2008 CHASE ACCOUNTS
APRIL 24, 2008: NORTHWEST KANSAS (SUPERCELL)
Brian Thalken and myself observed a long-lived supercell in northwest Kansas. After finishing supper in Arapahoe, NE, we saw on radar several cells showing signs of intensifying within a region of steep low-level lapse rates south and north of Goodland, KS. One of these storms quickly displayed supercellular characteristics east of Goodland, which we quickly decided to target. After maneuvering through a series of farm roads, we eventually reached highway 36 east of Oberlin, KS. We then gained a position between Oberlin and Selden on highway 83 (time was ~7:30 pm CDT), and parked directly east of the approaching supercell (this was our initial view of the storm). The storm was developing mid-level inflow bands, but was also high based due to the rather limited low-level moisture and steep low-level lapse rate environment. We hoped that as it moved east into deeper moisture, the storm would further intensify...we also knew that low-level shear/hodograph curvature was forecast to increase substantially by sunset...so we remained patient. By 7:50-8:00 pm, a second storm approached and merged with the storm that we were observing. It was after this merger took place that things really got interesting. Surface inflow steadily increased as we moved south down to Selden, KS (estimated to be around 40-50 mph), and mid-level rotation became much more apparent (inflow band picture #1, inflow band picture #2). The storm started taking a hard right turn, and by 8:30 pm, a large wall cloud began to develope (see picture here) as rain cooled air was pulled into the updraft base from the forward flank downdraft positioned to the north. We both believed (as I'm sure everyone else did as well) that the storm was getting very close to producing a tornado. However, a cold surge of outflow rapidly undercut the updraft base, causing the wall cloud to dissipate and the storm to accelerate further to the south and east. Interesting mid-level inflow features were still present (such as the one here) though, and new wall clouds formed every 10-20 minutes. We then made our way to highway 24 east of Hoxie, KS. A new mesocyclone developed east of the old one as we went south, with updraft rotation further intensifying and taking on a horseshoe shape. Darkness began to set in as we approached Hill City, KS...with photography becoming more challenging. Plus, I had to work at 8:00 am the next day...so we gave up on this storm just before it moved through the Hill City area (~9:30 pm). The storm continued to move east across northern KS through the night, and produced a 1/2 mile wide EF2 tornado near Beloit, KS at around midnight. Regardless, Brian and I were happy with what we saw...it was a great way to start off the 2008 season.
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MAY 5, 2008: WESTCENTRAL KANSAS (SUPERCELL)
Brian Thalken and myself chose a target along an outflow boundary oriented northwest to southeast (located north and east of Garden City, KS). We reached this location by mid afternoon, shortly after thunderstorm initiation took place. We had to deal with two storms located in close proximity to each other (both displaying occasional supercell characteristics). The northern storm had a large rain free base and dark forward flank precip core (see picture here and here), while the southern storm displayed a somewhat flanged base and slightly better visual indications of mid-level rotation (see picture here, and here). Rotation within the southern storm continued to increase through 5:30 pm (CDT), so we left the northern storm and gained a position directly in the path of the southern (picture of mid-level inflow band). As we moved southeast along highway 50, we began to hear reports over the radio of softball size hail falling back to the northwest over Garden City (all we observed on the southeast side of the storm were dimes). This picture shows what the storm looked like at around 6 pm as it was producing large hail at GCK (note the stinger shaped inflow band here and here). We could still observe the northern storm (through a veil of rain) and noted a developing wall cloud, which eventually (6:45 pm) developed into a large lowering that we thought was almost in contact with the ground. However, we could never verify whether a tornado was in progress. Meanwhile, the southern supercell became progressively cold and outflow dominant as it moved toward Dodge City, KS. We gave up on the cell during this stage, and went back to Garden City to observe the hail damage (where 4 inch piles of hail drifts were still present on the ground).
