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This is/was the final full chase day for me with the tour company this year. We began in Pierre, SD, and needed to be back in Denver midday the next day, so we were heavily favoring a High Plains target versus the low Plains (se NE) target. The forecast was definitely NOT clear cut, and lots and lots of mid and high clouds were overspreading the NE PH, w SD and e WY. Low-level moisture was very good, though, on easterly upslope winds through much of the NE PH and e WY by late afternoon. 500 flow was marginal, 25-30 knots or so from the west. NE Colorado was a possible chase target, but I preferred a target farther north of the hot upper high that was over NM. So, I kind of settled on the nw NE PH near CDR, where some high CAPE was forecast. Since I was floundering to some extent, I elected not to post a forecast to CFDG!

We had lunch in Wall, SD, and a supercell was drifting slowly south over the Black Hills shortly thereafter. Enough sunshine had gotten through to the hills and allowed some strong convection. The Black Hills storm didn’t last too long and we didn’t get there in time, but its deviant motion to the south was a harbinger of future storm behavior.

Another cell went up on the nw side of the Black Hills, but I elected to head around the south side of the hills to Edgewater given likely south movement of any future strong storms. We spent an hour or so waiting in Edgemont for something to get strong in the patches of blue sky to the west or northwest. Finally, a couple of healthy storm towers went up to our nw, in western Weston County, west of Newcastle. The road network here is quite limited, and I needed to see if the lead storm nw of Clareton was going to move se towards us, in which case we could sit tight and watch it approach. Well, we could see a large wall cloud and perhaps a funnel or two with the supercell to our nw or wnw, but it was about 40 miles away! I wanted to be on it NOW! After a few radar scans, it was obvious that the storm was barely moving. We blasted n to Newcastle and then w on 450. The front/south end of the cell exhibited fine sculpted structure and a lowered area, but we observed no tornado. The storm was now moving s or even ssw at about 20 mph, a little west of 116. The hail core was just clearing the e-w road 450 as we came up on the east side, and we continued west. I thought that we now needed to get west and then south on 59 in order to get a good look at the action area with this thing. In lt-mod rain behind the main core area, we stopped and sorted through two-to-three-inch size hailstones which were littering the side of the road.

After another 5-10 miles west, we had a splendid view of the updraft from its nw side, with some front-end flanged structure visible. But, the follow storm to our nw was sporting increasingly great organization and low-level structure, with a pronounced lowering! This supercell was drifting south to SWW on the east side of Wright, WY. We scooted from its south side (where structure was fantastic!) to its west side at Wright (with the massive storm tower looming just to our east). A large wall cloud had that look that it was going to produce, but it did not. The RFD was rather wet and cool. A third supercell updraft was just nw of Wright. It had a wall cloud and was more LP-like. We drifted south of Wright on 59, with eyes on both nearby updrafts and the fast cloud motions at the bases. A slender and slinky funnel emerged from the east-side cell, but never threatened to get large or to touch down. At sunset the east cell started to wind down, and the west cell perked up a little. We had a continuous hail roar with it, just to our west. This cell then weakened quickly as it got dark, and we lumbered south to Torrington for the night. It was great to get on a few beautiful and slow-moving High Plains supercells on this day, and somewhat of a surprise, too, given all of the clouds during the day and my uncertainty with regard to the forecast.

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And now it is happy image time!

The main street through, Pierre, SD, has suffered through some major flooding problems this spring, thanks to record flows on the nearby Missouri River.  Most of the businesses along Sioux Avenue were still “sandbagged” in early July.  We visited nearby Oahe Dam to experience the water releases, and then visited Tatiana at the Cactus Cafe in Wall.

The first of this series shows the west side of the leading edge of the first/southern-most supercell, looking sse, from 450 near the Weston/Campbell county line.  We were able to see the front of this storm from a great distance, while near Edgemont, but by the time we got near the storm, it had moved south of 450 and not much more than a precip core was visible.  Just behind the large storm (which dropped hail up to three inches in diameter along 450) was a small but strongly rotating updraft.

A second and third supercell were just north of Route 450, in southern Campbell County.  A supercell to the east of Wright, WY, was not too far to our northwest in these views.  The base of the third supercell, which was just northwest of Wright, is visible in the distance in the third and fourth images here.

