Model Watch For Tour 1

[chionomaniac]

Paul, what is the ideal jet pattern? Does it involve a jet streak with amplification - the more meridional the better? Cheers Ed

[Paul Sherman]

Hi Ed

Ideally we would want the Jet to be looping in the classic U-Bend Shape with the 70-90kt Jet Streak Maximum passing through the Plains in conjunction with a Tilted Trough ejecting across the rockies, So Jet coming down the California Coast then across Arizona and New Mexico, On these occasions there is usually a Warm Front draped from the Low from W-E and a Trailing Dryline (Triple Point) Any more than 90-100kt and Storm Speeds tend to be silly at over 50-60mph.

What usually happens in this scenario is Mist and Low Cloud are present along the Warm Front (Even Fog Sometimes) and Strong heating from the South mixes Northwards, Storms will fire North East of the LP And move North Eastwards, once they approach the Warm Front they usually go Tornadic, and when a Supercells turns right and rides underneath the Warm Front it can become a Cyclic Tornadic Storm. At the same time where the Gradient between the Super Dry Air and the warm sector meet the Dryline fire's up from North to South, with the Jet coming from across New Mexico, S California and Arizona this dry air sculpts the most amazing Dryline Storms.

Those Set-Ups are the most fabled with Storm Chasers, NOT The Cold Fronts as these are always HP Monsters.

Cheers

Paul S

[chionomaniac]

Hi Ed

Ideally we would want the Jet to be looping in the classic U-Bend Shape with the 70-90kt Jet Streak Maximum passing through the Plains in conjunction with a Tilted Trough ejecting across the rockies, So Jet coming down the California Coast then across Arizona and New Mexico, On these occasions there is usually a Warm Front draped from the Low from W-E and a Trailing Dryline (Triple Point) Any more than 90-100kt and Storm Speeds tend to be silly at over 50-60mph.

What usually happens in this scenario is Mist and Low Cloud are present along the Warm Front (Even Fog Sometimes) and Strong heating from the South mixes Northwards, Storms will fire North East of the LP And move North Eastwards, once they approach the Warm Front they usually go Tornadic, and when a Supercells turns right and rides underneath the Warm Front it can become a Cyclic Tornadic Storm. At the same time where the Gradient between the Super Dry Air and the warm sector meet the Dryline fire's up from North to South, with the Jet coming from across New Mexico, S California and Arizona this dry air sculpts the most amazing Dryline Storms.

Those Set-Ups are the most fabled with Storm Chasers, NOT The Cold Fronts as these are always HP Monsters.

Cheers

Paul S

Thanks I am trying to learn quick. Will you be doing a Model watch for tour 2 or be leaving it for someone on this side of the Atlantic?

[Paul Sherman]

It all depends on how active Tour 1 is really, at the moment the signs are quite active but will try as and when time allows. I am sure there is a Perfect Man for the Job and I hope Nathan will take the reigns on this seeing as his trip co-incides with the most part of Tour 2 ?

[Nick F]

I think the broadscale signs are still pretty encouraging for the first tour, having looked at the medium/long range projections for the last few days for late April/early May. There seems to be a continuation of a strong upper westerly flow across the USA with enough upstream amplification over the Rockies to allow gulf mositure to return across the Mid-west at times.

A look at this morning's ECM and GFS 00z 8-10 day H500 comparisons (27th-29th April) shows troughing from both ECM and GFS across the mid-west and a ridge over eastern US, the trough maybe a little to far east with any severe weather perhaps over and east of the Mississippi Valley, but we may see the trough ejected a little too progressively - especially from GFS.

T+240 ECM H500/T850 chart does show the trough too far east for Friday 29th April, with no warmth/moisture return in the right places, but this is too far off to take seriously:

Overall signs are to me looking like a fairly active first tour atm, with no break in the rather mobile and strong flow across the US into early May.

[multi cellular thunderstorm]

Can't believe only 10 days to go! Time has gone so quick.

Just wondering if at this stage we can rule out a death ridge or not yet? Also is that the same as an omega block? Still got a lot to learn!