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MAY 6, 2008: WESTCENTRAL KANSAS (HIGH BASED SUPERCELL)
Started the day off in Garden City, KS, trying to decide whether to target the KS/NE border, SW Kansas, or west central KS. Early afternoon TCU's a county or so to the west and a maturing storm crossing the KS/CO border convinced us that west central KS would work. A high based multicell developed 30 miles to our west by 3:30 pm (CDT)...so we drove about 10 miles north of GCK, and then west towards the updraft base (which was initially hidden behind a veil of glaciated anvil). By 4 pm, we were directly in the path of this developing storm (here is one view looking west/southwest), and interestingly, a brief surge of outflow from the storms rain core to the north pushed south and appeared to initiate broad cloud base rotation. This rotation continued to intensify during the next 30 minutes, and was fascinating to watch given we were almost directly under the base (view of the agitated rotating cloud base). A clear slot and RFD developed by 4:30 pm, kicking up large amounts of dust to our west and south, as well as numerous gustnadoes (developing gustnado to our west/northwest). The RFD also caused the storm to accelerate to the east, which eventually led the gustnadoes to begin chasing us down a series of farm roads. We eventually maneuvered east of highway 83 (going down the same farm road we were on the previous day), with a wall cloud quickly developing by 4:55 pm (here). A funnel was briefly produced beneath this wall cloud, but disappeared along with the lowering in a matter of 5 minutes. The storm progressively took on a cold look during the next hour, but mid-level updraft rotation was still observed, as a weak flanking line wrapped cyclonically into the main updraft tower (here). We eventually gave up on this storm (~6-7 pm time frame) as it morphed with neighboring cells into a squall-line/bow echo. As we began the drive back home north on highway 83, we got a chance to obtain some decent mammatus photography (here, here, and here).
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MAY 22, 2008: NORTHWEST KANSAS (5 TORNADOES)
Brian Thalken and myself decided to target the I-70 corridor just south of Hoxie, KS. Our plan was to pick up new cells moving north toward that location, follow them to the north side of a warm front aligned east-to-west (where low-level mesocyclogenesis would take place), and then leave the cell as it moved north into colder air and catch a new cell as it moved north toward the same location. This strategy yielded five tornadoes, produced by 3 different supercells. The first supercell we observed (here) was located 10 miles southeast of Grinelle, KS. It had some interesting scud-like fingers (here) dangling from the base which eventually consolidated into a big wall cloud (here, and here). However, visibility was poor beneath the updraft base, and we quickly left this storm after it crossed I-70. We then repositioned south of Grainfield, KS (time was ~5:10 pm CDT) and picked up a new supercell about 10 miles south of the interstate. This storm rapidly developed a classic wall cloud, followed by a strong occlusion that led to a divided mesocyclone. The clear slot continued to eat away at the base of the updraft, which eventually focused a new area of cloud base rotation on the northeast side of the base (here). A horizontal funnel soon developed at the updraft/downdraft interface, and the RFD then appeared to re-orientate it into a vertical position, producing a funnel that occasionally produced dust whirls at the surface ("touchdown" was at around 5:25 pm). The developing tornado (and here) continued to move north toward Grainfield, then crossed I-70 (~1 mile west of Grainfield) at which point it developed into a slinder elephant trunk tornado (here, here, here, and here) that was in contact with the ground until it roped out (~5:48 pm).
Believing that the tornado threat was over with this supercell (we were wrong, it went on to produce several large tornadoes), we headed back south to intercept the next supercell. By 6:11 pm, we were approaching a very large rain free base with a massive clear slot/RFD and large wall cloud about 10-20 miles south of Collyer, KS. The wall cloud was displaying strong rotation, which soon extended to the surface and filled up with dust and rain (picture here shows the large clear slot, RFD winds kicking up dust, and tornado filled with dust and rain on the right side of the image...time is ~6:20 pm). The tornado and RFD appeared to be moving toward our location, so we repositioned east on a county road. We then noticed a new tornado forming beneath the east side of the RFB (~1 mile to our south). It was weak, and appeared to dissipate...however, as we attempted to get east out of its way, I began to notice my ears popping and an increase in wind gusts. Apparently this weak circulation passed right over us, because in a matter of 1 or 2 minutes, we looked northwest across a field and saw a debris cloud with a funnel dangling beneath the updraft base (here). Its possible that this was an anticyclonic tornado due to its location with respect to the cyclonically rotating low-level mesocyclone. We then followed this supercell slightly behind and to the east of what was now very intense low-level rotation. We were anticipating the development of a wedge on the magnitude of Hallam or Greensburg (based on the width and intensity of the rotating wall cloud). While driving north, we observed another tornado embedded back within the clear slot (~5-10 miles to our west). As the storm crossed I-70, its RFD quickly filled with precip (here), and therefore we quickly gave up the pursuit. We then headed south to I-70 once again, monitoring weak-looking storm activity to our west.