The nearby supercell that was east of Wright was drifting south, so I needed to scoot west towards Wright to avoid any nastiness.  We were safely west of the updraft base when we reached Hwy 59, and I needed to find a high spot to stop at to photograph the magnificent structure now to my east!  We found someone’s driveway in Wright with a decent view without telephone poles and wires.  The sculpted updraft base here is south of the precip core, and the storm tower is leaning over nicely towards the east.

The first of these four images is a look to the northwest, towards the base of the LP supercell that was near or just northwest of Wright.  Both cells were moving slowly to the south, and we moved south of Wright a few miles to maintain good position on both storms.  The action area of the supercell to our east (2nd, 3rd, and 4th images) appeared set to produce a tornado, but it did not.

Three views of the Wright “LP” supercell, and another look at the wetter storm that was east of Wright.

At about sunset time, the supercell that was east of Hwy 59 began to slowly weaken, but still maintained some nice low-level features.

After sunset I took about 200 photographs, hoping to catch one of the few bright lightning flashes in the two storms.  I missed them all, except for one faint repeater flash in the eastern cell.

I got rooms in Pierre, and on the way south a cluster of very strong storms matured west and north of PIR. We managed to squeeze ourselves in between several of these very electrified storms, and we had an amazing 4th of July thunder and lightning show! Lightning in these nearly stationary storms was practically continuous. At, Pierre, around midnight, Sioux Avenue had about a foot of water on it, and we had to find an alternate path to get to the Super 8!

The images above show the towering cumulus clouds southwest of Mobridge during the late afternoon.  (This was near Trail City and Promise.  Promise is a barely-there place along BIA 7 between Trail City and La Plant.  I think it is named after the yummy buttery spread.)  It was quite miserable in the sun, with a temperature near 90F and dew point of 77F!  We drove back and forth on the road for a time to try to stay in the shade of the clouds.  We were right on the front, too, and had little or no breeze.  What do you make of this line-up of hitchhikers?

We were somewhat despondent when nothing matured in our cu field near Promise, and we took the dirt road BIA 7 south to La Plant (in case a strong storm went up farther west on 212).  I took the first two images of the four above at 6:56 p.m. MDT (0056Z), from La Plant.  The cell was — you guessed it — practically right over Promise, SD.  A little more than 40 minutes later we were just southeast of the storm, along BIA 7.  Though we heard a pronounced hail roar, I think that the storm was already weakening at this point.  In the first image of the supercell (3741), a second strong updraft can be seen on the extreme right.  It is along the front and about 50 miles ENE of our nearby storm.

The lightning pics from Route 1804 about 15 NNW of Pierre are below.  I got a little artsy with the colorful sunset shot by jacking up the foreground brightness (the same image without the drastic photoshopping is also provided) —- it looks unnatural, of course, but I thought it was worth sharing.

Today offers good upslope chase prospects from about Weld County to Lusk and into se MT and nw SD. The question is WHERE exactly along this axis?? I wish I knew. We are headed west along I-90 towards the Black Hills. There are plenty of pros and cons favoring the south, middle, and north plays today.

After a look at the 12Z NAM, I liked the area from about Lusk to Crawford in the nw NE PH (the middle option). It shows a little wave at 500mb moving through that area. 500 winds are west at about 35 knots, above moist southeasterly surface winds. It isn’t difficult to image a nicely sculpted supercell moving southeast through this area around 00Z.

I checked the HRRR, and its 13Z run has a nice big blob down by CYS, moving slowly south into Weld County. This certainly could be a beast, perhaps tornadic. The HRRR kept this thing going while diminishing the cells in western SD and around the Black Hills, which seemed weird. This southern target is somewhat out of reach and is south of the 588 line at 500 mb), which scares me a bit. I would prefer to be on a storm north of that line! However, the latest RUC shows the highest forecast CAPE values around here, over 4000.

The 15Z RUC paints a very nice picture for extreme se MT and nw SD from 00Z to 03Z. Instability would appear to be excellent, and surface winds are forecast to be nicely backed as the RUC has a minor surface trough/lobe extending northeastward towards ne WY/se MT. 500 flow and 700 flow look just as good here as the NE PH vicinity, too. Some junky debris cloudiness in that area, though, will have to move out in order to make me giddy. This area is north of the hot air and that 588 line—yeah!

