Major Pattern Change Coming Up ??

[Eric Bucsela]

We have not seen a classic, deep, energetic trough dig into the Four Corners area since last fall, and it seems that the pattern has bent over backwards to ensure this doesn't happen (e.g., the early April event I mentioned)

You guys have a point. One of the things I look for before buying my plane ticket is persistence: have recent similar patterns produced good storms in the Plains? In this case I guess it's a "no". But there's always a first time, and I've been burned both ways. Apart from a few caveats, I still think this setup looks promising. Will be interesting to see how it plays out.

 

[Kelly Sugden]

Ugh, this happens every year. Do not use the GFS for long range forecasting. It does not verify. This event next week was shown from the ECMWF since day one while the GFS showed NW flow aloft. Now the GFS is catching up to the ECMWF (as usual). If you are going to make blanket statements about the end of warm season convection, then base your dire prediction off the EC and not GFS and at least have a little more scientific credibility under your belt.

 

[Ryan Pfeifer]

Ugh, this happens every year. Do not use the GFS for long range forecasting. It does not verify. This event next week was shown from the ECMWF since day one while the GFS showed NW flow aloft. Now the GFS is catching up to the ECMWF (as usual). If you are going to make blanket statements about the end of warm season convection, then base your dire prediction off the EC and not GFS and at least have a little more scientific credibility under your belt.

I think there's a published study to back this up. I always wonder why anyone would pick GFS over ECMWF for a long range forecast w/out a good reason.

 

[Logan Karsten]

Kelly,

I guess I should have mentioned that I did look at both the ECMWF and GFS. The EC are in pretty fair agreement regarding next week now. I should also mention that I see potential opportunities next week, but I don't see any large outbreaks. The biggest problem next week is forcing weakens somewhat before it ejects out into the plains. For example, on Monday and Tuesday there is rich moisture across a large chunk of the plains, but flow at 500 mb is very very weak. The only areas where forcing seems to be decent enough for tornadoes is out west in Colorado and Western Kansas. As of right now, the only real good prospect over a large area is for Wednesday, per the 12Z model runs. After that, both models are in very good agreement beyond next week's trough, which is showing an enormous omega block setting up over the conus. The image I displayed on the previous page from the GFS is pretty much the same thing you will find in the EC if you look out that far. Hence, my pessimism.

 

[Zack Hargrove]

I would rather see a rather isolated event with a few photogenic tornadoes/supercells and not as much chaser convergence in the plains as compared to a major outbreak where you can't even get to a storm because there is so much traffic any day. That being said, from what I see, the Wed/Thurs time frame is looking to me like it could be a pretty substantial event and possible outbreak.

 

[Drew.Gardonia]

Such Pessimism... If you are waiting on a perfect setup, well, have fun with that. Calling this setup "crap" at this point is just crap. Next week looks very good for the SPs. Sun-Mon probably not. Tues-Wed I'll put my money on. If all holds true there will be great shear, moisture return, DL in western OK. Can't beat that! If the data I see today was for the morning of the "crap" day I would chase that "crap". I am excited about this!!!

amen, the Debbie Downer nonsense gets old. Makes me wonder why some of these people are even on here to begin with. A bad day of chasing, is a million times better than a good day at the office.

 

[Steve Smithson]

This is fast becoming the "doom and gloom season over thread" after 1st week of May, are we actually talking death ridge multi week shut downs from Mid May onwards?

I sure hope there are chasable days from May 22nd to June 4th!!!

I'm aware the traditional chase areas are pretty dry right now but I've heard a few rumblings that late May onwards will see more chases in the Northern Plains and East in poorer chase territory is this still the case?

For the record we've had a blocking pattern here in the UK for the last month keeping Westerly fronts at bay... the weekend should see the High shift further East allowing a more Southerly flow and allowing possible storms in the East Friday and Saturday night!

Steve Smithson.

 

[Steve Smithson]

A bad day of chasing, is a million times better than a good day at the office.

Second that!!! Friends you haven't seen in a year or more, dining out in a group and having a beer and a good time ...nothing compares!

Steve Smithson

 

[Greg McLaughlin]

I wouldn't call 35-50kt 500mb winds "very very weak". In fact, that is more than sufficient in May. May 24, 2008, June 12, 2004, May 12, 2004, May 5th and 7th, 2002 (just to name a few) all featured spectacular tornado events with 500mb flow at 45kts or less. All indications point to 3-4 days of quality southern/central Plains chasing, and it looks like those who are on their chasecations may have a chance to strike gold. Most of my best tornado days have come in May and June with "marginal" mid-level flow. Any experienced chaser who knows how to forecast is looking at early next week as holding huge potential.

