Recently in Meteorology Category

Monsoon storms got an early start on July 2nd. The night before, the HRRR model was trending toward an MCS rolling out of southern Nevada and into Flagstaff by around 6 AM. I set my alarm for 5 and sure enough she was right on schedule just west of town. I quickly threw myself and everything else in the car and headed out on east Route 66 to watch it plow through town. I love watching Arizona storm clouds when they’re in high-speed mode.

Storms towering over Flagstaff as seen from east Route 66 - 1226Z

Gust front making its way out of town - 1230Z

A nice eddy sculpts the gust front as it rushes by the south side of Mt. Elden - 1231Z

Since it looked like it might stay interesting, I headed east to Twin Arrows—and was reminded how much I disliked the view from that exit. So I headed a bit further east to the Buffalo Range Road exit—no real foreground elements to speak of, but at least it wan’t fences, power lines and dumpsters. As the gust front moved in, a northern stretch of it lunged out and sculpted an amazing, terraced shelf.

Beautifully sculpted shelf cloud between Twin Arrows and Two Guns - 1302Z

I jumped further east to Two Guns and composed some shots of the ghost town structures with the heavy morning sky. I’ve snagged a few photo ops with the stone structures in the area, but this was my first time working with the buildings on the east side.

Moody sunrise over Two Guns - 1313Z

Insane graffiti and advancing storms at Two Guns - 1317Z

After that, I raced ahead to Holbrook and then southeast on Hwy 180. The line of storms was messier at this point but still had some moments of shelfy goodness to offer.

Fangy, embedded shelf cloud southeast of Holbrook - 1451Z

Tantalizing scud photographed on the move, southeast of Holbrook - 1458Z

As that line weakened and moved off to the east, I had a look at the models again. Indications were that the morning cirrus shield would move on, the atmosphere would recover, and more storms would fire, despite subsidence in the wake of the morning MCS. So I headed back west and decided to explore Homolovi State Park for a little bit while convection slowly got going again.

Receding convection and windmill on Hwy 180, southeast of Holbrook - 1612Z

A Loggerhead Shrike keeping an eye on parking spaces at the entrance to Homolovi State Park

Pottery shards gathered on stone platforms at the Homolovi II Archeological Site

Cumulus bubbling south of Homolovi State Park - 1957Z

Convection strengthening over the San Francisco Volcanic Field - 2016Z

Collared Lizard showing off its colors at Homolovi State Park

Storms continued firing west of Leupp while tracking along and north of I-40, so I headed over to Rt 99 northwest of Winslow, then the Meteor Crater Road exit, and then back to Rt 99 south of Winslow. Storms were not as sculpted as they were that morning, but still enjoyable viewing on desolate roads.

Convection south of Leupp from Rt 99 - 2147Z

Lightning strike from north of Meteor Crater Road - 2246Z

Transient structure at the I-40/Rt 99 offramp - 2306Z

Storms forming along an intersection of outflow boundaries south of Winslow on Rt 99 - 2348Z

A hangnail of vorticity and a sunbeam along Rt 99 - 0007Z

I wrapped it up with a time lapse near Clear Creek as distant storms pulsed along a southward moving outflow boundary.

Convection and anvils along a receding outflow boundary from near Clear Creek - 0048Z

A short sequence of time lapses from the day.

We started the day out in Dodge City where we had viewed several tornadoes the day before. This day’s chase took us further east into Kansas looking for convergence and backed winds along the dryline and other boundaries. As we made our way east on Hwy 50, we stopped at a couple abandoned buildings east of Spearville, at a spot on the map called Ardell. We had passed these the day before while shooting some sunset pics after the Dodge City storm. My daughter is a bit of an explorer and spent a lot of time checking things out, including peeking into a window where she was hissed at by a huge, cranky gopher snake that had wound itself around some pipes dangling over an inky abyss.

Exploring a towering abandoned building in Ardell.

