Recently in Cumulonimbus Category

I woke up on day 4 ready for an awesome day chasing some powerful storms across Kansas. Hopes dashed: a quick check of satellite showed something had gone wrong. A huge MCS was moving northeast out of the panhandles and raining all over everything. The forecast for an explosive day took a nosedive and the south-Kansas target was getting washed away with cool, cloud-covered stability. There was a chance that all the elevated convection would move out in time for the sun to warm it back up and try for a recovery, but it was looking pretty slim. I bailed out of the grunge hotel and hung out at a gas station refreshing satellite, forecast models and SPC analysis. Some chasers were hoping for an earlier recovery in southwest Oklahoma while others were hanging tight for renewed hopes in southern Kansas.

Just across the street from the grunge hotel, the TIV team scavenges for parts.

Gradually, the MCS moved out and clear skies started to edge in from the west. At the same time, I noticed that new convection in north Texas was sending huge, dense anvils racing northward just in time to block out the sun again. That was all I needed to see. My forecast area was toast. I headed west toward Dodge City to look for a opportunities closer to the surface low and in clear air. By the time I reached Dodge CIty, the SPC had posted a tornado watch discussion for northwest Kansas. The dryline was sticking out like a sore thumb from my position and on northward, but the cirrus canopy was hugging right along its eastern edge. So I got on Route 23 and took off for northwest Kansas. As I made my way north, a check of the rear view mirror showed new convection popping up right over Dodge City and looked like it was reaching for the ground and trying to get surface based. I almost turned around to give it a shot, but that cirrus deck was heavy and I figured the storm was going to have a horrible fetch of inflow. So I kept hauling north.

As I got closer to I-70, I could see storms to the north along the stationary/warm front beginning to go up. And here I was approaching from the south again. One of these days, I figure I'll position myself to not be playing catch up. Spending 15 minutes with stop-sign guy on a one lane stretch of road construction, waiting for the pilot car was a time of great sadness and anxiety. Somehow I still managed to catch up with a decent severe-warned storm on Highway 83 south of Oberlin. I was on the wrong side, and it was outflow dominant, but it was still the best thing I had intercepted the entire trip. I caught sight of an interesting lowering behind the rain curtains, but it didn't go any further than that before gusting out in a spectacular torrent of ragged scud and spindled shear vortices. I followed its remains past Oberlin where I caught the beautifully lit sight of another cell to the southeast. Radar show it to be weakening, so I decided to head north then east and sample its core.

Panorama of convection looking north along Highway 83 in NW Kansas.

Very wide panorama of severe-warned cell south of Oberlin, Kansas.

Rain free base with tantalizing lowering.

Enhanced reflectivity view of the Oberlin storm.

Velocity scan showing broad rotation

Tattered scud and shear vortices twist and fray as the Oberlin storm gusts out.

Nicely sculpted pillar of scud flows along the gust front.

Dwindling light reveals another dying cell to the southeast.

Time lapse video of the day's chase. Click through to YouTube to view in HD.

As I drove through the blinding rain, I noticed a car riding my tail. If they want to go play Hydroplane-on-the-Highway, I figured that's their business. So I pulled off the side and motioned them to pass. Instead they pulled alongside and told me I better hurry since the worst was headed this way. I hollered over the pounding rain, that yes, thank you, I know, but that I wasn't willing to drive as fast as them. So off they went. A couple more miles got me out of the core, and a great view of another nice lightning display on a dark Nebraska road with the frogs and crickets jamming away into the night.

The last of the convection moves north, flickering with lightning as night descends.

I eventually made my way back down to Highway 36 and west to just beyond the Colorado border. I pulled off on a dirt road and caught bursts of sleep while the surface low spun overhead entertaining and distracting me with bursts of rain and lightning all night long.

Lessons Learned:

• Even the best setups can be demolished by situations that the forecast models didn't anticipate.
• I made a good call abandoning the southern target when I did. The early convection and continued cloud cover destroyed all hope for that area. I'm also happy with making the decision to not go after the Dodge City cell. The cirrus canopy strangled it and it died out soon after.
• There's always next year...

Day 1 - Night Storms in South Dakota

Day 2 - Anticipating Initiation in South Dakota

Day 3 - Positioning Practice in Kansas

Day 4 - Tough Decisions in Kansas

My third day on the plains was a travel and practice day, in anticipation of the big Kansas outbreak day on Wednesday. South Dakota, Nebraska and northern Kansas fell away behind me as I made my way to Pratt, Kansas by late afternoon. A chance for a few elevated storms was forecast, and I took the opportunity to practice navigating around one of them on the awesome Kansas road network. As my sample storm drifted north-northeast, I gave the sandy, dusty farm roads a try, and got a good feel for how some of the dodgier ones were mingled in with the better-maintained roads. The consistency was a lot sloppier than the South Dakota experience the day before--definitely not something I want to be on when it's wet. I gradually let the storm slip by to my north as it put on a nice lightning display for me.