 

[Chris Wilburn]

I wouldn't call 35-50kt 500mb winds "very very weak". In fact, that is more than sufficient in May. May 24, 2008, June 12, 2004, May 12, 2004, May 5th and 7th, 2002 (just to name a few) all featured spectacular tornado events with 500mb flow at 45kts or less. All indications point to 3-4 days of quality southern/central Plains chasing, and it looks like those who are on their chasecations may have a chance to strike gold. Most of my best tornado days have come in May and June with "marginal" mid-level flow. Any experienced chaser who knows how to forecast is looking at early next week as holding huge potential.

I agree that somewhat weaker than normal 500 mb is sufficient and has yielded some very nice days. June 12, 2005 is another example of what some may perceive as weaker 500 mb flow. Sun-Wed hold some very good potential with each day looking better than the previous. Moisture and instability will be quite high and no problem at all. Backed surface flow will also be present with drylines each day more than likely running from central to western KS into western OK into NW Texas. 35-45 kts of 500mb flow will also yield very classic and chaseable supercells. It will be nice to actually get out of the car and capture video on tripod without worrying about storm speeds and poor terrain/road network. I agree forcing may be an issue, but I have chased days with less than ideal 500mb flow that have turned out very nicely. I guess we will just wait and see. Capping looks like it may be an issue esp. Sun and Mon, but many times I have seen capping an issue 4-5 days out only to not be an issue as days get closer. 700mb temps. look to be in the 10-12C range each day.

 

[Kelly Sugden]

Kelly,

I guess I should have mentioned that I did look at both the ECMWF and GFS. The EC are in pretty fair agreement regarding next week now. I should also mention that I see potential opportunities next week, but I don't see any large outbreaks. The biggest problem next week is forcing weakens somewhat before it ejects out into the plains. For example, on Monday and Tuesday there is rich moisture across a large chunk of the plains, but flow at 500 mb is very very weak. The only areas where forcing seems to be decent enough for tornadoes is out west in Colorado and Western Kansas. As of right now, the only real good prospect over a large area is for Wednesday, per the 12Z model runs. After that, both models are in very good agreement beyond next week's trough, which is showing an enormous omega block setting up over the conus. The image I displayed on the previous page from the GFS is pretty much the same thing you will find in the EC if you look out that far. Hence, my pessimism.

Ken I see your point but this issue always comes up every spring that when the models don't show a classic textbook synoptic outbreak then people get frustrated and threw in the towel. You don't need textbook style synoptic flow to still have a good event. In fact, a coworker at the NWS DDC office conducted a study for large hail across southwest Kansas using reanalysis data which showed a minor trough amplification out west. The Campo tornado is another day that comes to mind that was not under the traditional "outbreak" setup. My main point is take NWP with a huge grain of salt. The GFS is a horrible model and the EC is vastly superior. It's still very early in the season and way too early to get pessimistic. Western Kansas is in a D2/D3 drought, however, that could quickly changed.

 

[Brett Roberts]

I wouldn't call 35-50kt 500mb winds "very very weak". In fact, that is more than sufficient in May. May 24, 2008, June 12, 2004, May 12, 2004, May 5th and 7th, 2002 (just to name a few) all featured spectacular tornado events with 500mb flow at 45kts or less. All indications point to 3-4 days of quality southern/central Plains chasing, and it looks like those who are on their chasecations may have a chance to strike gold. Most of my best tornado days have come in May and June with "marginal" mid-level flow. Any experienced chaser who knows how to forecast is looking at early next week as holding huge potential.

I completely agree that 35-50 kt flow at H5 is not something to get upset about, especially in May or June. I think the bigger issue some of us have with the trough *potentially* hanging back to the west for several days is capping. This concern is amplified by what have seemed like excessively-hot EML's so far this year, probably owing in part to the severe drought conditions over NM, W TX, and N Mexico. This is a new system, though, and anything is possible. If a) surface-based convection is able to initiate and sustain itself along the dryline or warm front any day from Mon-Wed, and b) low-level moisture does not mix out excessively as it's tended to several times this year so far (aside from the pooled area along warm fronts), I'm sure plenty of good chasing will be had.

 

[Drew.Gardonia]

Second that!!! Friends you haven't seen in a year or more, dining out in a group and having a beer and a good time ...nothing compares!

Steve Smithson

im sure glad someone has some spirit on here!!!! need more guys like you and me on here! the rest can go sit around the town cafe and continue to gripe and moan like a bunch of old women past their prime.

 

[Joerg Kudella]

todays 06z GFS is trending more to the ECMFW solution, which makes me very happy....new runs look more and more like the "omega block pattern" is everything but certain. Chasecation starts Friday, May 13th, hopefully it turns out to be a good start.

 

[Logan Karsten]

I just now looked at the 00Z ECMWF, and it is a relief to see that the major omega block may not be as prevalent as I feared.