4/25/09 FCST: NE/KS/OK/TX

[Brian Stertz]

I am still kind of torn on the Sat. set up...at least for any "good light chasing". Guess will continue to monitor the runs and hope for something to stand out to get me heading out west. The next day....now that looks juicy for the classic dryline event.

 

[Jeff Piotrowski]

Saturday NW OK

I like far NW OK & NE TX PHNDL area for late Saturday.

The Nam 72 HR sounding for GAGE OKLA looks great!
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=gag

A few significant tornados are possible along WF/DL. LI-10 Cape +3000 EHI +5

The med range models keep the WF & DL very active over the Southern plains the next 14 days.

Let’s all get ready to go film some beautiful storms & tornados.

 

[Alex Lamers]

Boy has the latest NAM shifted. The Perryton, TX area up near Buffalo, OK has about 3500 j/kg of SBCAPE on the latest model projection. Effective SRH values on the order of 200-300 m2/s2. Sig Tor Parameter of 3-4. Supercell Composite Parameter up over 20.

Overall the general setup in the "sweet spot" seems like it should stay relatively similar up until the event. However I'd expect the models to continue waffling on the exact position of the "sweet spot".

Revised target to Buffalo, OK, which stinks because that makes it close to a 4 hour drive, so it had better continue looking like a "can't miss event" or I might want to sit it out.

AJL

 

[Eric Bucsela]

Revised target to Buffalo, OK, which stinks because that makes it close to a 4 hour drive, so it had better continue looking like a "can't miss event"

Four hours - I really feel for you guys!

I'm sitting in San Francisco trying to decide whether to pull the trigger on a 2-7 day chase. The setup has potential. I really like the ample moisture under the persistent SW flow for most of the week.

 

[Mikey Gribble]

I just posted an updated forecast on my blog. I kept it pretty brief and not a whole lot has changed if you read my previous forecast (which is much better btw), but I figured I'd still link it. I also updated the tornado threat map I have on there, but it's almost exactly the same too. I'll post a real forecast in the morning when the 12Z data comes out. here's the link http://loadedgunchasing.com/blog1/
gotta hit the sack

 

[Connor McCrorey]

Well the 06Z NAM appears to be back on crack... I just posted a forecast on the blog, I'm really liking the potential for tornadoes this weekend.

http://blog.texasstormchasers.com/?q=node/2

 

[Darren Stephens]

After looking at the 06Z I think that Sunday appears to be the best chance for discreet supercells. Target area West Central Oklahoma then later moving into eastern Oklahoma. I agree with Jeff P. that we are entering a very active pattern the next 12-14 days.

 

[jamesmseitz]

Quote from Alex Lamers

Revised target to Buffalo, OK, which stinks because that makes it close to a 4 hour drive, so it had better continue looking like a "can't miss event" or I might want to sit it out.



I would agree that this is looking better every day. It looks good but I can not explain it but my gut isn't buying it yet. I also am not liking that it has shifted because I am coming from the Minneapolis area, a lot further than 4 hours. I hope the next day shows me something more.

 

[Adam Lucio]

I wish I only had to drive a measely 4hrs. I wonder how many people wouldnt chase if they didnt live in the alley. Try coming from my neck of the woods. This recent shift bumps my drive from 11 to 14hrs!

Anyways, I seems the GFS and NAM are both coming in better agreement. At least from what I saw on the 0Z data. I havent had a chance to go over the 6Z nor will I. Last I saw NAM backed off a bit on the CF and the GFS sped it up just a smidge.

The CAPE and LI bullseyes are right over each other, and the winds still back along the border and points south. The 500mb is coming in at a good WSW direction which will provide more than enough directional shear. If that shortwave can time itself just right we will be in business. Speed shear is not extreme but I think the mid levels will be strong enough to push a storm off the dryline and keep it isolated. I can see a small string of pearls type setup with 2 or 3 good sups while the northern area is more clustered given the stronger forcing with the cold front. I hope the GFS solution plays out with the front sagging not as far south.

Overall I think the potential is good. We all know moisture is not an issue for once so I wont even bother looking at that right now.

 

[Alex Lamers]

I wish I only had to drive a measely 4hrs. I wonder how many people wouldnt chase if they didnt live in the alley. Try coming from my neck of the woods. This recent shift bumps my drive from 11 to 14hrs!

Well this is true, 4 hours isn't that long in the grand scheme of things. But, me being a poor college student means that it's approaching my upper limits for chasing territory.

