2007 CHASE ACCOUNTS

FEBRUARY 20, 2007: SOUTHEASTERN MISSOURI (SPLITTING STORMS)

Adequate low level moisture and mid-level lapse rates became collocated in front of a weak cold front over southeastern Missouri today--coupled with very strong deep layered vertical wind shear...thus, when I saw convective initiation taking place, I decided to go take a look.  As I approached Sikeston, MO, a long anvil became apparent, originating from a cluster of storms just to my west.  The linear shear profile led to splitting storms today.  I managed to take a few pictures right before sunset of a right moving storm northwest of Sikeston, although the left split looked much more menacing (which went on to produce a long swath of large hail for a few hours).  It was nice to see a little storm structure in February, as well as quite a bit of lightning.

MARCH 31, 2007: SOUTHEASTERN NEB/SOUTHWESTERN IA (SUPERCELL)

I managed to reach southwestern IA around noon, just as a tornado watch was issued for the area.  Storms rapidly developed around the Nebraska City, NE area, displaying occasional supercell updraft structure.  I then drove east to the intersection of I-29 and highway 2 on the Iowa side of the Missouri River.  A storm rapidly intensified along the intersection of two boundaries, and developed a strong rear-flank downdraft.  This storm appeared to develop strong low-level rotation, and I decided to follow it north on I-29.  The storm went through a possible occlusion as it approached Omaha, NE, but rain quickly started falling around its updraft base and took on a 'cold' look.  I then let the storm go as it moved north past Council Bluffs, IA.  The setup today appeared to fit Jon Davies closed mid-level low pattern at first glance; but on closer inspection, a strong surface heat axis didn't really develop south-southwest of the surface low, possibly due to widespread showery cloud cover on the "dry" side of the pacific front.  This may have had a negative impact on possible tornadic activity.

APRIL 23, 2007: SOUTHWEST KANSAS (5 TORNADOES)

I started the day off in far western Oklahoma, and after a forecast update from Brian Thalken and Ryan Presley, decided that the northeast corner of the TX panhandle looked like a good place to hang out.  I arrived in Perryton, TX by 3pm, and watched an agitated Cu field evolve off to my west.  By 4pm, I decided that southwestern KS might have a better shot at significant severe weather due to stronger backing of the surface winds, so I headed north on highway 83, and reached Liberal, KS by ~5:30pm.  Weak updrafts were developing, and struggling to mature at this point.  I decided to follow a mushy looking cell northeast, but it was not showing signs of intensifying, so I then decided to race east toward Dodge City, KS and then head south on highway 283 in order to intercept a storm that was producing quarter size hail.  I punched through this cell at ~7pm, but the south side of the storm was also mushy, and seemed to be associated with a strong area of warm air advection/isentropic lift.  Things were getting a bit depressing for awhile, but I soon learned of a tornado warned cell moving northeast through Harper County Oklahoma, and I realized that I could intercept it as it crossed the KS/OK border.  So I moved south toward Sitka, KS (Clark County KS), sat in the storms rain core for 10 minutes, then decided to head further south through the core, sat south of Sitka for 5 minutes, then decided to turn around and move east along highway 160 toward Protection, KS (Comanche County KS).

As I drove east toward Protection, KS, I had to punch through the region of the storm with the most intense rainfall and hail.  Hail stones were easily 2 inches in diameter--any larger and I probably would have lost my windshield.  After 5 minutes of core punching, I emerged from the heavy rain, with only sporadic large hail stones falling.  I was directly to the north of the storms low-level mesocyclone.  I could see a long rain free base (RFB) to my south, with two bowl shaped lowerings, and a massive "vaulted" appearance to the updraft towering above the RFB.  A tornado quickly developed out of the eastern meso--it was a thin rope like tornado that was slowly being absorbed by a stronger meso ~2 miles to its west.  I moved about a mile east in order to let the western circulation cross the highway.  This circulation quickly contracted into a small barrel shaped tornado as it moved over hwy 160--there was strong cascading motion on its eastern side which seemed to bring the circulation and condensation funnel down to the ground.  A tornado shaped like an elephant trunk then formed about 4 miles west of the second tornado, and lasted for about 10 minutes.  A fourth tornado then formed 2 miles east of the 3rd tornado, and became wrapped in a thin veil of rain--this tornado was also shaped like a small thin cone.  A fifth slinder tornado then formed several miles east of tornado number 4, but only lasted about a minute.  The base of the storm continued to rotate as it slowly moved northeast of my location (and just northwest of the town of Protection, KS)...the storm almost produced a 6th cone-shaped tornado, but condensation never developed at the surface, and I could never verify debris or dust being kicked up (so I won't count that one, although it was 1/2 way to the ground).  The 'tornado window' lasted about an hour, and then rotation at the base of the storm steadily weakened.  Due to poor lighting and a rapidly evolving situation, I was only able to shoot video.  I let the storm go as it moved north of Protection, KS, and repositioned back toward Wichita, KS for the next days action.

