5/21/2010 FCST: TX, OK, KS, CO, NE, WY

[Chuck Robertson]

WOW! Am I just totally out to lunch, or does anyone else see a potential situation setting up in the TX Panhandle Friday afternoon? SPC doesn't even have a "See Text" for this area on their outlook issued on Wed, yet if the NAM verifies, this area will see CAPE AOA 3000, 40-50kts at 500, backed and strong, possibly upsloping sfc winds, and thunderstorms breaking out.

Maybe they are completely buying the GFS, which is far less impressive.

Another possible tornado day in the TX PH and adjacent areas this Friday, or am I just really missing something here?

 

[Skip Talbot]

Its definitely worth keeping an eye on. The NAM has been trending towards better moisture return over the past several runs while the GFS remains fairly consistent in keeping rather meager 50's dewpoints in the target areas. I know the NAM has overdone moisture return on setups earlier this year, but its interesting that it continues to bring in more moisture as the event approaches rather than knocking it down like you'd expect. We have a few more runs to see if this trend holds and if the other models come into agreement, as well as being able to compare actual surface obs with the model output. If the moisture is indeed in place, I'd be watching eastern CO and western KS for classic high plains supercells. The winds are more easterly up there for better upslope flow to aid initiation as well as stronger midlevel flow to maintain updrafts. The upper 50's/low 60's dewpoint should be adequate given the higher elevation. If the GFS is closer to reality, however, we're looking at meager instability and a capped environment.

 

[Andrew Stoller]

Wow, didn't see this one on the radar. Might want to add CO to the setup as well. 2 latest runs of the NAM are showing a lead disturbance ejecting out of the western trough through eastern CO/western KS, along with a surface low developing in eastern CO. Flow becomes very backed into northeast CO down into west central KS, with around 40-50 knots of bulk sheer and around 1,500 J/CAPE. Could see initiation along with I-70 corridor along the KS/CO border and possibly something fire further south along the dryline into the panhandles. Will be keeping a close eye on this for sure!

 

[Chris Hayes]

I've been watching this setup for a couple days now, especially along the dryline in the panhandles. NAM was showing a pretty sharp dryline in the Texas panhandle a couple days ago with a breakable cap and couple of lone storms breaking out east of Amarillo. If things continue to look promising for development there, we might head to Amarillo tomorrow in case anything develops. Colorado is a bit too far of a drive from OKC

 

[Andrew Stoller]

The cap is going to be a big fly in the ointment for Friday - 700 mb temps progged above 15C potentially, especially the further south you go. Might be one of those high plains type days where orographic forcing along the Cheyenne ridge and into the Black Hills are the only areas of initiation.

 

[Jeff Passner]

The cap is going to be a big fly in the ointment for Friday - 700 mb temps progged above 15C potentially, especially the further south you go. Might be one of those high plains type days where orographic forcing along the Cheyenne ridge and into the Black Hills are the only areas of initiation.

I don't see 700 hPa temps as being a problem anywhere except maybe at Midland. The 700 temp forceast of +10 to +11 C is not bad. Right now, the cap problem seems to be closer to 800-850 hPa, but even then the cap can be broken. The problem is a general lack of lift. There may be a weak vort max, but there's no convergence along the dryline. To me, the situation looks VERY favorable in NE Colorado, SE Wyoming and SW Nebraska. I really think the shear, 55 dew points, and better convergence can lead to a strongly rotating storm. To the south, in Texas there might be some high-based storms that form above the cap and work into better moisture, but I think tornado probabilities are much higher up north.

 

[Brandon Lawson]

Another possible tornado day in the TX PH and adjacent areas this Friday, or am I just really missing something here?

The forecast thread for last Tuesday (5/18/10) consisted of about 5 posts total. Everyone seemed to be focusing on the 19th (and yet there were still hundreds of chasers ) This appears to be the case with tomorrow. Everyone is focused on Saturday as far as forecast threads are concerned, but I know there will be a mass ninja chaser convergence tomorrow, despite the lack of discussion.

Moisture is all over the place with the 00z GFS and NAM. Currently, the west Texas Mesonet shows the 59-60 degree dewpoints along and east of a line from Altus, OK to Haskell, TX, and south of a line from Wichita Falls, TX to Sallisaw, OK on the Oklahoma Mesonet. Comparing to what the RUC, NAM, and GFS show at 06z, the models may be under-doing the moisture a tad. Who knows. It will be interesting to see how far the moisture can lift tomorrow. The panhandle has some appeal for me since it's closer, but that's just proximity bias on my part.

