State of the Chase Season: 2017 Edition

[Andy Wehrle]

Looking back to last year, it was one of the strangest evolutions of a chase season I have seen. That May produced three of the most spectacular tornadic storms of recent years, that would probably fill up a top five of the decade for OK/KS/NE along with Pilger and Rozel (I'm speaking of Katie/Wynnewood, Dodge City and Chapman). However, they all came from relatively subtle/mesoscale-driven setups, and were the only significant tornado-producing storm on the day. I remember there was a day later in the week of DDC/Chapman that a lot of people thought would be bigger than either, because it would be when the stronger 500mb SW flow finally overspread the bulk of the warm sector, but it ended up being another early junkvection/VBV-infested crapfest.

I wonder if this year could pan out in similar fashion. Great if you're out there on vacation at the right time/live in the Plains and have the mesoscale forecasting skill. If you're trying in advance to time your days off with the best chase days...not so much. I had banked on late May last year, which ended up being almost correct...except my vacation began on May 29th. Ouch.

 

[James Gustina]

Just echoing what others have said, it seems to almost always be better to have a quiet first week or two of May. Especially after the mesoscale-driven setups of last May, I'm definitely not hitting the panic button.

Just to kind of do a post-mortem on April, what a strange month. Outside of Dimmitt and now Canton, it feels like we haven't had much of anything in terms of a "standard" tornado day.

 

[JamesCaruso]

There is always an omega block or ridge at some point during a season. It is *optimal* to see it in late April/early May! Blocking patterns rarely last more than 10 days.

Exactly what I'm hoping for, have it in early May and re-open the Plains for business just in time for my arrival late in the month [emoji57]


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[Todd Lemery]

Fingers crossed, but it sure looks like the plains will be open for business the second half of the month in a big way. It's nice to see the last few days of runs sticking to the happy train. I just have to try not chewing my fingernails off waiting through this coming slow period....

 

[Jeff House]

Euro weeklies (5/1 issue) concur with the CFS back half of May becoming more active. Week of May 15 could feature the first West trough (not closed), but we might still be working out of an East trough. Week of May 22 looks a little better. This far out I would not split details of the weeks. Week 1 looks quiet. Week 2 might get Omega'd. Weeks 3-4 look better.

Non-model evidence for improvement is found in the tropical Pacific. Westerly wind push is relaxing. GLAMM is easing up. Though SSTs are trending toward El Nino, the whole atmosphere and the ENSO are not there yet. Slower transition is good for chasing. AO should relax in response to the above, also helpful.

 

[Paul Knightley]

There have been several signals of a more ridge-trough situation developing for a time into May. However, some signals a slow-moving trough may roll in from the SW next week, although it's still, essentially, a blocked pattern. The system to the east could hinder moisture return but a couple of chase days mid-late next week seem possible. Thereafter, perhaps a ridge building back into the west for a time, before this rolls east to allow a bit more progression into the w/c15th May. Beyond that, fantasy-land, as the predictability of the long-wave pattern in spring goes down the pan, somewhat. Interesting that @Jeff Duda mentioned 2008 - I remember it well. Early-mid May closed off for a time with a big ridge - then on the 22nd it started!

 

[chrisbray]

Yeah, it's interesting to note some CAPE building inbetween the cutoff low in the west and the east coast trough next week. Looks like there could be a few NW flow events in the middle of the conus

 

[Jay Bell]

Agreed. 2013 was a year that quickly turned around for the last two weeks of May; although I was beset by plenty of bad luck and bad decision-making, it was probably the greatest volume of good chase days in a two week period that I can remember since I started chasing in 1996 (at least insofar as the luck of the draw on my annual two-week chasecation). As long as there is no death ridge, it's hard to imagine not having chaseable setups once the instability of late May / early June arrives; even without good synoptic patterns, there are plenty of favorable mesoscale setups to be had.

