Central/Western Medium-Long Range Discussion

[jojo762]

6 hours ago, WhiteoutWX said:

The GFS is a dirty liar. 

I don’t know what it is, but there’s been a lot of late-range teaser GFS hours lately. Sigh. CFS as well...

For whatever reason, doesn’t seem to be able to hone in on any actual trend toward more activity; there’s a constant wind shield wiper from run to run with regard to the long-range, not that that is necessarily unusual.

[WhiteoutWX]

23 minutes ago, jojo762 said:

I don’t know what it is, but there’s been a lot of late-range teaser GFS hours lately. Sigh. CFS as well...

For whatever reason, doesn’t seem to be able to hone in on any actual trend toward more activity; there’s a constant wind shield wiper from run to run with regard to the long-range, not that that is necessarily unusual.

Eventually climo will win out as we get into May. But for now it seems any sign of a pattern change is far enough in the extended I’m just in wait and see mode.

[WhiteoutWX]

Put this in the wrong thread earlier:

Deterministic and ensemble guidance are all in relative agreement in this pattern persisting in the mid to extended range, with a trough over the east and ridge over the west. Even occasional hints of transient high-latitude ridging over the NAO domain which suggests this pattern may be slow to budge. I think it's pretty safe to say April is probably toast at this point for anyone outside the Gulf Coast states as far as tornadoes are concerned. May is still 10+ days away so we'll see how things evolve, but no real sign of a change to a more favorable plains tornado pattern for the foreseeable future.

That being said... looking in closer range. Tomorrow evening offers some localized tornado risk for portions of the TX Panhandle into western and southern Oklahoma as the warm front lifts northward. If sufficient moisture can return for surface based convection, deep and low level shear is favorable along this corridor for at least a tornado or two. 

 

[Sydney Claridge]

I guess there could be some northwest flow events in the Southern Plains even if we wind up with that pattern, provided there is enough moisture available to fuel severe thunderstorms.  There was northwest flow severe earlier this month in the Midwest and Great Lakes states, even though northwest flow is not normally favorable for severe thunderstorms there until the summer.

Northwest flow is not the most ideal for tornado activity, but it might at least be something. You would think that with cooler-than-normal water temperatures off the U.S. and Mexican Pacific coasts and warmer-than-normal temperatures in the Gulf of Mexico that we would be more prone to western troughing and eastern ridging.

[It's Always Sunny]

6 hours ago, WhiteoutWX said:

Put this in the wrong thread earlier:

Deterministic and ensemble guidance are all in relative agreement in this pattern persisting in the mid to extended range, with a trough over the east and ridge over the west. Even occasional hints of transient high-latitude ridging over the NAO domain which suggests this pattern may be slow to budge. I think it's pretty safe to say April is probably toast at this point for anyone outside the Gulf Coast states as far as tornadoes are concerned. May is still 10+ days away so we'll see how things evolve, but no real sign of a change to a more favorable plains tornado pattern for the foreseeable future.

That being said... looking in closer range. Tomorrow evening offers some localized tornado risk for portions of the TX Panhandle into western and southern Oklahoma as the warm front lifts northward. If sufficient moisture can return for surface based convection, deep and low level shear is favorable along this corridor for at least a tornado or two. 

 

Yeah I started noticing that possibly happening last week and today I was looking at the subtropical jet and it loses it's steam next week which further dampens any severe risk, at least here in the Plains however with some troughing remaining over the Southeast there still remains a possibility they get a day or two of severe potential, even with a "weakened" subtropical jet. This "lull" has the potential to spill into the first week of May based on what I was looking at but too far out for me to put much stock in it at this time.

[jojo762]

Operational models really did a 180 overnight on the large western CONUS ridge in the mid to long-term... Might be able to anticipate several chaseable/watchable plains severe days in 7 to 10 days.

[Snowstorm920]

CPC highlighting the southern plains for severe weather the first week of May 

 

[beavis1729]

Looks hot in Las Vegas early next week. It could be the first time in recorded history to hit 100 in April. 

[WhiteoutWX]

On 4/24/2020 at 9:54 PM, Snowstorm920 said:

CPC highlighting the southern plains for severe weather the first week of May 

 

I’m taking the under on that forecast 

 

[jojo762]

FWIW, there seems to be quite a bit of volatility in the 200+ hr range recently... Shifting from ridge fest to trough fest back to ridge fest.

[Chinook]

I downloaded Nexrad level-2 data to make this 3-d image of the Moore tornado, 5/20/2013

 

[jojo762]

So maybe some severe activity with an isolated tornado threat somewhere in the plains this weekend into early next week. Might get a day with some more concentrated tornado potential (looking at you Monday), but veered LLVL winds and capping could be an issue. LLVL winds being weak or veered and 700/850mb temps being quite warm will be an issue every one of the days more likely than not. Beyond that it’s looking like a large ridge, or at least higher-than-normal 500mb heights will setup across most of the western CONUS and into the plains — some uncertainty as to how this ends up exactly, but probably looking at a lull with some beautiful/warmer weather in the mid to extended period. 