The western suburbs of Ardell, Kansas :)

As we got further east, a long arc of clouds bordering hazy skies announced the dryline bulge. It was extremely cool to see it stretched out like that visually without even needing satellite. Although the satellite view was pretty impressive too, showing both the arc of the dryline and a boundary further east. Towers were trying to build on this eastern boundary, while others were brewing to our north near the triple (quadruple?) point. We gradually made our way eastward shooting landscapes along the way, watching the boundaries percolate, trying to decide between east or north.

Approaching the moist boundary of the dryline bulge [2010Z].

Radar view of the dryline boundary [2011Z].

Satellite view of swirling boundaries and growing cumulus fields [2030Z]

Landscape east of Macksville.

Triple point cumulus far north of Macksville [2031Z]

By the time we reached Hutchinson around 2145Z, convection was gushing anvils to our north near Claflin while the Wichita towers appeared to still be working on the cap, so we headed northwest to head for the northern target. When we got to a few miles southeast of Lyons by 2215Z, those anvils had gone orphan while a Wichita storm was finally taking off and looked like it had a nice, muscular updraft going. More self doubt followed as we drifted eastward and a new growing tower between Minneapolis and Lincoln to our north got going. I watched these two towers compete for attention north and southeast until Rt 61 a few miles southwest of McPherson when a final decision had to be made. I opted north, thinking that storm’s convection looked sturdier, had a backsheared anvil, overshooting top, hopefully the benefit of a boundary and better backed inflow to work with, and an easier intercept by this point.

By 2254Z, southwest of McPherson, the choice of storm target finally became clear. (Left: storm northwest of Salina—check! / Right: storm east of Wichita—farewell…)

As we got further north on I-135, the storm was looking pretty impressive as it approached the north side of Salina. I wondered if Bennington would see a repeat 2013 performance—and apparently a tornado did briefly touch down there while we were still making our way north.

Blossoming supercell north of Salina [2317Z]

We headed off onto the grid about 4 miles north of I-70 and had our first look at the base. It was working on an RFD notch, but didn’t look too impressive at the moment.

RFD notch nudging into the base east of Bennington [2339Z]

A corkscrew in the updraft west of Bennington [2349Z]

We got a little behind for a few minutes, but worked some very nice dirt road grid to catch up. After heading west another 5 miles, the storm really pulled together and we caught sight of a hazy, dark, cone tornado behind a thin veil of RFD precipitation. The pace of the chase really picked up after that. As we paced and worked to gain ground on the storm, the tornado grew in size while the choppy barrel meso above it took on Bowdle stylings.

First view of the growing tornado as seen from 7 miles west of Solomon [0009Z]

Strengthening cone tornado as seen from 5 miles west of Solomon [0013Z]

Wide view of the tornado and sculpted RFD cut [0013Z]

Growing tornado and chaotically detailed meso [0016Z]

At 240th road, I headed south and got onto I-70 to try and gain some ground on it, snagging blind photos out the window along the way. Just a bit before the Solomon exit, we encountered a sheriff hollering at a tour van operator who was parked on the side of the interstate while his tour group was loping across the median. Yikes.

Dashcam view of tour group getting busted for Interstate frolicking [0025Z]

Shrouded tornado lurking north of Solomon [0026Z]

View to the northwest from the northwest side of Abilene [0038Z]

We made our way to the east side of Abilene and Indy Road just north of I-70. It was a perfectly elevated spot to watch the dusty, stovepipe tornado approach and widen into a large cone as it crossed our road a little over 2 miles to the north. It served up the best set of photos and video I’ve ever gotten of a tornado. A couple of locals, a father and I think his teenage daughter pulled up and talked about this being the first they’d seen even though he’d lived in Abilene his entire life.

