Model Outlook For Chase Team 1

[Paul Sherman]

So here we are just 7 days before departure, so every day this week I will endeavour to look at the Models and see what we might have in Store for when we arrive, Obviously in the Lower Resolution these are subject to massive change but what I have noticed in the last week is a lot of Consistency in some quite Big troughs making there presence felt across the Plains, A lot of other Chasers are excited by the Outlook for the last 5-6 days of April as well, My only worry is that the System will be too fast and eject onto the Plains on Saturday and Sunday, In fact if the Models are to be believed we could be arriving in a Risk Zone or certainly might have some active Storms close to DFW - So some Lightning opportunities could be in the Offing from Close to the Hotel.

What I have put below is a quick look from Landing day up to Chase Day 6 for 3 different parts of the Models namely Jet Stream and Upper Flow - What we need to see is Strong Flow aloft and ideally from the SW - I think you will agree this is a great Outlook - The next is Cape and LI Which again is pretty amazing - I have included Temperature although the Dewpoint/Moisture is in Abundance as well.

Landing Day through to Chase Day 7

Obviously we need Low Pressure or Negatively Tilted Troughs or Impulses, or even Dryline Set Ups but the trend is Very Good and we should hopefully start to see some sort of Definate Answers mid to end of this week.

Paul Sherman

[Aunt Sally]

Thanks Paul for doing this. Its a great way to build up to our departure in a weeks time.

It certainly looks like it could be a promising start to our chase - I wonder if we might end up landing in a middle of a storm - it could be interesting if we do! :lol:

AS

[Paul Sherman]

Hi Tammy

It is certainly something that is possible this year, never had a problem before, as the flights all land purposely before the Severe Period of 4-10pm.

On looking at this Mornings data things really do look like playing into our hands at present. One thing I was worried about was the possibility of losing 2 very good Chase days as Saturday and Sunday were looking Severe, but the latest GFS Has slowed the System down to start attacking the Plains from Monday 27th :lol: :lol: Have also just spoken with one of the guys over on Ukww who has ECMWF Data and he has also said the Pattern looks favourable for a Severe Outbreak from the 27th-30th April Timeframe, so looks like Model Agreement is coming together, at the present time it looks like it could be up and out VERY Early on the Monday Morning with a Central to Northern Plains Target, Maybe Kansas to Nebraska area.

Regards

Paul S

[dogs32]

yes thanks Paul for taking the time to put that together for us newbies..and old chasers

IM glad its put back to the Sunday or Monday.It might of caused flight delays :lol:

But looking good now for the chase

Edited April 19, 2009 by dogs32

[John Hanrahan]

I remember about 7 or 8 years ago I was over in Arlington Texas (near FW) for some work related training. My boss was stuck in and AA flight for about 2 hours circling DFW waiting for a thunderstorm to deiminish. He wasn't happy. I was delighted. He was a twatt! I think it was Sept / Otc

[Nick F]

00z ECM looks great for the 1st team from Mon 27th onwards as an amplifying deep upper trough migrates from the Pacific coast towards the Plains and the sfc low over the Rockies draws on flow from the GoM.

Though I have to say the 06z GFS looks a bit indifferent, with the upper flow tending to be flatter with upper ridging across the Sern Plains despite the sfc low iin a favourable position - posibilities from the 06z of chasing over the Nern Plains ... but a long haul north!

... but still a long way off and subject to the amplification and phasing of the troughs moving in from the west being out atm.

All in all not looking bad ... especially if it comes off like ECM - remembering this tends to the favoured medium range output for the US in terms of verification.

[Paul Sherman]

Thanks for that Nick - 12z GFS Looking better again and quite consistent with Yesterdays

Still Looking like a Northern Plains Target at the Moment - N Kansas or Nebraska into S Dakota

If that is the Case would be a 7am Wake Up with a 8am leave - Getting to OK City by 1130am and pushing onto N Kansas by 4-5pm for Initiation, Nothing like getting up and straight into the action!!

- Nice Cape Progged up to 1,500jkg

- Convective Precipitation

- Dryline Action ??

- Nice Temperature Gradient in the Northern Plains

The rest of the week still looking good and also some other Sites now talking about another possible Outbreak for the Weekend of the 1-3rd May!

Paul S

[Mikel Nimbus]

Great thread. Should get me all clued up for my chase early in June with another tour.

What is the significance of the Jet when it comes to tornadoes/Supercells? I assume you want to be directly under a strong SW'ly stream? In the middle or at the exit point?

[Nick F]

MN, ideally for the best supercell potential - you want to be in an area under the left exit of a strong jet streak (80knt+). This area of the jet is where upper winds diverge which forces air to converge at the surface below and rise to fill the void caused by the wind diverging above - and of course convergence at the sfc and strong rising motion will help create strong t-storms and potential for tornadoes if low-level shear is strong too.

Also strong winds of the jet aloft tend to 'vent' the warm moist air which rises in storms which allows a constant supply of warm moist air to rise and replace that taken away - and also separates the downdraft/preciptn. from the updraft, prolonging the storm as otherwise the downdraft would tend to suffocate the updraft if it fell down vertically and shorten the lifespan of the storm. Supercells by their very nature can last for hours due to strong winds aloft keeping updrafts and downdrafts seperate.

Paul, ECM looks too like a Nern Plains chase during the early part of your first week, looks like a ridge over Sern Plains on the Mon and Tues, with heights falling the further you go N and NW though ... with the main upper trough still over NW US.

Sfc charts would suggest moisture return getting up into the Nern Plains, via a Serly sfc flow from the GoM.

