• Stormtrack's forum runs on Xenforo forum software, which will be undergoing a major update the evening of Wednesday, Feb 28th. The site may be down for a period while that update takes place.

State of the Chase Season 2023

Status
Not open for further replies.
Hey everybody! Figured I'd get the ball rolling on 2023 stuff as we are starting to heat up ahead of the official start of Chase season in March. A couple of quick things from last year, we are still waiting on the final Storm Data numbers so I can't run my spatial anomaly maps quite yet. However, myself and some other folks at SPC have revamped the WCM page (We have more ideas so stay tuned to this page in the future) so I can at least give you the inflation-adjusted prelim tornado reports to see how my initial forecast verified. Im hopeful we will have the finalized 2022 dataset in the next couple of weeks.

Here's my forecast from last year.


Mar 2, 2022

A few days late but ill throw my final thoughts for a seasonal forecast for 2022 into the fire to be burned up by mother nature. Sadly, this has the hallmarks of another meh year. I've long be resistant to the idea of a weak decay La Nina or possible third-year Nina in favor of a shift to EL Nino, but I'm finally backing off that. There has been a substantial drop in sub-surface warming over the last few weeks which has stalled any Niño condition development. The most likely scenario for spring appears to be a gradual decay of La Nina into ENSO neutral. The MJO while more active as of late has shown minimal activity thus far which is also another negative. Add that to the ongoing drought in the West and you end up with analogs like 2009, 2012 and 2018. You see where I'm going with this... These weren't the worst years but they were easily bottom half of the distribution. I think we are in for more of the same. Somethings that could improve our odds, a stronger MJO later in the spring, and continued warmth in the GOM.

A grand summary, I expect not a great year for chasing. A few notable outbreaks are possible through March and April. I'd pay special attention to the Midwest and Mid South as these areas have historically done better in these years. The southern Plains will likely be limited in chase opportunities so take chances. The southern High plains look to be very quiet sorry TX Panhandlers and southern Colorado. Big question mark in the central and northern High Plains. Its a mixed bag in these years especially late, but the predictability of tornadoes in the summer is low. Below are the numbers.



Forecast 2022 Tornado Season (MAMJ) :

Counts: Below Average (600 tornadoes across the CONUS during spring (MAM), 1050 plus or minus 100 for the year)


Outbreak Days (10+ Tornadoes within 6 hours): Average


Number of EF2+ tornadoes: Below Average (Greater than 1 STD below the normal mean)

Enjoy my very scientific graphic lol. Good luck this year everyone!

2022CONUS.png


Chasabillity Score: Average 5/10




2022_annual_map_torn.gif

torgraph-big.png

2022_annual_graf_torn.gif
1676842250691.png

Hey ma look no hands forecasting! Overall, (keep in mind these numbers are still preliminary) my call for 2022 being below average (1050±100) was right on the money with 1131 inflation-adjusted reports falling just below the 25th percentile! My total estimate for the number of tornadoes in MAM was also very close at 600 (755 prelim 642 inflation adjusted). I correctly predicted that it would be a very quiet year across the southern and central High Plains. The massive hole in the prelim reports map is almost prophetic of how bad drought conditions have been out west for a long time. The Midsouth and Midwest did show up in classic La Nina fashion with numbers way above average. I meant to highlight the Midsouth and Southeast but failed to do that on my graphic. I was also able to correctly predict that it would be an early season, and March/April really delivered running with near-record numbers for several weeks. It is quite remarkable the drop off in activity levels at the end of April into May and June! Spring essentially died, with only 2 days seeing 25 or more reports after mid-April! Finally, very similar to 2021, a late surge in events in the winter helped raise the overall average with several big days. Another hallmark of La Nina dominated years. I'll hopefully be able to look at some of the other predictions like sig tors and spatial anomalies in the next few weeks, but overall id say this forecast turned out well!

