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.
On my way home after photographing monsoon thunderstorms northeast of Flagstaff, I noticed smoke rising over the hills along Townsend-Winona Road. I thought it might be another tree fire, but as I rounded a bend, it turned out to be a terrible house fire. Checking radar, it looks like there were 3 lightning strikes over that location from 2:45-3:00 PM. Several fire trucks were on the scene but the fire was overwhelming and it took quite a while before it seemed to be brought under control. I’m afraid the house may have been completely lost.
A couple of the lightning strikes along Townsend-Winona Rd.
The house fire at Townsend-Winona and Bullion Hill Rd.
After noting a great supercell near Winslow, I opted to head toward Twin Arrows to see if some developing convection would take off there. It was good for a lot of heavy rain, but hardly any lightning and it didn’t manage to organize.
While I was toying with that mess, another storm north of Flagstaff crossed the threshold to the Colorado River Valley, west of Wupatki and went supercellular.
As I pondered my situation and whether I could race to that storm in time before it drifted into the extremely hard to navigate spaces west of Hwy 89, it picked up a tornado warning. So I dropped the slop I was on—to at least give it a try. By the time I had visibility on Hwy 89, it had the merest remnants of an elevated base.
On the chance it might cycle up on some new convection to the south, I took a pretty decent forest service road along the cinder cones north of Sunset Crater. What did pop up didn’t develop rotation but still managed to make for some nice storms and lightning.
More storms showing up with couplets this day, but I didn’t manage to intercept them during prime structure. The landscape made up for a lot of those issues. These shots are from Hwy 89 north of Flagstaff along the Mogollon Rim/Colorado River Valley margin.
A scud bomb merging into the updraft between Sunset Crater and Wupatki National Monuments.
More disorganized convection playing with sunbeams north of the San Francisco Peaks.
Benign convection percolating as the atmosphere begins to stabilize.
Sunset Crater is trying to peek between the trees on the right.
Convection has turned to mush almost everywhere, leaving a great sunset aftermath—just northwest of Sunset Crater National Monument, looking toward the San Francisco Peaks.
The Mogollon Rim Convergence Zone worked its magic the past 3 days with southwest flow leading to some especially favorable shear along the Colorado River Valley.
On my way north to meet the best shear parameters—which I thought would be best near Page and the Arizona Strip, I encountered some heavy convection and a nice roll cloud and gust front north of Cameron on Hwy 89.
I figured this one would probably stabilize the air mass pretty solidly, so after following it a bit, getting photos, looking for lightning and doing some roadside nowcasting, I started making my way towards Page. A couple hours later I found myself at The Gap to pick up a replacement 9-volt battery for the lightning trigger. Radar showed a couple strong storms lighting up to my south—where I thought things had already been played. So I raced back south and started catching sight of a very healthy looking anvil peeeking over the plateau to my west. Once I cleared the horizon-blocking hills, I got to meet a beautiful Arizona supercell drifting toward me from the west.
This is the first time I’ve caught Kelvin-Helmholtz waves along the elevated base of a supercell—and it was an hour from home. This view faces northwest as the cell moves over the edge of the Painted Desert.
Another view as the storm starts to pass to the north.
I followed it through Tuba City and further east where it was trying to hand off to a new base before slowly withering.
Our last chase day on the high plains was also set up to be a pretty marginal day. We headed out of Goodland toward far northeast Colorado and took in some more sights along the way.
Barn in northeast Kansas
We caught our storm of the day near Holyoke as it rolled southeast out of the Nebraska Panhandle. It sported a proto-wall cloud for a while as it churned closer. It had a buddy to its east that looked better on radar at a few points, but that cell was getting seeded and the base was obscured much of the time. We had a really good view on a hilltop south of Holyoke and spent about a half hour watching both cells kick up dust storms as the western one drew some of the dust up into its updraft.
Shooting time lapse with a farmstead and marginal supercell south of Holyoke, Colorado with followup gust fronts — 2150-2215Z
Eventually they swept by just to our north and teased some brief rotation in a quasi-RFD push, at the same time things seemed to be generally gusting out. We paced it along some pretty rugged roads through Alvin and southeast into Nebraska. The west edge of the convection wound down as the eastern cell took over. We were too far out of position on slow, twisty roads to catch it. As we wound our way back to better road options, we paused to get a box tortoise out of the road and get closer look at it.
