cyclone77 Posted April 17, 2011 Share Posted April 17, 2011 yikes on 12z GFS for mid mS valley and OH valley Pretty impressive. Also looks about 6 hours slower than some of the previous runs. WAY slower than the SREF. Link to comment Share on other sites More sharing options...
hm8 Posted April 17, 2011 Share Posted April 17, 2011 Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 17, 2011 Author Share Posted April 17, 2011 The ECMWF is on the faster side... SLP in North/Central Missouri at 18z and around the IL/IN border at 0z. Link to comment Share on other sites More sharing options...
Hoosier Posted April 17, 2011 Share Posted April 17, 2011 Terre Haute off the NAM Link to comment Share on other sites More sharing options...
BrentO Posted April 17, 2011 Share Posted April 17, 2011 Terre Haute off the NAM EHI of 10.2 and CIN of only 7, yike this could be a bad bad day Link to comment Share on other sites More sharing options...
BrentO Posted April 17, 2011 Share Posted April 17, 2011 EHI of 10.2 and CIN of only 7, yike this could be a bad bad day I have wondered about CINH parameters ........ I know down here in Evansville we are looking at around 100 or so. Didn't know if there was some sort of guidance that would say like 0-50 is a small cap 50-100 strong, 100+ forget about it. answered my own question here with a little help from google: CINH values above 50 J/kg are typically enough to inhibit convection, unless dynamic forcing is extreme. Values from 25-50 J/kg require significant forcing, but can be overcome with reasonable dynamics or heating. Values from 10-25 also require a decent amount of forcing. CINH values under 10 indicate a requirement for only minimal forcing. Link to comment Share on other sites More sharing options...
patrick7032 Posted April 17, 2011 Share Posted April 17, 2011 I have wondered about CINH parameters ........ I know down here in Evansville we are looking at around 100 or so. Didn't know if there was some sort of guidance that would say like 0-50 is a small cap 50-100 strong, 100+ forget about it. answered my own question here with a little help from google: CINH values above 50 J/kg are typically enough to inhibit convection, unless dynamic forcing is extreme. Values from 25-50 J/kg require significant forcing, but can be overcome with reasonable dynamics or heating. Values from 10-25 also require a decent amount of forcing. CINH values under 10 indicate a requirement for only minimal forcing. That's a good baseline reference but operationally it's a little under done. Usually when you get under 1000 j/kg you really start to watch the vis sat even more, but when forcing is very strong you're on the left edge of the LLJ/Theata advection then things can explode at 50 j/kg inhibition esp if you have mid level dry air advecting in to cool/destabilize the column. Once you get under 25 I disagree on the forcing. If you have good instability and/or shear 25 won't be much of a factor at all. Link to comment Share on other sites More sharing options...
VAwxman Posted April 17, 2011 Share Posted April 17, 2011 Terre Haute off the NAM Just back from vacation and starting to look at things, but from a first glance this looks like some serious potential especially with initial cells once the cap goes away. For a few hours, it's hard to find too many negatives based on the progs, though we'll see what it looks like tomorrow. Link to comment Share on other sites More sharing options...
BrentO Posted April 17, 2011 Share Posted April 17, 2011 Just back from vacation and starting to look at things, but from a first glance this looks like some serious potential especially with initial cells once the cap goes away. For a few hours, it's hard to find too many negatives based on the progs, though we'll see what it looks like tomorrow. Does it look mostly elevated? I see the 0-3km CAPE of only around 10j/kg or so Link to comment Share on other sites More sharing options...
Fred Gossage Posted April 17, 2011 Share Posted April 17, 2011 Does it look mostly elevated? I see the 0-3km CAPE of only around 10j/kg or so Often times, in a case like this a few days out... when you're dealing with lower grid resolution in models... if the models think there is convection at the time... or if the sfc temps or dewpoints are underdone by even a couple of degrees.... that can be underdone by over 100 j/kg. There are questions with the capping (although not nearly as much as a few weeks ago with systems) and the chance of a veer-back-veer pattern closer to the cold front (where it probably should be anyway).... but even with those in mind, this system has a much higher chance of being a major severe weather episode.... than not being a major severe weather episode. Link to comment Share on other sites More sharing options...
jdrenken Posted April 17, 2011 Share Posted April 17, 2011 KSTL NAM Sounding Link to comment Share on other sites More sharing options...