View from Indy Rd north of I-70/northeast of Abilene as a stovepipe moves across the landscape [0050Z]

Close view of the dusty stovepipe [0053Z]

Tornado and rippling RFD cut getting ready to cross Indy Rd. a little over 2 miles to the north [0054Z]

Crossing Indy Rd [0055Z]

Tight video frame view of tornado base after crossing Indy Rd. [0057Z]

As it passed to the east, RFD shrouded the view and was pretty intent on knocking my tripods over, so we packed up and pulled back east onto Old US 40. Because the storm was nudging increasingly south and we didn’t want to play tag with the approaching tornado, we turned south on Rt 43 at Detroit to get some distance from it. I was concerned that by the time we found a good east-west road we might not catch back up until the river infested, choppy road network south of Junction City. So we lost it at that point and snagged sunset photos of a beautiful trailing cell before heading further south and shooting some nightscape shots with fireflies, stars and receding lightning near Antelope.

Sunset and striated structure on trailing supercell [0134Z]

Stars, lightning and headlights reach into the sky near Antelope [0411Z]

Chase map for the day — 25 May 2016

Close up chase map showing photo locations and approximate tornado locations.

Zoomable/interactive chase map



Video highlights from the chase

NOAA Abilene-Chapman Tornado Survey — 25 May 2016

Our May 24th chase started out in Shamrock, OK. We got a really good rate at the Shamrock Country Inn—it was clean, new beds, recently refurbished by a motivated new owner. The doors are a bit sticky, but I can definitely recommend it.

We made our way north, looking for likely spots for storm initiation along the dryline or intersecting boundaries from the Oklahoma Panhandle up into southwest Kansas.

Backroad scenery in the Oklahoma Panhandle between Logan and Slapout.

Indian blanket flowers east of Slapout, OK.

Eventually, satellite imagery showed the cumulus field getting more agitated north of Englewood, KS. This gave us a chance to drive through Englewood and revisit a view we had over four years ago when we chased a lonely, low-topped LP supercell north of town (14 March 2012). I noticed Stephen Locke—another storm chaser whosephotography I admire—filling up at the gas pump. I had a chance to say hi before moving on to the growing towers to the north.

Silos and developing towers from Englewood, KS. [2102Z]

We made our way to about six miles west of Ashland and shot time lapse of the building towers to see what would take hold. The one I was shooting wound up gaining strength and we headed off to watch it develop.

Vorticity and random high-based funnels showing up in the developing cumulus field. [2138Z]

The storm of the day looms in the distance—west of Ashland, KS. [2156Z]

Roads were dry and in pretty good shape, so we stayed off the main highways for hopefully more unique perspectives and less crowds. It worked out pretty well. As we got about eight miles east-southeast of Minneola, the storm was developing a wall cloud that looked like it had potential.

Traveling the dirt roads but avoiding the dicier ones. [2238Z]

Wall cloud developing in the base of our rapidly strengthening supercell near Minneola, KS. [2240Z]

I hated to leave our spot in case it put down a brief tornado while we were on the move, but we needed to keep up. We made our way north and by the time we were a couple miles north of Bloom, the tendrils dropping out of the wall cloud looked pretty imminent. So we stopped in time to capture a developing condensation funnel touch down for our first tornado of the day. It turned out to be a great spot, with enough altitude to capture some intervening countryside as the silhouetted funnel danced and twisted against a distant tree line. We were about 12 miles away at this point, but the view was great. We hung out at this spot for nearly 15 minutes as it grew in size. At one point I was thinking that this must be how Rozel looked in silhouette—apparently this one is being referred to as Rozel #2 by some :)

Condensation funnel of the first tornado reaches for the ground. [2301Z]

Tornado #1 churns in silhouette west of Minneola—about 12 miles from our location. [2303Z]

Inflow tugs at my daughter and chase partner as the first tornado strengthens north of Minneola. [2308Z]

Tornado #1 bulks up as it moves northward. [2313Z]

We eventually had to keep moving to stay with the storm. While repositioning, the original tornado began to occlude behind a haze of precipitation. My daughter asked if there was a different tornado forming further to the right. Sure enough, a thin rope had descended from the fresher wall cloud while the previous tornado was still in progress. This was our first tornado pair. I hate to call them twins, because the emaciated second one wasn't even close in appearance to the first—more like the mole that shows up on the stronger twin when it absorbs its sibling I guess.

