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May 4th - 16th Severe Weather Thread


andyhb

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5/4-5 and 3/28 that year were similar to the setup from 3/17-18 this year (deep meridional troughs with similar orientation). As such, they were probably close to subjectively "busting" as this year's event did, just did not have quite the vort max, sfc setup and shortwave structure that either of those two events that ended as significant outbreaks did (plus the outflow boundary from the slow moving convection which screwed up tornadic potential on the 18th).

3/18 was really a disheartening waste... the trough simply didn't progress like it needed to for another 3/28/07 or 4/21/07. My personal empirical benchmark for the H5 low position at 00z the evening of a southern Plains event forced by a large longwave trough is the Four Corners. That's exactly where it was for both of the 2007 events; this year, it was over Vegas, so not even close. Along with April 12, it's emblematic of this year's main mode of failure so far on the big busts.

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5/4-5 and 3/28 that year were similar to the setup from 3/17-18 this year (deep meridional troughs with similar orientation). As such, they were probably close to subjectively "busting" as this year's event did, just did not have quite the vort max, sfc setup and shortwave structure that either of those two events that ended as significant outbreaks did (plus the outflow boundary from the slow moving convection which screwed up tornadic potential on the 18th).

Well, that's certainly not what chasers want to hear... :bag:

Actually, from what I remember, 5/4 had a beautiful trough setup, despite initial fears that it was going to cutoff/meridionalize (if that's even a word, lol). It was one of those rare deep, high-amplitude, long-wavelength troughs, and in fact the trough and parameter space reminded me of 5/3/99. Looking at the archives, I see that 3/28/07 was a bowling-ball type closed low, not the disjointed two-vort lumberjack of 3/18-19 this yr. I'd give the 2007 setups a slight edge over this year's setups. It's better to have a bowling ball but with strong lee cyclogenesis and heavily backed flow (read: deep moisture) than stuff that just kinda shears apart or ejects in pieces.

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Come to the dark side :P

I would think that too, but 2007 also had an anomalously strong SE ridge and we still got big events (3/28, 4/21(?), 5/4-5, etc). So the ridge can't be the only answer. Something about the stuff that's coming ashore from the Pacific...

This is mostly true, and nature tends to balance itself out over both medium and long timescales. And I think we will still get severe weather events before July. But over the last couple of decades, post-Nina or 2nd year Nina springs have generally had lackluster Mays (see 2009, 2006, 2000 to an extent), and the balance argument would favor a below-average spring after 2011. And if the ridge has been the problem, the approach of summer is not going to help. So I wouldn't be surprised if this was the start of a lengthy down period. On the other hand, who knows... things can switch on a dime just like they did last year. But if I were a betting man...

May 22-23 has been extremely ripe for tornadoes in the past decade (Joplin, Bowdle, Hallam, Quinter). I wouldn't be surprised if something happened then.

I have not done an exhaustive look but the analog years I've seen thrown around from various people I think sorta know what they are doing did not really have blockbuster May/June periods. We're clearly digging a hole in May it would seem if you're interested in just overall numbers. When I say near avg I assume below avg here out since we started above avg I suppose.

Depending on how this trip plays out this might be my last time for a while doing a two-week type trip. I think I'd roll the dice on flying out once or twice a year next go around. Will be other issues involved in that but eh.

I don't however see the east coast troughiness lasting unabated for weeks on end. For now I suppose I should sorta like the pattern evolution given my timeframe but I am leery of the fact that it's probably good to see some action in early-mid May rather than almost none.

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08/00z GFS: no western troughing or >30 kt SW flow on the Plains through May 24.

Tony hit the nail on the head. What scares me is not just that we're in an unfavorable pattern, but that there won't be any flow anywhere in the CONUS for an extended period. In recent history, that problem has been harder to shake going forward than something like a simple eastern trough.

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08/00z GFS: no western troughing or >30 kt SW flow on the Plains through May 24.

Tony hit the nail on the head. What scares me is not just that we're in an unfavorable pattern, but that there won't be any flow anywhere in the CONUS for an extended period. In recent history, that problem has been harder to shake going forward than something like a simple eastern trough.

Yeah. I mean, it may be a bit early, but hell I'll say it. The main tornado season is ovah. Done. Finise. Kapoot. Cooked. Smoked. That's not to say that a significant small-scale event won't occur (something driven almost purely by a mesoscale forcing with only adequate synoptics) but otherwise enjoy the summer. Baroclinicity over the entire Northern Hemisphere is abyssmal at best on the whole and that's not something that's going to magically change.

