05/21/05: TALK: KS/NE/IA

[mikegeukes]

RUC FORECAST SOUNDING FOR OMAHA

Date: 2 hour RUC2 valid 23Z SAT 21 MAY 05

Sounding variables and indices
Freezing level: 591.55 mb = 4512.06 m = 14803.15 ft
Wetbulb zero: 612.92 mb = 4221.59 m = 13850.19 ft
Precipitable water: 1.66 inches
Sfc-500 mean rel hum: 70.15 %
Est. max temperature: 32.73 C = 90.92 F
Sfc-Lift cond lev (LCL): 802.95 mb = 1972.33 m = 6470.83 ft T: 17.72 C
700-500 lapse rate: 7.37 C/km
ThetaE index: 11.05 C Layer 800.0- 350.0 mb
Conv cond level (CCL): 719.14 mb = 2904.69 m = 9529.70 ft
Mean mixing ratio: 11.96 g/kg
Conv temperature: 36.82 C = 98.27 F
Cap Strength: 4.40 C

Parcel Indices
Parcel: using surface
CAPE (B+): 1262.50 J/kg
Max Up Vert Vel: 50.25 m/s
Conv Inhibition (B-): 178.93 J/kg
Cap Strength: 3.89 C
Lift Cond Lev (LCL): 802.95 mb = 1972.33 m = 6470.83 ft
Lev Free Conv (LFC): 627.95 mb = 4024.58 m = 13203.83 ft
Equ Level (EL): 187.95 mb = 12626.44 m = 41424.84 ft
B at Equ Level: 1244.83 J/kg
Max Parcel Lev (MPL): 117.95 mb = 15476.39 m = 50774.95 ft

Wind level data
Storm motion: 299 at 22 knt

Wind Parameters
Mean winds (0-6000m): 268.8 at 29.7 knts
Storm direction: 298.8 at 22.3 knts
Shear (0-3000m) pos: 7.0 neg: 0.0 tot: 7.0 10-3/s
Storm rel Dir Shear (0-3000m): 110.4 deg
Storm rel helicity (0-3000m) pos: 371.7 neg: 0.0 tot: 371.7 m^2/s^2
ave: 123.9 10^-3 m/s^2 rel: 0.85
Storm rel vorticity (0-3000m) horiz: 10.3 stream: 8.7 10^-3/s
Energy-Hel index: 2.66
Bulk Rich Number: 6.77
Bulk Shear: 186.56 m/s

Mike

 

[Justin Walker]

Looks like showers that popped up have fizzled out or at least weakened. The tops on them just were sheared off.

Nevermind: They just moved off the front and accelerated off the front!!

 

[Jeff Lawson]

RUC FORECAST SOUNDING FOR OMAHA

Date: 2 hour RUC2 valid 23Z SAT 21 MAY 05

Conv temperature: 36.82 C = 98.27 F

This still concerns me, to be honest. It took surface temps in the upper 90s to get something to fire, but I'm not sure if we can realize such temperatures elsewhere in E NE. Also, the storms that have fired so far don't look as if they're rooted yet (notice how they're zipping along). Dewpoint depressions down there are in the 30-35 degree range.

Better moisture and slightly lower temps (hence, better LCLs) await anything that can develop and push east, but it has to survive first.

 

[Shane Adams]

I'm out here so I'm biased whether I want to be or not (Human Nature), but it seems odd SPC would issue a T-box when current temps are as high as they will get and are still 10 or more degrees below that forecast convective temp.

Sitting at the Best Western just off US75/2 in Nebraska City, waiting for the rogue storm that few had faith in :wink:

 

[Jeff Miller]

hmm

Understand the pessimism, Im starting to fear as well looking at visible satellite and the few wimpy little cells that couldnt.....

I dont know guys......wait and see as I guess we all are doing at this point.

 

[Jeff Lawson]

I'm going to go out on a limb and say the cap is probably going to win today. If you look at the UEX (Hastings) radar, you'll see that the front has made more steady advancement south of I-80 than it has north of I-80. I suspect temperatures soared into the upper 90s down there due to compressional heating ahead of the advancing front, which was enough to break the cap.

But, what happened once the storms down there moved off the front and into the strongly capped air to the east? They died a pretty quick death. The storms now developing in N KS may have a better chance of surviving, but anything in NE is going to have a tough time.

Unfortunately, I don't see much more surface heating in store for E NE. The cirrus canopy, while not overly thick, will shave a few degrees off your surface temps, and seeing as the area is still hanging in the mid 80s to near 90 at max heating, mid to upper 90s looks very, very unlikely.

We're going to need some upper level support or strongly-focused, localized moisture convergence at this point. That's not outside the realm of possibility, so we may yet find ourselves in business in a couple hours...I'm pessimistic, though.

 

[Robert Dewey]

18Z WRF out of DTX (provided the link earlier) still fires up some decent action over southwestern IA. If anything, that's where I would head if I was out there...

 

[mikegeukes]

Looking at the Topeka radar, line of storms now popping up.
Movement east-southeast.

Mike

 

[Dick McGowan]

ventured back to sapp bros near neb city, gonna analyze and go from there. NC ks has fires, let's hope something goes up here....

 

[Justin Walker]

THe cell SW of concordia, ks appears to have taken hold. Hopefully it can hang on. It even looks though is trying to turn to more of a SSE motion.

 

[JHadorn]

The line of storms in Kansas appears to want to quickly become a mess. Some pitiful attempt at cumulus lazily rolled over ten minutes ago. Sad looking, really.

 

[JHadorn]

Latest mesoanalysis has a nice bullseye of sorts for the sig. tornado values sitting right on top of Gage County. RUC is saying that CAPE values are going to get into the 4500 j/kg range in the next two hours in my area. Cap is allegedly eroding a bit. Precipitation is supposed to break out in the next hour or two.

Wait and bleed. That's all we can do.

 

[Dan Robinson]

Supercell composite is 36, Craven parameter of 90 over Marysville KS. I don't think I've ever seen those index values so high. Some converging boundaries are showing up on radar in the vicinity of Schuyler-North Bend-Fremont NE. Setup has so much potential, if only something can go.

 

[Brett Adair]

I'm going to wait and see what this dewpoint depression axis from TOP northward does as the storms head that way. The cap will begin to erode as radiational cooling begins as the sun sets. Things are going to become increasingly favorable for severe storms over the next few hours if the deep layer shear can catch up with the front.

 

[Brett Adair]

Supercell composite is 36 over Marysville KS. I don't think I've ever seen that value so high. Some converging boundaries are showing up on radar in the vicinity of Schuyler-North Bend-Fremont NE. Setup has so much potential if something can go.

I agree....but with convective temps of 103F.....and 98F....it's going to be rough as the cap is definately holding. Around sunset things should begin to fire. I believe Holton, KS has the best chance at tornadic potential today.