[WhiteoutWX]

I don’t want to keep posting the same thing over and over and be super pessimistic but I’m really struggling to find anything encouraging in the long range that suggests a pattern change. The western ridge/eastern trough just keeps reloading again and again. As we go deeper into May you don’t need perfect setups to achieve severe events but still, the long wave pattern is leaving little room for even smaller events.

[jojo762]

Monday is looking like a classic boom or bust triple point day... should be noted that there is a pretty wide disparity between the  ECMWF/UKMET/CMC and the GFS/NAM though... GFS and NAM show what would be a pretty upper-crust supercell environment (with some caveats/possible weak points).

[Sydney Claridge]

This pattern would have been good for winter in the Northeast, too bad it came too late.  At the same time however, western ridging in the winter would have meant reduced mountain snowpacks and worse drought.  A return of the Pacific "blob" would be good for big-time Northeastern snowstorms but very bad for western water supplies, especially outside of the coastal Pacific Northwest where the warmer water can serve to increase the amount of moisture available to a storm system.

Eastern troughing and western ridging has killed severe weather seasons in many recent years.  If I recall correctly, 2013 had somewhat of a late start to the Plains severe weather season, but once it got going in May, we had some very powerful tornadoes in Oklahoma, including the most recent EF5 on record (Moore, OK), not to mention the El Reno tornado (that would also have been an EF5 if it had it hit structures).  There have been strong and violent tornadoes in Dixie Alley so far, and a persistence of the eastern troughing pattern would lead me to believe that areas on the southern and eastern flanks of the trough, namely Dixie and the Carolinas, would remain prone to potential tornado events through May, especially with warmer-than-average Gulf of Mexico water temperatures.  Perhaps with some northward shifts into the Ohio Valley and southern Great Lakes region as warmer air gains a foothold in that region.

The Plains might very well be stuck with northwest flow in this pattern.  Provided sufficient moisture, severe thunderstorms (and possible derechos) on the rim of the building western heat are a possibility, particularly if this western ridging/eastern troughing pattern continues into summer.  I would also watch to see if the High Plains EML gets advected further east into any regions favorable for severe weather that are on the southern and eastern rim of the troughing.  Western ridging that affects the Rocky Mountains and High Plains could be favorable for making a stronger EML, but this might also kill severe weather events as well, if the cap is too strong.

[andyhb]

On 4/20/2020 at 12:57 PM, WhiteoutWX said:

Put this in the wrong thread earlier:

Deterministic and ensemble guidance are all in relative agreement in this pattern persisting in the mid to extended range, with a trough over the east and ridge over the west. Even occasional hints of transient high-latitude ridging over the NAO domain which suggests this pattern may be slow to budge. I think it's pretty safe to say April is probably toast at this point for anyone outside the Gulf Coast states as far as tornadoes are concerned. May is still 10+ days away so we'll see how things evolve, but no real sign of a change to a more favorable plains tornado pattern for the foreseeable future.

On 5/1/2020 at 8:39 AM, WhiteoutWX said:

I don’t want to keep posting the same thing over and over and be super pessimistic but I’m really struggling to find anything encouraging in the long range that suggests a pattern change. The western ridge/eastern trough just keeps reloading again and again. As we go deeper into May you don’t need perfect setups to achieve severe events but still, the long wave pattern is leaving little room for even smaller events.

Not that the upcoming pattern for the next week or so will be great for severe prospects, but this is indeed getting a bit repetitive.

Two days after you posted the bolded, there was a localized tornado outbreak along I-35 in S OK that was probably the best April chase day in a portion of the Plains in awhile (along with more tornadoes on 4/24 in SE OK/NE TX).

[WhiteoutWX]

35 minutes ago, andyhb said:

Not that the upcoming pattern for the next week or so will be great for severe prospects, but this is indeed getting a bit repetitive.

Two days after you posted the bolded, there was a localized tornado outbreak along I-35 in S OK that was probably the best April chase day in a portion of the Plains in awhile (along with more tornadoes on 4/24 in SE OK/NE TX).

Two sentences before the bolded it clearly says medium to long range which is what I was referring to. Regardless, I hardly think that one localized event which was focused east of I-35 and outside of decent chase terrain disqualified the broader point I was making that the overall pattern has been and looks to remain for the foreseeable future extremely poor for the plains states as far as a tornado/chase standpoint. So I’m not really sure what your point is here but I stand by what I said.

When and if the pattern changes and starts to look better I’ll be right there with everyone else getting excited but until that happens I’m just telling it like it is, the fact being it’s been a very slow season for anywhere outside the gulf coast states.

