4/18/04 FCST: N PLAINS & MIDWEST

[Robert Dewey]

After checking the 00Z WED GFS...Have decided not to update the graphic...Past several GFS runs have been very similar, as noted by Joel, and the outlook looks pretty much the same.

Overall... If the 00Z GFS were to verify - Pretty decent severe weather outbreak could occur across IA/northern MO Sunday...Agreeing that DSM has the best chance of action. Cold front will move through the area during peak heating, combined with good instability and good directional/speed shear, supercells appear likely, as of right now.

Still a solid 4-5 days before the event, so any minor changes in timing and/or location will have a significant impact on the location of severe weather.

Robert

 

[Jonathan Merage]

I'm based out of Lafayette, IN, (Purdue U.) and based on current model ouput, especially the most recent ETA, my prime target location is definitely southern IA. According to the 12Z ETA, all areas around DSM will have the highest CAPEs (~3000 J/kg), with the best mix of deep-level moisture and frontal lift right around there on Sat, not to mention LIs down to -8!!. ETA also projects that area to be in the right-exit quadrant of a decent jet streak, which will provide the upper-level support the supercells need once they get started. As far as the central & Southern Plains are concerned, good LUCK to all chasers headed out there! Even with a fairly potent dryline, assuming CI starts up on Sat., the CAP's gonna make targeting the right cells a chore!
I'm going to base myself somewhere in western IA and wait for the warm-front to come through, as that's where the best shear (directional) for supercells will be. Assuming the lift arrives in time before it gets dark, the southern IA area's in for one BIG show straight through Sunday 8) . I just hope it gets started before dark!
Again, good luck to everyone getting out there this weekend! Can't wait to see some new faces !
Jon

 

[Joel Wright]

Wow, I am amazed. The 12Z GFS is nearly the same still! It's been amazingly consistant with this storm which really surprises me. Central and southern IA still look great, things really look like they are coming together "on paper" to target DSM still. HOWEVER, ongoing convection and associated cloudiness can have a major affect on any event, and at this point that's nearly impossible to predict. So even though this is pretty exciting, I'm still cautiously optimistic about Sunday afternoon... 8)

 

[Joel Wright]

Man this thread got surprisingly quiet lol. The latest models have slowed things up a bit. The GFS is the slowest, with the ETA about 4-6hrs ahead. I'm still amazed how far north the warm front is placed. Based on everything I'm looking at central and southern IA still looks pretty good. I'm starting to feel more confident that skies should clear out in the morning allowing good heating. DSM, or perhaps half way between DSM and OAX along I-80 still look good for a target. Directional sheer, moderate moisture (Td's probably up a little over 60), nice divergence, and excellent heating seem to all be coming together for the best event of the season so far this far north. It looks as though storms will fire as far south as OK too if the cap can get overcome. Stronger upper level winds will be north of these locations though.

 

[Robert Dewey]

It has gotten quite, but the threat for severe weather still looks strong Sunday. My target would be central IA, just south of the warm front, just east of the cold front/dryline by 00Z MON, where convective initiation should occur, barring any significant model changes.

ETA has a narrow band of moderate CAPE ~2250J/KG and very good upper level jet structure across IA at 00Z SUN. ETA 12Z model run shows little QPF for that region though, but with strong VV's between 850-700MB layer, I would expect at least something. Given the linear fashion of the forcing, I would anticipate a very strong squall line or LEWP...With the potential for at least some supercell activity ahead of the main line.

Robert

 

[Joel Wright]

The models have slowed it up even more. Now it looks like eastern NE or northeast KS has the best shot of activity sunday afternoon now. I have totally lost interest in this day/storm system now. Chasers out to my west will have the best shot now. Bring on May, April 2004 sucks!!

 

[Buddy Sallee]

I cant wait for may either

Well after reviewing the current 0z charts for sunday if everything holds the definate hotspot will be northeastern kansas... tornado probablility is not showing strong values as of right now as to what i can gather... weak tornado's are possible.. If the helicity rises for the area we can definately see some strong tornados in the ne kansas area....

Also from what I can see it will be northeast kansas but more torwards the nebraska/kansas border...

Im going to be reviewing the 0z charts for each new 0z chart for the area and try and keep myself observing the area for sunday. I will also post my updates and stuff here (even though all you can forecast also) lol but this shall be an interesting weekend....