Visiting with a Nebraska box tortoise
Some messy convection was rolling east along Highway 36. So we headed back into Colorado between Idalia and Burlington to check out the gust front before ending our trip with great sunset views.
Convection struggling to stay cohesive south of Idalia with advancing gust front over Burlington — 0120-0200Z Fiery Colorado sunset and twilight convection over far west Kansas — 0220-0250Z
Apart from the rough road patch east of Alvin, the day was pretty easy-going and I had time for a lot of time lapse photography. Those time lapse sequences and other clips from the trip are in the first segment of the 2015 Storm Chase video I wrapped up last month.
This was the craziest and best chase of our five-day trip. After overnighting in the car near Wray, we headed back to a target area east of Denver and spent about an hour with a storm that struggled south of Strasburg. I was unsure about veered wind profiles downstream in the deeper moisture, especially noting SPC guidance that storms would probably tend to grab supercell structures early on before lining out. And that’s kind of what this storm was doing. It had joined some friends and wound up on the south end of a mushy line of storms moving to the east and northeast by 21Z. And it appeared to be weakening after that.
Developing storm south of Strasburg (left) — 2020Z Storm struggling south of Byers (right) — 2045Z
So I let it go, figuring I didn’t want to waste energy on eventual garbage. Not a good idea, as it turns out. But I was worn out and feeling kind of sorry for myself about missing the Simla storm a couple days earlier and not seeing so much as a cold air funnel on anything yet. As we sat in a spot with horrible data for accessing current radar, I figured the whole day was probably destined to be a wreck of grungy, linear convection. To show how miserable I was making myself, I even mulled the idea of heading into Denver to catch a movie so the whole day wouldn’t be a complete disappointment.
South end of line of convection moving away — 2135Z
I probably spent a good twenty minutes in my pity party, facing west, watching sad blobs of convection trying to get going over I-20. When I finally turned back 180 degrees, to my immense shock, the departing storm had separated from its linear friends and blossomed into an enormous, incredible mushroom cloud on the eastern horizon. My self pity turned to shock and then anguish. It seemed too far gone to catch up to. I had been re-defeated.
Sudden, explosive convection south of Last Chance || 2200Z
I’m not sure what kind of soliloquy I was rendering at that moment, but my daughter finally decided it needed to stop. With simple optimism: “We should try to catch it anyway.” I love that kid. I’m glad she said it and glad I listened to her. We hopped on I-70 and made our way eastward. The whole time I was working the math of two moving targets and the time/location of intercept. If only the storm would stay interesting that long.
RFD and wall cloud as we approached Bethune — 2345Z
We finally caught up to it near Stratton with decent wall cloud and RFD action ongoing. Then we got ahead of it a couple miles north of Burlington. There was a sleek, saucer shaped lowering on the original meso with a new base forming to its south. I’m not sure whether that bell-shaped base was receding behind its own RFD curtain or if it was getting hidden by the developing forward flank of the new updraft. Either way, it was the greatest view of a meso handoff I’ve had so far.
Saucer shaped base north of Burlington — 0000ZMeso handoff in progress north of Burlington — 0005Z
We were in good position on a fantastic road grid with an easy-moving storm, so the photo ops were excellent. At one stop, the new base was looking particularly awesome and I stopped to grab shots while the video camera was running. It wasn’t until reviewing video later that I realized a cold air funnel had been twisting around for a couple minutes on the west side of the base.
New base northeast of Burlington — 0015ZCold air/shear funnel behind rain free base — 0013-0016Z
We paralleled the storm as it moved eastward. An RFD surge carved an inverted soft-serve ice cream cone into the base at one point. Not ten minutes after that, a glance out the window revealed a beautiful funnel whirling away inside some sort of strange RFD eddy on the south edge of the storm. We pulled over quickly to hop out and get shots. Time was of the essence, so we didn’t wind up with the best foreground elements for photos. That issue took a back seat to the fact that we were standing on the side of the road looking up as a gorgeous funnel stared us down. Turning around to find my daughter embracing the outflow topped this off as the best storm chase turnaround ever.
