Central/Western Medium-Long Range Discussion

[jojo762]

I like our chances of seeing at least SOMETHING the end of this week/weekend... At least one day could be fairly impressive, depending on how a myriad of environmental factors evolve. CIPS GEFS analog percentage for Day 6-8 of at least 10 SVR reports. GFS for several runs has been moderately impressive -- to varying degrees, for a variety of reasons -- for Friday specifically, but Thursday and Saturday could feature severe storms as well. A bit too far out to determine potential hazards really, but the wind profile will be quite favorable for supercells with impressive veering with height.

[bjc0303]

Pretty good signal, tho think GFS probably a hair too east as usual putting OKC/Norman in risk area. 

 

Think we will get a quality two days of storms, 2013 style with a dry line/sagging cold/stationary front.

[jojo762]

24 minutes ago, bjc0303 said:

Pretty good signal, tho think GFS probably a hair too east as usual putting OKC/Norman in risk area. 

 

Think we will get a quality two days of storms, 2013 style with a dry line/sagging cold/stationary front.

This is somewhat reminiscent to 2013 imo as well, especially by Friday/Saturday, H5 map isn't exactly the same but has some similarities, notable differences being the presence of a large NE-trough this go around and the central CONUS trough isn't quite as strong, but other features are similar... Thursday looks mildly interesting, but thinking capping will hinder convective development, and therefore any potential it may have, as of now. GFS has trended with a weaker cap on Friday/saturday, so naturally given the progged thermo/kinematic profile, along with only subtle forcing, those days would both probably be fairly interesting if things were to evolve as shown now (doubtful)... We've all seen what these extreme instability/moderate shear environments have been capable of in the past...

[nrgjeff]

State of the Chase Season still looks good. Synoptic season may be winding down, but quality set-ups will continue as we roll through the peak weeks of tornado climo. Later this week features modest WSW flow over a high CAPE environment. LLJ responds to upper waves a few days. Should be a sharp dry line and other boundaries. Details have yet to work out regarding the cap Thursday and LLJ over the weekend. Expect 1-3 good chase days.

Late next week once again a trough may dig into the Rockies. Ensembles vary on timing but a majority have it dropping in there. Favorable pattern may be present into the week of June 5 as well. MJO and tropical Pacific are friendly to these weeks. Perhaps a couple good chase days both weeks of May 29 and June 5. Each week could also feature a sleeper day. Even if just normal activity, we have a friend in climo.

[bjc0303]

11 minutes ago, nrgjeff said:

State of the Chase Season still looks good. Synoptic season may be winding down, but quality set-ups will continue as we roll through the peak weeks of tornado climo. Later this week features modest WSW flow over a high CAPE environment. LLJ responds to upper waves a few days. Should be a sharp dry line and other boundaries. Details have yet to work out regarding the cap Thursday and LLJ over the weekend. Expect 1-3 good chase days.

Late next week once again a trough may dig into the Rockies. Ensembles vary on timing but a majority have it dropping in there. Favorable pattern may be present into the week of June 5 as well. MJO and tropical Pacific are friendly to these weeks. Perhaps a couple good chase days both weeks of May 29 and June 5. Each week could also feature a sleeper day. Even if just normal activity, we have a friend in climo.

Agreed. Synoptically driven patterns don't look completely dead however. FWIW (very, very little) the 06z GFS shows an active pattern into June.. Which would likely bring a string of active days over KS, NE, perhaps even OK (pending EML strength).

Jet certainly looks to remain active for at least another 2-3 weeks; this is reflected in the recent ERTAF forecast.

[Thundersnow12]

Victor Gensini and I are leading trip 3 with COD and we are out June 2nd-June 11th. Both optimistic as things look currently. 

[brettjrob]

The current 7-10 day period is looking pretty grim to me. This week's string of southwest flow days is highly flawed, with Saturday at least offering some legitimate potential given CI. Then the pattern goes back to pure ugliness for at least 4-5 days heading through Memorial Day weekend into mid next week. Hurts, coming on the heels of perhaps the biggest waste of a late May longwave western trough I've seen (last week).

