I-70 Dust Front and High Based “Cumulonimbus Junkus”

June 18, 2006 by · Comments Off on I-70 Dust Front and High Based “Cumulonimbus Junkus”
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East CO and west KS, 15 Jun 6.

SHORT: Tremendous windstorm and dust in east Colorado. High based linear mush in west KS.

LONG: On this 14th anniversary of the great, legendary superdupercell at Beloit KS, we left DEN hoping for a measly LP supercell.

We expected little and got less. The most interesting part of the trip was the result of the development of high-based convection over east Colorado: a collective plume of downburst related outflow than slammed us hard between Siebert and Burlington. This windbag, with severe gusts measured in some obs, raised temps into the mid-upper 90s (daytime heat burst action) and lofted a a lot of dust. Driving on I-70 was difficult for folks on motorcycles and in high-profile vehicles because of the gusty crosswinds and airborne grit. Standing outside in tropical storm force winds — but hot and dry and dusty — wasn’t a good omen for the rest of the storm observation day.

After that we transected a very high based line of crapola over west KS that was good only for marginal/junk “severe” reports, enough to technically verify warnings but not anything truly dangerous outside the lightning. [No actual severe weather was seen by us but we did not penetrate the most dense cores.] We did see a few pretty CGs but the line itself was basically amorphous and free of structure worth photographing.

After snagging some gifts for Steve C from an abandoned railroad right-of-way near Healy KS, we headed for a dinner and room in GCK. Some close CGs and their thunderous accompaniment awoke me shortly after midnight, a result of more storms that formed in the same band of ascent that produced the daytime “junkus,” as the zone of lift shifted E across the GCK area.

===== Roger =====

From Multicell Garbage to Electrical Spectacular

June 13, 2006 by · Comments Off on From Multicell Garbage to Electrical Spectacular
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Northeast CO, 11 Jun 6.

SHORT: Somewhat scenic, high-based, daytime multicell with supercell attempts along I-76. Spectacular anvil crawlers after dark.

LONG: We headed up I-76 toward the CYS Ridge target area and waited on a hilltop N of Ft. Morgan. And waited, and waited, and waited, in the baking sun. Storms were forming in a convergence zone between DEN-FCL, but we ignored them for a long time because of weaker moisture, hoping for development to our N.

Finally we grew impatient, and with eyes still trained longingly to a northern sky devoid of deep moist convection, we decided to backtrack toward DEN to investigate that activity. After a couple of hours of observation, we noticed development way off in the distant N, on the N edge of my original target area, but it was too late. I knew a good supercell was possible up there in the better moisture, and was hoping that whoever was there enjoyed a good show. Apparently such was the case. Chalk up another testament to the virtues of sticking with your forecast area.

In the meantime, we relaxed on a well maintained dirt road 7 NW Hoyt: just us, the wind, occasional distant thunder, and a horde of small black beetles migrating eastward as if to run away from the slowly approaching storm.

For a short time, this was a place to rediscover the wide views of Great Plains skies, treeless and filled with the tumult of convective power, hardly a building or wire in sight. It wasn’t hard to step back in time and envision this sky seen by the pioneer families venturing for the first time into this big and open landscape, storm and mountains looming in the near and distant west, obstacles temporary and permanent looming above and beyond, respectively, compelling a decision to forge forward or to turn back, or perhaps even to set root here in a place that was, at once, starkly beautiful and unmerciful.

So we observed and imagined, simultaneously appreciative yet wishing for much more from the atmosphere. A dense core with occasional “rainshaft-nadoes” gave someone some valuable rain as more thunder crackled overhead from unseen anvil crawlers. Our storm(s) developed a fair sized updraft base and an inflow tail and tried to rotate; they may have, weakly, before eventually gusting out.

A new storm formed along the NE edge of the complex near Brush, with a somewhat colorful shelf cloud. Still, we were disappointed as we headed back into Fort Morgan, wandering the roads between there and Brush in vain attempt to find short-fuse rainbow photography views unobstructed by trees, wires and buildings. [Yes, we found perhaps the one area of eastern CO where this is a major problem.]

However, as often is the case, our disappointment turned to elation. We finally found a fairly open view about 2 E Ft. Morgan. A few nice sunset photos were followed by an absolutely dazzling show of anvil crawlers and mammatus from dusk to dark. The back side of this MCS was strobing almost continually, with at least 2-3 good crawlers per minute shooting across a sky of mammatus and ebbing twilight. I shot more crawler photos in 30 minutes than in all my years of chasing prior as the last evening light faded to night. Occasionally a CG would erupt beneath, but offset about 45 degrees, from the locus of a simultaneous crawler discharge.

Much of the action originated from the same region to the E or ESE, as the complex slowly receded, making the choice of sky sector an easy one. Still, even a 17-35 mm lens wasn’t enough to capture some of the most brilliant discharges that swept almost from horizon to zenith and beyond, while reaching north and south in search of electrical equilibrium. About half the crawlers were accompanied by a single, staccato CG, with few or no forks (still another fine example), reigniting a longstanding curiosity I’ve had about the connection, if any, between the two forms of lightning strokes.

A short drive back to Denver and several days of R&R followed before the storm intercept vacation would wrap up.

