5/19/04 FCST: NE/IA/KS/MO/MN

[Tim Jones]

Guess I'm not seeing the cap issue according to the RUC. If we continue to get heating in SW IA/SE NE I don't see the issue. I can see things holding off until late afternoon/early evening which make things all the better. The RUC is blowing up convection at 21Z around OMA (which I'm not sure I buy) and continues from there. Guess we'll see.

 

[Jeff Snyder]

Originally posted by Tim Jones
Guess I'm not seeing the cap issue according to the RUC. If we continue to get heating in SW IA/SE NE I don't see the issue. I can see things holding off until late afternoon/early evening which make things all the better. The RUC is blowing up convection at 21Z around OMA (which I'm not sure I buy) and continues from there. Guess we'll see.

Tim,
It's important to remember that the RUC has way underforecast the cap in the past few days... On Monday it showed 0 cap and busted precip from DDC to SAL... Yesterday, it shower 0 cap in se KS and bust major precip from Emporia to south of Wichita... Obviously, neither of these days had much, if any, convection. I don't know why the RUC is having this problem (I don't know much about the convective parameterization in RUC), but it seems to be prevalent in this pattern...

 

[Craig Maire II]

Hello

I'm sitting at the Avoca public library right now (12:42pm) in Potawattamie
County Iowa waiting for the cap to break and for supercell development.

Craig

 

[Jason Montano]

Well today is looking a bit like yesterday, with low cloud cover and a cap holding off convection. I personally think today will come to fruition though, if I didn't just finish taking a midterm I would be up there. The RUC, much like yesterday shows no CIN in a couple of areas and convection breaking out between 2000z and 2100z. I just got done looking at CAPS forecast sounding for OAX and it shows a CIN value of 0 at 2200z, but then shows redevelopment of CIN at 2300z. So I don't know, but it sure looks worth the chance, could be a big day. Good luck to all out there!!

 

[Ben Engle]

Re: Hello

Originally posted by Craig Maire II
I'm sitting at the Avoca public library right now (12:42pm) in Potawattamie
County Iowa waiting for the cap to break and for supercell development.

Craig

what towns are there? I'm sitting on highway 6 in Council Bluffs right now, used alot more gas getting here than i thought i was going to. With things looking like they are, and having some stuff to take care of back home, I think i'm gonna head back home.

 

[Austin Ivey]

Just heard from my peeps hangin in Omaha with tons of other chasers. Apparently Omaha and Topeka did 18z soundings. Examining the resultant data should provide some more insight into probabilities for this afternoon.

 

[Mike Peregrine]

Originally posted by Austin Ivey
Just heard from my peeps hangin in Omaha with tons of other chasers. Apparently Omaha and Topeka did 18z soundings. Examining the resultant data should provide some more insight into probabilities for this afternoon.

Definitely anxious to take a look at these -

Jason - I think that better forcing today will translate into a better chance of initiation than yesterday - the dynamics are altogether better, so the chances are good that we'll see something. Strategic choices today will make ALL the difference ... I hate the idea of missing the show by a few miles or being out of position, and yet that is the hard reality we face on days like this.

 

[Kevin Scharfenberg]

The 18Z Omaha sounding is in here: http://weather.cod.edu/wx/public/raob/18Z/...AX.skewt.18.GIF and shows about 180 J/kg of CIN remaining. The 18Z sounding from LBF http://weather.cod.edu/wx/public/raob/18Z/...BF.skewt.18.GIF shows some very hot temps aloft lurking just to the west.

Given the look of satellite, I would say things aren't looking great. If I were already there, I wouldn't leave just yet though.

 

[Mike Peregrine]

Originally posted by Kevin Scharfenberg
Given the look of satellite, I would say things aren't looking great. If I were already there, I wouldn't leave just yet though.

No way - - - remember that even on days with a strong cap, there can be obscure weaknesses develop along boundaries that cannot be forseen ... go by Tim Marshall's rule - if the cap is big, chase anyway ... especially in May!

 

[rdale]

NSharp forecasts 85/64 from the 18Z Omaha sounding as a surface parcel and I see mid-70s over mid-60's as of 1820Z obs knocking on the door (with some stations at 79 in the area.) That leave no CAP, LI -8 CAPE 2711. Not much in the way of low-level wind speeds but good rotation.

But then again brings in those warmer temps from LBF would reduce chance of getting init regardless of sfc heating. Head to ND where the storms already are going ;>

I tried to overlay both but NSharp wouldn't export them at the same time - so here's OAX by itself: http://radioweather.us/sounding.jpg

- Rob

 

[J.B. Dixon]

I'm with you, Mike. We can't bail on this chase day just yet. I've seen warm front events with NO daytime heating prior to initiation. There's just too many other things that are right for nothing to happen. The April 8, 1999 SW Iowa outbreak comes to mind.

I think I might cross the river for a target. Mo. Valley, perhaps.

 

[Mike Hollingshead]

Just put yourself on the nw fringes of that clearing line and what happens happens. The 18z Omaha sounding showed a convective temp of 87...I think that can be reached...at least hope so. If I was a chaser chasing today I'd be sitting in Blair NE....oh wait I am! Had a day fairly similar May 16, 99 and that day around 2:30 or so the clouds broke up just long enough and bam, was in the Blair to Greenwood IA area, 2 slow moving tornadic HPs...weak sfc flow...extreme instability. Will be interesting to see what the temps are able to do south of the clearing. 80/72 under the weak cu field in se NE.

 

[J.B. Dixon]

Hey Mike, thanks for inviting all of your your fellow chaser bretheren over for lunch and data at the target of all targets, Blair, NE. Hogging the best target for yourself, eh?? I see how you are, dude. :wink:

 

[Mike Hollingshead]

Somewhat interesting there is convection north of the front already near Sioux City.

 

[mikegeukes]

OMAHA 18Z Sounding

Sounding variables and indices
Cap Strength: 3.19 C

Parcel: using 100 mb layer
CAPE (B+): 743.37 J/kg
Max Up Vert Vel: 38.56 m/s
Conv Inhibition (B-): 181.67 J/kg
Cap Strength: 3.15 C

OMAHA 00Z Sounding:
Sounding variables and indices
Cap Strength: 2.45 C

Parcel: using 100 mb layer
CAPE (B+): 2209.59 J/kg
Max Up Vert Vel: 66.48 m/s
Conv Inhibition (B-): 5.85 J/kg
Cap Strength: 2.38 C

Mike