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Central/Western Medium-Long Range Discussion

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Though we have not had a large outbreak, events and even sequences are happening. While the hemispheric weather pattern is far from ideal, it appears to be quite adequate.

 

Could get southern Plains action next week, but need better winds upstairs 500/250 mb. Model 850 and even 925 look okay, but out of sync with what little jet stream energy comes out. I think later weeks will be better. Mid-Atlantic ridge hints at returning the following week after Mother’s Day Midwest trough. Such a ridge was featured 3 weeks ago when the season suddenly woke up with a bang from Kansas to Illinois. 

 

Then the Pacific jet stream is shown strengthening out over the ocean early to mid-May. West Pac has been blocky too. Whether a stronger Pac jet stream benefits or hurts depends on how it comes into the US West. Kind of like shuffling the cards though, it certainly brings new hope. Also warm waters off the Baja Peninsula are starting to ease, relative to normal, which could help more West troughs – iff we the atmo responds in time. Concern about northern stream lifting to Canada early is noted, but southern stream is fine. Could get Panhandle magic and High Plains beauties in later weeks.

 

Thoughts on remainder of the Chase Season: The biggest synoptic outbreaks seem to be 15 April to 15 May. Are we at halftime? However those are not necessarily the best chase days due to storm speed, chaser convergence, and one-and-done. May is the peak, a blend of synoptic outbreaks, local set-ups, and perhaps a sequence. We are just in the first quarter. For a chase trip (chasecation) one could argue peak is actually 15 May to 15 June; we are pre-game. After Memorial Day outbreaks trail off, but sequences seem to peak late May. Then in June 1-3 day subtle set-ups can be a chaser dream. Much of the heard is out of time and funds; it is north of the herd bullseye; and, the meteorology can be superb. June offers guaranteed moisture, reasonable storm motion, and little risk of cold front intrusions.

 

Lovely weather is forecast over large areas this weekend. Enjoy it and stay optimistic about stormy weather later in May.

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Some missing pieces (in terms of severe) for the middle of next week and it's a shame. It looks like an active period may result in more heavy rainfall than anything. Although I would suspect at least a slight risk for severe thunderstorms during a couple of those days. The PW values are progged to be on the order of 2+ SDs across much of the Plains, another signal of the heavy rain potential. The Euro shows a general 2-4 inch rainfall event by the end of the week for much of the area. Considering portions of northern Texas have already seen their fair share of rain as of late, it's not's exactly welcome, at least not so soon. Although longer term trends still indicate some persistent drought conditions.

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Some missing pieces (in terms of severe) for the middle of next week and it's a shame. It looks like an active period may result in more heavy rainfall than anything. Although I would suspect at least a slight risk for severe thunderstorms during a couple of those days. The PW values are progged to be on the order of 2+ SDs across much of the Plains, another signal of the heavy rain potential. The Euro shows a general 2-4 inch rainfall event by the end of the week for much of the area. Considering portions of northern Texas have already seen their fair share of rain as of late, it's not's exactly welcome, at least not so soon. Although longer term trends still indicate some persistent drought conditions.

 

Agreed with all of this. Next week reminds me some of the first week in June last year. We finally had decent moisture and instability after an abysmal mid-late May, but upper flow was lacking. Still, it was the kind of pattern that can sometimes lead to a string of localized but impressive tornado events (ala late May 2010 or late May 2013)... or sometimes lead to virtually nothing except lots of wasteful chasing (ala early June 2014).

 

Now, because ET (evapotranspiration) should be at least somewhat better than we saw at any point last spring south of I-70, I think the odds of at least one day coming through are decent. But for chasers, it will require a lot of miles, skill, and luck to be there if something in the vein of Bennington 5/28/13 or Texline 5/23/10 pops up at the last minute.

 

These are obviously speculative and preliminary thoughts, though. After all, the ECMWF went from showing a crashing cold front late next week on last night's run to a decent Four Corners closed low around the same time this afternoon.

 

Oh, and that tropical low sitting off the Carolina coast next week dragging crappy air into the eastern Gulf can GTFO.