An elevated storm drifts along north of Pratt, Kansas, providing a nice opportunity to practice pacing and positioning along the local farm roads.

Radar view of my little practice storm.

Appreciating the sights along the way. This patched up old farm building was loaded with personality.

This was the one night I set aside for a motel to rest up for the big day on Wednesday. Money was tight, so I picked a low cost option on the east side of Pratt. The various long-term motel residents on the south wing were tailgate-partying and I probably would have been a little more unsettled if I wasn't so tired. There were no bedbugs that I could see, but I kept everything off the floor anyway. I asked for replacement sheets that didn't have hair on them. The new set of sheets had holes in them too, but thankfully no spare hair. I layered bath towels along my sleep area, maintained posture and had zero contact with the rest of the bed. Not ideal, but it was a great relief compared to the car seat sleeping position. It was so nice to have a shower too--don't touch the walls, or shower curtains of course.

Lessons Learned:

• Less maintained Kansas roads can be dicey for a Honda Civic even when dry--stay away when wet.
• Budget $60 for a less grungy motel experience. Bring a sleeping bag just in case.
• Set video camera to 1/30 sec. exposure to keep lightning from being chopped up by rolling shutter effect.

Day 1 - Night Storms in South Dakota

Day 2 - Anticipating Initiation in South Dakota

Day 3 - Positioning Practice in Kansas

Day 4 - Tough Decisions in Kansas

My second chase day started with the sun's warm rays piercing broken clouds above a nearby farm. I slept a little later than I wanted, but had plenty of time jump on I-90 and head west toward Murdo where I waited for signs of initiation along points further west. This setup was difficult to forecast. The best moisture/instability/shear was wrapping north and northeast of the surface low, north of the warm front. I had a hard time picking the best spot for storm initiation and was really hoping visual cues and satellite would point me toward development with enough time to adjust and intercept.

I wasn't the only one in Murdo watching the sky and refreshing satellite views and SPC observations. The Dominator crew and about a hundred other chasers were parked in various hotel and gas station parking lots hanging out, scarfing convenience store food, throwing frisbees, scrubbing windshields, jaywalking, and checking out each other's chase vehicles. I was concerned that the best, first storm would collect an instant caravan and I wanted to get out before that happened. Turns out this wouldn't be the problem. As I headed further west, the sky grew heavy with fast moving stratocumulus. It was frustrating to realize that I was going to have a terrible time visually spotting points of storm initiation.

Eventually, northbound radar returns started to pop up along I-90, east of Rapid City as well as a nice, tornado-warned cell far to the south near Crawford Nebraska. I started to drive south, thinking I could intercept the Nebraska storm somewhere near Wounded Knee. But then I second guessed myself and figured that I'd probably make this long drive through the badlands with difficult terrain and bad road options and the storm would be past its prime by the time I intercepted. So I headed back north of I-90 and traded one set of bad road options for another. I was positioned right at the southern end of several developing radar returns and finally caught a glimpse of one of the new towers to my east. To my north: wet gravel roads. I thought, ok, let's try these roads out and see if I can get ahead of the development and intercept around from the northwest.

Developing radar returns just before I began my long drive north to try and intercept the pick of the litter. (My location is shown by the blue target.)

Rough Kelvin-Helmholtz clouds forming in a nicely sheared environment.

A sunlit anvil blossoms to the east of my position.

My Honda Civic and the wet South Dakota dirt roads played nicely with each other. However, what with the Belle Fourche River Valley, majorly broken road grid, and wet dirt-gravel surface, I was no match for the storm motions. It didn't take long to realize that I wasn't going to intercept any of the storms I thought I would. So I plotted a path to hit Route 34, then Route 73 and work my way back toward I-90 and see if any new development would head my way.

Stunning overlook of the Belle Fourche River Valley.

It took forever to get back to a paved road, and night had fallen by the time I hit asphalt again. As I made my way back east, then south, severe and tornado-warned storms lit up the sky to the north and east. I was frustrated that I had failed so miserably at positioning myself, but the non-stop lightning show was a beautiful parting gift as I drifted along the lonely South Dakota highways.

Severe and tornado warned cells avoid my chosen route.

I parked for a few hours of sleep near Kadoka, SD, where the drizzling remains of the tornado-producing Crawford storm finally passed overhead and drifted off into the flickering night.