Chase vacationers like me see things much more differently than chasers that live on the Plains. For me, it's the luck of the draw; I can get a good two weeks in a bad season, or a bad two weeks in a good season. I know lots of Plains chasers didn't think 2013 was a great season precisely because all of the season's activity was condensed into just a two week period. Sometimes I have a little flexibility in when to chase and I then try to time the start of my trip with a week that looks favorable (in that scenario, the second week is still a crapshoot, but that's better than both weeks being a crapshoot...) This year, I am pretty much locked in for 5/26-6/10. I always feel like it's very unlikely that the entire season is consistently good. When it's active in early May I always assume it won't sustain itself into late May and early June. Maybe this is just anecdotal with no statistical basis, but selfishly I would rather see a slow start to the month so that there is still hope for the later weeks of the peak season.



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I'm with ya. Looks like we started around the same time and I have always had to be more of a chasecationer (is that a word?). I have missed MANY of the big shows just because of luck. I live close to the plains, but work doesn't allow me to get out like I would like. I am like you though....a slow start to May gives me hope for an active later May for chasecation. I have a longer stretch than usual this season from May22-June8, so maybe that will improve my odds. It's always a game of chance.

 

[Ethan Schisler]

Aside from the trough being shown early next week (May 9-11), the first 15 days of this month look to pass by rather quietly. Hopefully toward the end of the month we can get into a pattern that favors western troughing and a slight ridge in the east and some classic late May high instability along the dry line.

Depending on how the GFS/Euro trends the next couple days and when it gets into the NAM range, I may decide on chasing the next trough given the grim long range outlook.

 

[Andy Wehrle]

I took a look at some parameters and forecast soundings in SW OK on the 00z and 06z GFS runs for next Wednesday, May 10th (the day the SPC highlighted on today's long-range convective outlook) and they actually look surprisingly good, especially considering the presence of that pesky eastern trough. It looks like it wants to move it just far enough offshore that the western trough can progress partway into the Plains without shearing out over the top of the ridge. Of course, if every time the GFS depicted a favorable parameter space for significant tornadoes over OK in the 100-200 hour range so far this spring actually verified, much of the state would be in small pieces in Arkansas by now. At least its something for the locals and unfortunate chasecationers out there now to track, and the the threat if it actually materializes would be over good chase territory.

This might be the most frustrating evolution to a chase season I've seen yet. First we get an out-of-season outbreak as far north as I-80 in IL (which I might have chased had I not already committed to helping a friend move that day). Then an active pattern with lots of troughs coming through but they all have problems resulting in very few photogenic tornadoes and no real outbreaks in the Plains/Midwest. Now the pattern shuts down for the foreseeable future just as we move into what should be prime time. Gag.

 

[Harrison Cater]

Looking at the past few runs of the GEFS/EPS, I like the way they are going overall. The eastern troughing regime currently present finally gets kicked out and a large trough enters the west. This sets up nice SW flow for several days over the plains. Too early to talk much other than general pattern, but the pattern for late May certainly looks better than what we've got right now.

 

[Warren Faidley]

It's been interesting to watch the GFS try to handle the evolution of the mid-May, west coast trough. Some potential for a serious event or two if it moves into the Plains as currently forecast. I'm also liking that +RH appears to be climatically entrenched in the southern and northern Plains for the rest of the season.

 

[Chris Hayes]

The CFS continues to hint at an active 2-3 weeks from the last full week of May and into the first week or two of June (depending on the model run you look at.) The CFS Severe Weather Dashboard is also lighting up for those weeks as well. Thankfully I have time to pick out a week for my chasecation. In the meantime we have this coming Wednesday as well as next Sunday and Monday for potential fun and games. Mid month; right on cue, things start lighting up.

 

[Jason Harris]

The ERTAF has upgraded to "above average" for latter half of May. Always fun to track these long range forecasts.
http://weather.cod.edu/~vgensini/ertaf/

 

[JamesCaruso]

Not that we need to be reminded of this, but this week seems to be yet another example of why not to get too depressed or excited about long-range outlooks. I am only looking at SPC, not at data (since my chase trip is still almost three weeks away), but it seems that what was just a few days ago considered to be a dead week now has three consecutive days (including today) of potential supercells in prime chase regions, while the day that previously looked the best of the week (Wednesday) now has the potential to be screwed up by morning convection...


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