Jun 2, 2010

June 2: A Bit of an Early Exit

I am leaving the Plains about three days early. The pattern is going down to a large extent for tornadic supercells for a few days, so there is no point in sticking around.

The trip was successful in terms of both seeing tornadoes and good photographic documentation, including video, for one of those days. That particular day was one of the best that Thom and i have had together, and ranks with two days in 2004, one each in 1999, 1997, 1995 and 1990.

There were frustrations, including some bungled navigation (which led to incomplete documentation of tornado day 2), too much hemming and hawing about drifting to northest SD on the first tornado day, leading us to miss the biggest tornadoes.

The missed major tornadic supercell on May 31 in se Colorado may make an interesting case study. That storm became a prolific tornado producer. But it occurred in a totally inadequate deep layer shear environment. Only a very odd storm motion, given the wind profile, produced an environment relative to that storm that supported a long lived supercell.

There was no question that the low level shear could spin up a tornado as long as the storm remained existant. That latter issue was one Chuck and I have debated with our other case partners. If we are to learn from this episode, it may be important to go back and look at the radar to see the true storm motions, and get some prxoimity sounding and hodographs.

Whether by skill or my luck, those that chose that target were rewarded, and I certainly hasten to congratulate them. It would have been one of the best tornadic storms that Thom and I would have witnessed, if not the best.

Such is the life of a chaser.

But, we'll be back next year. These trips are always learning experiences. They are also humbling, for when you think you are riding a fast horse to success, the next day, you can be bucked to the ground.

Thom and I thank all of our chase partners....Scott Landolt, Daniel Porter, Cameron Redwine, and Chuck and Vickie Doswell. It was great....

Jun 1, 2010

June 1: north-central to east-central KS

Preliminary target is somewhere betweeen Topeka and Salina. We spent the night in Hays, KS, and noted that the forecast sounding and hodograph for the Topeka area (and a 75 mile diameter or so), is supportive of not only rotating storms, but tornadic storms.

But as the day progressed, it was apparent that the area with the best potential for tornadic storms was "capped", meaning that convection was inhibited by a warm layer aloft that was not eliminated during the day.

So we drifted north to play storms forming on the warm frontal boundary, and still hoping that new storms might form on the curling moisture band back west along and just north of I80.  But while a couple of those storms briefly became supercells, they were rapidly undercut by the cold air north of the boundary.

So we ended up "blowing off" this day with great potential.  Cameron and I then went west to spend the night in North Platte, which was an easy drive into Denver for my 7PM flight.

May 31, 2010

May 31: western KS

We are currently in Goodland, just in a wait and see mode.  There is a disparity between the RUC (out to 12 hr) and NAM-WRF models (goes out to 84 hours) in the view of where the focus will be today.

Both models suggest wind profiles favorable for rotating storms, and both models suggest that such storms will be briefly rotating in the south and long lived in the north. The difference is that the NAM suggests that storms will NOT initiate up this way, and the RUC suggests they will.

Anyway, we are holding at the Holiday Inn Express in Goodland, and watching the moisture fields/dew points as they evolve today.  If they evolve in a way that suggests the RUC is correct, we stay put.  Otherwise we drift south.

Tomorrow, the focus will be anywhere from southwest Nebraska to southeast Nebraska, and then the pattern goes down.  So I am departing the Plains on Wednesday, but just in case we are pretty far east at sunset tomorrow, I changed my flight to Wednesday at 7PM from Denver International Airport.  That would give me all day on Wednesday to drive back to Denver, if we are really far east.

And our forecast area never did get the moisture return forecast by the RUC.  Not only did storms not initiate in our area, but a single storm, essentially, did initiate in the southern target, about 175 miles southwest of us, on the Raton Mesa.  

That storm became a cyclic, repetitive tornado producer.  Congratulations to all who made the astute decision to be in that area in advance.  This is a storm worth studying.  Evening hodographs verified that 0-6 km shear should NOT have been adequate for long-lived supercells.

May 30, 2010

May 30: Down Day--Heading to Goodland

After watching some storms croak south of the boundary in northwest-central Nebraska, we put in for the night in North Platte. Since Sunday will be a down day, we are heading for Goodland, to be in position for what appears to be a chase day in the southwestern quadrant of Kansas on Monday.

Tuesday also looks like a chase day, perhaps the best one since last Wednesday.  However, since the pattern looks to go down after that, I am likely to leave the Plains on Wednesday.

