2022-03-05 EVENT: NE/IA/MO/KS/IL

Jesse Risley

Staff member
Apr 12, 2006
2,202
705
11
42
Macomb, IL
www.tornadoguys.com
It looks as if the first setup of the so-called meteorological spring may be on tap for Saturday, March 5th, offering at least the prospects for a 'gentleperson's chase' if nothing else. The system is still 5 days out and there will likely be vacillations, so for now we'll keep the discussion generalized.

A longwave troughing pattern over the eastern Pacific remains concomitant with several disturbances that eject out from the SW CONUS Friday evening and again Saturday evening into Sunday in the form of several shortwaves that traverse the central CONUS as we transition to southwestern flow beginning late week. The first major push of Gulf moisture northward into the eastern Plains and western Corn Belt commences with Td values progged in the mid to upper 50s reaching the mid-Missouri valley by Saturday morning as a warm front is poised to lift northward towards the I-90 corridor through the day on Saturday. An associated area of low pressure moves out of eastern CO and deepens as it approaches the mid-Missouri valley by Saturday evening with a strong cold front in tow, and this is associated with the penultimate shortwave that impacts the central CONUS in the FRI-early MON timeframe. The surface low initially deepens but then weakens slightly as it moves into NC/NW IA by Saturday night.

Warm sector convection looks likely with this system. Kinematics look favorable for typical early-season SVR weather, with all modes on the table, including supercells with all hazards possible. While kinematics are favorable for SVR convection, several caveats exist, including the extent of instability present, and thus overall lapse rate strength, actual storm mode, and an actual slight weakening of the surface low as it moves into IA. The biggest limiting factor at this juncture, expressed on all models, appears to be the extent of instability realized likely owed to more modest moisture depth and return and uncertainties this far out in regards to warm sector destablization. Decent EML appears to persist until later Saturday. The strenght of forcing and progged skew-T/Log-P profiles indicate eventual and perhaps relatively quick transition to a more QLCS mode is also possible, but again, still preliminary in the game to know for sure, though streamwise vorticity does appear to be present for some torndic risk if forecast soundings do indeed verify. The 06z/02 ECMWF was a bit more generous with instability than the 12z/02 NAM or the 06z/02 GFS. Placement of surface features and timing of the mid-level wave could alter the position of the greatest SVR risk, so I opted to include a broader geographic area initially as the greatest risk could be somewhere between the mid-MO valley eastward as far as far WC or NW IL.

In short, as of right now, it looks like an archetypal setup in this region for early March. I'd expect a low-end SVR event with several tornado reports, and UA profiles also indicate the potential for the typical range of non-tornadic SVR reports, including hail and some damaging wind events owed to sufficiently favorable hydrolapses evident on soundings across the region at the 78-84 hr mark as of this writing. A far more abysmal thermodynamic profile would limit this even more than it already appears to be and further temper the supercell tornado potential as well.

There's still time for things to change but it's getting close enough to warrant chatter.

J
 
Last edited:
Oct 10, 2004
1,264
368
11
36
Madison, WI
I'd be a lot more excited if not for the consistently paltry instability values on the forecast models, because the surface low is taking a pretty classic track for an upper Midwest severe event. Excellent kinematics and cold upper levels can get it done this time of year at this latitude with "just-enough/just-in-time" moisture (3/15/16 is a good relatively recent example), but I'm not sure if we'll be getting all that as things stand now. At any rate, it's nice just to have something to track this early in the season instead of more snow and Arctic air masses.
 

Jesse Risley

Staff member
Apr 12, 2006
2,202
705
11
42
Macomb, IL
www.tornadoguys.com
This certainly isn't looking any better (yet). The GFS looks downright awful. The ECMWF has the best instability, and a narrow window at that, displaced well southwest of the triple point area. The more recent runs of the NAM actually look the most magnanimous, and that's not saying a lot in terms of anything substantial coverage-wise. While overall shear profiles are more parallel to the forcing than not if better instability materializes that will definitely up the ante here. I don't suspect moisture quality and depth will overperform, so it may be tied to the degree of solar insolation which, right now, is mostly ongoing a bit too far east of the best parameters if you believe the ECMWF based on lower to mid-level RH profiles.