With 2022 out of the way let's look ahead to 2023. I see a couple of similarities and a few key differences. Taking a look at ENSO base states, it's clear we are in for a change. While the spring predictability barrier is still stubbornly there, it appears likely we are going to flip from La Nina to El Nino conditions either this summer or Fall. Warm anomalies are already intensifying off the coast of South America, and nearly all of the ensemble guidance hints at El Nino conditions developing within the next 6-9 months.
1676845706751.png

1676845687828.png
With La Nina seemingly on the way out, I expect the atmosphere will slowly respond to the transition much in the same way as the last few years. We are very likely to continue with La Nina-like atmospheric conditions across portions of the Southeast and southern Midwest through late winter and early spring. Those are fairly conducive to active severe storms through the remainder of February through March and early April. Looking at Ensmebles, there is already a strong signal for an early spring with above-average ridging over the SE and an active mid-level jet and potential troughing over the western and central CONUS through the next 30 days. CPC is on board with this showing huge warm anomalies over the eastern half of the CONUS through early Spring. Precip anomalies are also suggestive of an active wave pattern that we are seeing manifest through the next several weeks. Don't pack away your snow shovels quite yet as I think we are still in for some cold shots, but I think Spring and chase season are likely early and coming in hot! I expect a quick start this year with several big chase days potentially showing in Feb/March. As we continue the transition to El Nino, the Trans Nino Index (TNI = [Nino 1+2 -Nino 4] Regions) is starting to build some very large positive anomalies (+1.7). See this paper for a breakdown on TNI and its potential skill in predicting tornado outbreaks. Basically, large positive TNI values from transitioning La Ninas suggest active tornado potential early in the season across portions of the southeast Midwest and eastern Plains. Given everything else I've seen with the pattern, I think we might be in for some large outbreak days early.
1676846689680.png

1676846635663.png
A few things remain unclear to me from a seasonal perspective. One, the drought while improving over the West is still quite several in parts of the southern and central High Plains. I'm not sure thats going to change much between now and April. Secondly, as La Nina fades and we undergo full ENSO transition, the large-scale forcing should weaken and we may end up in a bit of a "no man's land" for the overall pattern. Without substantial El Nino or La Nina-like conditions, its anyone's guess exactly what the back half of the season might look like? But with that and everything else I've mentioned in mind, here's my guess for 2023!

2023 Spring Chase Season Forecast (MAMJ)!

Counts: Above Average (775 tornadoes across the CONUS during spring (MAM), 1400 plus or minus 50 for the year)


Outbreak Days (10+ Tornadoes within 6 hours): Above Average


Number of EF2+ tornadoes: Above Average (Greater than 1 STD Above the normal mean)

Chase Ability (7.5/10): Still opting slightly conservative here as I expect good numbers in places that are still challenging to chase. But, I think Plains chasers get a bit of relief this year.

A couple of notes, I'm choosing not to use analogs for this forecast as I haven't found any that really match all that well. Im targeting the top half of the distribution this year for a couple of reasons. My primary reasoning is the likelihood that we have an active early season and a more average back half. The GOM is above average and we have already seen anomalously high dewpoints make it back into the CONUS over the last few events. With everything prior about the active wave pattern and favorable ENSO state, I suspect March and April will be above normal. I expect the lower MS valley will be active early this season with the prominent ridging farther southeast keeping them warm. The Mid to Upper MS Valley, Midwest, and Ohio Valley should get in on the action as well with a potentially very active corridor shaping up here early to mid-season. As La Nina fades, things get more complicated. The primary driver for the past several years of bad seasons has been the sharp drop off in activity from mid to late spring into the summer. I suspect this has to do with the lack of persistent southeast ridging and quickly retreating flow aloft. I don't see much of a signal for that this year with the NMME and CPC vying for semi peristant western/central US troughing and a strong ridge down south. I don't expect a gangbusters year for the southern and central Plains, but more average activity. If El Nino conditions develop early, we might even approach some higher-than-average numbers as large-scale forcing would potentially shift preferential troughing farther west.