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Maybe a year with a minimal amount of tornadoes will help clear up the roads filled with chasers for those in the Plains. There will not be as much talk about storms on social media, and maybe it will help the chasing trend slow down.

Too late. 4/14 already happened, and if that's all we have this year, people will remember it. Moreover, fewer tornadoes this year means more people hankering for tornadoes next year.

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00z Euro is a different story in its later ranges, FWIW...

The ECMWF tosses a bone to chasers, but it still is really nothing to get excited about. This not a good way to forecast at all, but looking at the free plots just glancing at thicknesses/low level return flow trajectories... that east coast upper low screws moisture return completely. But that is a verbatim solution. It at least has a western ejecting trough.

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The ECMWF tosses a bone to chasers, but it still is really nothing to get excited about. This not a good way to forecast at all, but looking at the free plots just glancing at thicknesses/low level return flow trajectories... that east coast upper low screws moisture return completely. But that is a verbatim solution. It at least has a western ejecting trough.

Basically what I thought haha.

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May very well end up being below average, but after a April 14th and March 2nd outbreaks, I would hardly call spring a flop.

Well, we haven't had anything since April 14, so the second half of Spring is a bit of a flop. However, we still have 23 days left in May, and anything could happen.

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Well, we haven't had anything since April 14, so the second half of Spring is a bit of a flop. However, we still have 23 days left in May, and anything could happen.

Considering models are crap outside 7 days seems rather premature to call the season.

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I'm getting a sinking feeling about our trips. Keep the faith alive! :P I'd hate to think I wasted thousands of dollars.

I dunno.. too much fretting over long range models is sorta useless tho of course I've looked at the 384 GFS a few times already.

Agree the jet has not been its most cooperative of late and perhaps that's a worry going forward. But, I still strongly believe in the idea that tornado season does not end in early May.

I'd love to see an outbreak with 100+ tornadoes (other than the storm motions) ... I would not expect that climo-wise by the time we're going anyway. The most number-filled outbreaks and the highest number of strong tornadoes generally peaks out before the peak of all tornadoes.

This pattern won't last for a month.. I'd bet on that. Yeah, the EC trough is only one part but if you put a ridge in that area and can pump moisture into the Plains you don't need a 90-100kt jet to have some fun... However, given how things have played this season I'd not necessarily think we'll bounce out of this into a several week good pattern. It could be a one shot deal or a longer yet less than perfect setup.

If I was assured a good structure day or two and/or a few tornadoes I'd take slight risks over mod+ anyway.. keep the yahoos at home.

At least we're not out there now...

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There's no reason to season cancel at this point:

The ensemble GFS and Euro for the 11-15 day have...

Neutral to negative AO

Neutral NAO

Neutral to negative PNA

Neutral to negative WPO

Neutral EPO

Disagreement with the progression of the MJO

Doesn't exactly add up to a high confidence long range forecast.

Slow seasons still have tornadoes.

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2009 is a great example of a slow season which was redeemed for me by one fantastic day- June 5th in Goshen County, WY.

I think we are toast until at least the least week and a half of May but after that anything is possible. June can produce big-time, especially up farther north and NW which is fine by me. I will chase anywhere (in 2005 I saw tornadoes in eastern MT and western SD) so from my perspective at this point it is silly to declare the season dead.

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It all depends on whether you're taking a chaser's perspective or big-picture perspective. For the latter, I'm leaning slightly toward Tony's idea that we may be done with huge, synoptically-evident outbreak situations for the spring, though I'm not as confident just yet. However, for chasers -- especially those free to roam anywhere on chasecations -- it really is pointless to worry about the death of the season in early May.

Even if Tony is completely correct, it isn't particularly bad news for chasers coming out for the late season. For example, in both 2005 and 2009, we were essentially done with big western troughs and outbreaks by May 15. In fact, mid-late May both years were about as bad as the worst-case scenario we're looking at here. The 2009 pattern was incredibly similar. Nonetheless...

9 Jun 05

http://www.spc.noaa.gov/exper/archive/event.php?date=20050609

http://www.extremeinstability.com/05-6-9.htm

http://www.cycloneroad.com/2005june9.htm

12 Jun 05

http://www.spc.noaa.gov/exper/archive/event.php?date=20050612

http://www.mesoscale.ws/05-documents/050612.htm

5 Jun 09

http://www.spc.noaa.gov/exper/archive/event.php?date=20090605

17 Jun 09

http://www.spc.noaa.gov/exper/archive/event.php?date=20090617

All of these were candidates for the list of "top 50 chase days of the 2000s" (Goshen Co. being the least-likely, actually, if not for having 8 million people on the storm).