[Dorsetbred]

Just wondering if at this stage we can rule out a death ridge or not yet? Also is that the same as an omega block? Still got a lot to learn!

Nah never rule out a death ridge

[TEITS]

Accu weather are expecting the wild weather in the US to continue into May.

http://www.accuweather.com/blogs/news/story/48539/wild-april-to-be-followed-by-w.asp

Just add this is a fasinating thread because in my opinion the GFS doesn't recieve enough credit for its long range predictions. I can think of many examples of where the GFS has generally been spot on as far out as +384. Obviously detail will always be elusive at this range but it can still be a valuable forecasting tool.

[duckeyh]

Thanks I am trying to learn quick. Will you be doing a Model watch for tour 2 or be leaving it for someone on this side of the Atlantic?

What 's the significance of the U Bend in the Jet Stream ? I guess it's good for bad weather as I seem to recall we a had a similar formation over the UK when we had the snow

[Paul Sherman]

Nah never rule out a death ridge

Seem's GFS May have been listening closely to the negative vibes Mr H!

An absolute Horror Show from this morning's 00z Run. Can't really find any charts to post up that will lighten the mood It's a good job I have a limit on Smilies :lol:

- Who Dried up the Jet ??

- Coats and Scarves Everyone ??

Really cant find any charts that look remotely attachable........But there is still time for this to shift back...........Hopefully

[Dorsetbred]

See, yee of little faith, the season's first death ridge for almost a week in duration.

Now don't blame me, it was MCT that said it, and I quote

Just wondering if at this stage we can rule out a death ridge or not yet?

I applied my realistic outlook to his comment and said

Nah never rule out a death ridge

And GFS replied with what looks incredibly like a death ridge.

Footie anyone?

[multi cellular thunderstorm]

Oh no :ph34r:

Shouldn't have said the words!

Hope it switches back again quickly!

[Paul Sherman]

I have got to say it is indeed looking bleak. I was dreading a pattern shift and I hope it is not something new GFS Has picked up on as I believe it is the best medium to long range model at picking up trends, if the next few days shows similar it will indeed be footie and touring, no steaks as you only get those when you score a Tornado

The active troughing pattern has been across the States since about March 10th and looks to run right upto the 27th April just in time for us landing on the 28th when it looks like going into a "Ridge" Pattern from this mornings Model runs.

Outlook for the next 7 days is pretty amazing with a Slight today, another tomorrow and again a very good chance of Tornadoes across Missouri and Illinois on Friday. Then we have what looks like a possible Outbreak for the Texas Panhandle, then Oklahoma and then the Mississippi Valley for Mon/Tue/Wed next week 25/26/27th.

Could not have planned that better eh ?

[Dorsetbred]

I have got to say it is indeed looking bleak. I was dreading a pattern shift and I hope it is not something new GFS Has picked up on as I believe it is the best medium to long range model at picking up trends, if the next few days shows similar it will indeed be footie and touring, no steaks as you only get those when you score a Tornado

The active troughing pattern has been across the States since about March 10th and looks to run right upto the 27th April just in time for us landing on the 28th when it looks like going into a "Ridge" Pattern from this mornings Model runs.

Outlook for the next 7 days is pretty amazing with a Slight today, another tomorrow and again a very good chance of Tornadoes across Missouri and Illinois on Friday. Then we have what looks like a possible Outbreak for the Texas Panhandle, then Oklahoma and then the Mississippi Valley for Mon/Tue/Wed next week 25/26/27th.

Could not have planned that better eh ?

Just read my travel insurance small print.

It doesn't cover for the lack of tornado's, boo hoo

[Arron]

boooo *sends weather pattern shifting vibes over the pond

[Paul Sherman]

boooo *sends weather pattern shifting vibes over the pond

Yeah

I am going to step back from the forum for a few days and not look at any Models as it does my head in every year.

Probably come back for the possible Moderate Risk on the chase Streams on Friday Night.