We will continue to RAP, and I’ll have to decide which side of the Black Hills to camp out on. At this point in time, I am favoring Harding County and vicinity in extreme nw SD.

After lunch in Wall, we continued west, and were lured into ne WY as storms were getting strong.  One very strong cell appeared to be a “left-mover”, as it was quickly moving north into Crook County.  I decided to try to intercept it along I-90.  This storm was moving north so quickly that we barely got to it by the time it reached I-90, and at that time it was crashing into another strong storm just north of the Interstate.  As this “merger” transpired, the low-level organization seemed to strengthen and a tornado warning was issued.  Lightning activity picked up suddenly, and we had some very suspicious lowerings just to our northwest.  Unfortunately, we were stopped along I-90 at a mediocre viewing spot, without a good view beneath the storm base.  We had no place to turn around, and had just exited a construction zone to boot, so we were lucky that we didn’t have to continue on the one lane into the core of the left-mover!  Anyhow, it looked on one or two occasions that funnel clouds were getting close to the ground some 5 to 8 miles to our northwest, and we were unsure whether a tornado had touched down or not.  Video and some of my still images (below) show some suspicious stuff!  We were about 8 to 10 miles wsw of Sundance.  SPC storm reports shows a 1.50-inch hail report ten miles west of Sundance, and no tornado reports.

This activity weakened some and was moving north into a poor road network, so we set our sights on a new supercell just east of Upton, some 25 miles to our south-southwest.  We headed south from Sundance on 585, thinking that the storm would move east or northeast.  While still 15 miles or so from the storm, we observed a pronounced wall cloud and funnel cloud with the storm base, and a spotter near the storm reported as much.  We tried to get closer after stopping for a few minutes, but the road tracked sse into a hilly area and we were unable to see what was going on to our southwest for a while.  Worse yet, the storm was moving little, and then sputtered and died once we found a hilltop to its east.  I really do not like chasing around the Black Hills.  Here is a shot of the Upton storm base to our south, a little bit after it looked its best:

With plenty of daylight remaining, we sprinted east toward some new stuff near and east of Rapid City.  This looked good briefly, but never got its act together.  We stopped near New Underwood to watch the storm move from our north to northeast, and then went into photo mode as the light and colors on the back of the storm were insane!

Below are my posts to CFDG on this day, beginning with the forecast post made around  11 a.m. CDT:

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A fairly compact and potent upper-level cyclone is migrating from the Sand Hills and into sc SD late this morning. A line of convection with some strong to severe cells extends from near Ainsworth to near Pierre. Skies are mostly clear east of this line. A surface low is southeast of the convection, in ne NE. SPC’s slight risk today is near and northeast of the surface low into MN, along a boundary marked by high dew points and high forecast CAPE values. Very nice upper flow at 500 mb spreads over the surface low and surface trough this afternoon, providing an environment favorable for severe storms and probably supercells. There may be an area of slightly backed surface flow n or ne of the surface low in the vicinity of Sioux Falls this afternoon, so that is where we are headed for now. I think that tornado prospects are a bit better than SPC has outlined in its 13Z forecast (just 2%). The wild card today is all of that stuff happening back to our west along Hwy 183. We are in Mitchell now and will have lunch in Sioux Falls. The cap will not be an issue as it was yesterday in western MN and the eastern Dakotas (we played in w SD yesterday).

——- at about 5 p.m. I posted the following:

We were on the beast(s) near Colman and Colton in se SD for a little bit. These were generally big outflowing HP cells. We dropped south to the southern cell, and the northern one took over. It left us in the dust and charged ENE to NE at 45-50 mph. We waved goodbye to it at Pipestone. This cell had a tornado warning for an hour or so, and one had to be looking into the notch from the east or ne side to see anything, I suspect.

Apparently Flandreau, SD, was hard hit, and EMS folks are advising no travel into Flandreau. It is not apparent whether a tornado hit the town or not.

New tornado warning now with a tornado observed by spotters near Redwood Falls.

——- and my chase account written the following morning:

On this day a compact but potent upper-level cyclone swept northeastward through eastern SD and spawned an intense supercell/convective hybrid thingie. This large storm left a path of wind damage with occasional very large hail from se SD to near Duluth.