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2005 was a good year up here. Not sure what gave our season such a boost in 05 but it was fun. I think it was a basic zonal flow aloft but it produced consistent convective events (every 3 days or so).

I am concerned about a lack of moisture, however. It's been very dry here since last summer.

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It all depends on whether you're taking a chaser's perspective or big-picture perspective. For the latter, I'm leaning slightly toward Tony's idea that we may be done with huge, synoptically-evident outbreak situations for the spring, though I'm not as confident just yet. However, for chasers -- especially those free to roam anywhere on chasecations -- it really is pointless to worry about the death of the season in early May.

Even if Tony is completely correct, it isn't particularly bad news for chasers coming out for the late season. For example, in both 2005 and 2009, we were essentially done with big western troughs and outbreaks by May 15. In fact, mid-late May both years were about as bad as the worst-case scenario we're looking at here. The 2009 pattern was incredibly similar. Nonetheless...

This. The High Plains will be active through summer, that is a guarantee. You simply can't beat climo. Weak low amplitude undulations and the subtropical ridge may not be as secksy as say, April 14, but they can certainly deliver all sorts of excitement. I personally think high plains severe in midsummer is some of the trickiest severe weather to forecast anywhere/anytime. as the patterns are strongly augmented by the local terrain (i.e., Colorado DCVZ, high terrain forcings in southern CO, leeside effects across NE/SD/MT/KS/western OK/TX, etc.) and forcing has a tendency to be marginal/difficult to forecast. CAP always a concern, and cap busts are far more prevalent.

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Good luck man, looks like S Texas will be the place to be the next couple to three days.

I had chosen Eldorado for a forecast point today for severe hail. Agreed, it looked like an outflow dominant day with the very low LCLs and high CAPE/low shear environment. If you include surface - 8 km shear, there could be marginal supercells....but it doesn't look like that is being realized yet. Happy chasing today, hope you you see something worthwhile.

Good luck! That region of TX has pulled out a few nice surprises so far this year, so I have a good feeling about your chances of seeing something worthwhile.

Thanks for the support guys... This has been a brutal 3 days chasing. The most exciting intercept was the storm around San Angelo with the intermittent but legit couplet Monday. Too much cloud cover in south Texas today, we decided to play New Mexico. Some disorganized convective activity coming up from Mexico but we are hoping some easterly surface winds will enhance shear on any new cells that form.

The next 2 says are a loss too.

We'll see how Friday looks with some moisture returning into southern Texas.

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Well my C/W fellow posters, some interesting news. I have accepted a position as a general met in Anchorage, AK. I will be leaving NE in 1.5 months. I don't plan on leaving the forums or quitting as mod though, at least that is the plan. I am sure most of you would much rather see me leave ;)

But it is quite a day for me. Severe weather is something I am still delving into...I will fully admit my knowledge is noobish compared to some of the elite posters here, but winter weather has always been my love. Anchorage should fit me nicely.

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Well if this spring is gonna be a flop, time to start counting down for Fall tornado/hurricane season.

Yeah to be fair, as Baro mentioned, March 2nd was one of the worst early March tornado events the country has seen, and the OH Valley really hasn't seen anything like it in quite awhile. If you discount the 4/27 and 5/22 events last year, it is the deadliest outbreak since Super Tuesday 2008...

Leap Day in own right was quite significant, there hadn't been an EF4 in IL in a long time and the same with IN with the New Pekin/Henryville tornado on 3/2.

4/14 was one of the more impressive early season Plains outbreaks in quite awhile, and the Woodward tornado was the deadliest in Western OK in a long time (Piedmont/El Reno last year was more Central OK).

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Well my C/W fellow posters, some interesting news. I have accepted a position as a general met in Anchorage, AK. I will be leaving NE in 1.5 months. I don't plan on leaving the forums or quitting as mod though, at least that is the plan. I am sure most of you would much rather see me leave ;)

But it is quite a day for me. Severe weather is something I am still delving into...I will fully admit my knowledge is noobish compared to some of the elite posters here, but winter weather has always been my love. Anchorage should fit me nicely.

Wow Baro, congrats and good luck :thumbsup:

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