 

[Brandon Lawson]

Crap. I double posted on accident. Please delete.

 

[Marcus Diaz]

I'm liking the 0z NAM. In fact, the NAM has been ramping up this system in the past few runs. Low 60 DPs in the TX Pan, nice sharp dryline along the TX/NM border, 2000-2500 Jkg-1 CAPE all over the panhandle, and sfc-500mb bulk shear around 40-50kt over the panhandle. The NAM breaks out cells on the precip in the panhandle. Also showing virtually no cap along the dryline, which means it'll be easy for stuff to fire. 700mb showing a little cool air pool from about Dimmitt northward into KS, telling me that the cap won't be that strong. Hodos have a pretty good tight little curve. My target is going to be my backyard. I'll probably be at work watching the visible sat. waiting for the first towers to go up. Should be an interesting day down here.

 

[Glenn Dixon]

Everyone is focused on Saturday as far as forecast threads are concerned, but I know there will be a mass ninja chaser convergence tomorrow, despite the lack of discussion.

Can you provide a link to these Saturday threads? I've been unable to find them, and that is my chasecation Day1....would love to see some KS vs. NE vs. SD discussion...

 

[Brandon Lawson]

Just got up to look over things this morning. One can't help but notice upper 60s dewpoints just south and southwest of Abilene. Southern Texas is juiced today, but it may not have any affect on our severe weather chances further northwest if it doesn't go anywhere. I'll be waiting until later this morning to decide on whether or not to go out today. Mixing out of the boundary layer moisture this afternoon appears to be a problem, at least in the Texas Panhandle.

EDIT: 12z NAM looks much better

Can you provide a link to these Saturday threads? I've been unable to find them, and that is my chasecation Day1....would love to see some KS vs. NE vs. SD discussion...

Sorry Glenn. I'm obviously not doing a very good job of paying attention. I assumed people were more interested in this Saturday, but no thread has been started.

 

[Warren Faidley]

Target today: Amarillo to far SW KS region.

Target is in line with 13z SPC discussion and 5% tornado probs. The latest NAM and GFS cannot agree on the extent of CAPE by 18-21z. However, both the NAM and the GFS hint of a sharp dryline in the OK Panhandle / SW KS area in the late afternoon. I think this is one of those late May days when the **best** target will not be defined until much later in the day when its too late to make a long corrective drive. Looks like the air will be to dry for anything to initiate off the Mt.s in New Mexico, but this may not the case east of Denver.

The Colorado option looks good, but AM intelligence reports notes chasers massing along I-70, so I think I'll pick a target further south. (;

W.

 

[Jacob Ferden]

Preliminary Chase Target: Amarillo, TX

Chase Plan: Not for sure that I'm going out, but if I do, will leave Norman around 11 AM CDT. Will most likely wait in Amarillo for initiation.

Reasoning: This is far from a great chase setup, but I am in "chasecation" mode, and I would take a nice LP supercell or two. The 12z NAM which just came out is showing CAPE around 2,000 j/kg in the northern Texas panhandle, and no cap at 00z. Lack of a triggering mechanism may be somewhat of an issue. NAM shows 0-3km EHI values above 4.00 near Amarillo, and breaks out precipitation just to the north of there by 00z. Dryline is currently situated in eastern New Mexico, dewpoints are aoa 60F at Lubbock already. Hoping that a cell can get going somewhere in the vicinity, and provide good structure, with anything more substantial a bonus.

 

[Patrick Martin]

Mods - Please add NE, CO, WY to the target staes please.

I'll be playing the area east of Denver today with an initial target of Ft Morgan. Will be watching to see how/where moisture increases through the day along the front range and eastern plains, the degree to which we get a healthy Denver cyclone, and upper air patterns. Look to depart sometime after lunch once the details start to resolve themselves, and will make adjustments as necessary. Good luck to all chasing today.

 

[Mark Blue]

Early this morning I initially thought Sidney, NE had a crazy looking hodograph between 0 and 3Z tonight with all severe parameters in place and felt as though that appeared to be the best target area. However, the AFD for Denver sounds very nice with a Denver Cyclone setting up today with the type of ingredients in place for tornadic supercells. My gut tells me from experience to be close to the foothills and Palmer Divide, then follow the storms on their route towards Limon. The other play typically involves storms firing normally south and west of town, then moving up I-76 towards Ft Morgan. In any event, plenty of time remains to change our target as the conditions unfold today. Probably a good thing to pick a target close to home because I forgot my monopod (at home) when we left on Wednesday evening. Best of luck to everyone chasing today.