Jim Martin Posted April 17, 2011 Share Posted April 17, 2011 Here is the sounding for Tuesday afternoon for Beau's hometown of Metropolis, Illinois. Link to comment Share on other sites More sharing options...
jdrenken Posted April 17, 2011 Share Posted April 17, 2011 Ouch Our rivers are already rising - with multiple systems the next 10 days - this is also a concern Take a look at the Rock Island gauge on the Mississippi. They are forecasted to be a mere 2.3ft below '93 levels on 21APR11. Link to comment Share on other sites More sharing options...
csnavywx Posted April 17, 2011 Share Posted April 17, 2011 Careful with the dews/temps again. For instance, the NAM is using a shallow moist layer under the cap as solar shielding, resulting in anemic mixing in the boundary layer. Much like the last few times, we're probably looking at temps underdone by 4-6C and dews overdone by 2-4C. Link to comment Share on other sites More sharing options...
Fred Gossage Posted April 17, 2011 Share Posted April 17, 2011 Careful with the dews/temps again. For instance, the NAM is using a shallow moist layer under the cap as solar shielding, resulting in anemic mixing in the boundary layer. Much like the last few times, we're probably looking at temps underdone by 4-6C and dews overdone by 2-4C. Unlike several of the last times, both the NAM and GFS are showing dewpoints as high in the boundary layer as 850-mb... as significant as 13C and even 15C, especially when you get into Missouri and Illinois. That's going to make surface moisture much MUCH harder to mix out than we have seen all season, even in the presence of several hours of insolation. Link to comment Share on other sites More sharing options...
csnavywx Posted April 17, 2011 Share Posted April 17, 2011 Unlike several of the last times, both the NAM and GFS are showing dewpoints as high in the boundary layer as 850-mb... as significant as 13C and even 15C, especially when you get into Missouri and Illinois. That's going to make surface moisture much MUCH harder to mix out than we have seen all season, even in the presence of several hours of insolation. That's a great point. I know that last Saturday was dominated by shallow moisture and as a result, most of the storms struggled initially (bases 4-5kft before they lowered later). This setup screams very low LCLs. Definitely some high octane moisture in terms of depth and quality. Link to comment Share on other sites More sharing options...
Fred Gossage Posted April 17, 2011 Share Posted April 17, 2011 That's a great point. I know that last Saturday was dominated by shallow moisture and as a result, most of the storms struggled initially (bases 4-5kft before they lowered later). This setup screams very low LCLs. Definitely some high octane moisture in terms of depth and quality. It seems as if we've FINALLY tapped the deep Gulf moisture pump, which I know the chasers will be happy about. It seems as though the deadly system late this past week and into this weekend helped with that feat. Link to comment Share on other sites More sharing options...
Fred Gossage Posted April 18, 2011 Share Posted April 18, 2011 The further southeast you go... the stronger the cap is. I think the highest risk is going to be east central Missouri and west central Illinois... quite possibly centered on the St. Louis area. Link to comment Share on other sites More sharing options...
tornadotony Posted April 18, 2011 Share Posted April 18, 2011 The further southeast you go... the stronger the cap is. I think the highest risk is going to be east central Missouri and west central Illinois... quite possibly centered on the St. Louis area. I still think the capping will be too strong there for anything prefrontal. Even assuming the models are underdoing sfc temps, that is a hellacious cap. Add in that with higher sfc temps moisture would be more likely to mix out and I just don't see this being a big event. I see this being a major hype outbreak, though, especially on the heels of this past hellraiser. Link to comment Share on other sites More sharing options...
