tornadotony Posted March 12, 2012 Share Posted March 12, 2012 RUC at 18z tomorrow afternoon: Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 Td's were actually lower than that in some of the areas that were hit. ORD only had a dewpoint around 50 when the tornado passed near there. In terms of overall tornado production, that was an impressive event given the marginal moisture. Exactly true, that is one thing we always watched while storm chasing, where the gradients/fronts lie. Typically in MI a warm front will end up somewhere between M-21 and M-46 which is an area that historically has been hit several times with tornadoes some of which being violent on both sides of the state. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 RUC at 18z tomorrow afternoon: Both those images show some very high amounts of low-level instability, something to certainly monitor going forward. Link to comment Share on other sites More sharing options...
Hoosier Posted March 12, 2012 Author Share Posted March 12, 2012 RUC at 18z tomorrow afternoon: Well well Link to comment Share on other sites More sharing options...
Hoosier Posted March 12, 2012 Author Share Posted March 12, 2012 I'm not calling for a big outbreak, and although the 0-1 km shear is a little weaker than I'd like to see (at least initially) you can see how there could be some potential for a strong tornado or two either side of I-80 if something like the more aggressive NAM pans out. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 The thing that concerns me is that the source region for the low-level airmass right now is the rain-modified airmass behind the current convection. That might serve to bolster moisture return prospects, having that extra little jolt of ambient moisture feeding back into the airmass. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 The thing that concerns me is that the source region for the low-level airmass right now is the rain-modified airmass behind the current convection. That might serve to bolster moisture return prospects, having that extra little jolt of ambient moisture feeding back into the airmass. Agree plus could help lay some differential heating boundaries depending upon who gets how much precip and where the clouds might or might not linger. Link to comment Share on other sites More sharing options...
Geos Posted March 12, 2012 Share Posted March 12, 2012 Supposed to be mainly cloudy here all day tomorrow. I wouldn't think the instability would be that great. Link to comment Share on other sites More sharing options...
brettman320 Posted March 12, 2012 Share Posted March 12, 2012 Mini sups tomorrow? Link to comment Share on other sites More sharing options...
cyclone77 Posted March 12, 2012 Share Posted March 12, 2012 Surface cape looks a lot less impressive on this RUC map. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 Distinct timing differences but both do contain the same idea of what might happen in the dryslot tomorrow. Link to comment Share on other sites More sharing options...
nwohweather Posted March 12, 2012 Share Posted March 12, 2012 Either way, I feel this may be the prelude to something...bigger... I see what you mean. This weekend could be very volatile if what the models are showing verifies Link to comment Share on other sites More sharing options...
OceanStWx Posted March 12, 2012 Share Posted March 12, 2012 That's a nice increase over 21z, and a nice northern gradient too. Link to comment Share on other sites More sharing options...
thewxmann Posted March 12, 2012 Share Posted March 12, 2012 Yeah but you never bullseye chase. Often, the bullseye for severe parameters is in a location with poor forcing for convection, and you can have all the EHI in the world but it won't mean a thing if you don't have a storm there. A trick to forecasting enhanced severe threats is to look for the GRADIENT of the parameters (EHI in this case). The gradient is where you'll often get your best combination of parameters and forcing. And tomorrow looks to be no different, with a tight vort lobe rounding the H5 low. And unfortunately, that gradient basically sets up along I-80 in the southern suburbs of Chicago and into northern Indiana (NAM verbatim). Again, I am skeptical about the moisture return the NAM is depicting, but if it verifies, then I'll be a bit nervous tomorrow afternoon. Great post, could not have said it better myself. Link to comment Share on other sites More sharing options...
thewxmann Posted March 12, 2012 Share Posted March 12, 2012 One thing to note is that NAM seems to develop a mesolow invof Chicago later today. This aids in the local backing of winds in IN and IL. Not only would this backing be important in enhancing SRH, but moisture depth doesn't look all that great. The direction of 925mb and sfc winds will be important in keeping the moisture there. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 One thing to note is that NAM seems to develop a mesolow invof Chicago later today. This aids in the local backing of winds in IN and IL. Not only would this backing be important in enhancing SRH, but moisture depth doesn't look all that great. The direction of 925mb and sfc winds will be important in keeping the moisture there. Yeah I have noticed this mesolow showing up on several runs now going back for the last day to day and half. Link to comment Share on other sites More sharing options...
