Total Distance: 430 miles
Target Area: Childress, TX
Chase Area: Near Memphis / Wellington, TX
Maximum SPC Risk category: Moderate

A powerhouse upper-level low/trough was forecast to dig/amplify and move out of the Rockies during the late afternoon, evening, and overnight hours of Feb. 23rd. The two largest unknowns were moisture availability and timing of initiation. It wasn't surprising that the former was a known issue, since climatology argues strongly against a significant tornadic supercell event in western Oklahoma and the eastern Texas panhandle in late February. Regardless, the mid-upper 50s dewpoint forecasts were expected to lead to ~1000 j/kg CAPE in a slender corridor east of a dryline. With very strong flow at all levels, shear profiles were extremely supportive of tornadic supercells (50-60kt 0-6km shear, >400-500 m2/s2 0-3km SRH, etc). Despite this, there were many questions regarding the timing of initiation. With the main low/wave forecast to move into the Plains overnight, confidence was not high in daytime initiation (aided by the fact that sunset is ~6:30pm -- quite early).

Total Distance: 250 miles
Target Area: Stillwater and east (OK)
Chase Area: Stillwater to east of Pawnee
Maximum SPC Risk category: Moderate

Another early-season chase setup presented itself as another very strong cyclone was forecast to develop and deepen as a 150+kt 250mb jet streak moved out of the western U.S. Moisture looked to be less of an issue as the previous event, as we had more than a day for moisture return. Despite model projections of 58-62F dewpoints east of the dryline across eastern Oklahoma, afternoon surface obs indicated 53-57F dewpoints widespread in the warm sector. There was also concern about veered 850mb winds produced by a wave that passed through during the morning hours, which some feared would result in a very strong cap and drying surface conditions. A special 20z OUN sounding showed that the veered 850mb flow had little effect on moisture depth, with 100mb of substantial moisture in the low-levels. With strong shear profiles, supercells and tornadoes seemed quite possible, though marginal CAPE (750-1250 j/kg sbCAPE) was expected to be a limiting factor.

Total Distance: 600 miles
Target Area: Shamrock, TX, to Perryton
Chase Area: Turkey, TX, to Wheeler
Maximum SPC Risk category: Moderate

An atypical pattern was setting up for a couple of days, with a strong and large cut-off forecast to anchor over the Rockies, putting much of the central US in favorable southwesterly and southerly flow aloft. With more than a week of strong moisture return, climatologically-high low-level moisture was in place east of a dryline that was located across the western TX and OK panhandles, northward across extreme western KS and NE (where the dryline was replaced with a pacific cold front). Forecast CAPE was in the 2000-4000 j/kg range, with strong shear, making many chasers quite anxious of times to come. One of the primary concerns was storm mode, owing to deep meridional flow east of the cut-off aloft. With prospects of more southwesterly flow aloft south of Kansas, and with expectations of mid-60F dewpoints in the same area, my initial target was in the northeastern TX panhandle.

Total Distance: 85 miles
Target Area: None
Chase Area: Edmond to Mulhall
Maximum SPC Risk category: Slight

I wasn't planning on doing any chasing this day, owing to widespread moderate convection that was acting to inhibit destabilization across much of central OK and northern TX. With the successful chase the day prior, and the possibility of another chase the day following, I wasn't too anxious to head out. Despite that, I was alerted by my NWR of a tornado-warned storm producing a tornado on the western side of the OKC metro area. So, despite the relatively weak instability, it appeared as though the strong shear was enough to yield storm-scale rotation. Given it's short distance from me, and a radar image that showed relatively impressive mesocyclone to my SW, I hopped in the car and headed out.

Total Distance: 320 miles
Target Area: Breckenridge, TX
Chase Area: Near Decatur, TX
Maximum SPC Risk category: Moderate

The cut-off that set up over the central and southern Rockies was forecast to begin to move out this day. Ample moisture remained in place (62-68F Tds south of I40), though widespread convection was forecast to limit destabilization. Despite this, very strong shear was forecast east of the cold front that stretched from western Oklahoma into southwestern Texas. With ~20 SE sfc flow, 40-50kts SSE flow at 850mb, and 50kt SSW 500mb flow, shear profiles were moderate to strong, particularly by early evening. By the time we looked at things around noon, 0-3km SRH was already >400 m2/s2 near SJT. With a RUC forecast of widespread >400 m2/s2 0-3km SRH by 0z across much of Texas and Oklahoma, we were hoping that the strong shear and low LCLs were going to be enough to compensate for marginal instability (500-1000 j/kg CAPE).

