State of the Chase Season: 2019

Dan Robinson

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Jan 14, 2011
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Agreed, cautiously optimistic for some action starting in 7 to 10 days. Still a little early to fret about it, but the meridional nature of the flow shown without that really nice diffluent zone of a negative tilt is a little meh. But certainly much better than a ridge or NW flow! As it stands there should be a couple of decent days in the mix.
 
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Mar 8, 2016
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Euro/EPS is still pretty consistent with lighting things off starting the weekend of the 18th, as it has been advertising for a bit. GFS/GEFS has been flip flopping quite a bit, but overall trending towards it as well. Starting to look like I timed my chasecation pretty well this year as I head out Friday!
 
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Deterministic and ensemble output from the main global centres are pretty consistent with the notion of a powerful Pacific jet developing through mid-late week next week...models are not that great at handling the eventual collapse of such a jet into a tough/series of troughs - and so we should still expect to see shifts in timings/locations of any eventual collapse.

However, as others have said, later next week/through the weekend/into the w/c Mon 20th May, it seems fairly plausible that some form of trough/circulation will translate from the W Coast into the mid-section - but it's too early to say whether this will be in the form of a stronger southern stream (and consequential risks across the southern Plains) or a larger trough, which might open up a more classic multi-day dryline then front set-up.

Beyond that - well, given the uncertainties in the evolution due to what I've mentioned above, it's very tricky...if that is the collapse of the jet then we should expect a more blocky pattern to develop - then, it depends on how this is orientated - if we have a ridge over the SE states then we could have a slow-moving trough to the SW - meaning some multi-day High Plains fun - on the other hand, we could get a trough-ridge-trough pattern, which would be not such good news.
 
The last few runs of the GFS, Euro and ensembles are very encouraging - long-term SW flow, multiple ejecting shortwaves, moisture staying in place. Would be a 2004-like pattern if it verifies.
I have to agree. The model **trends** are quite encouraging, with a smorgasbord of possibilities over an extended period including an interesting negative-tilt trough / dryline fiesta possible next weekend. It would also appear the svr. potential might cover a wide range of locations from north to south depending on your desired flavor of storm modes. You have to figure sooner or later a good season will return and this might be it.
 
Analogs of the GEFS members point to a favorable pattern starting around the 19th when looking at temperature anomalies. 9-11 day average (5/19-5/22) and 12-14 day average (5/22-5/25) below (CIPS Analog Extended Threat Guidance).
19-22 Temp Anomaly.png22-25 Temp Anomaly.png

The CIPS experimental probability guidance is also starting to get in range of this potential pattern (Day 7 and Day 8). The guidance is based on the mean GEFS. (CIPS Severe Weather Probability )
Capture.PNG

Finally, Victor Gensini's SCP analysis page of the GEFS members shows promise when looking at the 5/18-beyond period as well (Extended Range Severe Weather Environment Forecasts )
gefs_scp_chiclet.png

Hopefully this ends up being a good period for those of us with chasecations in that range.
 
Jul 5, 2009
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Newtown, Pennsylvania
I’m pretty bummed out personally because I am definitely going to miss this next trough which should kick off the action on the southern Plains this Friday 5/17; SPC has today introduced a Day 6 risk in classic chase country. I can’t possibly get out there before 5/23 and per GFS the Plains look to be under a ridge around then. The next trough ejects a closed low up toward the Great Basin and does not dig into the Plains. Memorial Day Weekend doesn’t look too good right now except maybe in the northern Plains which is not my favorite stomping grounds. Of course, that’s not a particularly reliable range for the GFS so I will try not to worry too much, although either way I have to imagine my trip starts at an unfortunate time and I won’t be able to avoid a lull after this next trough. I just hope the lull is a short one. I will take comfort in the posts above mentioning “long term” and “extended” favorable conditions, surely those comments can’t refer to just one good week, I mean in 2013 there were two straight great weeks and everyone thinks that season sucked.
 
Apr 5, 2015
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The upcoming pattern looks quite favorable for a prolonged stretch of severe weather, with multiple days of significant severe weather potential likely.. A potent 150+ knot upper level jet that has tracked across the Pac ocean will finally undergo breakdown as it nears the US W coast. The result will be a deep longwave trough setting up over the W US. A very strong belt of SW flow should set up next week after the lead wave passes through this weekend. Extended chase opportunities with likely a few significant severe weather events will unfold, barring any drastic changes to the pattern. 10-day height anomalies tell the whole story.