Of note to me, however, is the degree of more robust "cold core" parameters present here with H5 temps AOB -20C, a strong surface low, and the depiction on some of the shorter to intermediate-range models of robust low-level lapse rates and ample mid-level lapse rates partially owed to Tds >50F. Again, the NAM is most generous here depicting STPs across WC and NC IA between 21z/05 and 00z/06 and, historically speaking, setups that have these parameters coalesce across parts of the midwest have produced cold-core tornadoes in the past. It's too close for me to ignore at any rate. If the lapse rates end up being more on the abysmal side, however, it may not be much to write home about.
 
Aug 9, 2012
549
1,221
21
Macomb, IL
stormoptics.smugmug.com
Some of the new runs of the NAM (18z) and RAP (21z 3/2/22) look interesting near the surface low in SW to West Central Iowa on Saturday afternoon/evening with a modestly unstable atmosphere and decent low level shear along with speed shear. Sig tors in the range of 2-3 along with relatively high EHI values for early March. Wouldn't be shocked if things keep improving to see a cluster of tornado reports near the surface low if we can get initiation during the 21z time period.

Could be the first chase of the season for me if it doesn't shift too far west given its only a 4 1/2 hour drive or so at this point to my W. However with gas prices sitting at 4.19, I will have to think on it a bit.

Still a few days out though, I could see damaging winds and QLCS tornadoes after dark being a threat as far E as perhaps Western IL if the instability can be realized along with moisture. Spring has sprung in the Midwest....

Edit: I agree with Jesse in not overlooking the "cold-core" aspect of this. Have seen many many setups in Iowa like this produce nice tornadoes on the surface low in what would typically be sub-optimal surface observations due to steep lapse rates, cold temps aloft, and decent 0-3km CAPE overlapped with strong vorticity.
 

James Gustina

Supporter
Mar 9, 2010
670
321
11
28
Dallas, TX
www.thunderingskies.blogspot.com
Last night's 00Z run of the NAM/NAM3K had a much more favorable low position than the Euro and GFS have been showing the previous few runs i.e. a much slower march into north central Iowa vs fast moving and into the bad terrain of northeastern Iowa.

Eastern Nebraska were it not for the paucity of Missouri River crossings would be an interesting option as well earlier in the period around 20-22Z. Rather large curvature in the lowest 3 km/a brief window of MLCAPE exceeding 1000 j/kg ahead of the front and low. Deep layer shear throughout the warm sector looks substantial on the order of 50-60 knots along with dewpoints in the upper 50s that will likely overperform a few degrees higher as Jesse noted yesterday. Would not be surprised to see a lone supercell right on the southern edge of the low produce a few tornadoes before sunset.

Definitely seems like a solid choice for an early season run for those within a few hours.
 
Oct 10, 2004
1,264
368
11
36
Madison, WI
Anyone else seeing lack of directional shear being an issue with this event? HRRR soundings across western Iowa (in the environment of what appears to be a robust supercell on sim ref/UH) show essentially unidirectional winds from just below 850mb up to above 500mb, with only slight veering to a little more westerly component. Is this a problem, or should ample 0-1km SRH (200-300 m2/s2) and speed shear compensate?
 
  • Like
Reactions: James Gustina

JeremyS

EF3
Mar 12, 2014
294
431
11
Omaha, NE
Anyone else seeing lack of directional shear being an issue with this event? HRRR soundings across western Iowa (in the environment of what appears to be a robust supercell on sim ref/UH) show essentially unidirectional winds from just below 850mb up to above 500mb, with only slight veering to a little more westerly component. Is this a problem, or should ample 0-1km SRH (200-300 m2/s2) and speed shear compensate?
My take on it is ample 0-1 SRH with backed surface winds, but also low LCL's with tons of low level CAPE (I've seen as high as 275), should hopefully be enough to get it done.
 
  • Like
Reactions: James Gustina

Jesse Risley

Staff member
Apr 12, 2006
2,202
705
11
42
Macomb, IL
www.tornadoguys.com
Anyone else seeing lack of directional shear being an issue with this event? HRRR soundings across western Iowa (in the environment of what appears to be a robust supercell on sim ref/UH) show essentially unidirectional winds from just below 850mb up to above 500mb, with only slight veering to a little more westerly component. Is this a problem, or should ample 0-1km SRH (200-300 m2/s2) and speed shear compensate?
In my experience with low topped storms where there is so much 0 to 3 km MLCAPE it doesn't seem to make as much of a difference, BUT it will possibly lead to a shorter window of time before your tornadic thread transitions more to QLCS. It may well limit the window of discrete supercellular development. The veer-back-veer isn't ideal but I think the amount of SRH is adequate. Critical angles aren't awful but I've definitely seen better.