APRIL 24, 2007: SOUTHCENTRAL KANSAS (2 TORNADOES)

I got lucky again west and north of Hutchinson, KS today.  A storm went crazy during the late afternoon--I nearly passed it up in order to make the long drive back to Paducah, KY, but gave it one last chance (I was well rewarded for my patience!).  I started the day off in Wichita, KS, gathering data in my hotel room.  Deep shear vectors were pretty much parallel to the dryline from TX north into KS, which seemed to hint at an early transition to a linear mode of convection.  The dryline seemed like it might arc back to the northwest over KS (which could increase the crossing angle between the line of forcing and shear vectors, favoring a more discrete mode of convection), and a surface low was forecast to deepen in southwest KS resulting in stronger backing of the low-level flow--so I decided to stick around southcentral KS, and drove west to the intersection of highway 54 and K14 (just west of Kingman, KS; ~2:45pm).  Skies rapidly cleared over this location, and the Cu field along the dryline began to perk up in response to the insolation.  Solid looking towering cumulus would occasionally develop, but then die off--this process continued through 5pm.  Once again, I was getting nervous that the day would be a bust, and considered taking off for home.  By 5:15 pm, I had repositioned to the intersection of highway 50 and K14.  A newly developed storm intensified and was producing an anvil.  Several other cells were forming to its south/southwest, so I raced west on hwy 50 toward the base of these storms.  A broken line of storms developed by 5:30pm, and by 6pm, a storm developed a strong inflow band feeding into its base.  This cell was moving north into the precip core of a storm downstream, and it soon weakened.  I let this storm go and went back south, eventually passing through the forward flank precip core of an LP'ish looking storm.  Once I reached highway 50, I decided to head east away from the updraft, contemplating leaving all of this 'weak' convection behind.  For some reason, I decided to pull off the highway 2 miles east of the storm in order to take some structure shots (see here, and here).

At around 6:45pm, this storm started to develop a small clear slot at the rear of its updraft.  The clear slot continued to notch around the updraft (here) as rotation intensified (here).  At ~7pm, a small funnel developed at the base of the rotating updraft (here), and started 'reaching' down toward the surface (here).  I heard reports over the radio that dust whirls were observed at the surface, but the funnel soon dissipated, although the broad scale rotation at the base of the storm was still strong.  The low-level mesocyclone reorganized during the next few minutes (here), and another weak funnel developed (here).  Rotation grew stronger, and dust was again observed at the surface (here and here).  The condensation funnel evolved into a cone shape (my favorite shots here and here), and the dust whirls tightened up into an intense vortex at the ground (although only briefly--dust whirls start to dissipate here).  The storms low-level mesocyclone started to occlude by 7:40pm (here), and rotation at the base of the storm weakened quite a bit (although a brief vortex reformed along the intersection of the rear-flank gust front and main updraft base).  I then raced off to the east in order to take a few more shots of the updraft structure (here and here).  There were at least 100 or so cars scattered across the county, and everyone was repositioning toward the northeast--it was obvious that the storm was considerably weakened and probably no longer a tornado threat, so I decided that I had my fill of chasing for the day, and took off in the other direction toward Hutchinson.  It is worth noting that thunderstorms north of the eventual tornadic cell put down quite a bit of rain--the southern cell then intensified and moved across this swath of precipitation.  The rainfall may have laid down a low-level thermal boundary, aiding in tornadogenesis as the southern cell moved north across the area--just something to point out. 

MAY 4, 2007: NORTHCENTRAL KANSAS (SUPERCELL)

Brian Thalken, Jeremy Wesley, Ryan Presley, and myself left Hastings, NE during the late morning, targeting an area northeast of Dodge City, KS.  We arrived in Kinsley, KS at around 3pm, and began the long wait for convective initiation.  We were sitting on the nose of an axis of steep low-level lapse rates, with a very unstable atmosphere in place coupled with strong vertical wind shear.  The atmosphere was primed for intense deep moist convection-the only caveat was a layer of warm air at around 700 mb.  Cooler mid-level temperatures were indicated by the RUC over far southwestern KS, and would reach our area by evening.  A Cu field was present east and north of Kinsley, which made us re-think our outlook on where convective initiation might take place.  We repositioned northeast toward Great Bend, KS, and at 6pm, decided that initiation was most likely to our north.  At 6:30pm, a large towering Cu erupted over Smith County, KS-so we raced toward it on hwy 281.  As we entered Osborne County, KS, a large back sheared anvil became apparent with a trailing flanking line feeding the main updraft tower (here and here).  We finally gained a position east of the updraft base in Smith County at the intersection of hwy 9 and 281 (time was ~8pm).  Updraft rotation was quite obvious, with a large bowl shaped rain free base and a long beavers tail feeding into the northern portion of the updraft (here, here, here, and here).  Low-level rotation quickly strengthened, which must have induced a downward directed vertical pressure gradient force, because the updraft quickly occluded, leading to a divided mesocyclone-like structure.  The storm was moving through a thin veil of broken stratus, which likely indicated the presence of significant convective inhibition-this seemed to be a negative factor toward the development of a tornado.  We then drove north through the storms hail core as the rotating updraft approached, and ended the chase east of Smith Center, KS with a vivid lightning display to our north.