Total Distance: 415 miles
Target Area: Decatur, TX
Chase Area: Decatur, TX, to Weatherford and Ft. Worth
Maximum SPC Risk category: High

A strong upper-level low was progged to move out of New Mexico, spreading strong southwesterly flow aloft over much of the southern plains. Cyclogenesis began the previous day, with mid-60 dewpoints streaming into central Texas by Friday morning. A surface low was forecast to deepen and move just south of the Red River, with a warm front stretching east-southeastward from the low. Original concerns revolved around the forecast widespread convection that would prohibit destabilization across most are the area north of I20. Despite questions about instability, there was very high confidence that the warm sector would be very strongly sheared. In fact, southeasterly sfc winds beneath 50kt southerly 850mb flow would create low-level shear profiles supportive of strong and violent tornadoes. When I awoke Friday and noticed that there was no convection across northern Texas, I had an awful good feeling that there was the potential for a very active tornado day.

Total Distance: 660 miles
Target Area: Turkey, TX, to Silverton to Plainview
Chase Area: Around Amarillo, Groom
Maximum SPC Risk category: Moderate

A potential significant tornado event was forecast, as a compact, but intense, upper-level low moved out of the southwestern USA. The Gulf saw a strong cold frontal passage earlier in the week, which scoured most of the significant low-level moisture well southward. Despite this, models were relatively consistent in forecasting mid- to upper-50 dewpoints across western Texas, the Oklahoma panhandle, and western Kansas. The upper-level trough was forecast to become negatively tilted as a strong 100kt 250mb jet impinged on the western Plains. Strong shear and moderate instability were in line for a significant tornado event, but, with surface dewpoints ~5 F lower than the 3-28-07 event, there was some uncertainty regarding convective mode and LCL height.

Total Distance: 620 miles
Target Area: Pampa, TX, to Memphis, TX
Chase Area: Buffalo, OK, to Protection, KS
Maximum SPC Risk category: Moderate

A potential "day before the day" event, as southwest flow aloft led to lee troughing. With moderate moisture in place, moderate instability was forecast to develop across the Texas panhandle, Oklahoma panhandle, western Kansas, and eastern Colorado by afternoon. With the upper-level trough still well to the west of the threat area, the flow aloft was forecast to be relatively weak. Given this, the dryline was not going to be particularly strong, and there were major concerns over convective initiation owing to weak low-level convergence. Regardless of what was going to play out, we liked the relatively slow storm motions, strong low-level shear, and nice terrain.

Total Distance: 550 miles
Target Area: Near Kinsley, KS
Chase Area: Around Woodward, OK
Maximum SPC Risk category: Moderate

Potential for a good tornadic supercell day as moderate southwesterly flow aloft above a moistening boundary layer was forecast to yield an environment favorable for supercells and tornadoes. A dryline bulge had been forecast across southwestern KS by the NAM for several runs prior to the day, and it looked as though there would be an enhanced potential for strong tornadoes immediately ahead of the dryline bulge near DDC. Strong shear + strong CAPE (>3000 j/kg) + low LCLs + discrete mode = potential for a good chase day.

Total Distance: 530 miles
Target Area: Around McLean, TX
Chase Area: Around Pampa, TX
Maximum SPC Risk category: Slight

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Total Distance: 410 miles
Target Area: Dodge City, KS
Chase Area: Near WaKeeney, KS
Maximum SPC Risk category: Slight

Me and others in my group (i.e. Howie Bluestein, Andy Pazmany, Robin Tanamachi, Mike French, Jana Houser, and Matt M.) left OUN around 1130am. We made it to DDC by late afternoon and dropped into the DDC NWSFO for a few minutes. With prospects of dryline initiation vanishing, we decided to bolt northward towards Wakeeny. We deployed the mobile phased array south of Wakeeny and collected volume scans every 15 seconds for about 90 minutes, while the dual-pol Xband group set up north of Wakeeny. Unfortunately, by the time we got set up, the supercell was beginning to fall apart a bit as linear convection developed WSW of Wakeeny. We experienced dime and nickle hail about 4 mi S of Wakeeny at 0130 and 0148 UTC (respectively) at our location, along with very strong winds. The amount of lightning with this QLCS / squall line was amazing!

