Central/Western Summer Medium/Long Range Discussions

[Dsnowx53]

The ridge axis though is in the eastern Plains, so it's really not a bad run for a lot of the north and western high plains regions. Obviously not as good as the GFS but I'd imagine that chasers would still manage, especially via upslope.

yeah it's not horrible. not necessarily amazing but probably relatively OK. as long as you don't get that ridge pumped way up and axis west of like 105-110 it's workable at least when waves pass by etc. one issue at times might be that heights tend to rise day to day on some models.

those high plains days are tough because they look like crap from range a lot and they are nerve inducing but huge payoff if you get a good one or string of good ones.

i loved how the gfs just kept piling moisture into places like the black hills last night. i doubt it's right but those would be fun chases.

Yeah, I could totally see why cap busts could be an issue, but as you said the payoff potential is quite high. Hopefully in the height rising scenario, a little wave could still be in the vicinity or something.

And yeah, that GFS pattern would be something. Fun chases on beautiful terrain.

A lot of this really depends on what happens with the weekend wave, though it's certainly appearing that it won't be a monster EC cutoff robbing GOM return. The faster it moves out of the way and allows ridging in the east, the further east the whole pattern can shift, which would bring a lot more of the Plains at play. I could see the weekend wave having enough of a lingering effect to make the pattern a little questionable at times but not enough to where chasers would be unhappy.

[HM]

yeah it's not horrible. not necessarily amazing but probably relatively OK. as long as you don't get that ridge pumped way up and axis west of like 105-110 it's workable at least when waves pass by etc. one issue at times might be that heights tend to rise day to day on some models.

 

those high plains days are tough because they look like crap from range a lot and they are nerve inducing but huge payoff if you get a good one or string of good ones. 

 

i loved how the gfs just kept piling moisture into places like the black hills last night. i doubt it's right but those would be fun chases.

 

The potential is increasing for something rather widespread in early June in the northern Plains-Midwest. Besides the analog data, the 12z GFS pattern is notorious this run. I'm interested to see the ensemble mean and new ECMWF data. If the pattern has a possibility or tendency to get stuck/cut-off, keep in mind the bias of the ECMWF I brought up the other day. It gets a little too rambunctious with it.

[Ian]

The potential is increasing for something rather widespread in early June in the northern Plains-Midwest. Besides the analog data, the 12z GFS pattern is notorious this run. I'm interested to see the ensemble mean and new ECMWF data. If the pattern has a possibility or tendency to get stuck/cut-off, keep in mind the bias of the ECMWF I brought up the other day. It gets a little too rambunctious with it.

Yeah I'd take the new GFS without much complaint.

It is interesting certain favored analogs featured a pretty decent flip with violent tornado days. Maybe already falling into that kind of deal.

I'm pessimistic as a whole with this stuff but I think we are running into a lot more potential than the last two years.

[HM]

 

Yeah I'd take the new GFS without much complaint.

It is interesting certain favored analogs featured a pretty decent flip with violent tornado days. Maybe already falling into that kind of deal.

I'm pessimistic as a whole with this stuff but I think we are running into a lot more potential than the last two years.

This time of year, you can't discount cut-off lows. It would be just stupid. But there will be things going on, globally, that will possibly prevent stagnant 10-day patterns. The +AAM anomaly has propagated to 30°N and the dAAM/dT is quite positive between 30-40°N. General Mid-Latitude to subpolar westerly flow should prevail with possibly the development of a Subtropical -AAM/sink. These large-scale anomalies in momentum don't equate to localized areas as much (you can average westerly throughout the globe but have a few locations of easterly, e.g.) so it's only an aid. Finally, the ECMWF MJO data is doing the "best-case scenario" which is looping in phase 4-5 and then dying for the foreseeable future. The tropical picture will be dominated by Kelvin/internal Waves with stagnant forcing associated with ENSO/QBO etc for a bit.

I wonder if the E PAC KW, responsible for the first tropical storm of the season there, will possibly fire off a smaller-scale response across the CONUS when it crosses the IO/Indonesia. I'm not sure yet if it is capable of doing so.

[andyhb]

Some of the 12z GFS ensemble members look pretty spectacular basically through the entire run (western troughing is dominant basically through the entire suite), the Euro mean isn't shabby either at the end of it's run. Also, the 12z PNA indices, aside from the OP GFS, basically hold negative for the entire period.

[Dsnowx53]

12z Euro looks pretty good. Initially isolated threats in the Northern and Western Plains...Nebraska/Dakotas/Wyoming areas for Friday, gradually becoming more widespread as the weekend goes and into early next week. It seems to particularly like Monday the 27th. Seems like chasers will initially be north, then will have a tad more flexibility to go south as the weekend progresses and as the trough moves east and broadens. 