Now before you think I wish casting let's look at some potential negatives. Number 1, the western US drought remains and extends into parts of west TX, OK and KS. There has been substantial drought improvement over the Intermountain west and California over the winter. I expect some additional improvement but it likely won't be gone as there are some pretty large anomalies. That could feed back into some problems with the EML later in the year for more weakly forced days. Number 2, Its not exactly clear to me where the preferential troughing may become established this Spring. Farther east as predicted by some climate ensembles keeps periodic northwest flow over the Plains. While not terrible, this might lead to a lot more MCS activity and fewer supercell/tornado days. Number 3, predictability is low for the second half of Spring and if ENSO doesn't behave it could tank numbers like the last few years. With neutral forcing comes any number of possible states. While I don't think it's overly likely that we end up in a very unfavorable pattern, the last few years suggest it's possible and that would likely drag numbers and chase opportunities down. We will hopefully know more as we get deeper into Spring and the ENSO evolution/upper pattern becomes more clear.

2023tor.png

So, some big takeaways:
  • I expect an above-average chase year with above-average numbers of tornadoes, especially early. Combined with an average back half our numbers should be up.
  • Several early-season events may produce a lot of tornadoes from the Mid South through the Midwest and eastern Plains. I would prepare to chase a bit earlier than average and be situationally aggressive. Positive TNI values favor increased vertical shear and moisture advection across the central US.
  • I expect an average Plains year for the second half of Spring. This is the most uncertain part of the forecast and is conditional upon the ENSO and general flow state behaving. We should see some drought improvement.
  • Things that can still go wrong:
    • Northwest Flow over the central US mid to late Spring.
    • Enhanced risk of Blue Sky Busts on the dryline late this Spring from a warm EML out west.
    • ENSO misbehaves and keeps us locked in neutral conditions and weaker background flow. With the Spring predictability barrier still up, it's possible we don't switch and just keep neutral. That could go either way but generally favors lower tornado counts.
Let's hope my 2022 forecast wasn't a fluke. But, it probably was :) Stay safe and happy hunting!
 
For what it's worth, there's more supporting evidence of your 2023 forecast if you choose to believe the CFS grid counts are an indicator. I'm totally not cherry picking this as confirmation bias for wishcasting this year, nope.

Line go up....
1676860967210.png
 
Going with the tried and true forecasting methodology of using fall and winter weather out west to "guess" what spring will bring. Generally a wet/cold fall and winter in Arizona (and the west in general), increases the odds of good chasing in the western sectors (western areas of TX, CO, OK and New Mexico). For example, if there is still snow on the ground as I drive through the mountains of s-central NM in May, it's almost always been a good year for me.

We just had the 24th wettest fall/winter period on record in AZ. It's also snowed twice in Tucson. As always, a great appearing, long rage pattern can stop on a dime and turn to drought conditions.
 
I will take that map @adlyons ! Would always prefer more regional chase opportunities. However as this past year showed, quantity doesn't always translate to quality. We had a lot of setups in the upper Midwest in 2022 (particularly the Memorial Day weekend one, also one in mid-June) with scary parameter spaces but that were very strongly forced; producing fast-moving, quasi-linear, grungy trash. The tornado counts looked impressive on paper but hardly any of them were from photogenic/at least moderately chaseable isolated supercells.
 
Last edited:
Things already looking up. Potential negatively tilted trough entering good chase territory, in February. Instability will be limited but hey everything can't go our way right. I could do without the severe weather if it will bring some drought breaking rain.
 
The strength of these shortwaves that are coming through is quite impressive. If we keep getting well-timed, potent waves like this going forward as we get better instability further north, it's going to be quite a season. I have been hearing rumblings of another arctic outbreak by mid March. That may set us back for a couple of weeks, but overall it seems like spring is here for the southern plains. I can see the central high plains (CO/WY) possibly having an active year. They have received a lot of snow this winter. The outlook for the southern high plains into west Kansas looks less promising with the ongoing drought. I think the best shot for that region will be early season. It may be another I-35 east type of year. I think this year will be more rewarding for chasers than the past few years.
 