Lessons Learned:

• If dirt roads are the only way to intercept a target already to my north, and there is a good possibility of a southern target, opt for the southern target.
• Committing to a long, unpaved route in an area that is not fully gridded is probably a one-shot deal.
• The Honda is compatible with at least some of the wet, unpaved roads in southwest South Dakota--although copiously wet would probably be a different story.
• Setups where the target area is north of the surface low are a serious weakness for me to anticipate development.
• South Dakota is a beautiful place to chase.

Day 1 - Night Storms in South Dakota

Day 2 - Anticipating Initiation in South Dakota

Day 3 - Positioning Practice in Kansas

Day 4 - Tough Decisions in Kansas

I chased some stunning high-based storms with brief supercell structure in southern Arizona earlier this week.

A trough moving in from California was forecast to take on a negative tilt as it drifted into Arizona. Dynamics would be favorable for severe storms with 40-50 kts of shear, positive vorticity around the base of the trough, and some chances for winds sufficiently veering with height to support multicell and weak supercell structure. The SPC forecaster commented that the NAM was handling parameters nicely, so I gave it more attention for my initial plan than the RUC and GFS. It forecast a tongue of modest instability (500-750 j/kg MLCAPE) moving eastward from Yuma through the central deserts and then lava-lamping a blob of CAPE northward through the Phoenix area by late afternoon/evening.

I was initially tempted to head west, toward Kingman that morning. Ongoing convection associated with another field of instability was being spurred by a streak of upper air support. It didn't help that Flagstaff NWS was discussing the remote possibility of an isolated tornado for the northern Arizona forecast area. The Phoenix forecast for southern Arizona conceded the possibility of brief supercell structures, but didn't go so far as to leave the tornado possibility on the table. Still, the best combination of instability and jet streak dynamics seemed poised to effect southern Arizona more favorably than elsewhere. I also wanted to play in some terrain that had better visibility. So that's where I headed. I planned my first stop for Wickenberg to sidle closer to the front and then have a good road option to the southeast as I watched how convection developed.

By 10:30AM as I was nearing Cordes Junction I could see storms already blossoming south of Wickenburg along the cold front. I chastised myself for getting a late start and possibly missing an early show. But better dynamics were still hours away, so I pushed the frustration aside. As I approached Wickenburg along Rt. 74, a gap in the hills allowed a brief birds-eye view of one of the early storms pushing out an arcing ring of dust--one of many I'd get to sample through the day.

As I sat at the intersection of Rt. 74 and 60 checking radar and satellite, I was dodging ongoing feelings of self-doubt. Convection in northwest Arizona was doing very well for so early in the day while storms popping up in southwest Arizona were blooming and dying in short order, shooting thin anvils eastward in spurts. I was starting to worry that the atmosphere was going to get tapped of whatever available moisture there was, and the show in the north might be the only real play for the day. Still, I decided that as long as I was part-way there, I might as well commit the rest of the way to my southern target. So I cruised the rest of the way past Laveen, and south of South Mountain. Along the way, the storms pulsing along the cold front were really starting to push the dirt around. Much of my drive south ran me right through the diffuse wall of a dusty gust front.

I parked the car off the road in the scrubby wastes northeast of Estrella Mountain (appears to be a perfect spot for disposing of contraband and bodies) and watched the merging arcs of dust pushed westward. A strong storm peeling away from Ajo dissipated as it approached and ran into a sad capping problem that was centered pretty much over my head. I held onto hope that the cap would erode as the dust cleared out and the surface heated back up. But the surrounding environment continued to be harsh on convection. One sad little cell pushed up over the mountain, but then faded into a mist.

Another batch of convection brewed back up over Ajo and then split as it moved over Interstate 8. The right mover looked really good, and I quickly headed south toward Maricopa to intercept it. As I rounded the east side of Estrella Mountain, I could see the dark core of the storm pushing up against the ridge. I soon caught a glimpse of the rain free base and a distinct lowering. Maricopa Road was thick with 75 mph rush-hour traffic, and I had a challenge finding a place to pull off safely. Casa Blanca Rd. did the trick. Although the storm had dwindled to a fraction of its former bulk, it still had a very nice show to put on. I spent the next several minutes photographing and filming a beautiful wall cloud being sculpted out of the storm's base.

After dropping into a nice, morphing cylinder, with a bit of RFD cascading down its south edge, it merged back into the base for a few minutes. As the storm moved further north, the base tightened up into a stunning barber pole with another, furry wall trying to form beneath.