May 29, 2010

May 29: western Nebraska

Despite SPC's low risk, the forecast soundings and hodographs look favorable for briefly rotating storms and, perhaps, for a window of about 2 hours, tornadic storms, in the region roughly where I76 and I80 merge in Nebraska.  Thom has gone home, and I will be joined for the last several days by Cameron Redwine as a storm chase partner.  My regular "second half" of the chase partner, Scott Landolt, is with VORTEX2 for the next three weeks.

May 28, 2010

May 28: eastern Wyoming/extreme western Nebraska Panhandle

The most favorable area for rotating storms will be in North Dakota and adjacent portions of South Dakota. Since Thom leaves from Denver early tomorrow morning, and I pick up Cameron Redwine as a chase partner for my last several days,, and also will be joining Chuck and Vickie Doswell tomorrow for the pattern setting up in Nebraska.

This is a picture of one of the Doppler on Wheels (DOWS) scanning the Tribune, KS supercell the other day. You can see Scott Landolt on the far left, and John Monteverdi next to him.

May 27: eastern Wyoming

This ended up being a down day. We thought there was a large chance for rotating storms in this area IF storms initiated. They never did.

We overnighted in Torrington, Wyoming. The picture at left shows one of the Doppler on Wheels (DOWS) from Vortex2. At far left is Scott Landolt and to his left Thom. I posted a similar picture with me in it in the next post.

May 26, 2010

May 26: Adjusted Target--eastern CO

We decided to chase into Colorado today as a Denver Vorticity Convergence Zone is setting up. And, we did indeed run into a nice looking, sculpted supercell. For a brief moment in its lifecycle (~30 minutes) it spun up a wall cloud, and looked good on radar.

However, the low level rotation never tightened up. The wall cloud never looked like a tornado producer, although a few funnel clouds did develop (you can see one on the left, south side of the wall cloud in the picture below).

We followed the storm as it slowly propagated northeastward. While it was near Inerstate 76, its base shrunk, and we decided to call it a day.

We overnighted in Fort Collins.

May 25 Southeastern CO/OK Panhandle Addendum--Mammatus and One More Tornado Shot

The first picture shows the main wall cloud getting wrapped in rain. This interferes with the tornado forming processes, but you can see what was left of tornado #7 for us on this day

The other shots are of the backside of the storm as it left our area. This is the best display of mammatus that Thom and I have ever witnessed. It's truly a Steven Spielberg special effect. Bh the way, we took many high resolution pictures, and have had time only to look at about half of them. Who knows what interesting features might emerge when we have time to look more closely at all of our photography and video.

May 25, 2010

May 25 Southeastern CO/OK Panhandle--Nine Tornadoes

What a terrific day.

We really maximized our good forecast with equally good luck, running into a storm at the time it was producing multiple "landspout" (non-supercell) tornadoes, and then watched it produce three supercell tornadoes.

Finally, we were treated to an outstanding display of mammatus.

May 24, 2010

May 23: South-central South Dakota

There is a volatile pattern setting up for fast moving supercells in South
Dakota, and perhaps northwest Nebraska. We are on the way....form Goodland.

Hodographs favor fast motions, but also a few tornadoes....with some strong and violent.There is a volatile pattern setting up for fast moving supercells in South
Dakota, and perhaps northwest Nebraska. We are on the way....form Goodland.

Hodographs favor fast motions, but also a few tornadoes....with some strong and violent....

....and we should have stuck with our target. But storms erupting ahead of the cold front in western Nebraska were supercells and were producing tornadoes early on. So we attempted to get along that line and wait for the rapidly moving storms to train up the boundary to us.

One in particular near Alliance (see radar) had a history of producing TVS (tornado vortex signatures) and was intermittently tornado warned by the NWS. However, by the time we got in position, the whole area erupted into a rapidly moving squall line. Outflows from neighboring storms crashed through our storm and it became non-supercellular and absorbed into the line.

If we had left at 7AM we may have made it to our target in time to see South Dakota tornadoes at 1PM. That's about 6 hours earlier than tornadoes normally form. But them's the breaks...

May 23, 2010

May 23: Northwest KS Tornado

Thom and I, with Scott Landolt and Daniel Porter, dropped southwestward from O'Neill, Nebraska to the Oakley, KS area, and were rewarded with an active chase day, culminated by a narrow cone/snake tornado about 20 miles west of Oakley. This was associated with a really nicely structured supercell, that was one of a group of such storms that developed or evolved over northwest KS as the dew point surge at the surface advected under gradually more favorable deep layer shear during the day.