[bjc0303]

7 minutes ago, brettjrob said:

The current 7-10 day period is looking pretty grim to me. This week's string of southwest flow days is highly flawed, with Saturday at least offering some legitimate potential given CI. Then the pattern goes back to pure ugliness for at least 4-5 days heading through Memorial Day weekend into mid next week. Hurts, coming on the heels of perhaps the biggest waste of a late May longwave western trough I've seen (last week).

Yeah, just gonna have to make due (Fri/Sat) with what we have. Still not buying Friday staying completely capped, and will eagerly await coming home with a burn/tan if it does fail to convect. 

I agree though, what a waste of TWO pretty severe-favorable looking longwave troughs. One in late April and the other last week. Unbelievable that neither quite panned out.. Both had outbreak potential, relatively speaking (as happens with pronounced, favorably-positioned longwave patterns). I wouldn't give up on June quite yet (although, if you're stuck with southern plains chasing, perhaps).. Central and northern plains through June could be rocking.

[beavis1729]

For Las Vegas, I wonder what their lowest relative humidity on record is.  Yesterday at 2:00 PM, it was 99/-1, which translates to a RH of 2%. 

[Quincy]

Confidence in this range is relatively good through day 10 and just wow. There were hints from a few weeks out that this period would improve, but now that's far from the case. This may be one of the worst late May/early June stretches (at least for photogenic and/or longer-lived tornadoes) for tornadoes in a while. Yes, there were a few events and some local accidents, like Wisconsin, but otherwise it's largely been a dud in the Plains. Bigger days have largely been busts or filled with messy storm modes. There have been very few long-lived supercells over terrain west of I-35. Most events (from a chaser/photographer perspective) have been "right place at the right time," otherwise a lot of hair pulling, highly challenging events  

The last couple of CFS runs are as quiet for a 7-10 stretch as they have been since early May. The support across the board is fairly consistent with general troughing in the East and few, if any notable shortwaves impinging on the Plains. 

As we move into June, you'd expect that eastern Colorado and vicinity will have a few events (even with marginal/questionable environments) and northwest flow can eventually be more meaningful in terms of severe across the Midwest/Great Lakes as the calendar shifts deeper through June, otherwise, it looks like a snoozefest. There's always the potential for a mesoscale accident, but...

[Derek30]

GFS has been hinting at big things for the central and northern Plains in early to mid June. Big time ridge followed by western troughing and the jet shifting north.

[tornadohunter]

3 hours ago, Quincy said:

Confidence in this range is relatively good through day 10 and just wow. There were hints from a few weeks out that this period would improve, but now that's far from the case. This may be one of the worst late May/early June stretches (at least for photogenic and/or longer-lived tornadoes) for tornadoes in a while. Yes, there were a few events and some local accidents, like Wisconsin, but otherwise it's largely been a dud in the Plains. Bigger days have largely been busts or filled with messy storm modes. There have been very few long-lived supercells over terrain west of I-35. Most events (from a chaser/photographer perspective) have been "right place at the right time," otherwise a lot of hair pulling, highly challenging events  

The last couple of CFS runs are as quiet for a 7-10 stretch as they have been since early May. The support across the board is fairly consistent with general troughing in the East and few, if any notable shortwaves impinging on the Plains. 

As we move into June, you'd expect that eastern Colorado and vicinity will have a few events (even with marginal/questionable environments) and northwest flow can eventually be more meaningful in terms of severe across the Midwest/Great Lakes as the calendar shifts deeper through June, otherwise, it looks like a snoozefest. There's always the potential for a mesoscale accident, but...

So #2017in

[cyclone77]

For two runs in a row now the EC has a relatively decent setup over the eastern Dakotas/western MN for Friday.  Hopefully it's on to something as the GFS is quite different.  Decent mid-level flow arrives atop a plume of deep moisture/instability.  Wind profiles look pretty respectable.  Something to watch anyway.

[hlcater]

27 minutes ago, cyclone77 said:

For two runs in a row now the EC has a relatively decent setup over the eastern Dakotas/western MN for Friday.  Hopefully it's on to something as the GFS is quite different.  Decent mid-level flow arrives atop a plume of deep moisture/instability.  Wind profiles look pretty respectable.  Something to watch anyway.

