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5/20/2004 Reports: CO,IA,KS,NE

Please post any reports for May 20, 2004. Below is my chase report and link to image of wall cloud.

I started the day in Des Moines, Iowa after a really awful bust yesterday in western Iowa. There were two possible target areas. The first was in southern Iowa along the boundary, the other was in northeastern Colorado. I didn't think the storms would fire because of the cap in Colorado, though I liked the backed winds. Making a decision was difficult since going to Colorado would require leaving before the 15Z RUC. I talked with Jeff Piotroski and we checked additional data. We finally decided to target an area south of Des Moines. We headed south on Interstate 35 as towers began to develop in a west to east line by mid afternoon. Visibility was poor. We stopped in the town of Osceola and followed a developing storm eastward and to the north. The storm exploded and a tornado watch was issued for the surrounding area. Other storms were also forming to the east and later the west of our position. We followed the initial storm northeast to near Lacona. We passed by several other storm chasers. The storm was initially linear but briefly became supercellular. A wall cloud formed but no tornado. We encountered small hail, frequent lightning and heavy rain. The storm then split and slowly died. Another storm formed to the southwest and started to make a right turn. We dropped south but as we neared the southern storm, it died. We kept in contact with other chasers in the area and were also given data by Jason Politte who was nowcasting from home. Thanks Jason! By 7:30PM, we decided the chase day was over and headed to Des Moines.

Wall Cloud near Liberty Center, Iowa


(the streaks below the wall cloud are from my windshield)

Much to my dismay, one beast of a supercell did form northeast of Denver. It was tornado-warned and had large hail. The cap finally broke but very late. I am surprised that I seen any posted reports on that storm. That was a dangerous storm since it was tornado warned after dark. Anyone fleeing the storm east on the interstate would have been nailed by the core as the interstate turned northeast. I hope everyone is safe.

Bill Hark

What a day and what a mothership! I do hope some one somewhere got some images from 15 miles away of this as darkness fell – it was a stack of plates!

We made the long haul from Omaha and was actually kicking rocks in Limon when the convection fired north of Denver. Within 45 mins were we right under the cell as it approached Wiggins. The cell had some great motion and was spinning like a top! A number of RFD gustnados were observed and these must have been the tornado reports as we had front row seats for the show. We were blasted by RFD as we were a little slow on a camera shot on one occasion.

Here are a few images, not that good I have to say – notice how high the base is as we approached from the south.


Regarding the SPC Tornado reports

I can confirm that the Wiggins and Fort Morgan reports are duff – I was there – there was a number of FRD gustnados that may well have been the reported “tornado.â€￾ We are stopping over night in fort Morgan so I will investigate the sugar factory in the morning just in case.[/url]
We observed a large tornado tonight about 9:46 Mountain Time in extreme northern Washington County in northeast Colorado after a marathon chase-positioning journey from De Soto, Iowa, where we spent Wednesday night. This tornado finally emerged from a long-lived LP and later Classic supercell that we intercepted around Hoyt, Colorado, having watched the storm since initiation from our vantage point in Last Chance, Colorado.

Wednesday night, we had noticed the 50 degree dewpoints ETA forecasted surging into northeast Colorado, but since we were in Central Iowa, we tried to ignore the strong midlevel flow and easterly surface winds feeding into the post-cool front environment. Several ingredients looked supportive of Front Range upslope storms, and the memory of last
Monday when I played southeastern Wyoming rather than the DVCZ was fresh.

This morning we decided to go for it.

The storm began as a miniature supercell which struggled with balance and frequently produced cool outflow and a ragged base. When the storm slid into southern Morgan County, it strengthened dramatically, such that within fifteen minutes the entire storm was rotating, surrounded by elevated inflow bands thatarced into the mesocyclone like the feeder bands of a hurricane. At this time, the storm was a beautiful LP, but suffered from a lack of rain-cooled air to add condensation to squared collar clouds.

West of Ft. Morgan, this trend changed. A large rain shaft developed, and the base lowered rapidly, including several rotating wall clouds and needle
funnels that never reached the ground after suffering from cool and blustery RFD, one instance of which reached about fifty knots. This was in Wiggins, where the initial report of a tornado was made. This report
was incorrect—rather than a tornado, a large RFD plume blew up southwest of the meso, and even held a columneque shape momentarily before blowing sand and dirt into our eyes and mouths. This was an understandable error—the plume looked much like the beginnings of a ground circulation but was not.

We followed the storm to Ft. Morgan, then used dirt roads to the north and east, zig-zagging from Brush, then down 34, and finally off the pavement into northern Washington County. The storm was perfectly
balanced and several wall clouds and cylindrical lowerings appeared and disintegrated. During one leg of the pursuit, we looked to the north and noticed a large cone. Everybody shouted “tornado†on the radio
and switched cameras to low-light settings. Frequent lightning from the core illuminated the smooth edges of the funnel and the dust plume beneath. Jeff Gammons rode in the passenger seat of the Weathervine
van and shot good video—his video captures will be up soon on www.weathervine.com -- within the hour, I suspect.

Jason Foster used my camcorder's nightshot to record the event while I drove. I won't have my own captures available until we get a down day.