Meanwhile, everyone is aware of what transpired back to the south.  We were too far out of position to retreat back to the south and intercept the massive supercell that initiated fairly close to where we had initially targeted.  It is obvious now that the approaching mid/upper level speed max from the southwest rapidly backed the low-level flow, bringing the high theta-e airmass westward...once it hit the axis of nearly dry-adiabatic low-level lapse rates, violent convective initiation occurred--the rare combination of very large CAPE and strong deep and low-level wind shear resulted in the violent tornadic supercell.  I hope for a speedy recovery for the people of Greensburg and the surrounding region.

MAY 5, 2007: SOUTHCENTRAL KANSAS (TORNADO)

Ryan Presley and myself spent the night in Concordia, KS-we woke up to a high risk over most of the high plains of Nebraska and Kansas.  After a data check, we decided on a target around the Jetmore/Ness City, KS area.  We reached the city of Hays, KS at around 1pm, and then went south on hwy 183--passing by marginally interesting convection every 30-minutes or so (here).  All of the updrafts we observed to this point would briefly intensify before turning to mush, which was likely a function of early convective initiation and a veil of cirrus that stretched east as far as the eye could see.  At 2:45pm, we encountered a storm that displayed significant bowing (here), but it did not appear to hold much tornadic potential.  So we continued south to hwy 50, and began heading east.  This chase appeared to be heading downhill in a hurry, and a long drive back to Kentucky still loomed large in the back of my mind.  At 4pm, radio reports noted a strong storm developing over Kiowa County, KS (which was to our south)--at 4:30pm we approached Stafford, KS, and observed the large storm to our south, which had a nice updraft tower with a massive anvil spreading out to its north and east (here and here).  We quickly decided to take a county road south toward the base of this storm, and within 10 minutes we could observed the rain free base, and a cone shaped funnel extending about half-way to the ground.  We pulled up next to the base, and observed scud rapidly ascending into the RFB (here).  We moved east and north several miles, and low-level rotation quickly strengthened, with a violently rotating wall cloud (here, here, here, here, and here) occasionally producing vigorously rotating vortices at the surface (~5:18pm).  We then re-entered the town of Stafford, and moved north and east one mile.  The storm produced an amazing rotating wall cloud over Stafford at ~5:31pm (here and here).  We then had to move through a maze of different roads in order to keep up with the storm, and ended up near the town of Lyons, KS.  The storm apparently produced another tornado while we were driving through an area of trees, but it had generally weakened as we reached hwy 56 (~6:40pm).  

Another tornadic storm was approaching Great Bend, KS (~6:43pm), so we repositioned back towards the west, and intercepted this storm as it moved along hwy 156 (~7:12pm).  Rotation was quite obvious within a rain-wrapped wall cloud, with thin rain curtains dancing around the base of the storm.  We then let this storm go, and approached another tornado warned storm near Seward, KS at around 8:40pm.  It was very dark at this point, but we could observe a lightning-lit lowering--we couldn't make out any rotation, and decided to end the chase shortly after that point.   

MAY 27, 2007: WESTERN NEBRASKA (TORNADO)

 Brian Thalken and myself picked a target of Ogallala, NE today.  We arrived during the early afternoon as thunderstorms began to develop to our south.  We drove further west to Big Springs, NE, then decided to hop on a severe warned cell that was moving northeast out of Colorado.  As we punched through the core of this cell (south of Ogallala), it seemed to be weakening.  So we blew the cell off and decided to target an isolated storm that was northwest of Lodgepole, NE (here).  As we gained a position ahead of the storm, it started to display a nice anvil, which likely indicated strong updraft growth from below.  Not soon after, a landspout tornado developed underneath the southern updraft flank.  This tornado lasted ~5-10 minutes, with the bottom portion moving quickly south (due to a surge in the storms gust front?), while the funnel attached to the updraft base remained stationary to the north.  After this activity dissipated, we decided to head north into the sandhills so we could observe a developing supercell.  This storm turned out to be an LP supercell, and we were able to get some decent photography before the storm shrivled up right before sunset (as so many LP's seem to do).

MAY 28, 2007: SOUTHWEST NEBRASKA (HP SUPERCELL/MULTICELL HYBRID)

Started the day in southwest South Dakota.  The pattern did not appear to be evolving favorably, so drove back south to North Platte, NE and observed a storm that took on HP supercell characteristics at times, but overall looked more like a multicell.  Brian Thalken and myself got a few pics of this storm as it developed some mid-level inflow.  We then left the storm to head back to Lincoln, NE just as it developed strong low-level rotation (which the NWS promptly issued a tornado warning for).  This rotation did not last long, and we continued east toward home.

June 6, 2007: NORTHCENTRAL NEBRASKA (SUPERCELL)

JUNE 7, 2007: EASTERN IOWA (SUPERCELL)