My chase time frame is end of May, first week June. The drought situation is definitely interesting how that may or may not evolve over the next 2 months or so. While I am sure it's a minor quirk in the otherwise larger scale dynamics, I wondered how enhanced areas of lofted dust, prior to convective initiation over the western end of southern and central plains may/could affect storm dynamics, cold pools, kinematics, etc., since it appears that this will be a higher likelihood, and of a notable additional safety hazard during chase events this year. From one of the AMS articles I read recently about it, it doesn't appear to have a significant effect on Super-Cell development, but I think it's going to have to factor into chaser safety again this year.
 
Are we allowed to discuss chase vacation plans here?

For the first time, I have a fully remote job, and can spend more than a lousy two weeks on the Plains… I still have limited vacation time though. So the idea would be, instead of taking 10 vacation days for a two week trip and chasing every marginal risk, spend 3 or 4 weeks on the Plains and spread those same 10 vacation days over that period, saving them for the better events and blowing off the crumbs.

Potential problems with this idea:
- If chase partners can only come for two weeks, they are going to want to maximize every opportunity. So I may end up using all my vacation time going after crap anyway, leaving no vacation time for the better days outside of the time my chase partners are with me.
- Repositioning days end up burning more vacation time than anticipated.

Possible solution: Stay on the Plains for 3 or 4 weeks, do a hard core 2-week period with my chase partners, and in the remaining time hope for (a) stuff on the weekends, and (b) use the evenings to position so that the next day I can work all day and still get to a “local” target.

Thoughts?
 
Jeff Duda seems to have the leverage on what is and isn't acceptable to discuss in rooms. One thought, chase with partners that have the same goal as you? 🤷‍♂️ lol
 
Quick update post.

Severe remains active early this year. The end of February outbreak on the 26th also pushed the total confirmed count above the 25 year average for the second straight year with 12 confirmed tornadoes in OK. As of now we now have 22 confirmed tornadoes with a few more likely showing up from the March 3rd event across the Ohio Valley. That puts us at 27% of the average annual tornadoes for March in the first 5 days. It still looks like we have a cool down into the middle of the month but global models and ensembles have trended much weaker and farther east with the cold intrusion over the last several days (see EPS trend gif below). I am wondering if this might not be all that impactful for the rest of the month. In fact, if the larger scale toughing over the east shifts far enough it may once again favor the development of a ridge over the northeastern Gulf and Southeast behind it. The sub tropical jet and east Pac troughing are still ongoing and with the MJO heating up substantially in the coming week. If we can sort the return flow problems and reestablish southeastern US troughing, the back half of March and April might get real interesting...

eps_z500a_namer_fh174_trend.gif
 

Attachments

  • 1678030318059.png
    1678030318059.png
    447.8 KB · Views: 0
With what appears to be a Trans Nina year continuing, it will be interesting to watch over the next 2-3months where MJO phasing, PNA, NAO, will be for AMJ. Given your recent post Adlyons, either this is an early marker of busy things to come, or like what's happened in the recent past few years, it shuts off quick after April. But like Warren said in his post earlier, there is definitely some ground truth to the season so far. snowpack in NM/AZ/CO certainly way above normal, (EML effects?), drought conditions in the plains? (will that improve any over the next 60 days?), CPC suggests no, but they do indicate higher precip chances for AMJ for the Ohio valley, and lower than average temps over the northern Dakotas. Interestingly the Trans Nina year does show enhanced risk of Tornados that line up to your forecast Adlyons.
 

Attachments

  • transition La Nina.jpg
    transition La Nina.jpg
    417.1 KB · Views: 0
Starting to see a strong signal for a large east Pac westerly jet extension developing over the next 7-14 Days. That large-scale jet energy should translate into western US troughing through mid March and posisbly into early April. The ensembles and climate mdoels continue to weaken the eastern US troughing and cold air intrusion which should keep the Gulf free. Water temperature anomalies are also elevated and should continue to rise as we get mroe sun. I think an active severe pattern is liekly to develop in the next few weeks. This could be one of the bigger bouts of the season if we get the jet energy and favorable return flow.
1678235418177.png
 
Are we allowed to discuss chase vacation plans here?