[Paul Sherman]

Just a quick heads up

Paul M is going to integrate the ECMWF Upto T240 To sit alongside the US GFS Charts for people wanting to see what other Models are showing, this might help as GFS Needs to come with an 18 Certificate at the moment :lol:

[dogs32]

i hope it changes for u guys..Still its a long way off..so nothing over until the fat lady sings

[Gorky]

For what it's worth, the 18z isn't so bad. It has chase opportunities in the Dallas area on the 30th and rather than a death ridge, the ridge is just transient before the next reload with possible upslope plays on the 3rd in the TX panhandle or NM. I'd only get worried once you are in the 4-5 day period myself as the models are still changing somewhat each run. Nothing on the 18z look special but there would be plenty of opportunities towards the later parts of the forecast foe chasing still... who knows what lies past T384 too.. could be an outbreak of epic proportions at T420 we can't see

[Dorsetbred]

In addition to our superb info, whist cruisin, I came across this site

http://weather.cod.edu/forecast/index.php

Seems to hang a lot of model info together for short term analysis.

Even this morning we are in a change status as the 00Z runs today are different to that described by Gorky, with nothing showing on the 30th.

[Gorky]

This morning still has an event on the 3rd though, but rather than upslope NM, it's showing a decent threat from the Dakota's possibly as far south as Kansas Whilst it still flips every update for now (it's T312 for the 3rd!), at least it's a few runs that show the ridging is not going to be the permanent deathridgy type to contradict some of the earlier models

[gpspete]

remember last year the models were not so good then what happened a big improvement as the big days happened so everything crossed it will be alright on the day

including on the 10th May Oklahomas 2nd largest Tornado outbrake if i remember correctly things were not looking too good stormwise even 5 days possibly even 4 before

Edited April 21, 2011 by gpspete

[Dorsetbred]

This morning still has an event on the 3rd though, but rather than upslope NM, it's showing a decent threat from the Dakota's possibly as far south as Kansas Whilst it still flips every update for now (it's T312 for the 3rd!), at least it's a few runs that show the ridging is not going to be the permanent deathridgy type to contradict some of the earlier models

Yep the 3rd does look much better and the 5th looks nice in Nebraska, and as GPS Pete says, it's still up for grabs yet, but we are entering the zone of fine toonin now with 7 days to go before people fly out

Edited April 21, 2011 by Dorsetbred

[Gorky]

I remember last year speaking with Pat about the outlook when I landed (may 7th) and the models were not that great. They showed a lower end risk for the 10th over AR, MO and eastern OK with turbo storm speeds which would not have been chaseable at all. Things changed big time and we ended up with tornadic supercells and wedges West of I35 that day (although storm speed was still an issue!) The same happened with the High risk on May 19th and previous days awesome moderate risk. They both only ramped up on the models in a couple of days prior to the event. You then have the slight risks which overperform. Bowdle was a slight risk day with a good chance of a cap bust and followed up from a very similar setup but underwhelming event the day before. May 26th and the campo day were both 2% tor days which spawned amazing storms which the netweather guys were on and nobody saw those coming. That's the reason I'd never get too dejected about the models. Even without great upper support, there's chances for isolated severe to go tornadic and the models are far from perfect, so you'll often get the odd surprise creep in, even into the 3-4 day outlooks. It's all part of the fun of chasing

[Dorsetbred]

I remember last year speaking with Pat about the outlook when I landed (may 7th) and the models were not that great. They showed a lower end risk for the 10th over AR, MO and eastern OK with turbo storm speeds which would not have been chaseable at all. Things changed big time and we ended up with tornadic supercells and wedges West of I35 that day (although storm speed was still an issue!) The same happened with the High risk on May 19th and previous days awesome moderate risk. They both only ramped up on the models in a couple of days prior to the event. You then have the slight risks which overperform. Bowdle was a slight risk day with a good chance of a cap bust and followed up from a very similar setup but underwhelming event the day before. May 26th and the campo day were both 2% tor days which spawned amazing storms which the netweather guys were on and nobody saw those coming. That's the reason I'd never get too dejected about the models. Even without great upper support, there's chances for isolated severe to go tornadic and the models are far from perfect, so you'll often get the odd surprise creep in, even into the 3-4 day outlooks. It's all part of the fun of chasing

Still so much to play for