Saturday, June 29, 2013

6/28/2013 High-based Supercell north of Seibert, CO

After awaking in Wichita, KS, we targeted northeast Colorado for a low probability of high-based supercells. The environment was characterized by a moderately unstable air mass (mostly due to steep low-level lapse rates. With such low surface dewpoints (upper 30s!), it was uncertain if any storms could become severe. While coming up on Burlington, CO, we noticed some towers to our immediate northwest. We turned north out of Seibert, CO, and latched onto a rapidly developing severe storm on state route 59 north of Seibert. We proceeded to chase this cell for a little over four hours! The storm displayed nice high-based structure and a very cool hail curtain. In fact, we sampled the hail curtain (when I felt the VIL was down to appropriate levels) and were able to find hail up to penny size. Overall, Friday was a successful and quite photogenic high-plains chase. Overnighted in Colby, KS.
Cool hail curtain north of Seibert, CO

Pretty high-plains sunset

Timelapse of the storm

Thursday, June 27, 2013

6/27/2013 Beloit Bomber

BLOG has been quiet as of late (usually a good sign for those who dislike severe storms), but our last CoD trip of the year had a pretty exciting day in north central Kansas on Thursday.  A convective outlook upgrade to a moderate risk for severe storms was in place by late morning, owing to large values of atmospheric instability and vertical wind shear.

We started the day in Lincoln, NE (Fairfield Inn) with an understanding that there would likely be ongoing convection in/near our area.  This essentially meant that we would have to drift southwestward to play a potential outflow boundary leftover from these morning thunderstorms.  After watching a fairly unimpressive elevated storm near Fairbury, KS, we booked it west toward Smith Center, KS, where towers were rapidly developing on the nose of steeper lapse rate air advecting from the southwest.  We didn't really expect the tornado threat to be too high this day as temperature and dewpoint spreads were unfavorable for tornadogenesis.  However, we were treated with nice supercell structure near Beloit, KS by late afternoon.  This storm had a "I'm about to do something nasty" appearance, and we were careful not to get to close this HP monster.  As we tried to stay ahead of the storm (now heading south on RT. 14), a barrage of some of the most intense CG lightning I have ever seen began to bombard us from all quadrants.  It was too dangerous to get out of the vans and try to take pictures but I assure you it was something out of a sci-fi movie.

As these storms began to congeal into a mesoscale convective system, we did our best to stay ahead of them by driving south on I-135.  We periodically stopped along the way for quick picture grabs, but the complex was easily keeping up with our interstate speed.  We found shelter along a sturdy brick building in Witchita, KS, before finally letting the complex move overhead.  Dang!  This line of storms snapped a 10" diameter tree branch right in our view (see video soon) and caused numerous power flashes.  We estimate that the winds were roughly 70 m.p.h. at this time, but it was hard to get exact measurements with so much surface friction in the downtown area.  Overall, not a bad day!

Overnighting in Wichita, KS.

About as close as this storm could come to tornadogenesis
Near Beloit, KS, looking west
Interesting shelf features
CG lightning as storm begins to surge to the southeast

Tuesday, June 18, 2013

6/14/2013 Dodge, NE Supercell

Walker and I targeted the area between Norfolk and Columbus, NE on this slight risk day. This region had strong surface convergence, moderate instability, and sufficient shear for supercells. The only concern was the strong capping inversion, which had us waiting in the Humphrey, NE park for a lengthy part of the afternoon. As strato-cumulus clouds took over, we became increasingly concerned about (the potential lack of) storms firing in our target region. We actually began to bail south toward less organized storms and, not even 10 minutes later, the first radar echo appeared northeast of Humphrey. We returned north and intercepted the slowly maturing storm near SR-91 and SR-15. The storm slowly matured into a majestic stack of plates supercell with numerous cloud-to-ground lightning strikes. The slow moving storm provided eye candy for a good hour or so, before convection to the south interacted with it, causing it to become increasingly disorganized. We punched west and then southwest toward Grand Island, stopping to take in a bit of lightning after sunset near Central City, NE. The night ended at a Fairfield Inn in Grand Island, NE (text modified from Walker Ashley).

Beautiful stack-of-plates supercell structure

Time lapse of the supercell

Monday, June 17, 2013

6/13/2013 Woodrow, CO Convection

Walker and I left DeKalb around 5 AM central with an initial target near Sterling, CO.  We weren't expecting supercells given the lack of vertical speed shear, but we thought storms may showcase an interesting view around sunset in eastern Colorado.  After dropping south out of Brush, CO, commencing a heckuva long drive on I-80 W, we soaked in a pretty view of developing convection near Woodrow, CO.  These storms provided a spectacular high-plains view for the next hour, before we slid east to stay ahead of the surging outflow winds.  These winds kicked up plenty of dust, including a few gustnadoes (see below).  We spent the night in Ogallala, NE, reminiscing about the spectacular scenery.

Mammatus on the high plains...ahh...

More mammatus

CG lightning strike

Bracketed exposure; probably one of my favorites so far this year
One of several gustnadoes observed
Timelapse of the day's convection

Friday, June 14, 2013

6/12/13 Mount Carroll, IL Tornado

Wednesday featured the first High Risk for severe storms across northern IL in nearly a decade.  It was nice to not be in a morning rush to get to a target area, as this was clearly going to be a "backyard" chase day.  I trekked over to DeKalb, IL around noon to pick up Walker Ashley (NIU; prof), Stephen Strader (NIU; Ph.D. student), and Matt Piechota (CoD; met student).  After glancing over some data, we jogged west toward Shannon, IL as a focus for an initial target.  Convection was beginning to form in all quadrants, and we wanted to make sure to "pick" the right storm.  We spent a few minutes time-lapsing a multicell storm southwest of Rockford, before heading toward the Rockford metro to latch on to a cell with a little better appearance on RADAR.  This new cell was quickly swallowed by a left-split produced by a supercell in southern DeKalb county (an impressive storm in its own right!).  We finally pit-stopped in Stockton, IL to grab a quick sandwich and monitor the RADAR.  While we were about to cut our losses and head back home, a new cell moving out of extreme eastern IA exhibited an interesting appearance and was drifting toward Jo Davies county in Illinois.  This area is less than ideal terrain for viewing storms, but it was really the only storm worth viewing at this point.  We latched on to this storm on Elizabeth road, roughly 8 miles northwest of Mount Carrol.  After finding a ridge to view from, it was clear that this storm exhibited numerous supercellular characteristics. We watched as a tornado formed (or perhaps was already in progress) roughly 7 miles to our northwest (still on Elizabeth road at this time).  We watched this tornado for ~10-15 min. before loosing sight of it due to poor terrain.  The next visual we had on the storm confirmed that our day was probably over.  Cool outflow was present at the surface, and it was clear that the storm was choking itself off. 

Oh, we still made it home to watch the Blackhawks play! 
Wide-angle view of the tornadic supercell northwest of Mount Carroll, IL (courtesy of Walker Ashley)

Initial view of the tornado (rain was making it difficult to see)

Look close and you can see debris in the sky...We later found out this was producing EF2 damage
Walker's Time-lapse

Matt's Video