Here is my target area as of right now... this will most likely change with time but this is the area im watching currently
[Broken External Image]:http://www.viperschase.com/images/sunday.jpg

thats my opinion...
Buddy

 

[Jon Miller]

The Des Moines NWS discussion ,for Sunday ,is predicting the chance for super cells - mainly hail/high winds but pretty "iffy" for tornado activity depending on cloud base etc. Check it out @:

http://iwin.nws.noaa.gov/iwin/ia/discussion.html

Jon Miller
WTØRNA

SPC Day 3 outlook is also including tornado's in their discussion for Sunday:

http://www.spc.noaa.gov/products/outlook/day3otlk.html

 

[Blake Naftel]

<< Your The Des Moines NWS discussion ,for Sunday ,is predicting the chance for super cells - mainly hail/high winds but pretty "iffy" for tornado activity depending on cloud base etc. Check it out >>

It's Iowa - don't waste your time ;0) I on the other hand will be venturing westward to the Hawkeye state tonight (see the 4/17 midwest thread); but as for Sunday... think the show will be a bit farther north around the I-90 region in S. MN.

It's yet another flip of the coin, roll of the dice, and slice of the pie.

See you under the grunge!

..Blake..

 

[ckbehnke]

I have no idea why this thread is so dead. Last response was Friday morning. Ouch.

 

[J.B. Dixon]

Extremely dead! Anyway, I'm gearing up and heading east. my target as of now is Fort Dodge, IA, with the option to drift farther north, which is highly likely. Good luck to all those venturing out. It should be a great day!

 

[Mike Peregrine]

This thread is probably hurting because people are:
-waiting for day one to update
-on the road somewhere
-scratching their heads about what will really happen.

Here are the upper soundings for:

-Omaha: http://www.rap.ucar.edu/weather/upper/oax.gif

-Topeka: http://www.rap.ucar.edu/weather/upper/top.gif

-Springfield: http://www.rap.ucar.edu/weather/upper/sgf.gif

-OUN: http://www.rap.ucar.edu/weather/upper/oun.gif

The biggest question is just how much moisture will be available for this system - a system where the winds are ideal for something big to happen. The TDs do come up south of Omaha and are already in the 60s from eastern KS south - all of which will likely advect northward with the movement of the warm front this afternoon. Just how much high quality, deep moisture is the big question. As Jeff pointed out, for the most part we've been working with continental moisture rather than Gulf moisture due to a frontal boundary that skimmed it over the Gulf. Has enough time past for the Gulf air to recover from that and shoot the juice back over the plains? - That's primarily what I'm waiting to see. With it, the Mod Risk is well-warranted, without it there will be a question of just how much punch these storms will be able to pack.

 

[Mike Peregrine]

I think in spite of the pessimism surrounding today's possibilities, I'll likely chase today. Will probably target the cold front this time, because I think the cap will probably break first somewhere on the NE/IA line in the vicinity of the CF somewhere around Sioux City. Since it's the last chance to chase somewhere other than around here before the work week, I'll probably head up that way to arrive around 4:00-4:30.

Best -

Mike

 

[Robert Dewey]

I generated some soundings for some interesting locations...

WI/IA State Line - http://www.yourimagehost.com/is.php?i=4110...western_wi.jpeg
IA/NE State Line - http://www.yourimagehost.com/is.php?i=4111...western_ia.jpeg
Northeast KS - http://www.yourimagehost.com/is.php?i=4112...rtheast_ks.jpeg
Eastern IA - http://www.yourimagehost.com/is.php?i=4113...eastern_ia.jpeg
Central OK/OUN - http://www.yourimagehost.com/is.php?i=4114...entral_oun.jpeg

These are forecast soundings from the 06Z ETA valid for 00Z (18HR Forecast). Each images is large and is roughly 350KB. Each location seems to have a CAP of about 2C. The OUN sounding shows the dry air which has mixed down, with CAPES < 500J/KG.

Robert

 

[Shane Adams]

I wonder if anyone is remembering the southern half of Kansas today? With all the attention the pseudo-outbreak day in IA/MN has been getting, the RUC has somehow managed to squeeze out some precipitation from SW Kansas through the eastern Texas panhandle. I just did a quick skim of the data and there's CAPE out that way, along with a decent windfield.

Moisture is an issue, but by now we're so used to that it no longer matters; Iowa somehow managed tornadoes (pending damage reports/video confirmation :wink: ) last night with low 50s dewpoints. So now I'm in that classic position of having expected the day off and made plans, only to now have to sit and watch this crap while foregoing my original schedule of being at a friend's to watch NASCAR.

If I go watch the race and hang out, I'll miss a great storm....if I stay home, miss the race, and monitor this situation, it'll be a bust. I wish I wouldn't have even looked at the damn model now, lol.