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I know better than to get too excited, but quietly the trends for next weekend have gotten better. Can't help but like the look of the Euro ensemble mean at 168h. I'm sure it will continue to evolve and we need to get through this mid-week mess first.

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I know better than to get too excited, but quietly the trends for next weekend have gotten better. Can't help but like the look of the Euro ensemble mean at 168h. I'm sure it will continue to evolve and we need to get through this mid-week mess first.

 

It has more western troughing developing after that too (as does the GEFS and GEPS).

 

5/1991 has been showing up a lot in the CPC analog composites over the past few days. I feel like that month gets overlooked a bit given the magnitude of 4/26, but it had 335+ tornadoes, including 5/16/91, which was nearly as good of a chase day as 4/26 (although there weren't any violent tornadoes during the month). Also had the Lazbuddie, TX tornado carousel on 5/10.

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It has more western troughing developing after that too (as does the GEFS and GEPS).

 

5/1991 has been showing up a lot in the CPC analog composites over the past few days. I feel like that month gets overlooked a bit given the magnitude of 4/26, but it had 335+ tornadoes, including 5/16/91, which was nearly as good of a chase day as 4/26 (although there weren't any violent tornadoes during the month). Also had the Lazbuddie, TX tornado carousel on 5/10.

 

Yeah, May 1991 easily blows anything we've seen since May 2010 out of the water, at least for my tastes (I know 2013 has an argument, if you ignore the I-35/OKC magnet aspect). Between 5/10, 5/16, and 5/26, it would be hard to ask for a lot more -- and there were a lot of other localized tornado days across the Panhandles and W KS.

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hail size and VIL are large (3.52" and 127 kg/m2) on this storm south of Lincoln Nebraska

2015_05_04_0000z_KOAX_hail_and_VIL.png

Outflow boundary set up in that area overnight so I can't be surprised it's taking off now. Some rotation also.

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Not sure I'd go to high end on anything right ahead but keep tossing and eventually something sticks, esp in May. Wed looks better than it has. Ensembles pretty enthusiastic about keeping troughiness going in the W/SW.

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Wenesday could be pretty active, as a shortwave will kick out from the southwest into the Plains from Tuesday to Wednesday. The NAM and GFS show plenty of rain in the southern Plains on Wednesday, perhaps meaning that broad-scale convection could hurt chances of destabilization.

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Not sure I'd go to high end on anything right ahead but keep tossing and eventually something sticks, esp in May. Wed looks better than it has. Ensembles pretty enthusiastic about keeping troughiness going in the W/SW.

 

I really like the LLJ strength on Wednesday, leading to large low level hodographs with relatively typical Plains profiles. Obviously the less than stellar for the season lapse rates (although GFS/Euro still both have 2000+ J/kg SB/MLCAPE in spots), possible early convection and questionable upper level winds are your three biggest issues (a bit better once you approach the OK/KS border and then further south into western/central OK on the left exit region of stronger 300 mb flow), but at least storm initiation/LCL heights seem reasonable.

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00z GFS looking pretty darn solid all things considered for this upcoming weekend (Saturday 5/9 specifically).

 

Edit: UK/GGEM looking favorable as well.

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Rest of this week has indeed perked up. Wednesday through Saturday look like a possible sequence. While there may be a less active day Thursday or Friday, not both, Wednesday and Saturday are looking pretty good.

 

Next week may set up again starting around midweek. Currently looks like a little shorter wavelength trough but with a better straight westerly jet stream. Jury is out on strength and low levels.

 

Finally the following week of May 18th all ensembles (GFS, Euro, Canadian) have a new big western trough. Southwest below normal heights signal is consistent. Also the East keeps verifying warmer, which is another plus in the US weather pattern.

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Not a huge fan of all the signs of early initiation on Saturday on the models, especially further south into Texas (although that is something that could change fairly easily).

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Not a huge fan of all the signs of early initiation on Saturday on the models, especially further south into Texas (although that is something that could change fairly easily).