In the EC's defense, the GFS verification scores are quite terrible lately. I saw a graph 2 or 3 days ago showing the scores, and the GFS is way(like significantly) lower than the Euro for the past week or so. I don't exactly know where to find it though.

[nrgjeff]

Euro is smokin' the GFS. Note the lead-in to Saturday. While the GFS and even NAM tried to get the LLJ going, though veered, Euro never really did so. Comparisons to 5/6/03 or 5/10/08 became invalid by morning as one realized no LLJ. While the GFS and 84hr NAM now want to get the late week going, beware of the Euro veto.

Story is similar next week. GFS is bullish. Euro is skeptical. However Euro is at least introducing modest flow over the Plains. Second week of June may perk up also. I know that is a delay from the first week of June. However it is not unusual for crap patterns to go a little longer than forecast. If the CFS and Euro weeklies are right, the pattern could become more bullish second week of June.

[bjc0303]

It's been brutal, this pattern. Making it worse is the persistence. They say persistence pays off..... Hopefully that applies to meteorology!

[jojo762]

1 hour ago, bjc0303 said:

It's been brutal, this pattern. Making it worse is the persistence. They say persistence pays off..... Hopefully that applies to meteorology!

Some hint from the GFS/GEFS that things could heat up a lot more somewhere cross the plains toward mid-month with appreciable SW flow and abundant moisture... so hopefully that pans out. Not quite in EC or EPS range yet. 

[Quincy]

On 5/31/2017 at 9:26 AM, bjc0303 said:

It's been brutal, this pattern. Making it worse is the persistence. They say persistence pays off..... Hopefully that applies to meteorology!

The next week or so looks like a continuation of the pattern. It's fairly unusual to observe such a long period like this given the time of year to see the Plains so quiet. (We will probably end up with a 2-3 week run featuring substantially below average tornado activity during the climatological annual peak of late May/early June) Aside from a few tornadoes in the western part of the state, Oklahoma gets off the hook again without much substantial tornado activity, despite a few "higher-end" threats in the state to finish off May.

The longer range guidance seems to be zeroing in on some pattern improvement by late next weekend or early the following week (beginning in the June 11-13 period), but given fairly prominent ridging over the Midwest, the area of focus may end up being from the northern High Plains into the Dakotas. While this is not completely unheard-of for June, it may mean a rare quiet spell for Kansas continues. 

Despite the above-average tornado activity, places like Kansas and Oklahoma have been relatively quiet. I guess all of the early season tornadoes in the Southeast and some increased activity in Texas account for much of the tornadoes so far this year. It's also been a year largely void of long-track and/or photogenic tornadoes.

Going back to the quote above, weather likes to balance out in the long run. Aside from April 27-28, 2014 featured a putrid tornado season until a stretch in mid-June. While I remain cautiously optimistic, any such pattern change remains to be seen. Will it be dampened out? Will trough ejections be displaced too far north? Will the change continue to be pushed back later and later in June? Only time will tell.

[bjc0303]

Yeah, I'm really hoping for some KS/NE/IA action. I really don't want to have to drive way up to the Dakotas.

[hlcater]

A strong June EML remains my biggest concern, although its really too far out to make this call, I really dont like that the past several GFS runs all have a very strong capping regime, so even if we do get excellent wind fields and solid CAPE, it may not matter. However, the main part of the trough is in Canada, which probably contributes at least a little to the whole plains being capped off. If the trough is able to slide south some and not eject so far north, I feel like eroding it should become much easier. This trough also has a huge area of 50kts+ 500mb flow, which is excellent for June, would be a shame to see it largely go to waste.

[Derek30]

Anyone coming up north in the coming weeks may need to bring their passports. Looks like the potential for a good setup or two in SK/MB ahead.

[nrgjeff]

Like to base out of Winnipeg for Friday, but I will have to do so vicariously. Keep in mind Manitoba is excellent chase terrain both south and west of Winnipeg. One can even go east or north slightly without running into the forest or lakes. Friday issue could be MCS favored over discrete but we'll see.