For the first time, I have a fully remote job, and can spend more than a lousy two weeks on the Plains… I still have limited vacation time though. So the idea would be, instead of taking 10 vacation days for a two week trip and chasing every marginal risk, spend 3 or 4 weeks on the Plains and spread those same 10 vacation days over that period, saving them for the better events and blowing off the crumbs.

Potential problems with this idea:
- If chase partners can only come for two weeks, they are going to want to maximize every opportunity. So I may end up using all my vacation time going after crap anyway, leaving no vacation time for the better days outside of the time my chase partners are with me.
- Repositioning days end up burning more vacation time than anticipated.

Possible solution: Stay on the Plains for 3 or 4 weeks, do a hard core 2-week period with my chase partners, and in the remaining time hope for (a) stuff on the weekends, and (b) use the evenings to position so that the next day I can work all day and still get to a “local” target.

Thoughts?
I like option two James. That’d let you maximize your quality chase days. You can’t chase if you’re not there. I’d bet there’d be a number of days where you could work half a day and then chase, especially if you had a repeating dryline.
 
I suspect the cause of the early season activity is related to the sudden stratospheric warming (SSW) event we just went through. We're in the late phases of this event, which takes several weeks to process, and it appears the stratospheric polar vortex (SPV) is effectively "rebooting," which suggests the active pattern will taper off within the next few weeks.

That's really all I can glean from what's currently happening. I'm not particularly knowledgable on S2S (sub-seasonal to seasonal) forecasting, and I'm not aware of any reliable methods of predicting overall activity more than a few weeks in advance right now...at least as far as the upper-air Rossby wave pattern is concerned, as that seems to be a top-two driver of overall activity. After all, it is hard to get widespread or predictable severe weather without synoptic scale forcing, even if a great mT airmass is in place!

I've seen others comment on some other factors that can be used to assess the potential for a good year. The big one to me is precipitation and soil moisture anomalies in the EML source region (SW US and N Mexico). While California and Nevada (and parts of Arizona) have been deluged this winter, those areas aren't really in the EML source region. So we have to look further to the southeast. I like the NASA SPORT Land-Data Assimiliation System website for analyzing this group of factors (Real-time 3km Land Information System over CONUS). The current relative soil moisture in the top 10 cm of soil is below:

rsoim0-10_20230309_00z_conus.gif

The value of the field is the fraction of available soil moisture that is realized (0% is totally dry soil, 100% is completely saturated soil). This is averaged over the 10 cm depth nearest the ground surface, where moisture access is most immediate. Soil temperature and moisture do have a memory, and the memory is longer in deeper layers since it takes a long time for water and heat to propagate upward towards the surface. Sensible heat flux generally only occurs right at the ground surface (referred to as the "skin" layer, and if you see "skin temperature" it is referring to the temperature right at the ground surface that IR satellite products measure when you look at IR satellite). Latent heat flux can occur directly from the soil surface, but also from plant evapotranspiration. But since most plants have fairly shallow roots, then the uppermost soil moisture will generally provide the highest correlation with potential latent heat flux. So if you're looking for more immediate impacts of soil heat and moisture transfer to the atmosphere, you want to look at the near-surface soil. But the deeper stuff can give you a sense of how "resilient" the upper soil layers will be to a period of high heat and no rain, for example.

Okay, so that's it for the primer on land-atmosphere exchange processes.

What I see is that it is quite dry across the EML source region, this is not necessarily atypical for this time of year. If we look at the soil moisture percentiles instead, we can see if this state is anomalous at all.

vsm0-10percent_20230309_00z_conus.gif

In areas of E NM, W TX, and NE Mexico, it is indeed pretty anomalous. But further west (AZ, NW Mexico) the current soil moisture is anomalously wet. So...a bit of a mixed signal right now. It doesn't help that the recent precipitation anomaly is correlated a lot with this.