[Nick F]

Having a look at 00z GFS this morning, still looking like a Nern-central Plains chase during the fisrt week for chase team 1.

The charts below for 00z UTC or 18z their time, and show upper ridiging across the Sern Plains (shown by the dotted red lines of thickness) but lower thicknesses towards the N and NW, the sfc low over the High Plains tending to advect warm moist air well north into the central and northern Plains to allow possible storms there where heights are lower with upper troughs than futher south with upper ridging:

- 00z Mon 27th

- 00z Tues 28th

- 00z Weds 29th

[Paul Sherman]

GFS 12z thrown up and absolute Stinker! And this goes to show why you should (Even with our Winter Model Watching) Just compare run to run (Eg 00z with 00z)

So This has totally disregarded to Northern Plains Outbreak and showed everything 600-800 Miles South

Some Fantasy Charts - Will Update the 00z in the Morning and Compare those with Todays I posted this Morning!

- Cape & LI's

- Convective Precip

- Moisture all but gone - DOH!

- 10C In the Ok Panhandle :lol:

- Very Different Upper Winds

Paul S

[Nick F]

The 4-8 day outlook earlier today highlighted the model uncertainty:

http://www.spc.noaa.gov/products/exper/day4-8/

At least though GFS is showing storm potential somewhere across the Plains early next week albeit shifting the potential several hundred miles between runs! If it were this week you'd be pretty stuck to find any severe storms over the mid-west over the next 3-4 days, maybe a few elevated non-severe ones today across Ern OK and that's about it. Think next week will be better hopefully, even if it means hauling butt on Monday.

[Tom Lynch]

GFS 12z thrown up and absolute Stinker! And this goes to show why you should (Even with our Winter Model Watching) Just compare run to run (Eg 00z with 00z)

So This has totally disregarded to Northern Plains Outbreak and showed everything 600-800 Miles South :lol: :lol:

Some Fantasy Charts - Will Update the 00z in the Morning and Compare those with Todays I posted this Morning!

- Cape & LI's

- Convective Precip

- Moisture all but gone - DOH!

- 10C In the Ok Panhandle :lol:

- Very Different Upper Winds

Paul S

Keep up the good work chaps and we will just have keep an eye on the situation. It seemed originally like a trip north was on the cards. I'm good to go, where ever.

Tom

[Paul Sherman]

Going to Set One of these Threads Up For Storm Chase Tour 2 as well over the next week.

Paul S

[Paul Sherman]

Quick One on Landing Conditions Based on Tonights 18z GFS

Looking a Tad Stormy! :lol: With Possible Heavy and Thundery Showers around

- Good Cape

- Convective Possibilities

- Moisture

- Jet

- Temps 22c

Paul S

[Nick F]

00z GFS continues the theme of shifting the storm potential early next further south across the Sern Plains, The set-up is looking good, with sfc low sat over TX Panhandle drawing moisture north from GoM and with the Sern arm of the jet stream with upper troughing and shortwaves moving east further south across Sern Plains too:

-00z Mon 27th

-00z Tues 28th

-00z Weds 29th

Could be some action in TX when the team arrive?

[Paul Sherman]

12z Continues the Risk much further South for our 1st Chase Day with a Southern Texas Panhandle Chase

Landing day still looking like a very Convective Day with a Nose of 4,000jkg Cape just West of DFW, So could be some nice Lightning Opportunities for 1st Overnight Stay.

- Landing Day Cape pretty good out in W Texas

- Convective Precip Chart

- Moisture Good enough for some Dryline Action

- Upper Winds

- Temps in the 20's

CHASE DAY 1

----------------

- Nose of High Cape nearing 4,000jkg around the Big Spring Area (Fab Chase Area)

- Precip ties In!

- Loving the Jet Max

- Low 30's Temps around Initiation area

All looking good!

Paul S

[John Hanrahan]

Nice!!

[Tom Lynch]

Thanks Paul

All is looking promising for a little action within a day of touching down. Sounds good to me. I am getting all my batteries charged and ready to go. I have been ticking off all my gear on a ticksheet as I pack them into my case. I am trying to travel as light as possible.

Tom

[Paul Sherman]

Dont want to drag it off topic............but dont forget that great Weather Radio you have! LOL

Paul S

[dogs32]

one word

:yahoo: :yahoo: :yahoo: :yahoo: :yahoo: :yahoo:

and thanks for the info

[Paul Sherman]

00z GFS - One Word!

OUCH!!!!!!!!

Hopefully Nick can post the ECMWF Charts but if the 00z was to verify then Sunday could be the Lightning day when we land and then the Cold Front wipes everything out, completely scouring the GOM Until at least the next weekend!

Absolute Horror Show from the GFS!

Paul S

**dogs I see you lurking - Go get some Prozac **

[dogs32]

I see what you mean just checked the charts...

Seems next Sunday looks better...

I hope these are not accurate and they change from what they are at present

I think I need Prozac now

Edited April 22, 2009 by dogs32

[Nick F]

00z ECM still not looking too bad, you keep the sfc low over the High Plains/Front Range with moisture return continuing - the main long-wave upper trough kept back over NW USA though even by the middle of next week, but should be enough height falls towards the High Plains IMO for some storm activity ... though hard to tell with the limited selection of public charts from ECM.

- 00z Tues 28th

- 00z Weds 29th

- 00z Thurs 30th

Still a reasonable set-up by 00z Fri 1st:

... so keep that prozac in the draw for now, GFS maybe too hasty clearing the cold front through with the high building in behind across the Plains.

[Stuart]

one word

and thanks for the info

calm down a bit :lol:

Edited April 22, 2009 by Stuart