March 10, 2010 "cold core" chase near Sedan, KS

I haven't had much luck chasing "cold core" setups (see this link) in recent years. My move to Missouri has tended to put me farther away from some of the more photogenic events in western Kansas and Nebraska, and I've also been reminded that there are many things can go wrong in trying to chase these type of events.

Yesterday's "cold core" event with a tight 500 mb closed low moving from central OK into southeast KS didn't produce any tornadoes -- the outflow air behind the cells we chased was 38 deg F (brrr!) according to our car thermometer! The tornadoes after dark (one deadly) in central Arkansas were deep in the warm sector well southeast of the upper low. But the "cluster" of cells that moved north-northeastward into Kansas west of Sedan (see arrow on satellite photo above), associated directly with the low aloft, was very photogenic. The late afternoon low-angle March sunlight brought out browns and blues (see 3rd pic above) very similar to my first "cold-core" chase near Pratt, Kansas on March 11, 1990 (ironically, 20 years ago today).

A few pics are posted above. The first is approaching the low-topped cell cluster near Sedan, KS, looking west-southwest along Highway 166. The second shows some brief funnels along the rain-free base looking southwest from west of Sedan. The third shows the gorgeous near-dusk lighting looking northeast as our cell of interest passes to the northwest of Sedan. The last shows another small cell developing to our east, and how the vertically-sheared updraft was stretched out horizontally, typical of early season low-topped convection associated with "cold-core" settings.

My wife Shawna posted some more of our pics with captions on Facebook, under Shawna Davies' photo album entitled "3/10/10 SE KS Cold Core album".

- Jon Davies 3/11/10

This week: 20 year anniversary of the Hesston tornado

It was 20 years ago this week that an outbreak of tornadoes on March 13 1990, including the Hesston Kansas tornado, shook the central plains out of a several-year lull in significant tornado activity.

The Wichita Eagle has an excellent article by Stan Finger on the Hesston tornado at:
http://www.kansas.com/2010/03/07/1213543/1990-tornadoes-increased-awareness.html

Stan also has some photos and discussion on his blog at:
http://blogs.kansas.com/weather/

Later this week, I'll see if I can get some other review info about this event up on my web site. The Hesston tornado day was certainly one of the big turning points in my meteorological life.

- Jon Davies 3/7/10

"Cold Core" type setting produces dangerous snow squalls in Kansas City area on 2/14/10

Just got back from ChaserCon in Denver -- great to meet and talk with many storm chasers there. Of course, while I was gone, a rather unusual weather event took place near home... Some convective snow squalls generated sudden white-out conditions in the KC area, causing trafffic accident pile ups at a couple locations on the Kansas side just after lunch on 2/14/10. Thankfully, no one was seriously injured. With as many as 40 cars piled up on I-70 near Bonner Springs (see KC Star photo above), it could have been much worse.

Believe it or not, these convective snow squalls were caused by an intense "cold-core" type closed low in midlevels moving southeast (see the NAM 500 mb analyses in 2nd graphic above). A strong vorticity maximum, or center of atmospheric "spin", was assciated with the midlevel low and moved right over the KC area around midday (see the "X" and red coloring on the NAM 500 mb maps above), providing a strong focus of forcing/lifting. A tight area of very cold temperatures just above the ground (-14 deg C, see the SPC 850 mb map at midday, 3rd graphic above) moved also across KC with this system. Combined with sun's heating (there was some sunshine just ahead of this system), low-level lapse rates increased rapidly (see orange area near Kansas City on the SPC 3-hr lapse rate change image, 3rd graphic above). All these ingredients working together generated a local area of CAPE and instability over the KC area (see RUC analysis sounding at KCI airport at 1:00 p.m. CST, 4th graphic above). Yes, there can be CAPE on days with surface temperature below freezing; this combined with the intense lifting/forcing system aloft undoubtedly contributed to the intensity and suddeness of the snow squalls.

The final graphic above shows a regional composite of radar reflectivity in low-levels around 12:00 pm and 1:00 pm as the "twisted" or curved area of snow squalls (see white arrow) associated with the vorticity center aloft approached the west side of Kansas City. The upper system was so intense and focused that an associated subtle trough in the surface wind field could be seen on the surface map at the same time moving southeast over the KC area (see blue dashed line on surface map in final graphic), even though the surface cold front was 400 miles to the south and east.

The Kansas City area National Weather Service at Pleasant Hill MO has posted a good page about this weather event setting at http://test.crh.noaa.gov/eax/?n=winter-02142010.

This event is a reminder that the contribution of low-level CAPE with some "cold core" midlevel lows to extreme weather isn't limited to just the warm season and thunderstorms!

- Jon Davies 2/15/10

ChaserCon talks, and 1/21/10 Huntsville tornado

FWIW, I'll be in Denver this weekend to do a couple talks at Chaser Con. The first on Saturday 2/13 will focus on the June 7 2009 supercell (essentially non-tornadic) in NW Missouri that was followed by what seemed like thousands of storm chasers. The second on Sunday 2/14 will look at some short term chase targeting issues as well as some tornado forecasting stuff in somewhat potpourri fashion.

A couple talks I'm looking forward to are Erik Rasmussen's about what's left to learn about tornadoes, and Chris Novy's talk about chaser responsibility and safety. Chris in particular is smart, entertaining, and cutting edge, and his talk should not be missed by anyone who takes storm chasing seriously.

On another subject, Andy Fischer has written an excellent analysis of the recent 1/21/10 tornadic mini supercell setting at Huntsville AL (associated with a "cold core" midlevel low). In this case, the tornado occurred with a cell well south of the surface low along the trailing front, which is somewhat different than the "typical" cold core setup. Andy's post is on his blog at: http://tornadoheadblog.blogspot.com

Hope to talk with some storm chaser colleagues in Denver!