We pursued the storm another hour before noticing clear skies and crisp starlight on either side of the shrinking updraft column. Tonight we’re in Sterling, Colorado, a group of very happy and tired chasers.

Tonight’s event comes five years to the day after my first tornado. It was also the last day of Raul Benitez’s chase vacation with the Florida gang; he’ll be returning to South Florida on Saturday morning so we were glad to show him his third tornado in a week. We enjoyed chasing with Tony Laubach, Ken McAllister, Garry Wellman, Garry's pal Travis, and a few others along the way.
Fabian Guerra, Pete McConnell, Damon Shaw and I left Omaha at 9AM and headed for northeastern Colorado, arriving in Burlington, CO by 3:30PM mountain time. After checking data at the Burlington library, we saw that we had two choices - go for the cells already firing in SE CO or stay in the Denver area and wait for new initiation in a better environment. After an hour of nothing happening in Denver, we sprang south to catch the cells moving through Lamar.

Caught up to the storms east of Eads, CO and followed them across the state line to Scott City, KS. We knew that these storms were mostly 'scenic photo' material, with little chance of anything becoming severe, let alone tornadic.

As the storms weakened after crossing the Kansas line, we observed many small gustnadoes under the shelf cloud, one of which was spinning a couple hundred feet off of the road. Drove through blowing dust on a few occasions.

Stopped and filmed some shelf cloud/lightning/sunset/rain curtain scenes west of Scott City as the cells continued to weaken:


After dusk, the storms rapidly re-intensified and several severe warnings were issued. We stopped just northeast of Scott City and watched what appeared to be wall clouds and funnels backlit by lightning. We hesitated on reporting these, as the winds were obviously westerly, cold outflow from the storms. WxWorx was showing many 'rotation signatures' in these areas, but they were all along the front edge of the line. Although they likely weren't rotating, they were still impressive, and kept making us look twice just to make sure they weren't what they appeared to be:


Recorded a gust of 34 mph as the cells finally passed overhead.

In all, a good, fun chase. We are currently staying in Colby, Kansas in preparation for tomorrow, most likely in central-northern NE. A thanks to Dave Crowley for nowcasting/updates!
Fort Morgan CO Supercell

Caught a beautiful high based tornadic supercell just outside Fort Morgan CO today, thanks to some great forecasting by my chase partner Shawn Keizer. Got lots of great pics and video and hope to have a full report and images posted once I return home from my chase vacation.

Jay Barnes
Funny no one included Northern IL in all this. Here NW of Chicago, there was a lot of low-based "grunge" cloudiness probably from the very HIGH dewpoint (highest recorded worldwide yesterday) After about 7:30, the grunge seemed to lower and thicken. I had to drive on an errand into Schaumburg at that time. On the return trip, some very LARGE drizzle started making what I estimated as 2 inch-diameter splashes on my windshield. Then some violent stacatto CG's began. By the time I got home, the 3/4" hail was falling with some very loud cannonball thunder. There was lightning in the sky untill shortly after midnight. One cell formed to my north later yesterday evening. The grunge had cleared on the south edge of the storm. I saw some amazing cloud to air discharges as well as anvil crawlers. Quite a few reports of lightning damage around Chicago. Cloud tops to 65K, and very low LCL's (1000-2000 ft) Great storms, ready to do it again today. :) We need a FCST 5/21 thread :wink:
A nice homecoming after many many days on the road. Since Sunday night's NE Colorado chase, I logged 3300 miles before arriving back home Thursday night. That was the highlight of the entire week, and what a highlight it was! With early day coordination between Kenneth (my HAM-alter ego); Amos and Scott along with the Weathervine gang, we all met up in Last Chance, Colorado for what would be my last chance for a few days.

A nice storm formed over the Northeast Denver Metro area and became the lone storm of the night. We trekked north and west along a series of dirt roads and caught the storm Southwest of Fort Morgan. We watched in awe as the hail shafts were being pulled into the mid-levels of the storm. It was an incredibly beautiful sight. We followed the storm south of I-76 as we watched it rotate like a top above us. Tornado Warnings went out when tornadoes were being reported near Wiggins. About this same time, RFDs were kicking up and overtaking the city of Fort Morgan. We stayed til the RFD began to overtake us, cruising east, finally crossing to the north side of I-76 near Brush.

I stopped on a dirt road as darkness fell as the rest of the chase crew began to continue east. I watched the storm pass to my north and east, letting the lightning awe me as it passed on.

I didn't continue the pursuit as my past experience with dirt roads and storms after dark weened me off. I hear a large tornado was sited not too long after that (DOH). Ah well.. it was still an incredible storm! :) Visually, one of the most impressive storms I have ever seen!

Thanks again to Amos for his awesome navigation through the roads to get us in terrific viewing of the storm. Also to Scott Eubanks, the Weathervine team, my HAM alter-ego, Kenneth, Gary, and Travis for great company.