PRISM_ppt_provisional_4kmM3_anomaly_202212_202302.png

I'd be more excited if that big precip anomaly on the central high Plains was displaced further south. But this signal could bode well for the later season activity further north.

One other resource I like to use (a bit shorter time scale) is Victor Gensini's dynamical SCP statistics forecast from the GEFS forecasts here: Extended Range Severe Weather Environment Forecasts. You only get about a 2-week lead window on this.

Don't forget about MJO either (CPC - Climate Weather Linkage: Madden - Julian Oscillation).
ensplume_small.gif
The GEFS is actually predicting a massive swing through the phase-8-1-2 range, which is the optimal phase range for active troughiness and storminess in the central US. It doesn't guarantee a stormy pattern, but it sets the stage. We'll see how the next week or two goes as this phase transition occurs and see if an active period accompanies it.

More as it develops.
 
Wanted to throw this in for some of the newer members as I learned a fair amount... those more experienced can probably skip it. I appreciated the effort, and I hope sharing it here is ok.
Teleconnections was something I had put on the back burner to study at a later date, and I thought this was a good primer.


As a summary, this gentleman finds previous years analogous to the current trends based on ENSO, DCO, and EML source region drought. His conclusions lead to an average amount of tornadoes overall for the year, with a very active March and April, and below average 2nd half of the season.

I understand most of this is wishcasting, but I enjoy reading into the different patterns and learning from all the various posters in these long range forecasting threads.
 
As I posted in the comments to Trey's video, it's interesting that he finds mostly favorable indicators regarding teleconnections and Gulf SSTAs (EML source region drought is present, but not as bad as it's been in some reason years), yet the analog years he found were mostly lousy to mediocre at best chase seasons.

I think the late winter SSWE is a big wild card, like @Jeff Duda mentioned above. If it behaves just like 2018, we're screwed. However, the EML region drought was more pronounced at this stage that year, and at this point it's looking like the cold air surges into the Great Lakes/East won't be quite as potent as they were that year, and that the Gulf might be shielded from the constant CP air intrusions through the third week of April like that year.
 
Andy my historical knowledge of how SSWE's enhanced or minimized tornadic years is minimal. Is there a historical trend or some data to go through that shows correlations of SSWE's tying directly or indirectly to tornadic years?
 
Andy my historical knowledge of how SSWE's enhanced or minimized tornadic years is minimal. Is there a historical trend or some data to go through that shows correlations of SSWE's tying directly or indirectly to tornadic years?

I'm not particularly knowledgeable about it myself. I think it's highly dependent on where the resulting trough sets up. In years like 2014, 2018 it allows for a trough to set up over Hudson Bay and just park there for most of the spring, dumping cold air into the Midwest and hindering moisture return as well as messing up the ejection of any troughs that do try to come into the west.
 
interesting. I forget if 2014 was a neutral or La Nina year, but it seems like given a notional trajectory of moisture and ridge to trough setups during those La Nina years that a SSWE would enhance the trough condition present in one region? or only neutralize it?, but I am not afraid to say I don't exactly know how those Rossby wave, SSWE, and ENSO relationships interact intimately. I need to see an animation of all of the systems at work at once. I tend to learn it better that way. So if someone can create a multi layered product of the globe showing all of these teleconnections and interactions, "that would be greeaaaaat" - office space.
 
Last edited:
For what it's worth, the CFS is liking the second week in April.

Jeff's detailed discussion on soil moisture is much appreciated and something I watch for both spring tornado chasing and during the monsoon for dust storm potential. "Soil moisture content" was a common discussion going back to my early chasing days -- noted by many "old timers" in E-NM and W-TX with tornado activity (+/-).
 

Attachments

  • cfs_bchiclet.png
    cfs_bchiclet.png
    287.9 KB · Views: 0
Last edited:
Status
Not open for further replies.
Back
Top