[Dsnowx53]

The 18z GFS seems to like Nebraska from Friday and on, provided they can get fast enough 500mb wind speeds...currently mainly progged between 30 to sometimes 40 knots, which is a little lackluster, but other factors look okay. It's not a super ideal look, but it's still a decent one. Next Sunday and Monday could be bigger there if things go right. 

[andyhb]

The long range modeling recently has been forecasting quite the active pattern here coming up, and then potentially to start June as well (both the 12z Euro and 00z GFS have a very large trough developing in the West towards the beginning of June).

[Dsnowx53]

The long range modeling recently has been forecasting quite the active pattern here coming up, and then potentially to start June as well (both the 12z Euro and 00z GFS have a very large trough developing in the West towards the beginning of June).

Yeah, some okay setups with perhaps more isolated cells starting Friday or so, but then come the following week --Monday and on has lots of potential.

GFS and Euro both seem to like Nebraska for Friday along a dry line. Would like to see the 500mb winds increase, though.

[andyhb]

The 00z Euro again has a massive trough dumping into the West in the latter range, with a very strong Pacific Jet enhanced by a powerful ULL upstream moving down the backside.

 

The 00z GEFS appears to generally agree with this thought as well. The models seem to be in agreement over an anomalously strong Pacific Jet streak making its way across the Pacific this week, the Euro at 168 has it off the coast of North America at 140-150 kts at 200 mb, which is pretty crazy for this time of year.

 

[brettjrob]

I've barely looked at the medium range for the past five days or so, but the 00z and 06z GFS today have continuous western troughing through the entire range, with 40+ kt mid-level southwesterlies consistently in place from about I-70 northward. There's a bit of a tendency for poor overlap of instability with the jet at times, but otherwise, it looks like a 2004 or 2010 quality pattern to close out the month and start June. Just wow.

[andyhb]

Well...the 12z GFS ensembles certainly look...interesting in the mid range to say the least.

[brettjrob]

Well...the 12z GFS ensembles certainly look...interesting in the mid range to say the least.

 

Can't remember ever seeing anything like it this time of year. 2010 was close, but not quite this persistent a favorable Plains pattern IIRC. Of course, they're just models, and the past 3 days of violent tornadoes looked quite iffy only 10 days ago.

[andyhb]

Euro/Euro ensembles and GGEM look rather menacing as well, I'm interested to hear HM's thoughts on this.

 

One thing is for sure, that high out in the Atlantic is going to keep the Gulf wide open here.

[Ian]

Can't remember ever seeing anything like it this time of year. 2010 was close, but not quite this persistent a favorable Plains pattern IIRC. Of course, they're just models, and the past 3 days of violent tornadoes looked quite iffy only 10 days ago.

We brought tornadoes back.

[andyhb]

About a week out, but the 00z GFS appears to be hinting at some sort of High Plains threat sometime around the 28th or so.

 

Also...what a monster of an UL jet...wow. Paging Brett, Ian, Thundersnow, anyone on a chasing trip...

 

[Dsnowx53]

Looks like some isolated threats for the next several days, slowly becoming more widepsread as the days progress, especially into next week. The last 3 days of the month could really produce.

 

I'm leaving tomorrow morning for my chase, btw! 

[Dsnowx53]

About a week out, but the 00z GFS appears to be hinting at some sort of High Plains threat sometime around the 28th or so.

 

Also...what a monster of an UL jet...wow. Paging Brett, Ian, Thundersnow, anyone on a chasing trip...

 

 

 

Wow. 

[andyhb]

Wow. 

 

What happens after is...well...the only word that really captures it is the word you used.

 

I would have strong considerations of trying to make my way out there if we continue to see stuff like this.

[Ian]

I keep expecting to open the GFS etc and see the pattern suck but it continues to look awesome. From Thursday (I'm actually not totally closing the door on tomorrow if the NAM is right, at least structure wise) on there could be daily isolated areas of potential in the High Plains. Rising heights the next few days could hurt potential a bit but if you're willing to shift around there could be a lot to see. I'm not even that worried about a big event if we can keep days and days of supercells in great terrain going. But yeah.. something big might be brewing in there too.

[andyhb]

Tbh, some of these various solutions look like a weenie chaser drew them up when they were bored.

[Ian]

Tbh, some of these various solutions look like a weenie chaser drew them up when they were bored.

The Euro op doesnt seem as totally sold as the GFS but the ensemble mean looks quite good. I'm not ready to buy in fully tho it's intriguing.

[Dsnowx53]

I keep expecting to open the GFS etc and see the pattern suck but it continues to look awesome. From Thursday (I'm actually not totally closing the door on tomorrow if the NAM is right, at least structure wise) on there could be daily isolated areas of potential in the High Plains. Rising heights the next few days could hurt potential a bit but if you're willing to shift around there could be a lot to see. I'm not even that worried about a big event if we can keep days and days of supercells in great terrain going. But yeah.. something big might be brewing in there too.

 

 

Exactly. There should still be a few gorgeous structural supercells pretty much every day in this pattern. I'm pretty excited.