- Jon Davies 2/7/10

Tornado setting in Los Angeles area 1/19/10

I haven't done a case study for awhile... Before today's tornadoes (Jan. 20) in Texas and Louisiana, it's been a quiet winter regarding severe weather in the southern states. But yesterday's little tornado episode on Jan. 19 (see 1st graphic above, a capture from video at Sunset Beach CA) near Los Angeles caught my eye, with some minor damage in the Huntington Beach area. Fortunately, the tornadoes/waterspouts around 2100 UTC (1 p.m. PST) were weak, as most California tornadoes are.

The 500 mb WRF model analysis showed a strong short wave of energy aloft with an intense vorticity max (atmospheric forcing and "spin") crossing southern California yesterday afternoon (see "X" and "orange" vorticity area on 2nd graphic above). At the surface (3rd graphic above), a small low pressure area (mesolow) was approaching the Los Angeles area from the southwest before 2100 UTC with an east-west boundary along the coast just south of L.A. (Huntington Beach is located by the black square in the same graphic). Dew points were in the low 50's F south of this boundary, and the tornado activity seemed to be focused along it where low-level shear and vorticity ("spin") were probably concentrated.

On radar from Santa Ana/SOX (4th graphic above), a "circular" pattern of small cells with red reflectivity was visible over the ocean to the southwest of the L.A. basin around 2000 UTC, moving northeastward (see black motion arrow in same graphic). This pattern of cells was associated with the mesolow mentioned above, and came onshore producing waterspouts and at least one tornado between 2030 UTC and 2100 UTC in the Huntington Beach area (black square in same graphic).

A modified RUC model sounding for 2100 UTC at Santa Ana (see last graphic above; just east/northeast of Huntington Beach) suggested that instability/CAPE was certainly not large (only around 200 J/kg). But the available CAPE was located extremely close to the ground, probably inducing strong stretching for storm updrafts in low-levels near the surface focus of the mesolow and boundary. In addition to CAPE, the wind profile on the same graphic suggested large low-level shear (storm-relative helicity, SRH > 300 m2/s2) available for tilting and stretching contributing to tornado formation near the focusing boundary.

In many ways, even without a closed 500mb low aloft, this setting has some common features with "cold-core" tornado settings in spring and fall in the Plains (e.g., strong forcing and sharp vorticity max aloft, surface low and boundary extending east of the low, surface dew points only low 50's F, but CAPE located very close to the ground). In fact, most California tornado settings, whether in the L.A. area or farther northward in the central valley of California, are some variation on this type of setting, with total CAPE often less than 500-1000 J/kg.

- Jon Davies 1/20/10

Update: 2/19/10 (1 month later) - L.A. area storm chaser Will Wilkens has called to my attention that photos from this tornadic event that I originaly posted here (and have now deleted) were "phonies". One was from the 5/22/08 Riverside CA landspout event, and another was a generic waterspout image. I've replaced those with a video capture above of the real tornado that Will pointed me to (Thanks!). I'll have to be more careful in the future... Various websites of TV or news viewer photos are increasingly posting stuff that's labeled wrong these days just to appear current, it seems. Thanks for the information, Will.

Final thoughts for 2009

I haven't been much into blog posting or blog reading lately. That's expecially true for me about storm chasing, which seems to have evolved into a largely clickish, competitive, petty, and fame-seeking "activity" recently. Where has the wonder of nature aspect gone? Where is the true interest in learning how nature and weather works?

As people who know me understand, I've always been interested in severe weather forecasting research. But now I'm even a little down on that, too. I don't see forecasting and warnings getting significantly better in the near future with the data density and observational equipment we have currently available, and the increased reliance on computer models. Honestly, warnings for big weather events are already pretty good. All the talk about in TV storm chasing shows about saving lives with more weather research seems moot and more than a little silly when people don't respond to warnings, or even seem to hear them through all the noise of our 24/7 media these days.

Events with excellent warnings like Hurricanes Katrina and Ike (Tim Marshall gave an excellent November talk in KC about Ike and how poorly many people in the Galveston area reacted to the intensely-worded warnings), and the Super Tuesday tornado outbreak in 2008, underline that saving lives these days in extreme weather events is more a sociological issue (getting people to hear and respond) than a meteorological one. These thoughts aren't new or ground-breaking, and are certainly being recognized and studied in programs like UCAR's WAS*IS (see http://www.sip.ucar.edu/wasis), which is a good thing to see.

Anyway, I feel that I'm in transition with my focus and goals at this point in my life, and it will be
interesting to see where that leads in 2010.

- Jon Davies 12/31/09

Jon to serve as Associate Editor for Weather & Forecasting

I've been asked to be an Associate Editor for the AMS journal Weather & Forecasting (WAF) in 2010. I'll be reviewing papers in a more "official" capacity than in the past (I reviewed 3 papers for WAF in 2009), and I appreciate editor Bill Gallus asking me to serve.

In other news (it's been a busy month for me, so no new case studies to post), I've been asked to speak again at the National Storm Chaser Convention (now known as ChaserCon) Feb, 12-14, 2010. I've been taking time off from talks lately, but Shawna and I always enjoy the Chaser Convention, and are looking forward to going this year. Roger Hill and Tim Samaras always do a great job putting ChaserCon together, which is not an easy job!

Finally, I've had a few people ask me when Tornado Road will be shown again. All 6 episodes of the show will be re-aired on The Weather Channel on Thanksgiving evening 11/26/09. FWIW, Shawna and I are in episodes 1 and 2 (6:00pm-8:00pm), and episodes 4 and 5 (9:00pm-11:00pm).

- Jon Davies 11/24/09