HillsdaleMIWeather Posted February 27 Share Posted February 27 lol the SPC basically ignored Michigan in the text 1 Link to comment Share on other sites More sharing options...
madwx Posted February 27 Share Posted February 27 1 hour ago, CheeselandSkies said: When you have a relatively shallow low-level moist layer (only up to about 850mb or a little above at best on a couple soundings I just cherry-picked off this morning's 12Z 3KM NAM), vertical mixing (helped along by sunshine) can bring down that drier air, lowering surface dewpoints, thus raising LCLs (cloud bases) and possibly increasing low-level capping. At least, that's how I understand it. it would actually decrease capping but higher bases decreases the odds of tornadoes. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted February 27 Share Posted February 27 42 minutes ago, Stevo6899 said: Thanks for the reply/info. I always thought sunshine early is good to help with instability and help with moisture and severe development but as always there's so much going on and things to look at and it only takes one component to mess it all up. That's true in a broad sense, but too much of a good thing is possible when you are dealing with shallow moisture. Link to comment Share on other sites More sharing options...
Harry Perry Posted February 27 Share Posted February 27 50 minutes ago, HillsdaleMIWeather said: lol the SPC basically ignored Michigan in the text Noticed that too. GRR update did mention their thinking hasn’t changed and that with the realized surface heating and continued heating through the afternoon, the cap will erode as the wave approaches and will set the stage ripe for severe weather of all types across south central MI. 1 Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 27 Share Posted February 27 59 minutes ago, HillsdaleMIWeather said: lol the SPC basically ignored Michigan in the text They tend to do that at times, and there's no real rhyme or reason as to why. 2 Link to comment Share on other sites More sharing options...
Harry Perry Posted February 27 Share Posted February 27 9 minutes ago, Chicago Storm said: They tend to do that at times, and there's no real rhyme or reason as to why. Typically this time of year the lakes keep warm frontal boundaries from surging northward past the MI/IN/OH borders, but this year the water temps are well above average and no ice - albeit still cold enough to create a stable boundary layer, just not as profound. They’re probably thinking that the warm frontal surge along with cooler waters will slow the forward propagation of the aforementioned surge while keeping the threat suppressed further south… but for interior regions of southern Michigan, especially away from the lake, I would beg to differ. Pretty conditional still, but may be in for a surprise. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted February 27 Share Posted February 27 15Z HRRR started to downtrend the impressive supercells the earlier runs had across northern Illinois, and 17Z effectively loses them entirely. 1 Link to comment Share on other sites More sharing options...
Stx_Thunder Posted February 27 Share Posted February 27 1 hour ago, madwx said: it would actually decrease capping but higher bases decreases the odds of tornadoes. Normally the risk of all severe hazards is virtually non-existent in very elevated or high-based storms. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted February 27 Share Posted February 27 1 minute ago, Stx_Thunder said: Normally the risk of all severe hazards is virtually non-existent in very elevated or high-based storms. It's true that it's difficult for tornadoes and damaging winds to occur when storms are not surface-based, but the elevated significant hailer is very much a thing. 1 Link to comment Share on other sites More sharing options...
frostfern Posted February 27 Share Posted February 27 21 minutes ago, Harry Perry said: Typically this time of year the lakes keep warm frontal boundaries from surging northward past the MI/IN/OH borders, but this year the water temps are well above average and no ice - albeit still cold enough to create a stable boundary layer, just not as profound. They’re probably thinking that the warm frontal surge along with cooler waters will slow the forward propagation of the aforementioned surge while keeping the threat suppressed further south… but for interior regions of southern Michigan, especially away from the lake, I would beg to differ. Pretty conditional still, but may be in for a surprise. With a strong due south wind the lakes can actually help convergence, except for directly over the lake. I think the problem is more the timing. The cap doesn’t really break until after dark. Not that tornadoes can’t happen after dark, and all the other hazards will be there. If the cap breaks early anywhere though, watch out… Link to comment Share on other sites More sharing options...