Total Distance: 530 miles
Target Area: Near Canadian, TX
Chase Area: May, OK, to Libscomb, TX
Maximum SPC Risk category: Moderate

Our group called it quits about an hour ago. We deployed thrice this afternoon and evening -- north of May, OK; in Shattuck, OK; and east of Lipscomb, TX. As I should have guessed today, experience tells me that storms hate Oklahoma. Sure enough, the better mesocyclones never really made it through central Lipscomb County. I think I remember seeing 2 or 3 mesocyclones that had been healthy previously weaken rapidly as they neared Lipscomb and points in the eastern part of that county. It's either supercells that produce immediately after crossing into KS from OK, or it's supercells that fall apart as they move from TX into OK.

Total Distance: 0 miles
Target Area: Near Guymon, OK
Chase Area: Stratford to Gruver, TX
Maximum SPC Risk category: Slight

A marginal chase day, with weak flow aloft and relatively marginal surface moisture. Robin Tanamachi, Dan Dawson, Chad Baldi, and I collected about an hour's worth of data in Gruver, TX, with the mobile phased array on a short line segment that traversed the OK/TX panhandles border. We sat for a couple of hrs in Guymon before heading southwest towards DHT and Stratford to see what would come of the supercell that was traversing far northeastern NM. That cell fell apart as it neared the OK panhandle border, so we sat in Stratford to see what would happen as the dissipating cell hit the deeper moisture that was streaming northwestward through the central and northern TX panhandle. As the OFB from that cell neared Stratford, convection rapidly developed. We found a good place to stop and scan at the Gruver airport in the south side of town. Fortunately, the precip stayed just north of our location for the most part.

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Total Distance: 0 miles
Target Area: Elkhart, KS, to Boise City, OK
Chase Area: Elkhart, KS, to Guymon, OK
Maximum SPC Risk category: Moderate

With stronger northwesterly flow aloft and deeper moisture in the low-levels, there was better hope for tornadic supercells across far eastern CO, western KS, the OK panhandle, and TX panhandle this day. By the time we made it to Guymon, OK, a couple of cells were developing in far southeastern Colorado. Given easterly storm motion, we headed northwest to Elkhart, KS to await the approach of the storms. We deployed and collected data from this location with the MWR-05XP, before we had to head southward as the eastern-most cell developed a significant mesocyclone and took a hard right turn.

Total Distance: 0 miles
Target Area: Near Childress, TX
Chase Area: Near Vernon to Throckmorton, TX
Maximum SPC Risk category: Slight

Another in a slew of marginal chase days. Not much to say, other than that we didn't get to the supercells SW of Vernon quickly enough before it gusted out and before more convection developed to its southwest. We continued to move south in attempts to get ahead of the cells and get on the "tail-end charlie", and we finally did so a few miles ENE of Throckmorton. By this time, a mesocyclone had developed to the NW of Throckmorton, and we collected some data on this feature before we were overtaken by the storm. Though we only experienced 30-40mph winds, the heart of the bow echo moved several miles to our southwest.

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Total Distance: 1063 miles
Target Area: Kearney, NE
Chase Area: NE of Broken Bow, NE
Maximum SPC Risk category: Moderate

An extremely strong upper-level trough was forecast to move across the northern US, inducing bomb cyclogenesis across the northern Plains. The 975mb low was strong for any time of year in this part of the country and nearly unprecedented for June. Very strong shear profiles existed east of a dryline that extended from far southwestern South Dakota to the Texas Panhandle, with widespread >400 0-3km SRH present by late afternoon.

Total Distance: 100 miles
Target Area: OKC to TUL
Chase Area: BUST
Maximum SPC Risk category: Moderate

Well, we were supposed to have the radar back by noon this day, but we were lucky enough to be given another day with the radar. With deep Gulf moisture in place (70-74F tds) east of a dryline that stretched from near Kansas City, KS, to Wichita Falls, TX. Though shear profiles weren't quite as strong as the previous day's, 0-3km SRH of 250-300 m2/s2 would work with >4000 j/kg MLCAPE and 40-50k5 0-6km shear to produce a risk of supercells and significant tornadoes. Several high-resolution WRFs initiated precipitation in the area between OKC and TUL. Game on.