My target was Sioux Falls, which was northeast of the surface low in ne NE and which had backed winds with a dew point in the mid-70s midday. Skies were mostly clear here, but the cyclone to the west was already causing heavy storms in central SD all morning long. I was hoping that new activity would form during the afternoon to the east of the primarily elevated morning stuff. After lunch in Sioux Falls, a cu field had formed a little north and west of town. We headed towards the northeast side of the cu field at Pipestone, MN, in order to make sure that we would be ahead of any development. With CAPE values of 5000-plus, it seemed likely that storms would go up very fast once the cap was breached. Well, that plan wound up somewhat ill-founded as two big storms formed on the southwest side of the cu field (some 50 miles distant), near Spencer, SD (and just one county east of the “morning” convection, which continued). We headed west on 34 towards I-29 and Colman, SD, for an intercept. When we reached SD, the road went to rough and unpaved for 16 miles thanks to one of those famous SD road destruction projects. During this grueling ordeal, we watched on radar as the McCook County storm blossomed significantly and became warned. We finally reached the east side of the supercell on the N-S road from Chester to Colton. It was a massive thing, green and dark, but quite HP-ish without much structure evident.

So, we had managed to get in position on the beast-of-the-day storm here between Colman and Chester…but there was a second severe storm just to its south, along I-90. This one was not quite as strong, but it had a good shape on radar and was tail-end Charlie, so we scooted south just past Colton to take a look. Bad move. The southern storm had a top of 50k feet, the northern one was up at 60k feet, and the southern one was no match for the northern one. It basically became a non-entity as it approached us. We were instantaneously out of position, on the south side of the big beast. It proceeded to gobble up towns to its northeast at a fast pace. We didn’t stand a chance to get back on its east or northeast side to look into the notch area. The cell became tornado-warned on its approach to Flandreau and it continued into sw MN, moving about 45 mph. The cell turned a bit to the right and moved ENE—Marshall and Redwood Falls were in the path and suffered damage due to wind and hail.

We stayed somewhat close to it up to Pipestone, but there wasn’t much to see on its south side except a dark and menacing precip blob. Some new stuff went up near or along the big storm’s outflow boundary and we played with that until about 7 p.m. around Fulda to Windom. There was some so-so structure on the leading edge for a while, but this was also moving quickly northeast and was wet and outflowish, so we let it go.

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some pics of the southern cell west of Colton as it was beginning to croak:

and a look at the cell near Fulda later in the afternoon:

We threw in the towel relatively early, had a leisurely dinner in Sioux Falls, and drove west on I-90 to Plankinton for the night.  At dusk, Marcia spotted some noctilucent clouds along the horizon to the northwest, from the Mitchell area.  See the other July 1 post for the rare cloud photos!

Today was the final chase day for the Tour 8/Doswell group.  The previous day featured the murk and messy nonsense in central and eastern NE, so I was ready to head out west for some pristine skies.  The outlook for severe weather along Colorado’s front range was rather slim, but the surface flow was upslope and moist enough for some high-based updrafts.  We made our way from Cozad to Limon and west to Interstate 25, between Castle Rock and Colorado Springs.  This is right along the Palmer Divide:  the elevated, favored area for storm formation on many late spring and early summer afternoons.  Given the “35-40 knots of deep layer westerly shear” here, according to SPC, I was hoping for a picturesque, isolated, rotating updraft.  Well, we got about four of them, one after the other!

Storm cells went up west of Larkspur (which is along I-25 north of Monument) and moved east.  We waited near the Interstate, and moved east a little with one or two of these.  The updrafts sputtered east of the Interstate due to a decrease in low-to-mid-level instability, and we headed back to the Interstate as the next pulse  strengthened over the mountains.

The first couple of cells were unimpressive, but the last two were somewhat strong (see images above).  I elected to place ourselves in the path of the core of the last supercell, and we caught a rainbow and some one-inch hail a little south of Larkspur.  I was going to continue east with this updraft, but then the sun came out and the light on the backside of the storm was quite nice.  We stopped on a hill on the west side of the Interstate a little north of Palmer Lake and set up the tripods.