frostfern Posted February 27 Share Posted February 27 12 minutes ago, Stx_Thunder said: Normally the risk of all severe hazards is virtually non-existent in very elevated or high-based storms. That’s not really true. High based storms can be extremely severe. It’s only really an issue for tornadoes. Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 27 Share Posted February 27 Typically this time of year the lakes keep warm frontal boundaries from surging northward past the MI/IN/OH borders, but this year the water temps are well above average and no ice - albeit still cold enough to create a stable boundary layer, just not as profound. They’re probably thinking that the warm frontal surge along with cooler waters will slow the forward propagation of the aforementioned surge while keeping the threat suppressed further south… but for interior regions of southern Michigan, especially away from the lake, I would beg to differ. Pretty conditional still, but may be in for a surprise. I wasn’t talking about the threat, just that they didn’t mention that region. Link to comment Share on other sites More sharing options...
Stx_Thunder Posted February 27 Share Posted February 27 3 hours ago, frostfern said: That’s not really true. High based storms can be extremely severe. It’s only really an issue for tornadoes. That depends on what you’re meaning when you say, ‘high-based’. It usually means a step above ‘elevated’. High-based cells usually means that they’re rooted well aloft in the mid-levels above 700 MB (10 Kft above sea level), typically because the low-levels below that or the boundary layer all the way to the surface is too dry and/or stable. So obviously, the severe risk would be low because the depth of the storm is much shallower, if it’s actually high-based. Elevated thunderstorms usually means they’re rooted below that in the boundary layer or below 700 MB. Where they typically still have better access to more substantial warm/moist inflow (despite not being surface-based), in the appropriate environment. Usually in shallow polar/arctic frontal air masses rooted in the surface layer no more than a few thousand feet above the surface (basically a cold dome with warmer air overrunning it causing cloudiness down here in the south). So in that kind of scenario, the severe risk would obviously be higher. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 27 Share Posted February 27 Mesoanalysis looking spicy Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted February 27 Share Posted February 27 10% sig tor introduced for South of Chicago into NW Indiana 1 Link to comment Share on other sites More sharing options...
BYG Jacob Posted February 27 Share Posted February 27 1 Link to comment Share on other sites More sharing options...
MidwestChaser Posted February 27 Share Posted February 27 Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 27 Share Posted February 27 Wish I were able to be chasing today, but couldn't swing it at work. There two targets overall that I would have considered... •N Illinois near the SLP/CF/DL/WF intersection. However, it's unknown if this activity will be surface based or not. •I-80/southern Chicago suburbs down into E IL/IN. Dryline play for discrete supercells, should the cap erode. 1 Link to comment Share on other sites More sharing options...
frostfern Posted February 27 Share Posted February 27 Elevated and high based don’t mean the same thing. You can have either one and not the other. Out west you often have high based storms that are still rooted in the boundary layer, because the boundary layer is extremely deep. Storms that move over Lake Michigan are almost always elevated, technically, in the spring and summer because surfaces based parcels are rarely unstable, but the cloud base is often way lower than what you’d see in Colorado, New Mexico, or Arizona. Neither elevated or high based is ideal for tornadoes, but other types of severe weather are not uncommon at all. High based storms over a deep boundary layer are notorious for causing downbursts because the negative buoyancy for downdrafts is extreme. It happens out west all the time. Last spring an elevated supercell a few miles from where I live produced tennis ball sized hail with a surface temperature in the low 50s. 1 1 Link to comment Share on other sites More sharing options...
frostfern Posted February 27 Share Posted February 27 Sorry for being pedantic. I think you know what you’re talking about but you aren’t using the correct terminology. Link to comment Share on other sites More sharing options...
MidwestChaser Posted February 27 Share Posted February 27 Some of you can't help but bicker over little things, huh? 1 Link to comment Share on other sites More sharing options...
Indystorm Posted February 27 Share Posted February 27 Didn't think I'd be signing in for svr season this early in the Calumet region, but parameters for later tonight are quite concerning. Link to comment Share on other sites More sharing options...