===== Roger =====

Cumulonimbus Barfus Maximus Nebraskus

June 10, 2006 by · Comments Off on Cumulonimbus Barfus Maximus Nebraskus
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Southeast WY, West NE and Northeast CO — 10 Jun 6

SHORT: Long drive for a little bit of good photography, a short-lived/high-based supercell near BFF, no legit tornadoes, and a lot of dusty outflow between east WY NE Panhandle and NE CO. Abundant small hail found after isolated high based storm near Cope CO.

LONG: Although there was enough shear for supercells (and we did see one), one of my fears was that the large scale ascent ahead of the west WY trough may arrive too soon. It did.

At noon MDT, the sky over east WY (behind the dryline-like surface feature) began filling in fast with high-based, fuzzy storms all-quadrants. The first of many of these was visible as we headed into Lusk WY, at 12:26 p.m. MDT (looking SW). Note that time, dear reader. That’s too blasted early!

Soon, more high-based storms formed all around east WY, spewing some beautiful CGs but also a lot of cold outflow. This is when the realization hit that the chance of seeing a legitimate tornado for us today was near zero. A patriotic, red-white-and-blue windmill framed one neatly lit cell S of Lusk, and then it was off to the races to get and stay ahead of the outflow.

Turning ESE out of Torrington, we noticed a high based storm distant ESE, near BFF, with a broad, shallow wall cloud. [No photos…I was driving, it was distant and did not impress me from that angle.]

As we crossed the Nebraska line, the pretty lighting of the arcus behind us caught our interest more than the high-based supercell near BFF, and we stopped to get some panoramics of the former (looking W and the companion shot looking WNW).

A few miles further down the road, near Morrill, we heard that the lofty little supercell to our ESE was TOR warned! It did have a legit meso that wrapped some precip filaments around its W side, but there were three problems:
1. A base way too high,
2. Undercutting from its own storm scale outflow, and
3. A building, mesobeta scale outflow surge about to smash to smithereens whatever remained of the storm.

After turning S from Bridgeport toward SNY we noticed a pronounced blocky lowering with a pendant, conically shaped cloud feature centered beneath. The problem was: It was behind the arcus cloud, made of thick scud, and not rotating. Shortly after that we passed some chasers parked nearby, atop a hill, on a side road. Elke said, “Somebody’s going to report that as a tornado.”

She has a keen sense for the presence of incompetent observers, because not 30 seconds later, the NWR alarm sounded with a tornado warning…for that storm, based on “spotters reported a developing tornado” in that very location. We pulled over and I took a few documentary photos of the sorry excuse for a “developing tornado” as it quickly devolved from solid scud into ragged garbage, then went away. The whole feature lasted less than two minutes and was about as tornadic as hoarfrost on the beard of a buffalo.

We stayed to do some equine photography with the arcus in the background, in a classical Great Plains scene. A herd of very friendly horses, initially on a hilltop about 1/4 mile away, galloped right over to beg our company and, in one case, vigorous human scratching of its apparently itchy forehead. Their company was all too brief. Within minutes, the gust front that had been several miles away overtook us with thick choking dust, 58 deg F surface temps, and howling NW winds — ahead of the arcus. Horses and humans cleared the area in a hurry.

Meanwhile the “tornado” warning suddenly vanished from NWR. Imagine that. “Developing tornado” — my _ss! Whoever reported that needs to go back to basic spotting class to be taught that tornadoes actually do rotate. Oh, and they don’t tend to occur behind arcus clouds rising over deep, cold outflow. Duh.

Southward to Sidney we cruised, stopping briefly to look at the visual manifestation of a LEWP off to our NNE. Now, on rare occasion, *those* sometimes spawn spinups, but this one got undercut so fast it didn’t have a chance. Maybe others up the line toward Cherry County did, but we had no interest in racing east for hours across NE trying to keep ahead of a deep, mesobeta scale (and growing) blob of surging outflow that felt like some weird mix of Saharan particulates in Antarctic katabatics.

“Spotters report a line of thunderstorms capable of tornadoes” was the last thing we heard from that NWR as we roared off into NE CO, trying to find isolated development S of the horrendous pile of outflow. Dusty gusts near SNY may have been severe, causing us to struggle to stay on the road at times in a heavy, low-profile sedan. That said, I won’t venture an estimate since neither my estimates nor anyone else’s on this planet are reliable to within +-20 kt at those speeds.

N of Sterling we passed what appeared to me 5 or 6 TTU mobile mesonet vehicles and, just a little ways down the road, a non-DOW portable radar (Howie?).

We did intercept the back side of a small SVR-warned Cb near Cope that had a pretty backshear as viewed from the N, but also, a very high base. Precip curtains prevented us from viewing the updraft region until we let it get SE of us, and man, was it ever high based. A good deal of hail that was marble sized (but conical or candy-corn shaped) covered the ground along US 36 in the Cope/Joes area, on both sides of the Washington/Yuma County lines.

We ended the storm day with some dinner in Limon, and photography of the old grain elevator under sunset-lit ACCAS. Cold NNE winds soon blasted us there, two hours and 100 miles removed from our last encounter with the same outflow current near Sterling. Even in the north suburbs of DEN, after 11 p.m., we got a shot of the outflow pool sloshing in from the ENE. That gave us nearly 12 hours in and out of outflow from the same huge mess of storms.

===== Roger =====

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