RFD carving the base northeast of Burlington — 0025ZFunnel and core between Burlington and Kanorado — 0035ZMy daughter embracing the outflow as the funnel dwindles — 0035Z
By now, the storm had fallen too far behind the expanding outflow boundaries and started to wither away. So, we paused to photograph an idyllic farmscape south of Kanorado. Then we enjoyed the view of an inbound gust front moving in from Colorado before calling it a night at a comfy hotel in Goodland.
Farmstead southeast of Kanorado — 0120ZGust front moving in south of Kanorado — 0150Z
Our third chase day came after a very late night of bailing out of our hotel as a tornado-warned storm approached Limon at 2:30 in the morning. But a hotel stay is awesome after sleeping in the car the night before, and we were close to our target area between Limon and Denver. Insolation was a problem and I think the morning’s cloud cover hurt potential for the day, but we still wound up on several supercells.
We caught our first two storms on Kiowa-Bennett Road east of Denver. We followed the second one for about an hour. I made an attempt to get ahead of it on Rector-Leader Road, northeast of Byers, but had to back off. The dirt road was turning to mud the further north we went, and gust front moving in too quickly to give it a shot.
Wall cloud on supercell #1 from Kiowa-Bennett Road — 2015ZTIV looking for another target on Kiowa-Bennett Road (top left) Rain free base on supercell #2 from Kiowa-Bennett Road (top center) — 2055Z Gust front south of Strasburg (top right) — 2120Z Advancing shelf on Rector-Leader Road (bottom left)— 2200Z The closest we could get (bottom right) — 2205Z
Road options wouldn’t let us stay on that storm, so we bailed on it. While storms 60 miles to the east were getting ready to spin up tornadoes, we waited for another close optin to roll up from the southwest. This one was more strung out, but still nicely structured as it crossed Highway 36 and morphed into a beautiful shelf north of Last Chance.
Storms 60 miles to the east that eventually produced tornadoes (left) — 2230Z Watching as supercell #3 moves in between Byers and Last Chance (right) — 2230ZSupercell #3 crossing Highway 36 east of Byers — 2235ZGust front between Byers and Last Chance — 2240Z Storm moving over Shamrock — 2300Z Terraced shelf cloud north of Last Chance — 2355Z
After that, I decided to head east to see if we could thread to the other side of a couple tornado-warned storms near Kirk. It was a long shot, and didn’t work out, but we eventually wound up in spectacular country along Highway 385. The lightning show north of Wray wound things down for the day.
Back side of supercell #4 facing east from Kirk — 0100Z Sunset on the landscape south of Wray — 0150Z Lightning show north of Wray — 0245Z
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 — 2115-2140Z
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 and mystery structure on an active supercell north of Nicodemus — 0235-0302Z
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.
This was the first day of a five-day chase on the high plains with my daughter. After overnighting in the car near the New Mexico-Colorado border on I-20, we made our way up to Castle Rock and watched for initiation along the front range. Before long, a worthy tower went up to our southwest and got sheared into an impressively long escalator of cumulus.
Convection southwest of Castle Rock — 2030Z
We repositioned further southeast to the east side of Lake Gulch to get in front of it and watch it develop. Before long, we had a beautifully sculpted supercell over the gorgeous Colorado landscape. This is such an incredible place to watch a storm evolve.
Supercell over Perry Park — 2115ZSupercell and gust front over Perry Park and Elizabeth — 2130-2255Z
We eventually found ourselves east of Kiowa on Highway 86 as the storm grew more linear and started to wither away.
Old and new cells along Rt 86, east of Kiowa — 0005Z
Further west, another cell had taken over and was looking pretty serious as it moved over Elizabeth. Rotation developed in the base as it drifted eastward, but it never wrapped up tightly enough to do more than that.
