2015-05-27 EVENT: TX, OK, KS

[Ben Holcomb]

Another potential chase day with sleeper possibility. Not a lot of upper level support, especially earlier in the day with shortwave ridging per 00Z NAM tonight showing up. By 00Z a small impulse seems to eject and provide a much more favorable environment for large tornadoes in the OK/TX panhandles and SW KS much as the May 24th event.

Seems like it will be quite isolated if it happens, but worth watching.

 

[Rocky Rascovich]

This may be the only day I can chase for the next week or two. Opportunities have been few and far between due to other priorities. Based on the 12Z data of the GFS and NAM, possible outflow boundaries from last night's convection interacting with subtle impulses moving in from the southern Rockies may give me some hope from the Dodge City area to Higgins TX. region by 22Z. Shear and cape values will keep my interest pegged for this area and may just go for it. I'm so overdue for some convective nirvana!

 

[Jeff House]

Above target still looks good. Maybe try to hedge just in case southwest OK. CAPE is impressive down there but low level shear is all the way into Kansas. Two diffuse boundaries noted southern OK and also southwest Kansas. The KS one appears to be synoptic and the OK one an OFB. Generally I prefer to chase OFB intersection (OK today) but tough to ignore parameters into Kansas especially if stationary front becomes WF. Try to hedge and enjoy a sit down lunch until target becomes more clear. Maybe both will verify.

 

[JamesCaruso]

My initial target is Greensburg to Pratt. Mid/upper flow appears to be slightly better up there, and both surface and 850 winds should be more backed, especially with low pressure in southeast CO. There appears to be little or no convergence along the dryline to the south but appears it will be better (not great) in southwest KS.

NAM is significantly more bullish than the GFS in pulling moisture into southwest KS. Noted the following in the Norman NWSFO AFD:


THE 00Z AND 06Z NAM GENERATES A CONVECTIVE SYSTEM OVER EASTERN
OKLAHOMA THIS MORNING...THEN DRIVES IT WEST-SOUTHWEST ACROSS OUR
FORECAST AREA DURING THE DAY TODAY. THERE APPEARS TO BE NO REAL
JUSTIFICATION FOR THIS SCENARIO...SO HAVE IGNORED THE NAM FOR THE
FIRST 12 TO 24 HOURS OF THE FORECAST.


GFS shows moisture remaining further east in southern KS, so will re-evaluate based on surface conditions once I'm up there. GFS also shows nice supercell composite parameters in south central KS. Suspect actual best area in southern KS will be east of where indicated by NAM but west of where indicated by GFS. Wichita AFD seems to concur on severe risk being west of its own forecast area.

Have about a 5 hour drive from Childress and cannot leave until 11 due to a business conference call I need to be on (yes, even though I'm on a chase vacation ) but I don't think it will be a day of particularly early convection.

Jim

 

[Ben Holcomb]

Jim I'm in Childress as well and thinking of heading up towards the Dodge City/Garden City area. I don't expect things will go early as the NAM seems to be firing stuff after 4pm in W/SW KS. The HRRR not so much in that part of KS. I think having a late start will give me some time to get north on 83 and evaluate as we drive.

No cloud cover in the area is a big positive. Forecast hodos by the NAM in SW KS are sicle-shaped much like the hodos were yesterday in North Texas. I'm pretty confident today should be the last good day for awhile as it looks like our pattern really settles down after this for a bit and I return to real life and work.

 

[JamesCaruso]

Jim I'm in Childress as well and thinking of heading up towards the Dodge City/Garden City area. I don't expect things will go early as the NAM seems to be firing stuff after 4pm in W/SW KS. The HRRR not so much in that part of KS. I think having a late start will give me some time to get north on 83 and evaluate as we drive.

No cloud cover in the area is a big positive. Forecast hodos by the NAM in SW KS are sicle-shaped much like the hodos were yesterday in North Texas. I'm pretty confident today should be the last good day for awhile as it looks like our pattern really settles down after this for a bit and I return to real life and work.

Sounds good Ben, we are on 83 at the moment. Hope you're wrong about the next few days, it has been an unproductive 10 days for us and we fly out of DEN on Sunday. But I have a hunch you're right, not to go into another day's thread but it looks like poor timing on the upper trough coming into better position overnight tonight, kicking off overnight and morning convection yet again...

Jim



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[Jeff House]

1910Z: Cell northeast of Garden City may be the hard right mover HRRR keeps advertising riding Kansas boundary. Meanwhile CU field in Texas Panhandle is on another boundary approximately along I-40 into Oklahoma. Good luck!

 

[JamesCaruso]

Would appreciate any insights on why the more northern storms near Garden City and the more southern storm in Canadian performed well whereas the in-between area of Sublette to Meade did not... Was it the location of outflow boundaries per Jeff's post above ?

EDIT: re-read Jeff's post, one of the boundaries he mentioned was on I-40 so that shouldn't have been a factor in the Canadian storm...

 

[Wesley Luginbyhl]

You could see that boundary sitting right by the Canadian area before storms even fired. Winds were SE at Canadian while at Pampa they were SSW. Big reason why the storm didnt move as it was anchored to that boundary. Why did the middle not go, I have no idea, but it was obvious why the Canadian storm performed so well.

 

[Ben Holcomb]

If you were looking at visible satellite when the storms first blew up, it looks like there was an OFB from canadian back through AMA and then west of there that cu/storms blew up on. I think the Canadian storm was actually sitting on a boundary.

The other thing I noticed was some much higher dewpoints there than other places. 66F dewpoint in Canadian when the storm went up, 64 in Perryton. Amarillo and Pampa were both somewhere down in the upper 50s.

 

[Jeff House]

Yes the Canadian outflow boundary had lifted north from I-40. Probably I should have mentioned the possibility of it lifting with time. The idea is to spot the boundary early in the day when it is sometimes more obvious. Then it is easier to tack it on visible and surface as the day unfolds.

Kansas storms that produced were on the synoptic stationary front turned warm front lifting north, another great set-up. I still kind of prefer OFB over synoptic, but on a good day like Wednesday 5/27 they both produce anyway.