4/18/04 FCST: N PLAINS & MIDWEST

[Amos Magliocco]

For the potential second round of severe weather this weekend...

[Robert Dewey]

The threat looks decent...As of now. Event is still 6 days away, so I am not too excited just yet.

Robert

[Joel Wright]

The low pressure is weakening and occluding by this point. But, moisture is readily available. Looks like a non-event for my part of the midwest. I'm not too impressed at all at this point. The best day will be Saturday down in Kansas and Oklahoma, and maybe parts of southern NE.

[Robert Dewey]

Originally posted by Joel Wright
The low pressure is weakening and occluding by this point. But, moisture is readily available. Looks like a non-event for my part of the midwest. I'm not too impressed at all at this point. The best day will be Saturday down in Kansas and Oklahoma, and maybe parts of southern NE.

I just checked the latest 12Z GFS and your right. The low looks like it is weakening and filling in. I'm not gonna give up on it just yet though , its a little under a week away, and plenty of time for things to change for better or worse.

Robert

[Amos Magliocco]

I actually thought the 12Z improved Sunday's setup a little, with the system coming out more negatively tilted and improving the wind fields up there in NW IL to E IA. Plenty of time for return, strong deep layer shear, and a surface low still more than adequate. I agree it's more likely to be the typical post-plains, upper-midwest, unidirectional squall line.

However, if we're seeing a gradual slowing trend--which would not be at all surprising--Sunday could become the marquee day and Saturday a nocturnal affair in deep west Texas. I'm hoping that doesn't happen, but it's possible. Anything's possible six days out--LOL!

[Scott Roberts]

Originally posted by Joel Wright
The low pressure is weakening and occluding by this point. But, moisture is readily available. Looks like a non-event for my part of the midwest. I'm not too impressed at all at this point. The best day will be Saturday down in Kansas and Oklahoma, and maybe parts of southern NE.

I'm liking Sunday better for our area. Models seem to be slowing down just a bit, and with the earlier mention of a triple point in the ICT CWA, and our forecaster's feel that Satruday will be a late-day event, I'm holding out for Sunday (besides, I get more overtime that way :D )

[Robert Dewey]

Just checked the latest 18Z (I will be checking models every run every day until the event happens, or doesn't happen... :o ). The system speed has actually increased some, which is opposite to what Amos (and I) were thinking. By 00Z Monday (around 7PM EDT I believe) the SFC low is located in central WI with a mslp of 997MB. Have yet to look at moisture charts and instability, but overall synoptic setup appears favorable for severe thunderstorms from eastern IA, northern MO, ENE into IN and lower MI. As of right now, supercells look possible (again, just based on synoptics and jet structure only) in the eastern IA and northern MO area, which should form into a squall line and move into the other mentioned regions. The low actually deepens over lake superior some, and given the strong nocturnal low level jet, suspect that a relatively strong squall line could traverse across southern lower MI/IN/northwest OH...But all this is 6 days away and I'm getting too far ahead of myself :o .

Below is a forecast map which I generated real quick, and it will update as I change the forecast (when I ever get the chance), since it is an absolute image URL on my server. So to see my latest forecast for the event, just check this post.

http://www.waveformpc.com/outlookSunday.GIF

[Joel Wright]

Well taking a look at the new 00Z runs have restored some hope for Sunday. One thing I noticed the models seem to be "forgetting" is the MAJOR influence of the very cold great lakes. This will have a big impact on where exactly the warm front ends up lying. Moisture seems to be well in place, and relatively deep as well. From the surface to 200mb there's nearly a 90 degree veer. There appears to be nice divergence. Definitely a lot of positives there.

Right now I'm thinking the low will end up tracking further south, along a further south placed warm front. A very early guess would be far southern Iowa down into Missouri and west central IL. I feel a little goofy making a guess this early, but ah what the heck. It's been a LONG time since we've had anything exciting to forecast around here! :)

[Robert Dewey]

Originally posted by Joel Wright
I feel a little goofy making a guess this early, but ah what the heck. It's been a LONG time since we've had anything exciting to forecast around here! :)

Thats what I say, just look at my previous post! :o

Robert

[Jon Miller]

NOAA's Climate Prediction Center US Hazard Assessment is showing severe storms from NE New Mexico NE to western Michigan on April 18,19
and from central Texas NE to Ohio on April 21-23 of next week.
http://www.cpc.ncep.noaa.gov/products/expe...nt/threats.html (http://www.cpc.ncep.noaa.gov/products/expert_assessment/threats.html)

So it looks like a potentially active chase week (and a lot of travel) is in the brew ! Good luck & take your credit card - gas prices are going up, up up !!!

Jon Miller
WTØRNA

[Robert Dewey]

Thanks for the link Jon. They mention severe weather 9 times, and they use pretty strong wording such as Severe storms are expected for parts of the Central Plains from April 18-19.


Severe storms are expected for most of the Mississippi and Ohio Valleys from April 21-23.