The weekend could feature mostly MCS-like patterns but mesoscale details will work those out. I think the main show holds off until Monday at the earliest, but again I think that next week will feature several sig severe weather days. GEFS is probably too amplified with the ridge, so wouldn't count out KS. Time will tell.ecmwf-namer-z500_anom_10day-8915200.png
 
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Jun 1, 2008
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ECMWF does not strengthen the said lows too much. EPS keeps the pattern going the full 14 days. @JamesCaruso I think you'll be fine, even if up north. Good eastern ND/SD terrain/roads go into southwest Minn.

First wave this weekend could be a little MCS-y and/or backed at 200/500 mb, but I agree mesoscale targets should be available. Also models won't get the EML details for a couple more days. MCS action may calm down a bit. No promises though.

May 20 work week does look active. Details are muddled on the awful GFS Op. However both ensembles keep it going. Main thing is 500/200 mb looks more WSW. That could change, but overall I really like the May 20 work week. EPS has been very consistent.

Non-model indicators add confidence. Odd combo of +AAM and -NAO actually keeps the buffet line going. Models have backed off the GL trough thanks to +AAM. The -NAO actually boosts baroclinicity with this nice West trough.
 
Jun 16, 2015
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I don't get too caught up in the extended range (2+ weeks), but as we get closer in, as many have echoed, it looks fairly active beginning around Friday/17 and lasting through much of next week.

Details are still TBD, but the upper level signal is favorable. MCSs are a concern and it could also be a scenario in which there are 2-3 good days, following by a day or two off as the western trough reloads, followed by another favorable multi-day chase setup.

Anyone chasing between roughly May 17-24 should be very encouraged by the signals. While not every single day may be a "solid" chase day, most of the days should. If you're willing to travel, you might even see 7/8 or possibly 8/8 chase days in a row. Moisture return will become less of an issue with time, but you also have to factor in the potential for an MCS to temporarily overturn the atmosphere. As usually is the case, be flexible and realize that you may initially see a string of chase days in Kansas evolve into a chase or two down in West Texas with some driving back and forth. If that's the biggest challenge in the coming 1-2 weeks, then it's looking pretty darn good for chasers.

I wouldn't go as far as to say it's looking like the best setup in over a decade (as some chasers have), but I think it's safe to say it's the best mid/late May potential since 2016. Could it be a second half of May for the record books? Possibly, but the devil's in the (mesoscale) details.
 
Jul 5, 2009
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Newtown, Pennsylvania
@Jeff House thanks for the vote of confidence in a second week of activity but I’m still going to be a nervous wreck sitting here in Philadelphia missing all the action hoping it doesn’t peak out before I get there... It would suck to get out there for maybe the last day or two of the “big week” and then endure a lull of 3-5 days before the next trough, if there is one... Even if the trend does continue for 14 days, there’s no way it’s going to continue for 21, so the first week of June (second week of my chase vacation) could be a waste for me regardless. Too soon to worry about that just yet... What a year to not have the flexibility I have had in prior years... And here I was feeling good about having dates fixed and not having to agonize over the models, but I think this might be even worse, to know I am missing a great pattern and not being able to do anything about it. What a gnawing, agitated feeling...

I am actually toying with the idea of flying out just for the one day of Friday May 17. I would have to fly back on Saturday for a family event on Sunday. Not sure it’s worth the time, money and trouble. It will also leave me playing catch-up at work for a deadline on the 22nd.
 
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Todd Lemery

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Jun 2, 2014
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I’ll be heading down the 16th and will stick around until there’s 2-3 crappy days facing me. Last year was a personal disaster as far as storm chasing goes. As Jeff pointed out, it easily looks like the best stretch since May 2016 coming up.
James, the East coast is a hell of a long way to travel from for one day of chasing. I wouldn’t do it. One option to consider may be chasing the 17th and 18th. Could you catch a red eye Saturday night or maybe an early flight Sunday morning? That might take some of the pain away from missing out on the following week at the cost of some money and sleep.
 