We began to get the impression (or at least I did) that the chase was coming to an end. However, there was one more cell way down to the south that we wanted to let intensify and move north, hoping that we would get one more tornado before sunset. We drove east to Wakeeney, got gas and food, and then reassessed the environment that this southern storm had to work with. Ingredients still looked good for tornadoes, which seemed to be confirmed by a tornado warning the second we got on highway 283 to drive south toward the storm. As we approached the updraft base, we soon spotted another fairly classic looking wall cloud, with a long tail-cloud streaming in from the north (here). Lightning was occurring in close proximity in every direction, and the sun was setting, so that wall cloud picture was the last photo-op of the day (but video was still good...time was ~8:26 pm). The wall cloud was soon infiltrated by RFD winds from its back side, and this set in motion a processes of vortex intensification as the RFD contracted around the broadly rotating low-level meso. As we were repositioning toward the northeast, a large cone shaped funnel extended toward the ground. It was quite a site to have this developing tornado fill my rearview mirror as I was quickly moving east away from the location. Just after the cone shaped condensation funnel made contact with the ground, rain curtains rapidly wrapped around the tornado, and our view was blocked. More excitement was on the way though! The storm was turning sharply right (possibly due to a change in upper-level flow during the evening), which seemed to favor a quick transition to an HP supercell. For those of you who chased near Concordia, KS on May 29, 2004 and were caught by that land-hurricane of an HP supercell...this was a repeat of that experience. As we reached the intersection of I-70 and highway 283, we were quickly engulfed by near-hurricane force winds with quarter size or larger chunks of hail. What was worse is the fact that we knew there was probably a rain-wrapped tornado moving northeast toward our location. So I decided to jump on I-70 and drive through the landcane away from the most likely path of the rain-wrapped tornadic circulation. It was a huge relief to eventually see the outer edge of the rain-filled RFD...and our day was done.
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JUNE 1, 2008: NEBRASKA PANHANDLE/NORTHEAST COLORADO (LONG-LIVED SUPERCELL)
I intercepted a developing supercell (initial view) 20 miles southeast of Bridgeport, NE at around 5:40 pm (CDT). This storm had a large rain free base (here), which was beginning to produce an agitated region of ingested scud by 5:50pm (here). As the storm continued to intensify and develop stronger mid-level rotation, it began to turn more sharply to the right. So I began to move back to the south on highway 385. A ragged wall cloud began to develop (6:40 pm) as I did so (here), and began to grow in size during the next several minutes (here), though rotation was still fairly broad. A tornado warning was now in effect for this storm, and the wall cloud became more impressive (here, here, and here). Interestingly, scud was being sucked off of the ground immediately to my southwest (here), which was fascinating and a bit intimidating (given this area was closing in on my position quickly). In order to stay close to the updraft base, I decided to go east on a county road near Dalton, NE (luckily I didn't get lost), and occasionally observed gustnadoes forming along the flanking line of the supercell (which apparently led to a bad tornado report later in the day at sunset). While driving through the backroads of the NEB panhandle, I was able to capture a few scenic pictures of the countryside with the storm in the background, such as this one. I eventually reached Lodgepole along highway 30 by 8:06pm, and had a nice view of the storm while moving east (here). Six minutes later while moving through Chappell, NE, broad cloud base rotation increased again, with a beavers tail noted off to the northeast and a hail-filled precip core off to the north (see picture here). While driving south through Julesburg, CO, I finally gained a better position to take in the full structure of this supercell (here). I continued moving south of Julesburg by a few miles, and was able to observe some incredible storm structure at sunset--complete with a newly formed wall cloud at the base and a laminar inflow tail streaming into the storm from the east (here, here, here, here, and here).
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JUNE 2, 2008: NORTHWEST KANSAS (BUST)
Not much to say about this chase. Brian Thalken and myself waited for initiation over CO/KS/NEB Panhandle in North Platte. We saw a supercell blow up near the CO/KS state line during mid-afternoon...so we decided to race south to intercept. This storm was reportedly producing hail up to the size of grape fruits as we were driving. By the time we got in front of the cell (or at least underneath its anvil) it disappeared into thin air. A lack of large scale forcing/destabilization and persistent cirrus over its source of instability were probably largely to blame for its short lifespan.
JUNE 11, 2008: EASTERN NEB/WESTERN IA (SUPERCELLS/LINE SEGMENTS)
I followed a supercell with Brian Thalken into Elkhorn, NEB during the late afternoon. This storm had an impressive wall cloud for awhile, but new storms to its immediate south likely disrupted/prevented tornadogenesis (by dumping precip into the updraft). With Omaha looming just to the east and a strong storm to the west, we decided to move into Iowa (in order to prevent being trapped in case the storm produced a tornado). Near the intersection of I-680 and I-29, we observed a new storm which quickly developed a rotating wall cloud. However, this storm was merging with the other off to the southwest, and we had to move south in order to avoid being ingested by this bowing line segment. Another storm became tornadic in western Sarpy county, so we maneuvered toward that location, making it just in time to observe the low-level mesocyclone become filled with precip. We followed this cell to Plattsmouth, NEB, but couldn't continue east due to the Missouri River and a closed bridge. It was now night, and everything looked outflow dominant, so we gave up the chase and returned home.