It was great to be in good company this week. I am home to Denver to relax and regroup for the weekend in hopes of a last fling sometime next week. It has been an incredible couple weeks as this has been my first "chase vacation". Since Monday, May 10, I have accumulated 5674 miles over 7 states; bagged 7 tornadoes; seen some incredible sights, and chased with some terrific folks. Hopefully I can get one more week of good chasing in before work returns on June 2. Again, major major thanks to everyone whom I chased with these past couple weeks; Blake, Amos, Scott E., Kenneth, Gary, Travis, Todd, Scott R., the Weathervine gang, and Jerry for his nowcasting among the many others whom I spent many of my Sprint minutes on the phone with. Its been an awesome couple weeks. Maybe one more before I return to work; thanks all!
Am am posting the following report from Jason Persoff, M.D.

So, I woke up in Des Moines (actually just north of there), and was highly troubled by the day's set up. The static front had not proven to be a good focusing mechanism the day before: not enough to bust the cap or focus storm energy, so I thought I'd head to the CO front range due to the orographic benefits and the dryline. CAPE was going to be meager, but the shear looked great. By the time I arrived in McCook, Nebraska, I was horrified to see a TOR watch box up in the area I had just spent 6 hours traveling away from (hate that). Sulkily I looked at the data and had concerns that CO would also be a bust. I decided I'd drive to Yuma, CO, and find a motel to call it a day.

As I arrived in Yuma I had decided nothing was going on and pulled into a motel there. As I got ready to exit my vehicle I noted a sharp vertical line in the air through the haze. I stared at it for a while thinking to myself, "That's a very odd thing: could it actually be a tower?" I got back on the road and saw that the vertical line was indeed a tower...on a storm all by itself...forming on the dryline. I about fell over...Yuma NWR had NOTHING about this storm. So I sped down Hwy34 targeting I-76, and arrived as the storm really got cooking. As I left Akron, I was able to get NWR from Sterling, CO, and was shocked to hear that a TOR watch was effective for the area (SOOOO didn't think that would happen).

I positioned myself on a hilltop overlooking Brush (S of I-76), and watched as the cell evolved from LP to classic in <45 minutes. The storm was very high based and had monster RFD. It appeared that the RFD actually caused the storm to split in the middle. RFD gustnadoes prompted a TOR warning, though I really didn't think these were entrained in the updraft (either of them).

Inflow was intense and the storm rapidly developed a plate-like updraft. The southern split died (occluded?) and the northern updraft moved VERY slowly eastword (I didn't have to move for 2 hours!).

After dark, the storm began to take on outflow characteristics. I was able to see numerous condensation funnels and some debris clouds. Still, the more I look at it, the more I'm convinced that these were more likely gustnadoes. The reason I say this is that there were brisk outflow winds right immediately south of the updraft base (by this time I was due east of Brush, south of I-76 by about 10miles). These condensation funnels, though, were likely attached to the updraft and so would be considered tornadoes. [these reminded me of gustnadoes I'd seen several years ago in Turkey, TX, that formed at the intersection of the updraft and RFD]

I got plenty of video. The storm was remarkably electrically active--especially during the "tornado" formation when no less than 2 bolts/sec were visible. A lot of it was sheet lightning, and not CGs, but it was almost as active as the Pampa, TX storm 2 years ago.

Settled down in Sterling, CO. It was then that I found that I had bumped my SLR from autofocus into manual focus and that resulted in blurry post-dark photos (bah!). Nevertheless, there are some good photos in the mix (though I'll be more careful about the focus in the future :)).

Updraft during LP phase

High based funnel with RFB

At this point the FFD provided ample return and lift and can be seen here getting entrained into the updraft base

Knuckles appear on the rapidly-developing back sheared anvil

Storm splits with a clear slot occluding the southern updraft

Plate-like appearance of the northern split as it streams overhead

Just a pretty picture


Out of focus, but a definite feature confirmed on video. Note that it is forming at the convergence of the updraft and RFD

Again, out of focus. Taken two minutes after the first photo. The location would be approximately 25miles NW of Akron, CO

Target today: Valentine, NE :)


Jason Persoff, MD
Originally posted by Bill Hark
Am am posting the following report from Jason Persoff, M.D.

After dark, the storm began to take on outflow characteristics. I was able to see numerous condensation funnels and some debris clouds. Still, the more I look at it, the more I'm convinced that these were more likely gustnadoes. The reason I say this is that there were brisk outflow winds right immediately south of the updraft base (by this time I was due east of Brush, south of I-76 by about 10miles). These condensation funnels, though, were likely attached to the updraft and so would be considered tornadoes. [these reminded me of gustnadoes I'd seen several years ago in Turkey, TX, that formed at the intersection of the updraft and RFD]

Our video of the tornado about 9:45 Central Time is pretty convincing, with a congruent funnel and a debris cloud at the base. I wish I had time to do captures and post them, but I don't. We observed this torndo north of Akron and south of Sterling, in northern Washington County. Maybe we'll have a chance to post some grabs tomorrow.

Here's Jeff Gammons' quick caps from Washington County Colorado about 9:45 Mountain Time, about ten miles north of Akron, CO.

My video, which was shot by Jason Foster, shows the entire updraft with the tornado underneath. I'll have those up later this week; right now we're in York, Nebraska waiting for the outflow boundary in southern NE to light up.