Jul 5, 2009
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James, the East coast is a hell of a long way to travel from for one day of chasing. I wouldn’t do it. One option to consider may be chasing the 17th and 18th. Could you catch a red eye Saturday night or maybe an early flight Sunday morning? That might take some of the pain away from missing out on the following week at the cost of some money and sleep.
Todd, I appreciate your thoughts on this. Yes it does seem crazy and quite frankly I would rather avoid it. I would only do it if it’s a truly high-end, potentially historic event; not sure at this point how likely that is. Not sure how flying home Sunday would work out, I have a family event at 1:00 so it would be risky to make it back in time especially with the hour time difference and the possibility of delays or cancellations related to aircraft that couldn’t come in the night before due to severe weather. A red-eye would be tough too, for the same reasons and because of limited time to get to the airport after a chase. Not sure if there even are any red-eyes available, probably only from DFW. But it’s a thought, I’ll check it out, thank you.

Your own start date seems darn near perfect, so best of luck to you!
 
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The beginning of next week is looking potent. The 12Z GFS and Euro both paint a pretty insane looking run from the 20th through the 23rd with a break between troughs followed by a shift further north onto the central High Plains. Obviously it's still a week and some change away but the consistent, massive trough parking over the western and central CONUS is hugely encouraging as others in this thread have noted.

I'm betting if we do see that brief period of ridging from the 24th-26th, there's a chance at some slower-moving northwest flow days across the southern Plains with the moist airmass looking to remain generally untouched after the first trough ejects.
 
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Apr 5, 2015
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Like alluded to above, the 20th of May is looking like a classic, severe weather outbreak type of pattern with unusually strong (for this time of year) SW flow atop a moderately-extremely unstable boundary layer. Sub-995 mb lows are hard to come by in mid-late May, and this pattern has raised some huge red flags for me as it relates to public safety.

A lot will change in a week, but this is pretty telling and alarming. 18072

18076

18077

A lot of signs are pointing to a relatively high-impact severe weather event on Monday.

I know a lot of people get hyped for big, high-amplitude troughs but it's really broader troughs with embedded S/Ws in the flow that are responsible for some of the biggest tornado events (singular or outbreak) in history. An unusually strong jet taking on a broad SW flow ahead is a recipe for trouble and that is why you're seeing consistently huge runs for Monday/Tuesday. Broad troughs bring the background ingredients needed (lapse rates and moisture) in place, and they also maintain favorable shear orientation for discrete supercells.. among other things.
 

Bobby Little

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Mar 18, 2013
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I hate getting ahead of myself on future chases ( one week out or more) because as i have experienced how weather models change so much and can disappoint. This is looking like a great setup. Problem is, i just got back from last week chasing, driving from Michigan ( 2800 miles in 5 days) am a little exhausted from driving. That said..next week vacationing at my camp in Michigans U.P. >OR< driving out for a great? week chasing with a billion people who are also waiting for this gem? hmmm? o_O
 
Jun 1, 2008
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Chattanooga, TN
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Last night I was toying with skipping the upcoming sequence and gambling on week 3 up North, which still looks great. We know the North is photogenic and less crowded. Both weekly products still look great through the end of May.

SPC has given me a moment of clarity, all 5 days of the 4-8 Day. I could see that myself, but I needed the jolt out of chaser apathy (CA). We talked about CA on Discord. You spend weeks getting excited, watching weeklies, checking ensembles, and reeling it into the 7-day. Then by the time the set-up is obvious, you're already exhausted. Think of (bad) reasons to delay and viola CA sets in. Think of failure modes, more CA. Dread the long drive etc.

Welp. This looks like the greatest set-up since at least 2016. Brandon reminded me 2016 had less shear/kinematics. Do we go back to 2013 for the whole second half of May? I'd enjoy another Rozel-Shawnee minus the casualties. We can definitely do without an El Reno, but 2013 was a good chase year with persistent troughs. Others that included both mid-May and late May include 2008 and 2004. I'm not into the generational sequence talk. However there's an outside shot at that 2003 berserk week.

On the flip side the floor could be lots of MCSs and wave timing issues. That'd still yield target pickers set-ups, but it'd be hard. Ceilings are already well covered. Most likely outcome is (in-between) 1-2 good broad chase days with 1-2 other target picker days.

If 3-4 total chase days it looks like a great 4-9 day period. Friday and Saturday have challenges, but Monday looks great. Then number 4 could still be Wednesday, but more likely Tuesday. Friday could be mainly hail, or some tornadoes. Saturday could be sloppy, but re-development looks more likely today. Next week details TBD but looking great! And SPC still talking Day 9+
 
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