You have greater than 7 C/km lapse rates advecting along with the ridge axis. In the top left you have H5 temps, and the bottom left is H8 temps. So you have very warm (+20 to +25 C) temps moving in at 850 mb. And while you would expect the center of the ridge to be warm aloft, because of the steep lapse rates being advected in the EML, temps at H5 are actually quite cool. That's how you build the high CAPE. You combine that with typical New England shear and you get significant severe. Link to comment Share on other sites More sharing options...
CT Rain Posted September 8, 2013 Share Posted September 8, 2013 EML.jpg To emphasize that point, here is a procedure from Ekster. Basically, we're looking at the progression of the EML by Tuesday afternoon. You have greater than 7 C/km lapse rates advecting along with the ridge axis. In the top left you have H5 temps, and the bottom left is H8 temps. So you have very warm (+20 to +25 C) temps moving in at 850 mb. And while you would expect the center of the ridge to be warm aloft, because of the steep lapse rates being advected in the EML, temps at H5 are actually quite cool. That's how you build the high CAPE. You combine that with typical New England shear and you get significant severe. Pretty classic setup for northern areas. Not really expecting much down this way unless we're able to pop a solid MCS upstream Tuesday afternoon in NY. Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 MSLP Oh, ok..lol. I thought something else when you said 875mb, but I get what that graphic was. Link to comment Share on other sites More sharing options...
OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 Oh, ok..lol. I thought something else when you said 875mb, but I get what that graphic was. The white lines are MSLP, but the image and winds are at 875 mb. I like the signs I see so far Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 The white lines are MSLP, but the image and winds are at 875 mb. I like the signs I see so far Yeah could be fun up in NNE. I'll admire the cirrus canopy. Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 The white lines are MSLP, but the image and winds are at 875 mb. I like the signs I see so far I see it now that I'm not mobile. I like that idea you got from DVN. Link to comment Share on other sites More sharing options...
CT Rain Posted September 8, 2013 Share Posted September 8, 2013 The NAM has a sweet LLJ move in after dark Tuesday night. With plenty of CAPE upstairs thanks to the remnant EML plume we may be able to sneak some convection into SNE after dark. Lapse rates remains somewhat steep Wednesday once the EML plume moves on so I could see severe during the afternoon if we're able to initiate convection? Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 The NAM has a sweet LLJ move in after dark Tuesday night. With plenty of CAPE upstairs thanks to the remnant EML plume we may be able to sneak some convection into SNE after dark. Lapse rates remains somewhat steep Wednesday once the EML plume moves on so I could see severe during the afternoon if we're able to initiate convection? You think SNE sees anything outside of western areas Wednesday? It looked like the pre frontal type stuff over NNE and NY. Maybe western SNE? The ridge sort of parks overhead. Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 Look at this push aloft. There is going to be a hell of a complex in NNE. I mean big. LOL at the NAM 700mb winds with this. Link to comment Share on other sites More sharing options...
CT Rain Posted September 8, 2013 Share Posted September 8, 2013 You think SNE sees anything outside of western areas Wednesday? It looked like the pre frontal type stuff over NNE and NY. Maybe western SNE? The ridge sort of parks overhead. Will be tough to do. All going to depend on where convection fires upstream and if we can cash in. I'm sort of intrigued by Tuesday night. Link to comment Share on other sites More sharing options...
OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 Look at this push aloft. There is going to be a hell of a complex in NNE. I mean big. LOL at the NAM 700mb winds with this. eta_850_theta-e_48.gif The NAM verbatim would have one helluva MCS initiate across southern Ontario Monday night, spilling down across the northern lakes. Ukie kind of likes that too (and generally doesn't suffer from runaway convective feedback). Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 Will be tough to do. All going to depend on where convection fires upstream and if we can cash in. I'm sort of intrigued by Tuesday night. That may be our best shot, but wonder how much sneaks south with all the forcing north. I could see maybe the srn end of the complex tickling the nrn regions, but we'll see I suppose. Link to comment Share on other sites More sharing options...
OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 The NAM verbatim would have one helluva MCS initiate across southern Ontario Monday night, spilling down across the northern lakes. Ukie kind of likes that too (and generally doesn't suffer from runaway convective feedback). Chuck the Euro in that camp too. I mean you put that kind of theta-e on the nose of a 50 knot LLJ and you'll fire something off. Link to comment Share on other sites More sharing options...
CT Rain Posted September 8, 2013 Share Posted September 8, 2013 That may be our best shot, but wonder how much sneaks south with all the forcing north. I could see maybe the srn end of the complex tickling the nrn regions, but we'll see I suppose. I like the LLJ signal on the GFS and NAM Tuesday night. May help force some elevated convection. Link to comment Share on other sites More sharing options...
CT Rain Posted September 8, 2013 Share Posted September 8, 2013 Chuck the Euro in that camp too. I mean you put that kind of theta-e on the nose of a 50 knot LLJ and you'll fire something off. It's nice when you fire stuff off and can go dry adiabatic at 700mb lol Link to comment Share on other sites More sharing options...
OceanStWx Posted September 8, 2013 Share Posted September 8, 2013 It's nice when you fire stuff off and can go dry adiabatic at 700mb lol Some of these NAM soundings are ridiculous really. Eastern tip of Lake Ontario on Tuesday evening/night is literally dry adiabatic from 800 to 600 mb. Goose farts will set off convection with that kind of atmosphere. Link to comment Share on other sites More sharing options...
CT Rain Posted September 8, 2013 Share Posted September 8, 2013 Some of these NAM soundings are ridiculous really. Eastern tip of Lake Ontario on Tuesday evening/night is literally dry adiabatic from 800 to 600 mb. Goose farts will set off convection with that kind of atmosphere. Yeah I know. It's fun to loop on BUFKIT and watch the temperature profile just start hooking left and hugging the dry adiabats when the plume moves in. Link to comment Share on other sites More sharing options...
weatherwiz Posted September 8, 2013 Share Posted September 8, 2013 Tuesday could be highly interesting up north both AM and PM and I could see a tornado threat develop from NY into VT and maybe NH...perhaps even NW MA. I'm with Ryan on Tuesday night, depending on what's going on with the forcing and the boundary, we very well could see convection fire or slide south into the rest of MA and perhaps into CT during the overnight hours. Could be looking at a hail threat as the main threat but microbursts are also a possibility. Link to comment Share on other sites More sharing options...
CoastalWx Posted September 8, 2013 Share Posted September 8, 2013 Pretty classic EML advection though per Ekster and Banacos. There is a long wave trough over the west, but a stronger s/w dips into the nrn Rockies and then slides east. Despite Monsoon flow, the ridge and EML underneath it over the high plains get entrained and then shoved over the top of the ridge with minimal moisture taint from the monsoon. Link to comment Share on other sites More sharing options...
Quincy Posted September 8, 2013 Share Posted September 8, 2013 Here's a look at the 850mb wind forecast from the 18z NAM. If that's not good enough, here's an obscene hodograph for the Montreal area Tuesday afternoon. Images courtesy of College of DuPage and TwisterData.com, respectively. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted September 8, 2013 Share Posted September 8, 2013 How about Thursday? Link to comment Share on other sites More sharing options...
weatherwiz Posted September 8, 2013 Share Posted September 8, 2013 How about Thursday? Tuesday/Wednesday are the better days for any significant severe potential, though Thursday could feature severe...it just all depends on whether or not we still have really steep mid-level lapse rates around and of course cloud debris. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.