Saturday could be a break between waves before the Northwest trough settles in more Sunday. Then looks like pieces of energy eject Sunday and Monday, with the main trough Tuesday. Biggest problem I see is surface low and boundaries under the cap. ND is not capped but it is cool sector. Low and boundaries appear in SD. Still a few days for those details to iron out though.

One bearish shift for chasers is the ensemble members are falling into line with operational models. Previously 30-40% of members were better than the ops. They were deeper with the trough, but no more. Odds of cap issues are up. One might be forced to chase the WF which requires a delicate balance between the cool sector and the cap.

Tuesday the WF and quasi-DL could both go. However we know how main trough ejections have panned out the last couple years. Need to avoid the slop and/or going into the Minnesota trees. This is a good sequence for northern Plains chasers, but I'm not sure it is a travel set-up.

[Quincy]

Agree with the points above. If I had Friday off, I'd venture north, but I concur that this weekend not a setup to make a long haul out for. I'm taking the down time to get work in, as we may have a lengthy active stretch coming up.

Saturday may end up being an in between day before the late weekend/early next week pattern looks to feature at least a couple of solid severe potential days. The 00z Euro was very encouraging, but remember that models will adjust a bit in the medium range, so details are TBD.

Speaking of models, the CFS has been consistent in showing a sharp turn around in the pattern. While high-end days don't seem likely, it appears that down days next week will be more the exception than the rule. While the CFS has little to no skill over climo beyond day 10 (so don't get too excited about the second half of June being a blockbuster period just yet), in my experience, it's quite good at general patterns inside of 7 days. 

For positioning, it looks like a bit of a late June/early July-like period with the northern Plains/upper Midwest being the favored areas. You may see some threats shift east into the Great Lakes vicinity, while capping becomes a big concern with southward extent over the Plains given the strength of a ridge over the South. 

[Chinook]

1 storm report in Oklahoma. What a tragedy

[jojo762]

13 tornado reports during one of the most active periods of the year, typically. Only two of which were in the plains... eek.

[CheeselandSkies]

*New member, longtime lurker and refugee from the veritable ghost towns of TalkWeather and Stormtrack here. I held off on joining because I despise the Eastern snow weenies and their subforums which fragment the discussion for severe threats, but it seems the knowledgeable severe people only post on this site*

2 hours ago, jojo762 said:

13 tornado reports during one of the most active periods of the year, typically. Only two of which were in the plains... eek.

Brutal. No way I thought this severe season could be delayed as bad as 2014, since that year featured the winter that wouldn't die. This year we had plenty of warm, pleasant (sometimes unseasonably so) weather here in the Midwest from February through April, but we rarely "paid" for it the way that I expected. The one day we did (February 28, significant tornadoes up to I-80 in IL), I had a prior commitment because it didn't even occur to me that chasing would be a possibility in this region in February.

Copied and pasted from what I just posted on Stormtrack:

Well, I went ahead and took Monday morning off to keep open the option of chasing in the northern or central Plains Sunday evening. Whether I actually go or not remains to be seen. It continues to look darn near gorgeous on the GFS if you just look at the CAPE and surface pattern, but at 500mb things get a lot more iffy. The trough hangs back well to the west and the 500mb southwesterlies are 25-35kt at best over the warm sector. The big question is, do the favorable factors (namely CAPE and low-level directional shear) compensate resulting in slow-moving, easily chaseable supercells, or do you have insufficient mid-level shear and thus disorganized, marginally severe multicells?

Capping also remains a concern although I think it should be breakable at least in some areas. I'd rather have that than too little cap and everything going up at once in a convective mess which we have seen all too often thus far this year. Low-level directional shear, SRH and hodograph critical angles look excellent along the warm front and near the triple point, which is another thing that has been lacking in many setups we've seen this year.

Anyone remember what the 500mb winds and capping looked like on Bowdle day? As I recall, that was a pretty low-key risk setup (slight/5%) that paid off big time. I don't recall 500 mb winds being that strong on Dodge City or Chapman day last year, either.

Monday is pretty much my only option since I'd be a huge jerk asking my coworkers to take extra days or work shorthanded again more than that so soon after what was supposed to be my chasecation, so any potentially better days later in the week are off the table for me until/unless something presents itself locally as the trough ejects toward the upper Midwest toward next Thursday/Friday/Saturday.