Tornado #1 occludes while whisker-thin tornado #2 reaches down to the right. [2321Z]

About seven miles south of Dodge City and still on the dirt roads, we found a really good spot to watch as a new tornado took on Rozel-like proportions as a thin rope tornado flicked around on the east edge of the elongated wall cloud. There may even have been another tornado intertwined with that rope, but from my perspective I couldn't tell if it was just extra scud tendrils. The view of the main tornado at this point was spectacular. We were further south of it, so now it had some side lighting and showed a lot of dimension. We hung out at this spot for another 13 minutes or so before heading off to the dreaded main highway. (Rain was starting to effect the area and I didn't want to get us stuck in the mud.)

Tornado #3 gains strength while at least one rope—tornado #4—reaches down at far right. [2330Z]

A wider view of tornado #3 as it is southwest of Dodge City and about 10 miles to our northwest. [2331Z]

Tornado #3 taking on Rozel characteristics. [2332Z]

A wide view of tornado #3 as seen from about 7 miles south of Dodge City. [2333Z]

Wide view of the second pair of tornadoes we observed. [2335Z]

A wide structure view as the storm feigns being tornado-less. [2338Z]

Ropeout of tornado #3 rematerializes while its parent supercell continues northward. [2338Z]

Closer view of tornado #3 ropeout. Wall cloud at right is producing ground circulation—not sure if it's a continuation of tornado #4. [2339Z]

Hwy 283 was about as insane as I was worried it would be—absolutely packed with chasers and locals. Despite how crowded it was, most everyone was driving, parking and loitering in an orderly fashion. We parked at a couple spots to get photos as a fifth tornado morphed into various forms—barrel/multi-vortex/cone/elephant trunk/rope—west of Dodge City. We took the highways around the east side of the city, watching as the #5 occluded and roped out while a new, sixth tornado descended from the apex of a wasp-nest shaped meso. The highway was at a decent elevation, so we had pretty good views of the action north of the city as we made our way around. By the time we got northeast of Dodge, the sixth tornado had sprouted a satellite rope funnel of its own—video from other chasers shows this in contact with the ground as well, so—tornado number seven.

One of the many forms of tornado #5 as it was moving northwest of Dodge City—as seen from Hwy 283, about 9 miles away. [0002Z]

Ropeout sequence of tornado #5 as we navigated the east side of Dodge City. [0004-0008Z]

Tornado #5 occludes while tornado #6 drops north of Dodge City. [0010Z]

Tornado #6 sports a satellite, tornado #7 north of Dodge City—about 9 miles to our northwest. [0016Z]

By this time, new supercells were encroaching from the south it looked like our original cell was jogging to the east. So to avoid getting pinched, we bailed out to the east and made a half-hearted attempt to get on some other tornado warned cells east of Kinsley. That wound up seeming like more effort than it was worth, especially after the spectacle we just experienced, so we hung out for a while just west of Lewis on Hwy 50 and grabbed sunset photos.

One of the DOW vehicles samples a different storm east of Kinsley. [0109Z]

Sunset lights up the cold west flank of a passing supercell east of Kinsley. [0134Z]

Sunset and flooded back roads east of Kinsley. [0144Z]

A fire rages south of Lewis—presumably lightning caused. [0150Z]

A spectacular roll cloud sporting Kelvin-Helmholtz waves drifts by west of Lewis, KS. [0215Z]

After the stunning sunset, we headed back to Dodge City for dinner and a hotel for the night. While eating dinner, Arizona storm chasers Adri Mozeris, Trey Greenwood and Corbin Jaeger stopped by to say hi and we got a chance to talk about all the unbelievable things we had seen that afternoon.

Throughout our chase, I'm pretty sure we observed seven tornadoes, where two were on the ground at the same time on four occasions. I'm still having trouble believing we actually witnessed all of this. Other chasers reported seeing on the order of twelve tornadoes. So the numbers in my account don't represent the actual sequence of tornadoes on the storm—just the ones we saw ourselves. Like the Rozel/Sanford tornadoes, I could be convinced that what I counted as two tornadoes may have been continuations—where say one of the thin ropes seemed to disappear, but may have actually still been stirring up ground circulation before turning into a larger tornado later. I'll update things if I find out differently.