New supercell churning over Elizabeth — 0023-0040ZWildflowers and messy RFD core east of Kiowa (left) — 0050Z Wildflower and departing supercell near Spring Gulch (right) — 0140Z
We followed it as it started to move more to the northeast getting an excellent twilight lightning show out of it before calling it a day.
Twilight view of a departing supercell from Wilson Creek — 0300Z
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 — 2150ZMarcus Diaz, Mark Eslick, Tyler Hudson and Jason Boggs check out radar and the storm base east of Lake Kemp — 2151ZEncroaching 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 — 2242ZTerraced vault with arcus/inflow tail racing westward from SR 25 — 2247ZArcus 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
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).
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.
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.
It’s been three years since I’ve had a really good storm chase in Arizona. This past Saturday, I had a chance to make up for the last couple of missed years. I wound up tracking three supercells along Highway 93 between I-40 and Wickenburg. The last of those three was difficult to observe due to bad positioning, surrounding convection, and unexpected freight trains, but the first two were spectacular amid some stunning Arizona landscapes.
The day before, I had set an initial target of Kingman, Arizona by sunrise, based on NAM and GFS placement of a closed low over Nevada. This was forecast to wrap up 30-50 kts of deep layer shear on top of a cold front over the Colorado river while rich moisture surged northward bringing mid 60 degree dew points. As is usually the case, targeting was based on a compromise between better instability further south vs. better dynamics further north. Instability and backed surface winds appeared to be maximized around daybreak and weakening by midday (1000-1500 j/kg with 100-150 m2/s2 SRH). By the night before, all models were trending downward on lapse rates, so forecast instability was dwindling. However, there was still enough to work with, and hodographs were very tantalizing by Arizona standards. This did adjust my perspective on positioning and timing. So I was able to get a bit more sleep and head out of Flagstaff a little later than planned (5AM instead of 3AM).
I stopped at Seligman about 6:00 AM. As I looked west, I was treated to a line of storms flickering with constant lightning as they trained along the cold front near Kingman. HRRR was forecasting the convection to quickly fill in eastward, along sheared out bands with some stronger embedded storms. HRRR’s version of SRH, bulk shear and CAPE still looked promising and was trending toward batches of storm helicity tracks over western Yavapai county by mid to late morning.
Anticrepuscular rays lead into a line of storms as seen looking west from Seligman, AZ. 6:05 AM / 1305Z
Once I reached Highway 93 a little before 8AM, a weak line of storms was passing overhead while a stronger line was approaching from the west. That stronger line featured a healthy cell just to my southwest with a persistent velocity couplet. It looked like it would cross Hwy 93 a couple miles south of I-40 and I had some difficulty deciding on which highway to intercept it (no decent side-road options in this area, just the two main perpendicular highways). I would have preferred the east-west option of I-40 for more fine-tuned positioning and safety margin on storms that are moving mainly northward. But I finally decided on my north-south Hwy 93 option since it would give more opportunities to pull off, start and stop instead of being trapped on the interstate with fewer offramps. As the updraft for the embedded cell moved by my position, it wasn’t much to look at, and just seemed to be putting a bit of a kink in the line.
Updraft base in a line of convection as seen looking west from Highway 93 about six miles south of I-40. 8:10 AM / 1510ZA line of convection as seen looking west from Highway 93 about six miles south of I-40. 8:30 AM / 1530ZA supercell sports a lowering where the highway disappears into the hills. Meanwhile, trailing convection begins to merge into a bowing segment. View is to the northwest from Highway 93 a few miles south of I-40. 8:35 AM / 1535ZReflectivity and velocity radar of the embedded mesocyclone. 7:54 AM / 1454Z
Because of the added safety cautions being on the north-south road, and new convection fluctuating to the south of my target cell, I decided to stay a lot further south of it than I wanted. About the time it neared the I-40/Hwy 89 junction, it didn’t look as strong on radar, but the trailing gust front finally pushed hard and it expanded outward in spectacular fashion. As a kink in the shelf took shape, a rugged, conical lowering materialized behind the surging gust front before getting smeared out.