 

 

[Derek30]

Leaning towards the GFS solution over the NAM for Friday. Surge of moisture leads to increase in instability especially late into Friday night in MB. Not really seeing a surface based threat but instead a classic MCS/elevated scenario along and north of the warm front heading into Saturday morning.

You folks think southwest MB could be a surface based play at some point Friday? Tough call as models hint at a dying MCS in that area early. MB historically has had a hard time with afternoon recovery behind MCS activity but we shall see.

[Quincy]

7 hours ago, CheeselandSkies said:

Anyone remember what the 500mb winds and capping looked like on Bowdle day? As I recall, that was a pretty low-key risk setup (slight/5%) that paid off big time. I don't recall 500 mb winds being that strong on Dodge City or Chapman day last year, either.

Addressing the 500mb wind threshold, the median value for northern Plains significant tornadoes in the summer is about 40 knots (Grams et. al 2011), with less than 25% of significant tornado cases featuring 500mb winds below 35 knots. 

With that said, Chapman (5/25/16) was associated with 31 knots of h5 flow (00z TOP) and the northeastern Nebraska tornadoes of 6/17/14 also saw about 31 knots, based on the 00z OAX sounding.

Dodge City's 19z sounding from 5/24/16 sampled 36 knot winds at h5. Bowdle was much stronger at 500mb with 52 knots sampled by the 00z ABR sounding.

I prefer 30 knots at 500mb as a lower bound for tornado favorability, but would like to see at least 40 knots. Substantial 0-3km SRH (and/or extreme instability) can make up for otherwise marginal 500mb speeds, but I can't immediately come up with any long-track tornadoes that occurred with <30 knot winds at h5.

[bjc0303]

1 hour ago, Quincy said:

Addressing the 500mb wind threshold, the median value for northern Plains significant tornadoes in the summer is about 40 knots (Grams et. al 2011), with less than 25% of significant tornado cases featuring 500mb winds below 35 knots. 

With that said, Chapman (5/25/16) was associated with 31 knots of h5 flow (00z TOP) and the northeastern Nebraska tornadoes of 6/17/14 also saw about 31 knots, based on the 00z OAX sounding.

Dodge City's 19z sounding from 5/24/16 sampled 36 knot winds at h5. Bowdle was much stronger at 500mb with 52 knots sampled by the 00z ABR sounding.

I prefer 30 knots at 500mb as a lower bound for tornado favorability, but would like to see at least 40 knots. Substantial 0-3km SRH (and/or extreme instability) can make up for otherwise marginal 500mb speeds, but I can't immediately come up with any long-track tornadoes that occurred with <30 knot winds at h5.

Should note that shear values (specifically, low level shear (strong SRW and SRH) abs deep layer (effective bulk shear) are far more important than the 500 mb flow values. Hence why OFBs are important in late season tornado events. They don't alter the flow aloft, but alter low level flow increasing low- and deep-layer shear... while also providing a rich source of low level horizontal, streamwise vorticity owing to barpclinic zone (often leading to accelerated low level mesocyclogenesis). 

You can have 55 knot 500 westerly flow, but it won't mean much with 45 knot surface westerlies... odd example, unrealistic even, but the point remains. Shear, and SRW, dominate over the pure mid level flow. 

 

Would be interested though in examining borderline cases where low level shear is high (ESRH greater than, say, 250?) But deep layer (effective BWD) fails to meet 35 knots. 

[jojo762]

Well looking like our final legit chances in the central plains could be taking shape next week possibly into next weekend, still some timing differences between the euro/GFS, but appears there will be several opportunities for severe storms for at least the northern plains, but probably extending into the central plains on a couple days as well. EML is progged to be quite strong so that will play a big role in how things evolve, but prospects look fairly good with an unseasonably strong mid-level trough ejecting into the N/C Plains. 

After this period remains a bit uncertain ATTM... But currently leaning toward the inevitable, and dreaded, death ridge developing by ~June 20, likely ending any legit severe/tornado prospects for the central/southern plains for quite some time.