 

The Euro wants to make this an issue virtually every day this week, with at least one convective QPF bomb somewhere along the dryline by 18z. Aside from that, I'm becoming very optimistic about this four-day stretch from Wed-Sat. There isn't a day in there that doesn't feature realistic potential for classic tornadic sups across the Panhandles, W OK, and SW KS. Wednesday could be big, and Saturday almost certainly would find a way to be big even if it fires early, unless the synoptics change substantially from the current Euro depiction.

 

The fact that several setups in April were wrecked by morning convection makes me nervous, but we'll see. It's May, and I doubt that can be a dealbreaker four days in a row.

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Yeah Saturday aside from that almost looks like a prototypical bigger May day, might be the best looking synoptic system we've seen so far with a pretty decent chance of kicking at least neutral tilt if not slightly negative with the upper jet ejecting out the base. LLJ strength looks solid on pretty much every day in this upcoming stretch. Not only that, but something tells me (after looking at ensemble guidance) that we aren't done after this either, i.e. what Thundersnow is mentioning.

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Ensembles look good thru the runs overall. April was really active considering... Even with issues a lot of those events performed about as much as possible. Should be good till at least May 24 or so. ;)

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Yeah Saturday aside from that almost looks like a prototypical bigger May day, might be the best looking synoptic system we've seen so far with a pretty decent chance of kicking at least neutral tilt if not slightly negative with the upper jet ejecting out the base. LLJ strength looks solid on pretty much every day in this upcoming stretch. Not only that, but something tells me (after looking at ensemble guidance) that we aren't done after this either, i.e. what Thundersnow is mentioning.

 

post-266-0-24410500-1430774126_thumb.png

 

post-266-0-51868400-1430774134_thumb.png

 

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Been awhile since we've seen a May pattern (I suppose you could argue second half in 2013, but I digress) like that.

 

And I see some pretty volatile May analogs showing up here (not just single events either, a few of these were prolonged active stretches)...

 

814analog.off.gif

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May 2013 was a weird pattern -- it has been a while since a potential classic setup comes along in peak season, which certainly seems possible given the looks.

 

Nino spring/summers seem to have a tendency to go bigger in middle or late season at least the few I've looked at. Think when you put that plus the signs of prior as far as KS/panhandle type targets.. outlook is quite positive for the season as a whole. I guess it'll shut down at some point but the main story has been an active pattern for quite a while.. severe ramped up in late Mar and never fully died off till recently, and even that die off was relatively tame for early season. Some of those April events would have been more memorable if there was just a little bit more surface moisture.

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May 2013 was a weird pattern -- it has been a while since a potential classic setup comes along in peak season, which certainly seems possible given the looks.

Nino spring/summers seem to have a tendency to go bigger in middle or late season at least the few I've looked at. Think when you put that plus the signs of prior as far as KS/panhandle type targets.. outlook is quite positive for the season as a whole. I guess it'll shut down at some point but the main story has been an active pattern for quite a while.. severe ramped up in late Mar and never fully died off till recently, and even that die off was relatively tame for early season. Some of those April events would have been more memorable if there was just a little bit more surface moisture.

It's been mentioned, but all of the beneficial rain this week should take a big knock out of the regional drought too. Not to mention that bodes well for available moisture later this month.

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Random question, but does anyone know why the SPC has been consistent in putting "Potential Too Low" over the past few days? Especially today, it's thrown me off a little.

It's especially odd since they have 15% probs now to outline in the day 4-8 period (was only 30% in the past). It's perplexing since the Euro and GFS have been in very good overall agreement through Saturday.

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Random question, but does anyone know why the SPC has been consistent in putting "Potential Too Low" over the past few days? Especially today, it's thrown me off a little.

 

Seems to be forecaster preference over anything.

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Ensembles look good thru the runs overall. April was really active considering... Even with issues a lot of those events performed about as much as possible. Should be good till at least May 24 or so. ;)

 

When are you chasing?

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When are you chasing?

May 22-June 7. Maybe can blame recency bias for shifting a week later compared to past two years. May sting a bit lol. We've done well in that period before, tho off the top of my head I want to say the first week of June hasn't been a big performer of late. But the Panhandle is returning to service so fingers crossed.

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