Chase map for the day — 24 May 2016

Close up chase map showing photo locations and approximate tornado locations.

Zoomable/interactive chase map



Video highlights from the chase

NOAA Dodge City Tornado Survey — 24 May 2016

This was an incredible day for a lot of chasers who targeted eastern Colorado. If you don't already know, just run a Google image search for "Simla Colorado Tornado" and bask in the amazement. My morning forecast perusal had dabbed a target option in the Simla vicinity as an 'Upslope Magic' option. I opted for a Kansas triple point target near Oakley instead.

The morning forecast analysis

We eventually drifted even further east near Zurich where better parameters seemed to be evolving. It wound up being a long wait. This part of Kansas was strikingly beautiful and begged for some photos while we waited for the cap to break along the warm front.

Kansas countryside near Zurich || 2115Z

Lone tree and capped sky at Zurich || 2120Z

Freshening up with a view

Loitering cattle that can't get any further southeast || 2140Z

After more waiting and hoping, and getting hints of amazing things happening in Colorado, we made our way to Stockton. I was really worried the cap was going to win and we were going to wind up with a complete bust. However, as convection started to fire in western Kansas, thin bubbles of cumulus finally started trying to hold their own in our area around 8:30 PM.

Thin streamers of cumulus finally taking a jab at the cap || 0130Z

Stockton homeowners about to get a great light show in a couple hours || 0130Z

More cattle not worried about building storms and anvils || 0140Z

We moved back west to view a storm that quickly blew up north of Nicodemus. We stayed on this awesome, nearly stationary lightning producer while grabbing time lapse footage. A nicely lowered base swung into view to our north and lightning told a staccato tale of scuddy, ground-scraping wonders beneath.

Lightning strike beneath an active supercell north of Nicodemus || 0235Z

Scary scud & who-knows-what beneath the Nicodemus supercell || 0302Z

A storm further west near Seldon wound up with a tornado warning around this time. We stuck with our storm though because I figured it had as good a chance of doing the same, and it was in a lot better road position for an after dark chase. Despite tantalizing goings-on beneath the updraft, our cell never went beyond a severe warning.

After our Nicodemus storm seemed spent, we slowly made our way westward. I wanted to get back to Limon for the night, but storms were stalking our path back and I didn't want to risk hail cores or worse after dark. So we waited them out and shot a bit more lightning photography.

Roll cloud/shelf cloud and lightning lurking over our way to Limon || 0340Z

We made it to our Limon hotel around 2AM just in time for a cell to go tornado-warned to our west as it headed straight for town. So we got back in the car, tired and cranky, and headed south of town to let the storm move through.

Tornado-warned cell approaching Limon || 0653Z

Storms of 2015

2015 went down as another year without a tornado. However, awesome weather was still in abundance, and I got to enjoy some exhilarating storms with at least one gorgeous, white funnel that stared us down between Burlington, Colorado and Kanorado, Kansas.

This year I put a lot more effort into tracking down mesocyclone potential in Arizona and wound up with some beauties. Three of them were solid, daylight examples of Arizona supercells, with deep rotation lasting over an hour. A couple more nocturnal supercells hid their structure behind terrain and darkness while other daylight examples of rotating storms were more transient and weak—but still fascinating during their brief, messy lives.

This is a video and time lapse compilation some of the amazing storms I chased and photographed across the high plains and Arizona in 2015.