The day ended with all of us trying to get a view of the storm of the day, a cyclic tornadic supercell that nearly clobbered Goodland.

The "trying" part is a bit of a story, particularly for Thom and I. We missed the short cut to the 83 southbound exit in Oakley to get to the first storm, and then when we back tracked down 83 from I70, we missed the Highway 40 west bound that would take us to the storm. As a result, we were nearly late, and it did cost us good photography. However, we did see the tornado and its parent bulbous wall cloud. It was a relatively distant view, but it was beautiful and exciting.

Then, we tried to get north to I70 to perhaps stay with that storm, only to be stopped by a cross-highway accident. Thus, we had to backtrack to H40, then east to H83 before coming up to I70. And, thus, we missed an opportunity to see the wedge and cone tornadoes with the Goodland storm.

It was still a highly successful day....(there was another chase of another briefly supercellular storm before all of this)...and ended with Thom and I iin Goodland as a line of severe storms passed through, with 60-70 mph winds, knocking out power until around 10 minutes ago.

Tomorrow, Thom and I are off to Nebraska, to explore what might be yet another very productive weather pattern during this week.

May 22, 2010

May 22:Tornadic Supercell in North-central South Dakota

We eventually ended up playing the dry line bulge in north-central South Dakota. We were rewarded with a series of amazing storms, and did make it to the area in time to catch up to a long-lived cyclic supercell, repetively producing tornadoes. We caught up to the storm in one of its last cycles before the whole area erupted into a line.

The storm had a monstrous hook and the picture shows a wedge tornado about 20 miles southwest of Aberdeen, South Dakota. As we dropped south away from this storm, in the dusk, we outraced the lowering and the shelf that hung out east-southeastward from it. We could see it hanging like the lip of a mother-ship spacecraft over the road to our west (right), with a suspicious underhang directly over us (which did not become a tornado).

We dropped south to O'Neill, Nebraska for the night.

May 21: Into Nebraska Panhandle

Expecting storm formation on the Cheyenne Ridge and on the mountains, Thom and I hung around Goodland for a while, before we began drifting northeastward. Forecast storm motions would take such storms towards Goodland. But temperatures and dew points never reached their forecast values.

However, further north, storms forming on the eastern ranges of the Rockies began drifting out into the Plains north of the Cheyenne Ridge. So, after joining Scott Landolt near Scotts Bluff, we hung with a tornado warned storm moving into the Nebraska Panhandle. It briefly had a wall cloud, and looked good on radar, before it began to disorganize.

We overnighted in Chadron, Nebraska.

May 20, 2010

May 20: Moving towards northeast Kansas/ne Colorado

I think that the upslope area of northeast CO/NW KS/sw Nebraska looks interesting tomorrow. We are in Dodge today and will reevaluate our destination for tonight based upon the 12 UTC run of the models. The huge discrepency betweem the SPC outlook for Saturday and the 0000 UTC NAM. The latter has a gigantic potential for north-central Nebraska, but SPC has the risk way up in the Dakotas.

Anyway, there will probably be some lightning photography opportunities this evening up in ne Colorado/nw KS, so we will probably head up that way today, and then the next two days look great.

Meanwhile, we upgraded from a full sized car to a mid size SUV. This drives great in the rain, and also gets reasonable gas mileage. Here's a picture of our Chase Vehicle, a Dodge Jericho mid-size SUV. Be sure to check out the other side of the story at Chasing Storks.

May 19, 2010

May 19: Arrival and Long Drive

We changed our flight to a 6:25 Am departure (from 9:20 AM), to give us a shot at the terrific setup forecast for central Oklahoma. It was a long shot....we figured 590 miles to get to the Clinton-Taloga area, and then if and only if the storms did not fire early and stayed back west.

As it is, the storms DID fire early, and were along I35 before we got to the Oklahoma border about 150 miles west of that at around 7PM. Faced with still doing a "catch-up chase" (called "stern chase" by severe weather meteorologists) to storms moving away from us, we called it a day, and pulled back to overnight in Dodge City KS.

Turns out that there was enough vertical shear and low level instability to generate a class of storms called "low topped" supercells in western KS. We arrived in Dodge City to the sound of tornado sirens, and an interesting looking sky near sunset, with a low hanging base with inflow fingers. Too dark for pictures. Here's a radar plot.

May 10, 2010

2010 Chase Begins May 19

Flying into Denver...