In any event, it looks approximately the same this morning. There will be a sweet spot somewhere around NE TX Panhandle to NW OK to SW KS. Where it lines up is all a matter of patience. If it's closer to NW OK I plan to chase.

For what it's worth it looks like there's going to be plenty of other setups in the next week or two as the models are painting a pretty active pattern across the Plains.

AJL

 

[Mikey Gribble]

I just started getting into my detailed forecasting for today (been waiting for COD to update) and my god the NAM is out to lunch. I'm not buying it at all. It's impossible to tell much from the ECMWF since they provide so little data from it, but at least the low level pressure and thermal fields are matching up pretty well with the GFS. The GFS has been consistent from run to run too. The NAM is changing with every run. Add to that the fact that the GFS has been much more reliable in most cases this far out. I'm pretty much sold on the GFS with this setup. I'm sure the surface features will move around a bit, but I don't think we'll see any dramatic swings like we've been getting with the NAM.

That is a really good thing to because the 12Z NAM looks like ass compared to the GFS IMO. The kinematics are probably the biggest difference. Deep layer shear is marginal ahead of the dryline and the area where it fires convection with the NAM. 850mb winds are like 10-15kts ahead of the triple point with the NAM while the GFS shows more like 30-35kts (that is huge for the tornado potential IMO). The GFS has a more well organized deepening surface low which creates stronger south to southeast surface winds and very good backing along the front. 700mb flow is 10-15kts stronger over the prime target area with the GFS when compared to the NAM. The GFS clearly has better lowlevel shear and even though I haven't seen one yet the hodograph should be quite favorable for tornadic supercells in the area ahead of the triple point, the northern portion of the dryline and along the frontal boundary. I've always been a big fan of low level shear when forecasting tornadoes (especially 1km SR winds, 0-1km SRH, etc which I haven't seen numbers on but I'm guesstimating they're pretty good) and the GFS looks quite good in the lowest few kilometers.

On the thermodynamics side of things both models have good moisture with dewpoints in the low to mid 60's with temps around 80 yeilding SB CAPE AOA 2000J/kg. The NAM keeps the best instability in a tight little pocket near the triple point though while the GFS has a wide spread area of moderate instability ahead of the dryline in Oklahoma, up to the triple point and then eastward down the front.

Not only does the GFS present a more favorable environment for tornadoes, it is also showing a setup that could have tornadic storms over a wide spread area compared to a tight target area with the NAM.

Like I said I haven't really done my forecasting yet, but I am fed up with the NAM and going GFS all the way. I'll finish up my forecasting over the next several hours and post it along with a map on my blog. I'm pretty pumped about Saturday. I think the odds of a cyclic tornadic storm are fairly good. Let's just pray the GFS holds true.

 

[jamesmseitz]

I love it. Everyone think NAM has lost it....I am likeing the last SREF run. Saturday is good but I am thinking that this now could truely be a two day thing. If this holds true the Drive from MN will happen. Things are begining to look much better

 

[Matthew Crowther]

18Z NAM sticking to its slower guns- with a farther south/more concentrated target over the SE TX panhandle and SW Oklahoma. This is still in conflict with basically all other guidance- but given how persistent the NAM has been, and taking into consideration the idea that it tends to get better the closer the event is, I would not be surprised if the GFS comes a bit in this direction in future runs. So maybe the target for Sat ends up being up in the NE panhandle, extreme NW Oklahoma- maybe near Buffalo?

One thing about the NAM- if it ends up verifying Sunday may turn out to be a even bigger day as the main short wave comes out with perfect timing for the High Plains all the way from KS to West TX. I have a hard time seeing a scenario where both days bust, but stranger things have happened...

 

[Greg McLaughlin]

I am having a hard time buying into the NAM right now. As consistent as it has been, the GFS and the ECMWF have been equally as consistent with a further north frontal position. The GFS has been consistent with a more progressive wave as well. I am thinking the models will either come to terms somewhere between their current solutions, or the NAM will finally jump on board with the other models....kinda like it hinted to last night. Either way, I agree in the thinking that one of the two days may result in at least a localized tornado event.

 

[Andrew Stoller]

The 18z NAM has the front almost to Texas on Saturday, then at 18Z Sunday, the front has retracted back to Nebraska/northern Kansas.

OK, I'm now with you guys that think the NAM is broken.