By this time, another cell to my south started raining on me and feeding my target storm some cool, misty air. As I rushed northward to to get out of the rain, the storm base began to erode into a tattered claw, painted across a dusty, desert landscape. I hated not having a good place to pull over and capture the amazing sight to my left. To make the best of it, I rolled down the window, and snapped several uncomposed shots while concentrating on the road ahead of me, hoping one or two of them would frame it nicely. Fortunately that worked, and I came away with a couple in that series that I actually liked.

Before leaving that morning, I tried to sober myself with some rough odds:

• 80% chance of seeing some storms.
• 30% chance of getting a good look at a severe or otherwise interesting storm
• 10% chance of intercepting a storm with supercell structure
• 5% chance of a wall cloud
• <1% chance of seeing a funnel or better

Four out of five's not bad, I figure! I was pretty happy with how things went as I spent the next 160 miles driving back up the mountain in pouring rain. Although the Maricopa storm possessed some key elements, I'm not sure I would call it a supercell--maybe a 'marginal' or 'brief' supercell. After reviewing the time lapse video, it did show rotation in the updraft, but it was not vigorous and had a very small radar signature by the time I intercepted it. In hindsight, I think that outflow from the earlier convection was what was killing the storms that I hoped would "come to me". I should have taken the extra driving hit and headed further south to Interstate 8 to catch a more pure fetch of moist southerly air where the convection was happier.

Taking a queue from Skip Talbot--

Lessons Learned

• Don't let the early show distract you from the main play for the day.
• Do factor in the atmospheric consequences of the early show when positioning for the main play.
• Clean dust off my camera's sensor--cleaning the blobs out of the images later is a pain in the rear.
• Southern Arizona has better chase terrain and visibility than the mountains of northern Arizona...but the road network still stinks compared to the plains.
• Invest in a swatch of black velvet for the dashboard. Positioning the video camera on a huge, dark jacket to hide dashboard-window reflections is an obnoxious balancing act.
• Blindly shooting photos out the side window can actually work if you have no other options.
• Even at low speed, cruise control on my car is a force of evil when it encounters flooded highway ruts.
• September/October in Arizona is my new second-chance chase season.

The second week of September has been a great week for organized storms in Arizona. A cutoff low developed over southern California, and has been drawing up moisture for several days and providing decent shear aloft. Lower level winds haven't been very strong and veering with height in the first kilometer not very promising. However, bulk shear from 30-40 knots, cooling and diffluence aloft, and ample moisture led to strong storms and support for occasional supercells.

Supercell thunderstorms are not common in Arizona, but after missing the storms that led to last year's Arizona tornado outbreak, I've been keeping an eye out for California cutoff lows. Being at the right place at the right time to view and film a rare Arizona tornado is so close to being unrealistic, that I'm not too anxious about it. However, catching an Arizona supercell seemed doable and would be a very nice gem to collect.

I've had my cameras ready in the car and kept an eye on radar in hopes of catching a good storm. I made a couple local chases the week before, caught some broad rotation in one storm and brief barber pole structure in another, but not much else. Then on the afternoon of September 13, I noticed weak, but sustained, rotation on a couple storms on doppler radar. I headed outside to get a look and to the north I saw a robust storm perched over the San Francisco Peaks. The rain free base sported a zone of rising scud, and I was surprised to see what appeared to be a wet RFD slot slicing into it. As the razor edged rain band pushed in, the rising scud quickly congealed into a wall cloud with a laminar profile and nice rising motion. All I had was my cell phone, so I had to suffice with a couple low-quality photos.

Hoping it would hold together, I quickly ran to my car to grab my cameras. By the time I got back to a good clearing in the trees, the original updraft cycle had eased off and the wall cloud had broken up. I was pretty disappointed, but the storm still looked strong, so I found a new vantage point along a stairway leading to the roof of my office building. I set the video camera up for a time lapse while shooting still photos as the storm cycled two more times.

While shooting photos, I called my wife while she was running errands about a mile further north, closer to the rain free base. Besides describing a wicked looking storm and an occasional spray of hail, she mentioned the warm inflow that was feeding it.

The videos below show a time lapse view of the storm. I suggest clicking through to Youtube and viewing in high res

By now, a flanking line and gust front had developed along the storms southwest flank, and there appeared to be an inflow tail stretching eastward behind Mt. Elden. One area of rotation drifted eastward through Shultz Pass and dropped a broad, tattered wall cloud. This area seemed to be occluding while new circulation was trying to develop just south of it on the other side of the RFD gust front.

This second video shows detail in the wall cloud, including an interesting, conical structure drifting through it. The structure persisted for about 40 seconds. Although I wonder if it was an embedded funnel, I can't be sure--I can't discern motion in the dark silhouette.