Fred Gossage Posted April 18, 2011 Share Posted April 18, 2011 I still think the capping will be too strong there for anything prefrontal. Even assuming the models are underdoing sfc temps, that is a hellacious cap. Add in that with higher sfc temps moisture would be more likely to mix out and I just don't see this being a big event. I see this being a major hype outbreak, though, especially on the heels of this past hellraiser. The cap is gone near the triple point not far from the STL metro area at 00Z, and is weakening along I-70, west of the metro, near the triple point by mid to late afternoon. That's based on forecast soundings... not just guessing around with CIHN. Also... I really don't understand how moisture can mix out when good low-level moisture extends to at least 850-mb... and 850-mb dewpoints are as high as 13-15C. Link to comment Share on other sites More sharing options...
csnavywx Posted April 18, 2011 Share Posted April 18, 2011 My main area of concern is just ahead of the triple point and slightly eastward along the warm front. The cap is definitely strong enough to prevent an unzip too far ahead of the CF as it's being progged now, but it wouldn't shock me to see a pre-frontal convergence zone a little bit ahead of the main front, given the orientation of the mid/upper winds with the CF. We've seen some atomic capping inversions so far this season, and this one will be no different, but with strong synoptic forcing in association with that mid-level jet, and strong low-level convergence near that monster warm front and triple point, there's not much doubt in my mind that it'll break. Now if you give me this situation during June, when synoptic pre-conditioning is much weaker, I'd be singing a different tune. Right now, it simply looks like a textbook convectively unstable layer. Link to comment Share on other sites More sharing options...
Hoosier Posted April 18, 2011 Share Posted April 18, 2011 SREF continues to hit the eastern half of central IL and Indiana with the best sigtor probs. Link to comment Share on other sites More sharing options...
PatrickSumner Posted April 18, 2011 Share Posted April 18, 2011 SREF continues to hit the eastern half of central IL and Indiana with the best sigtor probs. Eastern Illinois, Indiana, Ohio special anyone??? Link to comment Share on other sites More sharing options...
nwohweather Posted April 18, 2011 Share Posted April 18, 2011 Idk about you guys but I feel like this is going to be linear by the time it gets to Indianapolis. Definitely though west central IL has to be the bullseye with this system Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 18, 2011 Author Share Posted April 18, 2011 Eastern Illinois, Indiana, Ohio special anyone??? The cap is still in place at that time. Link to comment Share on other sites More sharing options...
Hoosier Posted April 18, 2011 Share Posted April 18, 2011 The cap is still in place at that time. Somebody tell the NAM Link to comment Share on other sites More sharing options...
PatrickSumner Posted April 18, 2011 Share Posted April 18, 2011 The cap is still in place at that time. This time of year, the CAP can easily be broken earlier than what computer models are depicting. We have already seen that at least one time this year. We can talk about the cap all day (and it is a BIG player) but in the spring, the cap is more prone to bust earlier than the summer time (obviously) Link to comment Share on other sites More sharing options...
baroclinic_instability Posted April 18, 2011 Share Posted April 18, 2011 Hello to everyone from Colorado:) Looks like another case of deep cyclogenesis and "dynamically" induced low/mid level height falls helping to significantly erode the capping layer during the evening. Should the NAM/GFS verify--it will be a significant event with the cap likely breaking late. Euro would be less impressive with weak phasing and weaker height falls. This is another conditional event which will be determined by the quality of the phase. Link to comment Share on other sites More sharing options...
Indystorm Posted April 18, 2011 Share Posted April 18, 2011 OMG...Up to 50 on that tor probability for south central Indiana? Am I seeing that correctly? We haven't had too many 50's yet this season. Did not look at progs for the Carolina outbreak. Link to comment Share on other sites More sharing options...
Hoosier Posted April 18, 2011 Share Posted April 18, 2011 Idk about you guys but I feel like this is going to be linear by the time it gets to Indianapolis. Definitely though west central IL has to be the bullseye with this system That is a possibility, but the shear is absolutely disgusting well into the evening so there would still be at least a threat of spinups within a line. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.