 

Rising heights could lead to capping issues for sure, but yeah if you find the right places, you'll do well. 

[andyhb]

The Euro op doesnt seem as totally sold as the GFS but the ensemble mean looks quite good. I'm not ready to buy in fully tho it's intriguing.

 

Yeah, I noticed the ensemble mean was showing quite an impressive, broad trough (for being at the range we are at) developing across the West on the 12z run, that UL jet is pretty anomalous looking for this time of year, so we'll have to see if this stuff continues.

[Dsnowx53]

Yeah, I noticed the ensemble mean was showing quite an impressive, broad trough (for being at the range we are at) developing across the West on the 12z run, that UL jet is pretty anomalous looking for this time of year, so we'll have to see if this stuff continues.

 

 

The block retrograding west, combined with the MJO being favorable, leads to a strong, displaced PAC Jet. I think it's possible. 

[andyhb]

The block retrograding west, combined with the MJO being favorable, leads to a strong, displaced PAC Jet. I think it's possible. 

 

There'd certainly be the potential for something pretty substantial if this does work out, I think HM mentioned something about the 12z GFS the other day showing a "notorious" pattern, I'd say the GFS tonight falls into that category as well, and, to a lesser extent the 12z GEFS/Euro Ensemble means.

 

Edit: 00z GEFS mean is essentially on the same track. The 00z Euro decided to do something completely different (has a small cutoff that acts as a weakness and the incoming energy decides to find that weakness). This same cutoff (west of the Baja initially) retrogrades on the GFS/GEFS mean and becomes a non-factor. There also appear to be many high-latitude blocking differences between the 00z Euro suite and the 00z GFS suite.

[HM]

Sorry for my recent absence; I was in Norman for a few days with Jake and Sam (great hosts!). The MJO, while "dead" in a technical sense, did the classic behavior for continued threatening weather. It did a loop in phase 4-5 before becoming incoherent. This means that the tropical forcing has heightened and stalled in the favorable walker forcing/uplift area of Indonesia-western Pacific. For a while, Kelvin Wave activity will be the leading mode of propagating tropical waves.  

 

An extended favorable pattern for tornadoes will continue through mid-June possibly. And yes, the threat for a widespread outbreak still exists in the last few days of May / early June for the northern (possibly central) Plains and Midwest. There is some data that is suggestive of a 1990 redux, but my confidence is not as high as it was when I made the long range call for May 15-20 (and yes, it was one of the reasons I booked my tickets to Oklahoma in April, haha). Either way, active period should continue into early June. Good luck chasers!  

[Dsnowx53]

I'm on the road now! We might run into the squall line in Ohio, and then be in Nebraska by Friday.

[Dsnowx53]

I think we're actually gonna try to get to the Texas Panhandle for tomorrow, since the new outlook is hatched. The structure should be GORGEOUS provided that the cap breaks. Great ML Lapse rates and very high ML Cape...this will produce ginormous cloud tops, and considering the terrain and the directional shear with these, I'm sure the supercells could be quite photogenic.

[HM]

 

This time of year, you can't discount cut-off lows. It would be just stupid. But there will be things going on, globally, that will possibly prevent stagnant 10-day patterns. The +AAM anomaly has propagated to 30°N and the dAAM/dT is quite positive between 30-40°N. General Mid-Latitude to subpolar westerly flow should prevail with possibly the development of a Subtropical -AAM/sink. These large-scale anomalies in momentum don't equate to localized areas as much (you can average westerly throughout the globe but have a few locations of easterly, e.g.) so it's only an aid. Finally, the ECMWF MJO data is doing the "best-case scenario" which is looping in phase 4-5 and then dying for the foreseeable future. The tropical picture will be dominated by Kelvin/internal Waves with stagnant forcing associated with ENSO/QBO etc for a bit.

I wonder if the E PAC KW, responsible for the first tropical storm of the season there, will possibly fire off a smaller-scale response across the CONUS when it crosses the IO/Indonesia. I'm not sure yet if it is capable of doing so.

 

Just wanted to comment on this after looking at things today. The CCKW of interest is currently spanning the East Pacific-Atlantic sector and will be reinvigorating the "MJO" signal over the next week or so. In reality, as the CCKW reaches the western edge of the Walker Uplift / forcing, the "MJO" signal will grow more coherent further west again but not necessarily reflect a true MJO (if that makes sense lol).

 

I'm pointing this out because if you're checking MJO modeling, you might want some explanation as to why they are showing what they are showing over the next 10 days.

 

Also, again, always refer to this to help sort through the various waves:

http://mikeventrice.weebly.com/tropical-waves.html

 

 

I'm becoming increasingly confident that this will lead to a significant outbreak at the end of May / start of June for the areas we have been discussing in this thread. Beforehand, the threats are being modeled well across the Plains and fit with the teleconnections (retrograding blocking in Canada-WPO sector).