The gust front south of a supercell pushes out over Highway 93 a few miles south of I-40. View is to the north. 8:40 AM / 1540ZA kink in the gust front develops, leading to a conical lowering. View is to the north from Highway 93. 8:40 AM / 1540ZA shelf cloud lines up along Highway 93. View is to the north. 8:45 AM / 1545Z
After that amazing encounter, I headed further south to get in front of some more developing convection. Along the way, I caught brief views of stronger updraft bases between precipitation cores, and irresistible stormy views in the desert terrain.
A dark rain free base peeks out from between two rain cores as seen from Highway 93 looking southwest. 9:50 AM / 1650ZDisorganized convection paints the sky above a soaked desert landscape. As seen from Highway 93 looking southeast. 10:20 AM / 1720Z
By this time, HRRR was trending toward better options further east into central Yavapai county. So I headed east to Congress when a strong cell with a developing couplet started moving in from the southwest, so I headed back south toward Wickenburg on Highway 89. As I cleared heavy rain on some cells popping up overhead, the base of the Wickenburg storm came into view. It was sporting a lowering and a huge tuft of scud was rising up from the ground to meet it. As that merged with the rain free base, the storm had the embryo of a wall cloud.
A wall cloud begins to form beside the forward flank of an approaching supercell. As seen from Highway 89 between Wickenburg and Congress looking southwest. 11:25 AM / 1825Z
While photographing it, I noticed that the storm appeared to be deviating a bit to the right. So I jumped back in the car and headed further south to avoid getting cut off. During that short drive, the wall could got sturdier as it made attempts at a tail cloud along the interface of a the forward flank. It reminded me a lot of another beautiful supercell I intercepted in Wyoming back in May.
Wall cloud on a supercell north of Wickenburg. As seen from Highway 89 facing southwest. 11:30 AM / 1830ZReflectivity and velocity radar of the Wickenburg supercell. 11:32 AM / 1832Z
I was so busy trying to coordinate video and photography, and keeping track of overall storm motion that I couldn’t relax and see if any slow rotation was present. At this point, if there was any rotation in the wall cloud, it wasn’t fast enough to make me think it was about to plant something out in the mesquite and palo verdes. However what was concerning is that the storm was turning even further to the right and I had to hustle out of the way. As I raced south, I started getting shoved around by RFD that was starting to fill in with rain. Once I was clear, I got view of the back of the RFD core and right edge of the wall cloud as it moved away.
RFD partially obscures the rotating wall cloud on a receding supercell between Wickenburg and Congress. As seen from Highway 89 looking north-northeast. 11:35 AM / 1835Z
I still wasn’t confident if I was seeing low level rotation, but I did call it in to the Phoenix NWS office as exhibiting supercell structure. Looking at the video and time lapse sequences later, it definitely was twirling behind the RFD. The view of the entire cell moving away over the desert was incredible. The dark base and flanking line contrasted against the bright white RFD core and anvil against a deep blue sky. It was spectacular.
A receding supercell thunderstorm dumps rain and hail over Congress, AZ. As seen from Highway 89 looking north-northeast. 11:45 AM / 1845Z
After savoring the experience, I had a choice between more cells moving into Yavapai County, or a building squall line moving into Phoenix. I was feeling a little hooked on the supercell storm mode, so I didn’t head into Phoenix for the amazing show that storm put on. Instead, I repositioned west of Congress for the next line of storms as another cell with a velocity couplet was moving in. Unfortunately, it was surrounded by more developing convection and I only had brief views of structure between morphing rain cores. I was about to make a hopefully decent intercept, but was stopped short as a freight train took its sweet time blocking my best approach.
A striated shelf cloud approaches the intersection of Highway 93 and 71. The rain free base on this supercell was obscured by surrounding precipitation. View is to the southwest. 1:05 PM / 2005ZReflectivity and velocity radar of broad circulation in a passing storm. 1:04 PM / 2004ZA new updraft base forms to the south of a passing supercell as seen from Highway 71 in Congress, AZ. View is to the southwest. 1:15 PM / 2015Z
Once that storm was gone, I decided to take the scenic route back toward I-17 and took Highway 89 to Prescott. The long drive up the mountain switchbacks took me into the dark of the foggy cloud bases where mounds of small hail still survived in places against an onslaught of heavy rain. As I descended the east side of the mountain range I came across several sections of road that had recently seen flooding and had to stop at one point to pull an 8-inch diameter log out of the road while essentially taking a full on shower.