Total Distance: 280 miles
Target Area: Cheyenne to Weatherford, OK
Chase Area: N of Fairview to Watonga
Maximum SPC Risk category: Slight

Well, let's give chasing in Oklahoma another try... A cut-off upper-level low was forecast to move little this day, anchored over the panhandles and far southwestern KS. Flow at all levels was unimpressive in terms of speed, but strong direction shear was present, with southeasterly surface winds veering to southwesterly mid-level winds. Deep moisture was in place, as was ample insolation, which resulted in moderate to strong instability developing by afternoon. A cold front of sorts was located in the far eastern panhandles, and an outflow boundary from early-day convection was moving very slowly westward, stretched NW-SE across northwestern OK. I was hoping that the very backed surface flow would be just enough to create deep-layer shear sufficient for supercells.

Total Distance: 200 miles
Target Area: Near Lawton, OK
Chase Area: Near Cyril, OK
Maximum SPC Risk category: Slight

Marginal, marginal, marginal. Flow at all levels was leak, but there was some decent directional shear north of an outflow boundary that stalled near the Red River. Though most parameters were weaker this day compared to the previous, including CAPE and shear, I still held out a little hope for a non-supercell tornado threat owing to the presence of low-level CAPE (>150 j/kg 0-3km CAPE) and low-level vorticity in vicinity of a weak surface low S of Lawton and a couple of outflow boundaries.

Total Distance: 520 miles
Target Area: Liberal, KS
Chase Area: Near Woodward, OK
Maximum SPC Risk category: Slight

Extreme instability developed this afternoon south of I70 across western Kansas, Oklahoma, and the Texas panhandle. With temperatures in the 88-93F range and dewpoints in the 75-77F range, MLCAPE >6000 j/kg and a weak cap would support very intense storms. The best flow aloft was north of the OK-KS border, and even that was rather marginal at ~25-30 kts. Despite this, southeasterly low-level flow helped develop 30-35kts 0-6km shear in Kansas, and 25-30 kts 0-6km shear in Oklahoma. I headed up towards the Oklahoma panhandle knowing that a nearby boundary (an OFB from previous convection) might combine with the extreme instability and marginal-but-hopefully-sufficient deep-layer shear to yield a significant supercell threat.

Total Distance: 455 miles
Target Area: Nowata, OK, to Parsons, KS
Chase Area: Thereabouts
Maximum SPC Risk category: Slight

Not much to say. Strong low-level shear was present east of a cold front moving eastward through the Plains. Moderate instability and sufficient deep-layer shear yielded an environment that may have been supportive of supercells. In the end, strong linear forcing yielded a marginal squall line across much of the eastern Central Plains. We saw about 30 seconds of good structure near Vinita, but it was, by all accounts, an uneventful chase.

Total Distance: 340 miles
Target Area: Near Altus, OK
Chase Area: S of Hobart to SW of Anadarko
Maximum SPC Risk category: Slight

A disappointing day for me, given that I wasn't expecting such a relatively solid line of convection to be the mode that far south. I waited with my 'usual' chase group down in Snyder, before we shifted northward to ~2mi west of Roosevelt, where we parked and watched the convection approach from the west. There looked to be a few times during which the convection attempted to break up, but quasi-linear mode dominated. We saw the apparent tornado down there, but I'm not comfortable enough to call that a tornado YET... There was a lot of rising dust along the gust front W and SW of Roosevelt, and we noted rapid cloud-base rotation occurring along/above this gust front. I suppose a vortex may have wrapped up along the gust front and become defined enough to be called a tornado, though. I'll have to review my video.

Total Distance: 200 miles
Target Area: Chickasha to Norman, OK
Chase Area: Oklahoma City to Cushing, OK
Maximum SPC Risk category: Moderate

Similar story to most folks who chased in Oklahoma... I left OUN with Mike French, Jana Houser, and Howie B. upon seeing initiation down near Chickasha. We got in good view of that storm as we passed through Moore (driving nearly alongside Roger E and company), and we ended up chasing it to Cushing. It was apparent to us that things were not going to go well upon feeling cold, westerly outflow after stopping between Tryon and Perkins miles southeast of the primary updraft base. We meandered southward towards sunset to see if anything coming up from just east of OKC would do anything. The storm(s) appeared to have weak rotation on radar as they passed S and E of Stroud, but it was then getting dark, so we called it off.