Sunday, June 28, 2009

06/27/09 Central Illinois Linear MCS

Linear MCS north of Annawan, IL

Saturday, consisted of a very short local chase in Henry County, IL along I-74 and I-80 to intercept a very healthy MCS as it crossed the Mississippi River. Originally, I planned on targeting an area north of Davenport, IA, but with such "marginal ingredients" i.e. shear-wise I decided to nowcast from home most of the day instead. As far as the target: Well, as initiation occurred near Anamosa, IA a supercell did develop with a brief hook, but was undercut by its very own outflow. If there was gonna be a tor report on this day that's where it would have been. Anyhow, convection continued to congeal and I followed the MCS along I-80 for the most part to keep ahead of it and I later called it a chase near Bradford, IL. It appeared the MCS was beginning to weaken especially on the northern-end at that point. Also, road options with heavy construction near I-80 kind of forced my hand to end the chase abruptly. Nice to chase something different than tornadic supercells every once and awhile though!

First view of the shelf as it approached Geneseo, IL
Tis' the season now for the "shelf"
A very picturesque whales mouth near Atkinson, IL
Shelf as it crosses I-80 in Henry County, IL
Whales mouth yet again moving overhead...
View southeast of Sheffield, IL
View from behind the departing MCS
The previous nights sunset
Cirrus clouds illustrating a possible pattern-change this past Friday night? this case...Yes, as another 24hrs told the story!

I added a short YouTube time-lapse as the shelf first past overhead (above)

Looks like a break from any severe weather for a good while. Check back every so often for new projects and local weather events however!

Monday, June 22, 2009

06/21/09 Cleves, IA Tornado

Tornado touchdown near Cleves, IA

Sunday (Father's Day), consisted of a relatively short drive to north-central Iowa. A SLGT risk chase! Iowa has busted me twice already this month, but I thought well just maybe this would be the right setup that would actually "verify". An initial target of Williams, IA pretty much completely verified to my liking. After morning rains ahead of a warm front skies cleared by mid-morning leading to enough instability along the warm front for a few tornadic supercells later in the evening. On the drive, storms initiated just west of Williams, IA near Fort Dodge, IA as anticipated near 4:00pm. At first these cells looked really ragged, but got there act together rather quickly. I sat near U.S. 20 to get a elevated view and witnessed the first funnel cloud (rope) report that came in to my west. Storm quickly goes tornado-warned and wraps up a nice wall cloud quickly thereafter. From here I continued east on U.S. 20 as the storm began to interact with the warm front showing lots of rotation and rope/brief funnels that lasted a few seconds. Also, it had a beautiful clear-slot as well for a time. The storm continued east running nearly parallel to U.S. 20 through its life cycle and than dissipated outside Waterloo, IA. Unfortunately, other storms developed to its southeast obscuring some of your view toward the end of the chase. However, I was able to catch many funnel clouds, wall clouds, and a tornado touchdown near Cleves, IA. A HP-ish transition lead to some poor contrast visually, but oh well. Storm reports including the tornado reports can be found here. Also check out Walker Ashley's blog as he captured a tornado touchdown near Dike, IA to my immediate west.

First sign of convective initiation...
Convective initiation southwest of Williams, IA
First sign of rotation (background-right)
First wall cloud of the day...
Wall cloud now a mile away with funnel organizing (center-right)
Flanking line into the supercell along U.S. 20
Supercell with nice crisp updraft along U.S. 20
While watching the previous supercell I kept my eye to my southeast
as a another cell along the warm front was showing signs of rotation...
Wall cloud and tornadic circulation producing
a faint/weak touchdown

(Not the greatest contrast though center-background)
Click to enlarge...

Structure shot here with rotation present
Clear-slot wrapping in...hmm
Wide-angle shot of the Cleves, IA tornado
Inflow was quite juicy here as I make another play on the supercell
Odd green-ish look from the gust front seen here
Sharp abrupt change in weather eh?
blue sky (left) tornadic supecell (center-right)
Convective tower shot being sheared at sunset
Yet another...
Another cell I caught at sunset west of I-380
TIV2 calling it a chase at sunset

I've added a time-lapse of the day (above)

Another rewarding chase that showed tornado potential and this time verified. My first Iowa tornado! Now I will no longer be annoyed with Iowa after a couple busts out there this month...Persistence paid off!