Storms of 2015

Music:
Beautiful Shapes by Louis Romanos Quartet
Forgotten Shore by Dhruva Aliman
beatpick.com

Storm Chase || 19 March 2015

This was a chase-of-opportunity with my kids while visiting family in western Oklahoma. Before heading out, I brewed up my traditional personal estimate for success for the day:

  • Thunderstorms 75%
  • Transient Structure 50%
  • Supercell 15%
  • Rotating Wall/Funnel 5%
  • Tornado 1%

I got a late start getting out of the fog and drizzle of Elk City and got to my target in Vernon by 20Z — about an hour later than I wanted to. It was nice to see clearing and bubbling cumulus to the south. After fueling up and messing around with the latest data for too long, we headed further south into the clear and near the junction of Hwy 183 and 277 by 21Z. There were two areas of initiation at this point: some early development to my northwest north of Seymour, and a more mature cell near Archer City. The Archer City tower looked great, but I opted for the Seymour target since it didn’t involve playing catch-up, and being closer to the triple point, I thought it might have a better fetch of backed surface winds. The problem with this is that the western target was also further north and so was first to greet the cold front. It also got to choke on stable inflow from the Archer City storm. (click images for larger versions)

My daughter checking out the Archer City tower — 2110Z

Until it got wiped out though, it was a nice early-season chase. After grabbing a few shots of that tower to the east, we drove back north to watch the inbound Seymour storms. At an overlook east of Lake Kemp I met Marcus Diaz, Jason Boggs, Bobby Hines, Mark Eslick, and Tyler Hudson. We shared the views for a while as the convection gained strength and developed some structure. As the forward flank gust front finally started spitting rain on us, we hopped in our cars and headed our separate ways. Road options were pretty scarce, and we had to get a ways south of the storm before getting back east on Hwy 277 to get ahead of it.

Some structure on the developing cell near Lake Kemp — 2150Z

Marcus Diaz, Mark Eslick, Tyler Hudson and Jason Boggs check out radar and the storm base east of Lake Kemp — 2151Z

Encroaching outflow — 2204Z

A north option on SR 25 put us in a spot to look into a beautifully sculpted vault with a lengthy arcus/inflow tail spanning the sky and racing into the storm base. As the forward flank started gusting toward us, we cruised back south to get out of the way.

Storm base and pump jack from SR 25 — 2242Z

Terraced vault with arcus/inflow tail racing westward from SR 25 — 2247Z

Arcus and shelf gusting southward along SR 25 — 2247Z

Heading south, I wondered why truck traffic was backed up. Turns out a chaser had a yellow vehicle parked partway into the southbound lane and placing his body even further into the lane. So the trucks were waiting their turn to safely pull into the opposing lane to get around him as he waved people around. There were plenty of great pull-offs on this road—I used a couple of them. And the grass shoulder was huge and in good shape too, so there was no reason for treating the shoulder and pull out areas like hot lava. It was really really frustrating and embarrassing. I needed to get ahead of the gust front and didn’t have time stop and attempt a chaser-101 session, or get a good read of the decals on the vehicle.

Chaser obstruction — 2249Z

The storm was pretty strung out at this point but still dishing out some interesting sights. We got further east to Holliday and noticed a bell shaped lowering. It appeared to be a new updraft trying to forming well to the east of the base I had been watching, and it had what appeared to be a bit of RFD curling in and lowering a wall cloud/RFD shelf around itself before gusting out and merging with the forward flank.

Transient updraft/lowering seen west of Holliday — 2305Z

After that, we bailed out on the storm and headed south for some views of the other storm as it approached Bowie. We got a look at the back of the storm and its upswept flanking line before calling that one off too in some beautiful country.

Backside view of the other storm approaching Bowie — 2349Z

I’ve been watching the GFS signals for this Thursday (19 March 2015) flicker on & off for the past week. It’s nice to see a thin glimmer of hope for tomorrow. Moisture is forecast to move up to the Red River with dew points around 60 degrees. Lapse rates aren’t so great, and NAM and GFS vary on the degree of instability from 250-500 j/kg for GFS and up to 1000 j/kg from NAM. A cold front will sag southward and into this area of instability with storms firing as it forces its way into the warm sector. A shortwave trough over the southwest will feed 40-50 knot H5 winds over the area. So this leads to the possibility for some severe storms with a lot of caveats—especially marginal instability and an undercutting cold front.