[Quincy]

After tomorrow, the following seven days look very quiet and generally unfavorable for severe weather across the central states. NW flow can’t get it done this early in the season, as moisture return is usually anemic north of I-40. 

With that said, it is common for a lull in activity that in early May. We just had the most active April since 2011, so it was bound to quiet down eventually. It’s rare to have an extended period of consistently active severe weather during the first half of spring. 

Interestingly enough, 2011 has followed a similar tornado curve to this year. Recall that in 2011, after late April, the pattern basically shut down for two weeks. It wasn’t until mid to late May (roughly four relatively quiet weeks) that the pattern became active again. 

[Snowstorm920]

18 minutes ago, Quincy said:

After tomorrow, the following seven days look very quiet and generally unfavorable for severe weather across the central states. NW flow can’t get it done this early in the season, as moisture return is usually anemic north of I-40. 

With that said, it is common for a lull in activity that in early May. We just had the most active April since 2011, so it was bound to quiet down eventually. It’s rare to have an extended period of consistently active severe weather during the first half of spring. 

Interestingly enough, 2011 has followed a similar tornado curve to this year. Recall that in 2011, after late April, the pattern basically shut down for two weeks. It wasn’t until mid to late May (roughly four relatively quiet weeks) that the pattern became active again. 

First half of May 2011 was very quiet, then Joplin happened. All it takes is one 

[Calderon]

On 5/3/2020 at 11:11 AM, Snowstorm920 said:

First half of May 2011 was very quiet, then Joplin happened. All it takes is one 

And then Oklahoma 3 days later with another EF-5 and two upper-end EF4s.

[Chinook]

The SPC has put out a day-3 slight risk for the Red River area. The forecast soundings have around 75 kt of 0-6km shear, if any (high-based) storms develop there.

The College of Dupage GEFS page shows higher supercell indices on Wednesday 5/13 and Thursday 5/14, as well as several days beyond that. I don't know how many people usually look at the GEFS for this, but it might be interesting.

[WhiteoutWX]

Ensembles definitely showing a relaxation of eastern US troughing towards and beyond day 10. Light at the end of the tunnel perhaps.

 

[Snowstorm920]

Wonder if this one will work out better than the last one of these I posted 

 

[WhiteoutWX]

2 hours ago, Snowstorm920 said:

Wonder if this one will work out better than the last one of these I posted 

 

I guess technically there was severe weather in portions of the previous outlined area. I just question the utility of the CPC putting out such a graphic when the area is huge and the time period is a week long. I mean yeah there’s likely gonna be some severe weather somewhere in the plains any given week in May. That’s just climo. A more useful forecast would be above or below normal chances for it IMO.

 

[jojo762]

6 hours ago, WhiteoutWX said:

I guess technically there was severe weather in portions of the previous outlined area. I just question the utility of the CPC putting out such a graphic when the area is huge and the time period is a week long. I mean yeah there’s likely gonna be some severe weather somewhere in the plains any given week in May. That’s just climo. A more useful forecast would be above or below normal chances for it IMO.

 

And if this were the case... I would say that that time frame would end up being equal chances for both... maybe slightly below normal chances? Not sure yet, because it’s so far out that it is almost pointless to try to predict severe weather given the various  intricacies of a severe weather forecast. Bleak forecast for storms, or even just tranquil weather the next week. 

[jojo762]

 Not a whole lot of model agreement or high predictability, but mid/late next week was pretty interesting on the 12z Euro, especially Thursday. Obviously slightly veered SFC winds aren’t exactly preferred in the plains, but it’s a start.

P.S. Highly recommend getting Pivotal Weather Premium, at least for severe season; it’s not that expensive, and being able to get high quality ECMWF soundings is fantastic.

[jojo762]

00z GFS jumped on the bandwagon for next week as well... depicts two severe days across the plains on Wednesday and Thursday. With Wednesday possibly featuring higher-end tornado potential... stay tuned!

[Snowstorm920]

9 hours ago, jojo762 said:

00z GFS jumped on the bandwagon for next week as well... depicts two severe days across the plains on Wednesday and Thursday. With Wednesday possibly featuring higher-end tornado potential... stay tuned!

Soundings on Wednesday look nasty across portions of Kansas and Oklahoma. Going to be a day to watch for sure 

[WhirlingWx]

16 minutes ago, Snowstorm920 said:

Soundings on Wednesday look nasty across portions of Kansas and Oklahoma. Going to be a day to watch for sure 

Could end Kansas' tornado drought this year if we do get some action there

[Radtechwxman]

Seems like after the middle of next week most models push the ridge to the Midwest and it is still pretty stout. I do like the big trough digging into the west and the ridge to the east causes very slow movement of that trough and likely multiple days of severe potential. What I don't like and something that could change is how the upper level winds really back as they get squashed against the ridge. Would prefer to see the ridge a little more east and a bit less amplified