Sunday, June 21, 2009

06/17/09 Aurora, NE Tornado

Large tornado west of Aurora, NE

Ah, finally I have a chance to sit down and post some photos and video from a 3-day chase trip. I guess I'll sum up the past 3 days in one post since two of the days were disappointing chases. Most of this post will consist of Wednesday's chase however. All 3 days consisted of a MDT risk of severe weather and tornadoes. Wednesday, was clearly the best day in Nebraska. Thursday, consisted of a bust in north-central Iowa. To sum it up, the cap held. I'll use this analogy to describe it: Think of a champagne bottle...a cork allows pressure to build up, but unless a strong force is exerted on the cork it will not allow the rapid rise of champagne out of the bottle. That's a good example of a "capped" atmosphere. Unless a strong enough force/lifting mechanism is exerted air parcels will not be able to achieve buoyancy and accelerate vertically into the atmosphere with enough vertical momentum to break the cap (warm-layer aloft). Visually, you'll see cumulus towers hit this layer in the atmosphere and collapse. The reason the cap held Thursday was due to a very weak trigger i.e. a weak shortwave in Nebraska that moved east into Iowa. The cap eventually broke at dusk in Wisconsin, but after chasing there once in 2007 I've since made a decision to never chase in that state again. A poor road-network, rolling hills/bad terrain doesn't make Wisconsin a good state to chase at all. In my opinion, a state like Missouri with lots of trees and rolling hills is a much better chasing territory than Wisconsin surprisingly enough. Friday, had great "potential" as well, but a very moist profile didn't help our cause as the downdrafts of just about every storm took over. Sometimes having too much moisture is a bad thing! Friday, was a great example of this as convection resembled a hurricane in most of the state. Tropical moisture in place with many areas getting 2" of rain in an hour and 50-70mph microburst/downburst winds. Behind the departing MCS(s) though provided the only real picturesque photos of the day with a nice alto-cumulus field and sunset. Backtracking now, Wednesday was one of those chase days I'll never forget in my short storm chasing career. A prime example to never forget about your target-area if you bite on early storms during a chase. I got out the door at around 8:00am with a target of Kearney, NE. I continued west-bound on I-80 and to my surprise a supercell quickly develops along the warm front in north-central Kansas around noon. I thought well either this is gonna be a real good day or a real bust! I managed to leave earlier than I thought I needed to on this day yet to only begin the day behind the 8-ball...argh! After seeing this storm visually as I entered western Iowa I decided to drop south on I-29 and head into north-central Kansas. My thought process was that I could catch these storms along the warm front and I'd still have a reasonable chance to get back to my target-area later in the evening if it still appeared storms would develop there. As I neared this supercell near Seneca, KS it appeared elevated visually. I heard rumblings of a large tornado on the ground at this time, but never saw a funnel or tornado with this storm as it progressed northeast. It quickly weakened around 3:00pm and I made the decision to let it go into Missouri and head back north and northwest toward central Nebraska. It was a decision that's always tough to let storms go on the hope of a better storm later in the day. It turned out to be a great decision and the most rewarding in a couple years of chasing! As I headed west on I-80 through Lincoln, NE a storm began to show signs of life along an area of convergence just outside Kearney, NE. A wall cloud and a tornado report quickly came in from chasers and I thought for sure I missed my opportunity. As I continued to approach the storm it looked fantastic visually still around 7:30pm. It would turn out I made it in time for the stellar show. I made it just to the west-side of Grand Island, NE near the town of Cairo, NE where I first got a view of the mesocyclone and wall cloud. I sat here for nearly a half hour which was insane thanks to a storm speed of 15-20mph! It nearly produced a tornado at this time. After the area of interest was within a mile of my current location and being the track I got back south to I-80 and back east to catch another view. This is where I observed the best structure of the year at this point! This cyclic supercell continued to cycle all evening dropping brief tornadoes, funnels, wall clouds, and a large tornado at sunset. I watched a brief rope-tornado touchdown while driving east on I-80 that lasted 2 seconds that I wish I could have got a photo of. Luckily, I had an exit coming up and I pulled off the interstate to witness tornadogenesis again with a large tornado! This was my first "large tornado" in a couple years of chasing and one I'll never forget! The NWS damage survey of the Aurora, NE tornado can be found here. It was ranked EF-2 with winds between 111-135mph.

Supercell still elevated with some rotation still evident north of Seneca, KS
Interesting structure to this supercell as it weakens
A once healthy supercell becoming progressively outflow dominate
 Cool stuff...
Hint of a funnel beneath the circulation initially
A still image of the intensifying circulation of this cyclic supercell
"Wrapping up"
Wall cloud a mile away with rapid rotation...what a treat!
Similar event/circumstance to the Assumption, NE tornado
2 days previous (see Walker Ashley's blog)

I blast south to find the circulation dropping this funnel near my previous location
Spectacular portrait-view
A mouth-watering structure shot along I-80
Lots of wicked-motion going on at this point
Farther east again as it's very close to producing...
 Amazing stuff!
Cone tornado with a beautiful clear-slot (Click to enlarge)...
A beast becoming shrouded by RFD rain curtains
One of my favorite shots of the year!
The bell and crawler at dusk...Wow!
If that wasn't enough...mesocyclone (left) and crawler (right)
Long exposure with some crawler and anvil-zit action

Well it appears the chase season will shut down now for most chasers and myself alike as we enter the traditional summer pattern. I'll still be partaking in local weather events this summer (chasing locally), but the 2009 chase season is pretty much over for the plains. I'm happy I ended the official season with a bang after an uncooperative few months from Mother Nature. I can say that the 2009 chasecation ends on a positive note for this storm chaser.