18Z NAM shows 0-3 km Helicity maximized up to 250-350 m2/s2 narrowly along the cold front near the triple point at 00Z in the vicinity of Childress. 0-1km SRH is localized and probably barely worth noting near the triple point in the 50-100 m2/s2 range. 18Z GFS is much more conservative and also points further east—south of Wichita Falls. Obviously wouldn’t mind NAM’s optimism working out moreso than GFS at this point and I’m planning to give it a shot just in case. I’m planning to head out of Elk City with an initial target of Vernon, TX by early afternoon.

19 May 2013 Oxford Supercell Diagram

In my previous post, I diagrammed the Oxford, Kansas supercell from 19 May 2013. About 90 seconds after that shot was taken, a new area of low level rotation developed just ahead of the occlusion. This is a diagram of that moment as the inflow was forced into the updraft at that point and rapidly exposing circulation at the cloud base.

Oxford, Kansas Supercell Part 2 - 19 May 2013
Oxford, Kansas Supercell Part 2 - 19 May 2013 - Diagrammed

On the Continuum of Walls and Shelves

In 2010 after my first Great Plains chase, I spent a lot of time going through my photos and working to improve my understanding of storm structure. For one of those exercises, I diagrammed the Bowdle supercell. There was a lot of excellent feedback and discussion on all the structure in that beautiful, terrible, amazing storm.

Each new supercell I chase broadens my appreciation for all the ingredients and dynamics that make each one unique and awesome. I enjoy recapping each one and visualizing what was happening, so I've been keen to diagram some more recent storms.

What I especially wanted to work on were transition points in space or time where a shelf cloud is merging or morphing into a wall cloud/tail cloud and vice-versa. A lot of times it's pretty clear what's what. But because the storm and its environment don't care about taxonomy, there are plenty of cases where things ride along a diffuse spectrum. To me, it's educational to watch these things unfold and look for transitions where one thing becomes another, and what that means for the fluid movement and interaction of near-storm air masses.

So, here is a batch of a few more.

Denver Supercell - May 21, 2014

While this storm was still strengthening over Denver Metro and headed toward the airport, it had a very compact RFD shelf that I wanted to call a wall cloud at first glance. But the RFD appears to be responsible for lifting this prominent feature out ahead of the base while the true wall clouds spins away behind. Mike Olbinski's time lapse nicely demonstrates the dynamics (See the 6:24 segment of the video).

Denver Supercell - May 21, 2014
Denver Supercell - May 21, 2014 - Diagrammed

Goshen County Supercell - May 20, 2014

This was a view that to me, beautifully demonstrates the source of a weak wall cloud’s formation as the forward flank's rain foot intrudes into the updraft, drastically lowering the condensation level in that area. How much of the foreground lowering would technically be considered a wall cloud vs. RFD shelf was questionable to me.

Goshen County Supercell - May 20, 2014
Goshen County Supercell - May 20, 2014 - Diagrammed

Newkirk, Oklahoma Supercell - May 19, 2013

This is an example of a transition point where the RFD is smearing a weak wall cloud into a shelf cloud. At least that's how it seems to me. You can see that the foreground lowering is "pointing" toward the forward flank, and benefiting from lowered condensation as it rises into the base. But now it's being hurried and lifted on its way by the RFD gust front (which it "points" away from). It seems to be in a place between both 'definitions' and both dynamic conditions.

Newkirk, Oklahoma Supercell - May 19, 2013
Newkirk, Oklahoma Supercell - May 19, 2013 - Diagrammed

Oxford, Kansas Supercell - May 19, 2013

This storm had a shelf feature on the forward flank leading straight into the the RFD core that made me think of video of the Long Point, Illinois storm on November 17, 2013. Skip Talbot had commented that the forward flank shelf on that storm seemed to behave like a hybrid shelf cloud and inflow band.

Oxford, Kansas Supercell - May 19, 2013
Oxford, Kansas Supercell - May 19, 2013 - Diagrammed

I just finished editing and uploading video to the September 27, 2014 chase report.

Arizona Storm Chase and Supercells - September 27, 2014 from Jeremy Perez on Vimeo.

Video account and time lapse sequences from the chase.