Flash flood debris on Highway 89 just south of Prescott (Had already pulled the huge log out of the road at this point). 2:56 PM / 2156Z
As I made my way into Prescott, DPS was roaming around pulling debris out of the streets. Further in, I passed a storm drain that was fountaining water, and the town was a waterlogged, debris strewn mess. The worst had passed though, and there were no ‘turn around don’t drown’ scenarios to deal with.
Overloaded storm drain in Prescott. 3:04 PM / 2204Z
As I made my way up I-17 back to Flagstaff, I skirted the west edge of the weakening line of storms and noticed an eddy on radar moving over east Flagstaff. Looks like this might have been a bookend vortex on the line. I wish I could have seen what that looked like, but that will have to wait for another time.
Reflectivity radar of possible bookend vortex southeast of Flagstaff. 5:06 PM / 0006Z
What an amazing chase. No tornadoes, but three Arizona supercells in one chase day is so much better than I could have hoped for. It has me seriously itching for springtime in the Plains—only 6 or 7 months to go!
Today, a strong multicell hammered east Flagstaff, dropping up to 2 inches of precipitation including mounds of hail during a 45 minute time frame. Some meager vorticity got stretched into the blue-green updrafts at times and made me wish I had a better vantage.
Still, the view from the middle of town was pretty good as a clearing eventually showed a nice rain free base west of Mt. Elden.
I noticed some laminar striation under the base, but thought it was just an indication of strong inflow. After checking the photos, I noticed that structure may have actually been a shear funnel that lasted a little more than a minute from 4:42 to 4:43 PM.
I wasn’t fully prepared, and decided to shoot a 96 frame time lapse when all I had was a monopod. After Effects stabilization managed to rescue the time lapse pretty nicely.
The 2013 Southwest Monsoon season still has three more weeks to go. Before it moves into the sometimes interesting transition period at the end of September and early October, here are some highlight photos. Except for the lightning shots, the rest of the shots were taken with my iPhone. It has drawbacks with noise, especially in low light areas, but it’s so handy, and always with me that I’m getting shots that I otherwise might not be prepared for. (What that means is I need to make an effort to keep my camera with me more often.)
July 2, 2013
Panorama of a storm developing south of Flagstaff as seen near I-40 and 4th Street at 2:18 PM.
New development overhead a few minutes later was drawing in a bit of vorticity and sculpting a brief cinnamon bun into the cloud base.
July 3, 2013
The base of a dying updraft over east Flagstaff tapers to a point.
The dwindling remnants of the eroding storm base reveals a slowly rotating spindle–not rapid enough to be a shear funnel.
July 4, 2013
An active storm north of Mt. Elden puts on a beautiful show of ongoing anvil crawlers.
July 11, 2013
Pop-up convection develops west of Flagstaff as seen from Rt. 66 in east Flagstaff.
July 20, 2013
Lightning flickers behind a weak gust front east of Flagstaff as seen from Rt. 66.
July 23, 2013
Inflow, chilled by heavy precipitation, creates a rugged lowering in the rain free base of this storm over Schultz Pass. As seen from 4th Street in central Flagstaff
August 23, 2013
Dry outflow pushes a growing wall of dust northward from Tucson, as Picacho Peak rises above the dust and desert floor. The photo was taken by my wife, Amanda, as we drove north on I-10 toward Phoenix.
August 26, 2013
An ominous haboob blew into Phoenix, featuring a laminar updraft, intermittent shelf cloud and spectacular lightning after the gust front passed. This view is facing southeast as seen from near central Phoenix.
September 2, 2013
A beautifully lit and structured thunderstorm brews over the San Francisco Peaks as seen from Highway 89 in northeast Flagstaff.
September 7, 2013
Looking south as a clump of northbound thunderstorms pushes a ragged shelf cloud into east Flagstaff. September 7, 2013. (Another iPhone panorama, so some of the seams are a bit jumpy.)