Bryan Wood Posted March 12, 2012 Share Posted March 12, 2012 Yeah but you never bullseye chase. Often, the bullseye for severe parameters is in a location with poor forcing for convection, and you can have all the EHI in the world but it won't mean a thing if you don't have a storm there. A trick to forecasting enhanced severe threats is to look for the GRADIENT of the parameters (EHI in this case). The gradient is where you'll often get your best combination of parameters and forcing. And tomorrow looks to be no different, with a tight vort lobe rounding the H5 low. And unfortunately, that gradient basically sets up along I-80 in the southern suburbs of Chicago and into northern Indiana (NAM verbatim). Again, I am skeptical about the moisture return the NAM is depicting, but if it verifies, then I'll be a bit nervous tomorrow afternoon. Completely agree. If you look at the Pekin-Henryville-Marysville tornado from March 2, it traveled along the gradients, including EHI, CAPE, Theta-E. Link to comment Share on other sites More sharing options...
L.B. LaForce Posted March 12, 2012 Share Posted March 12, 2012 1.33km Fire Wx Nest is out for the threat area FWIW. http://www.emc.ncep.noaa.gov/mmb/mmbpll/firewx/firewx_06z_refc_animate_1h.html Link to comment Share on other sites More sharing options...
A-L-E-K Posted March 12, 2012 Share Posted March 12, 2012 liking my pinger chances downtown...iso tor thread western IN/MI border area. Link to comment Share on other sites More sharing options...
RobertSul Posted March 12, 2012 Share Posted March 12, 2012 Latest SPC outlook bumped up significantly for Southeastern Michigan with the possibility of severe winds. Went from 5% to 30%. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 I wouldn't say that. If temperatures weren't going to be this warm, I would write it off. But with temperatures approaching 70F, MLCAPE >1,000, veering winds, low level shear, EHI >1, cold 700mb temps, I wouldn't rule out the potential. Everything spells out an isolated tornado event, and widespread hail, and damaging winds threat across SEMI. Solid 30W/30H/5T slight risk for the southern 4. I have to give you some props here, besides the hail part you nailed the probs right on. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 1.33km Fire Wx Nest is out for the threat area FWIW. http://www.emc.ncep....animate_1h.html This has my interest significantly, depending how tired I am later on this afternoon maybe thinking of a local chase, certainly will be monitoring trends. Link to comment Share on other sites More sharing options...
outflow Posted March 12, 2012 Share Posted March 12, 2012 I have to give you some props here, besides the hail part you nailed the probs right on. i think the spc went a little overboard on the risk, we are going to need sun for anything to get going and looking at the vis. there sure isn't much clearing behind the rain right now, granted it is only 930am. I would have waited til 1630 to up the probs. after seeing how much clearing would take place. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 i think the spc went a little overboard on the risk, we are going to need sun for anything to get going and looking at the vis. there sure isn't much clearing behind the rain right now, granted it is only 930am. I would have waited til 1630 to up the probs. after seeing how much clearing would take place. I would be watching the dryslot that is currently over IL which does have pockets of sunshine in it currently, furthermore we won't need too much to get things going in a big way, an environment similar to a 63-67/53-57 would get the job done. If you look at IL/IN you have mid 50 dewpoints in place moving northward and temps already in the upper 50s to 60 and those are 9am/8am EDT/CDT obs Link to comment Share on other sites More sharing options...
outflow Posted March 12, 2012 Share Posted March 12, 2012 I would be watching the dryslot that is currently over IL which does have pockets of sunshine in it currently, furthermore we won't need too much to get things going in a big way, an environment similar to a 63-67/53-57 would get the job done. If you look at IL/IN you have mid 50 dewpoints in place moving northward and temps already in the upper 50s to 60 and those are 9am/8am EDT/CDT obs thats true, i see gary is already 59/55 or so, i guess it would only take about 2 hours of sun to jump the temps in the mid 60s. Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 thats true, i see gary is already 59/55 or so, i guess it would only take about 2 hours of sun to jump the temps in the mid 60s. Yep probably why SPC is going hard at this, I could actually see parts of the area possibly getting a good amount of sun 3-6hrs, if that happens look out. Link to comment Share on other sites More sharing options...
tornadotony Posted March 12, 2012 Share Posted March 12, 2012 You don't want too much sun today. That'll mix out the moisture. We want sufficient but limited heating to keep moisture in place if we want severe wx today. Though personally, I don't really want it. I just have a bad feeling that if something happens it's going to be too close to home. Link to comment Share on other sites More sharing options...
nwohweather Posted March 12, 2012 Share Posted March 12, 2012 Well dynamics seem strong enough to make today go off despite limited instability but I just think it could play a bigger factor than many think. As Stebo said 3-6 hours is what we'll need for a solid severe day and it definitely seems doable. Also I noticed there's no CINH which is some good news Link to comment Share on other sites More sharing options...
Stebo Posted March 12, 2012 Share Posted March 12, 2012 You don't want too much sun today. That'll mix out the moisture. We want sufficient but limited heating to keep moisture in place if we want severe wx today. Though personally, I don't really want it. I just have a bad feeling that if something happens it's going to be too close to home. Yeah you make a good point there, especially with the amount of winds just above the surface we would easily mix out if we got abundant sunshine. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.