I will certainly be watching this situation!

Robert

[Jeff Miller]

Fortunately next week on the 20th, my chase partner and I were slated to attend a Spotter class in Iowa. Now, if this pans out, we may well be doing some serious chasing. Looks like I'll be out next week....will keep all posted on wether or not this will be my first serious chase week of 2004.

Dare I allow myself to get excited?? just a tinge at this point...but I will say its looking better!

[Robert Dewey]

I will probably update my forecast graphic as the 00Z GFS pours in tonight, I'm getting kinda bored :o . Make sure to check it, and add constructive criticism.

Robert

[David Schuttler]

Guess I did get lucky in my vacation time this year and thank you Bank of America for raising my limit last week.

I would pick a week in May but the company I work for doesn't allow vacations after April.

[Joel Wright]

Looking at the latest 00z GFS run that just came in shows that things are almost nearly identical to last nights 00z run. By late sunday afternoon the GFS plots the warm front north well into Wisconsin. I still find this very hard to believe with the combination of MAJOR lake cooling and ongoing convective clusters traversing the boundary further enhancing low level cool pools. But since the LP is still progged to ride all the way into southern MN before occluding, I'll hold on to a little hope that the storms fire as far north as the south half of Iowa. I would target the afternoon warm front/triple point which will likely end up somewhere in Iowa, near DSM. All other parameters still look pretty good. If things don't change there will be some tornadoes in the midwest on Sunday. :)

[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 :D !
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 :D

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

[J.B. Dixon]

After pouring over updates......in a perfect world, I would be sitting in Marshall, MN waiting for initiation. Instead, like Mike, I'll be playing along the cold front. Looks like the moisture is on it's way. Although probably weak, I think there's a shot at a tornado on an isolated cell along the CF. There's shear, but not enough to go crazy about. It's the best shot we've had to come through here this year. See you in Sioux City!!

[Mike Peregrine]

Shane, I don't think the dryline should be completely discounted from Kansas possibly down to the panhandle. I was thinking more along the lines of NC Kansas (where I'm scared there might be that rogue supe pop up while I'm up in Iowa) ... but we've all seen setups like this in the past that end up producing sporadically all the way down the pike. I wouldn't put anything completely out of the realm of possibility. As for choosing whether to see a race or chase - that's one of those wonderful decisions we all get to make a million times this time of year. I was supposed to be having dinner with friends tonight - have already called and cancelled. hehe

[Amos Magliocco]

Originally posted by rdewey
Central OK/OUN - http://www.yourimagehost.com/is.php?i=4114...entral_oun.jpeg (http://www.yourimagehost.com/is.php?i=4114&img=central_oun.jpeg)

All weekend long these forecast soundings have been totally and completely out to lunch, but I bet if you do a survey of the threads for each of the three forecast periods, you'll find three times as many URLs posted for forecast soundings than the real thing. That ETA soundings for OUN bears no resemeblence to reality as of this morning:

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

[Mike Peregrine]

It's interesting that the OUN sounding you posted Amos cuts off moisture at 800mb, while the OAX sounding shows decent saturation there.

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

Some convergence in Omaha already this morning? - Wonder where it's coming from exactly, because it doesn't appear to be from the south. Springfield's sounding even looks worse than OUN ...

[Robert Dewey]

I decided to make a quick outlook graphic... http://www.yourimagehost.com/is.php?i=4119...img=outlook.gif (http://www.yourimagehost.com/is.php?i=4119&img=outlook.gif)

The reason I didn't extend the risk further southwest is because there is some really dry air and weak instability, and convergence is on the weaker side...Further north into MN/IA/WI (western)...While there is still a decent CAP, strong and persistant convergence later today, combined with CAPES of around 2000J/kg, and excellent shear will present the risk for severe thunderstorm development. Looking at forecast soundings, supercells appear probable on the western side of the "35%" area...With the potential for a few tornadoes. Supercells should consolidate into a line or lines...With bow echos likely in western WI (HP supercell ingredients and bow echo ingredients overlap). Expect main storm initiation around 21Z-00Z.

I put an "X" on my "target" area...Just to see how it verifies later today/tonight.

Robert

[Chris Hayes]

PDS Tornado watch has been issued for central minnesota. I'm worried about the leftover grunge over the area though. Warming up nicely into the 70s and 80s though. As of right now I'll target Minneapolis but no further north than 30-40 miles. In the 60s well north of Minneapolis. Still got time though. The chase is on :D

Too bad it's a virtural chase

[Larry J. Kosch]

Hey,

While I'm waiting for a NOW 04/18/04 NE thread to be set up, check out the storms firing up near Mullen, NE:

http://www.crh.noaa.gov/radar/loop/DS.p37c...r/si.klnx.shtml (http://www.crh.noaa.gov/radar/loop/DS.p37cr/si.klnx.shtml)

Looks like central and eastern NE could be in for a stormy day!!

Happy Chasing :blob7: LJK.