Stevo6899 Posted February 27 Share Posted February 27 7 minutes ago, MidwestChaser said: Some of you can't help but bicker over little things, huh? Pretty sure it's just a discussion to clarify things, rather than bickering. For those that aren't as educated in severe weather like myself, we appreciate all posts and know it's a difficult science to explain fully. 1 Link to comment Share on other sites More sharing options...
Stx_Thunder Posted February 27 Share Posted February 27 9 hours ago, CheeselandSkies said: It's true that it's difficult for tornadoes and damaging winds to occur when storms are not surface-based, but the elevated significant hailer is very much a thing. Well it seems that even very elevated storms rooted close to 700 MB, but especially, storms in majorly lower than normal CAPE environments are producing more severe/larger hail instances & lightning than before. Those baseball diameter hail reports around Tyler, TX that happened just a few weeks ago on the early morning right around sunrise of Feb. 11 (despite the favorable hail-producing environment aloft with quite cold mid-level temps this far south just below -15 C, steep mid-level LRs, and favorable shear parameters), was awfully interesting to say the least. Looking at the 12 Z FWD & SHV (Dallas and Shreveport LA) observed soundings ahead of a front, there was essentially no CAPE whatsoever in that area (including MU). I posted that info/data about it in the 2024 Texas discussion thread: https://www.americanwx.com/bb/topic/59912-texas-2024-discussionobservations/?do=findComment&comment=7228417 There was also 3.00” diameter hail reported from a fully discrete supercell between the I-10 corridor that runs from San Antonio - Houston TX on Jan. 8 (this year) also. But the environment in the area that day did have some actual CAPE on 12 Z observed SPC soundings (a little surface-based probably too) as it happened in the early afternoon. But even then, to have that kind of hail going on in early January is very unusual down around here close to the Gulf coast (looked at historical data also). As that’s normally only severe season type hail in spring. There was also a confirmed tornado report in an embedded, elevated (but likely near sfc-based) supercell in Brazoria county (near Houston TX) that happened in the very early morning near sunrise around 6:00 am last month on Jan. 5 that was also in a very low CAPE (< 500 j/kg) environment. Even though it was influenced by a warm frontal zone nearing the coast with favorable shear profiles and lapse rates aloft. The elevated storms also had a good amount of CG lightning going on that developed around TX coast when I was looking at lightning data early that morning and in another, weaker storm that developed near me. - - - Personally, looking at all those severe events I wrote above that happened this month and last month so early in the year is quite concerning to me. Especially when normal severe season this year starts next month. Link to comment Share on other sites More sharing options...
KeenerWx Posted February 27 Share Posted February 27 2 minutes ago, Indystorm said: Didn't think I'd be signing in for svr season this early in the Calumet region, but parameters for later tonight are quite concerning. Wonder if locally this is the earliest 10% hatched tor outlook. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted February 27 Share Posted February 27 2 minutes ago, KeenerWx said: Wonder if locally this is the earliest 10% hatched tor outlook. Would beat 2/28/17 by a day, lol. https://www.spc.noaa.gov/products/outlook/archive/2017/day1otlk_20170228_1630.html 1 Link to comment Share on other sites More sharing options...
frostfern Posted February 27 Share Posted February 27 Anyone else notice the super sharp dryline forming over Missouri and Illinois? I don't think I've ever seen a dryline like that so far north and east. Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 27 Share Posted February 27 1 minute ago, frostfern said: Anyone else notice the super sharp dryline forming over Missouri and Illinois? I don't think I've ever seen a dryline like that so far north and east. That's part of why there is a risk today. 1 Link to comment Share on other sites More sharing options...
Indystorm Posted February 27 Share Posted February 27 Tor watch coming for ne IL and nw IN per SPC meso Link to comment Share on other sites More sharing options...
MidwestChaser Posted February 27 Share Posted February 27 Don't think I've ever seen baseball sized hail mentioned for NE IL. 2 Link to comment Share on other sites More sharing options...
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