May 29 2008 chase



I took a limited number of digital stills during this stormchase, but until I can make some video captures I will post this relatively brief account.  Keeping in tune

with other spring 2008 events I'd been able to chase, this was a somewhat challenging severe weather forecast/chase day.  Medium range models really struggled

with the setup in the days leading up to the event.  By the morning of, a High Risk was issued by SPC for eastern NE/northwestern IA, with a Moderate Risk

extending into northwestern/northcentral KS.  As a mid-level wind max translated through parts of SD/NE/MN/IA, initiation would occur a bulging dryline

across the central high plains.  Upon departing I favored southcentral NE targets, where favorable low-level thermodynamics (richest boundary layer moisture and

relatively cool capping aloft) would seemingly be the "most backed up" to the dryline.  I was somewhat concerned with how convection would evolve,

as relatively widespread initiation would occur by mid-afternoon... and with initially high LCLs and low-level shear not increasing until ~23Z, I feared that

cold pooling and upscale growth might result in outflow-dominant and/or clustered supercells.  I reached Kearney around 17Z, and my thoughts changed little

after analyzing new data.  A number of storms initiated over southwestern NE/northwestern KS by 1930Z.  Though cloud bases would likely remain too high

for an appreciable tornado threat until one reached longitudes nearer Kearney, I was still afraid of an "early show" and rushed west to intercept.






Tornado-warned supercell moving swiftly between McCook and Lexington NE... viewed here at ~400pm CDT looking WSW from a point 4 miles south of Elwood.  I had arrived at this location about 20 minutes prior, but initial views were quite hazy and low-contrast

The storm would occasionally display rather chunky wall clouds, but they'd then take on an outflow-ish appearance as shown here.


I moved back north and headed east out of Elwood as a large, broiling, forward flank gust front appeared to form.

As the storm moved into Phelps county around 440pm, supercellular characteristics became pronounced once again.  A beautiful, classical-looking mesocyclonic structure evolved, with a clear slot revealing vigorous convection quite low to the ground.  I was a bit lazy and stayed on the main highways curving ESE while the storm scooted ENE away from me.

I caught back up with the storm around 520pm near Kearney.  I could see a well-defined, occluding meso to my north, which strongly looked like an "active" tornadocyclone.  I noted a powerflash or two amidst occasional cloud-to-cloud lightning strokes (a rain-wrapped tornado causing isolated EF-2 damage, as surveyed by NWSGID).  By the time I pulled close to the area of interest, I came upon an increasingly ill-defined low-level meso as in photo.
I chased the storm ENE along Highway 30 as strong HP characteristics became apparent (~600pm, as in photo).  The storm crossed the highway near Shelton, cutting my route off.  I dropped back south to I-80 and continued east... but near Grand Island made the decision to abandon the storm and drop south to the cells in far northern Kansas.  As gorgeous as the 00Z Omaha RAOB was, I suppose I am partially lucky the storm I abandoned didn't get its act back together and become a tornado machine; if not for the way the convection ended up evolving (early transition to HP-mode), the most prolific/visible tornado outbreak seemingly should have been over southcentral/eastern NE on this day.


I made my way south on Highway 281 and then Highway 78... targeting two persistent, tornado-warned cells moving ENE from the Stockton/Plainville KS areas.  I considered stopping for gas just north of the state line at a lone convenience store in the town of Guide Rock... but pressed on, naturally fearing "being late" and hoping I could get by on what I had left.  I crossed into Kansas and encountered the first target storm near Ionia... and immediately bypassed it given its weak and high-based presentation.  Unfortunately, by this point it was becoming clear that continuing on without gassing up would be a gamble... and I was forced to rush east to Beloit and grab a few gallons.  After doing so, I headed south and then west on Tipton Road and encountered target storm #2--an incredibly beastly supercell--at ~820pm, as in photo.

Conditions were very hazy and my video and photo stills did not turn out particularly well, at least initially.  The storm was quite laminar in the lowest couple kilometers (a manifestation of weak to nil low-level bouyancy and increasing CINH)... which served to further enhance the unbelievable "mothership" structure.

I headed a bit farther west and stopped at a point 7SW of Glen Elder or 7SE of Cawker City.  The low-level structure was extremely "beefy" (somewhat comparable to the Kent county storm of 06/12/2005), replete with an ominous wall cloud... and it was tough to imagine tornadogenesis not occurring soon.  Strong east or even northeast inflow winds were blasting into the updraft, and were unbelieveably warm and moist such that it literally felt like a steam bath.  (METARs revealed it was likely 80/68, which in hindsight is not terribly impressive I suppose).  By this point, my day had already been "made" given the incredible supercellular structure... possibly the best I have ever witnessed.

A truncated stovepipe tornado was born at 831pm in advance of the wall cloud, and persisted for about a minute and a half.  The wall cloud then began rotating violently and evolved into a multiple vortex tornado at 833pm.  Meanwhile, intense cascading rotation on the forward lip of the meso just to the right/north of Tipton Road (not pictured) produced a second simultaneous tornado at ~834pm.  The wall cloud began to break apart as the tornado continued as a dust bowl (as in photo).  The tornado weakened around 836pm, crossing the road to my immediate west in the form of slowly/broadly rotating rain curtains.

I repositioned east a couple miles.  The "Glen Elder to Jewell tornado" more or less initiated at this time (840pm), with occasional multiple vortices condensing beneath an increasingly beefy low-level mesocyclone.  Note one of the vortices in the photo.  A couple of these were quite thick in the form of beautiful "ropes."

Larger vortices began forming and revolving around one another.  Some wrap-around rain began to fall at my location.  I think I inadvertently had the flash on for this photo.

Tornado took on a truncated cone shape as it passed over Waconda Lake and toward the town of Glen Elder... with a gorgeous "midnight blue" color to the clouds.  What a sight this must have been at ground level had one been positioned right near the lake.

I drove north on Glen Elder Dam Road, noticing (EF-2 rated) damage to some farm buildings.  I encountered widespread tree damage in the town of Glen Elder, with many of the city streets completely blocked by fallen trees.  (Luckily, it seems as though the tornadic circulation stayed primarily south/east of town).  Highway 24 was blocked off by a couple of downed powerpoles... ending the chase.  I could still see the tornado continuing to my northeast, though it was a bit non-descript... looking high-based and partially rain-wrapped in the twilight.  Oddly enough, the supercell produced a second even longer-track tornado along the Courtland KS-Belleville KS-Fairbury NE corridor, with very strong SRH apparently compensating for lacking low-level CAPE and considerable CINH.



Maps, weather data


observed supercells


observed tornadoes (paths estimated)


NWSGID storm survey


21Z subjective surface analysis


03Z modified RUC sounding at Belleville KS (representative of second long-track tornado)

Sfc T/Td: 75/69 F

MLCAPE: 2765 J/kg

MLCINH: 122 J/kg

0-3 km MLCAPE: 0 J/kg

MLLCL: 936 m

MLLFC: 2934 m


03z modified RUC hodograph at Belleville KS, with 02Z Haviland profiler substitued in 2-3.5 km layer

storm motion: 232 deg @ 34 kts

0-1 km SRH: 661 m2/s2

0-3 km SRH: 742 m2/s2

0-1 km bulk shear: 55 kts

0-6 km bulk shear: 61 kts

7-10 km SR flow: 34 kts