The new area of rotation began to pull in rising scud and even started to form a tail cloud. It was definitely exciting to see it try to tighten up as rotation got faster, but it lost cohesion, and the storm pulled away to the northeast and out of view over the mountain.

This cycling supercell was a real treat to view. While I imagine it would be a disappointment by plains standards, it was pretty awesome as Arizona storms go. Unfortunately, the core was planted right over the Schultz Fire burn area and led to another round of serious flooding for neighborhoods downstream.

The station that recorded the radar images below is located to the southeast.

I got on the road Saturday afternoon, left Flagstaff, drove most of the night, and made it to eastern Nebraska by Sunday late afternoon.

I'll try to do a more detailed summary later with more photos. (I'm extremely worn out.)

After checking models and spc discussion each time I stopped to fuel up, I decided I would head to the warm front. Unfortunately, eastern Nebraska turned out to be a wasteland of uncooperative cloud streets. The cap wasn't budging there at all. I figured I was going to have a complete bust on my first day out. But then inhibition started to part in South Dakota, a few storms started to blossom. Most were too far to consider, but a small, fresh one was within reach, so I raced north. As I got closer, I realized the cap had clamped down and nothing was left but an orphan anvil.

I kept going north, just in case, and was suprised by a view of a new tower going up on the other side of the Missouri river, half-lit by the coppery light of the setting sun.

Satellite view showing my target storm as a bright blip in the far south-southeast corner of South Dakota. (Note the only tornado-producing cell in the south-central part of the state--too far out of reach.)

The new tower was farther north than I thought, and was moving north at about 25 knots. I decided not to keep chasing it in the dark, so I broke off, satisfied to see it sputter with lightning as it drifted away. At least I got a distant storm and some lightning for day 1.

I fueled up again and did some supply shopping. Afterward, as I drove to a section of gravel roads south of Mitchell, SD to park for the night, I was overwhelmed by nonstop lightning behind me. I pulled over to figure out where it was coming from. Sprawled out to my west was a huge, sculpted shelf cloud, gaping with rain, wind and lightning--and it was visibly expanding in my direction. I didn't want to get the car golf-balled, so I raced down the dirt roads, going after a good north-south paved road. Along the way, I made some brief stops to photograph this majestic thing.

At one stop alongside a small lake, the sound of katydids, frogs and other nocturnal creatures blended in with the non-stop thunder of the approaching storm. It was wonderful. As I continued south and east, I realized the entire gust front was going to chase me into Missouri if I let it. So I hunkered down in a farm field access and embraced the drenching rain and unceasing lightning. It was an amazing way to end the day.

Radar showing my position with the approaching gust front.

Lessons Learned

• Argh. Just play closer to the triple point--don't get creative with points further out along the warm front.
• The cap likes to be stronger further south.
• A shorter focal length lens would be nice for capturing massive gust fronts and shelf clouds.
• After night fall, shut off the car, get outside and enjoy the sights and sounds of lightning, thunder, and wildlife.

Day 1 - Night Storms in South Dakota

Day 2 - Anticipating Initiation in South Dakota

Day 3 - Positioning Practice in Kansas

Day 4 - Tough Decisions in Kansas

We've enjoyed some evening lightning lately--the best kind of fireworks.

This first shot was from Edmond, Oklahoma on August 5, 2009. While sitting outside, we watched as a line of anxious cumulus to the north finally pushed their way through the cap and sprouted a healthy storm. The frequent and constant lightning illuminated the crisp, sculpted edges of the cloud and occasionally revealed bright stitching as warped streamers fell from the sides.

Click image for larger version.

Subject	Cumulonimbus and Lightning
Location	Edmond, Oklahoma, USA
Date	AUG 05, 2009; 10:07 PM CDT
Equipment	Canon EOS 300D + Kit Lens
Settings	30 sec, f/9.0, 18.0 mm, ISO 800
Processing	Noise reduction, power line removal, contrast & color management in Photoshop CS3

This next shot was taken from home earlier this evening as a storm was pushed north by a line of convection along the Mogollon Rim. Flagstaff doesn't often see evening lightning displays since the storms fire up earlier in the day before racing off to the lower elevations leaving more stable air behind for the rest of the night. That wasn't the case tonight and we saw some brilliant webs of light igniting the sky to the south.

Click image for larger version.

Subject	Lightning
Location	Flagstaff, Arizona, USA
Date	AUG 12, 2009; 08:26 PM MST
Equipment	Canon EOS 300D + Kit Lens
Settings	30 sec, f/9.0, 18.0 mm, ISO 200
Processing	Noise reduction, contrast & color management in Photoshop CS3