This map gives a general layout of the three storm cells that moved through west Oklahoma. The middle storm got the name "west storm" since it developed late in the evening as the other storms were dying out. Chasers had to head west!


Click here to see a batch of chase photos from this storm day!

MAY 1, 1997

Tim Marshall

FLOWER MOUND, TX: Short wave is progged to come out onto the plains after 00z tonight. Warm, moist surface air is moving north from the Gulf of Mexico but I question whether deep moisture will move northwestward into the eastern Texas panhandle as front which passed yesterday wiped this out. The front did stall in central Texas (not as far south as progged). There are 70 degree dewpoints along the coast and mid 40 degree dewpoints in the Texas panhandle. Winds across north Texas and the eastern Texas panhandle have shifted from northeast last night to southeast this morning. Progs indicate a surface low will develop in northeast New Mexico today. Anticipate severe storms will develop later tonight from Amarillo to Silverton and move east into western Oklahoma. No low clouds in Dallas this morning, blue sky all quads. Target area is the eastern third of the Texas panhandle today. I'll head towards Childress on Rt. 287.

Time Odom Town/Heading Remarks

9:20 686 FLOWER MOUND - Rt. 35W northbound.

9:35 703 RT 380W. SE winds at 15.

10:00 728 DECATUR- Rt. 287 NW. Clear skies, SE wind at 15.

11:00 800 WICHITA FALLS: Clear sky with cirrus on the northwest horizon. SE wind at 20. Stopped briefly for lunch.

11:15 800 RT 287 heading NW. NOAA weather radio says 70 percent chance of severe storms tonight. 11 am dewpoint is 41 at Lawton and 49 at Wichita Falls. 29.85F.

11:37 828 ELECTRA: Clear skies. Cirrus NW. Mid-level overcast W-N horizon. 10% of sky

12:00 851 VERNON- Mid-level overcast is breaking up and covers 30 percent of the sky. Cirrus is also evaporating. Winds are SE at 20. Blowing dust in open fields.

12:10 868 CHILLICOTHE: 50% of sky, western half is overcast with some BINOVC.

12:20 880 QUANAH: 70% of sky low overcast now.

12:50 910 CHILDRESS: Overcast sky. SE winds at 20. Quick pit stop.

1:00 910 ON 287 moving NW.

1:28 942 MEMPHIS- BINOVC. Clearing west on the caprock. This should be interesting.

1:50 968 CLARENDON: Clear skies overhead. Band of low clouds north, east, and south. arcing like a backwards C. SE winds at 20. No cirrus now. Blowing dust.

2:16 996 CLAUDE: SE winds at 20. Line of frothing towers can be seen through the dust and haze to my west. Evidently the dryline is between Claude and Amarillo. (Weather radio says there is a moderate risk of severe thunderstorms. Dryline is from Guymon to Amarillo to Lubbock. "Vertical wind profiles are also expected to remain favorable for isolated tornadoes.") Stopped and topped off gas tank.

2:39 005 W OF CLAUDE: Stopped west of town in an open area to watch congestus. Cirrus distant N. (Amarillo reports 52 dewpoint at 2pm with south winds.) Took 4 photos of barbed wire fence, dirt road, and towers.

3:00 WX CONDITIONS at AMARILLO: 78/56 47% 26g35 29.60F
DHT 81 SW 32g39
BOR 74 S 25g40
CDS 78 SE 22g30
LBB 87 S 28g38
DFW 76 SE 16g23
MAF 85 S22g29
SPS 77 S21g31
OKC 74 SE 24g33
DDC 57 S 36g48
COS 55 NW 24g35

3:33 Two agitated areas on the dryline: Lone tower SE and lone tower NW, Cirrus distant N.

3:39 005 Developing Cb SE. Leaving site west of Claude.

3:40 Vertical shot of tower SW on dryline.


3:46 012 Rt 207N.

3:51 019 I-40E. Tower west, Cb ESE Very dusty. Main tower E is large and straight up.

3:54 021 1 pict ESE of Cb, nothing is in the foreground. Another tower S of that Cb.

3:59 027 1 pict ESE of Cb with flank. Green sign is in lower left corner. Lps developing N.

4:03 032 GROOM - 3 picts ESE of Cb with large cross in it. Crisp, vertical towers. SW flank.

4:06 037 1 wide angle pict E with road in center of picture. Two towers on flank.

4:12 044 1 pict NE of clear slot on LP storm.

4:16 048 First pair of Cg's E from LP storm to my north.

4:17 049 Stopped breifly at FM 2477. 1 wide angle NE and 1 super wide angle of Lps. Bases are elongated on the LP storms to my north and towers are tilted -sheared. 1 pict NE of arc shaped beaver tail. Road is to the right. LP storm N is dying. Backsheared anvil on SE storm. Vertical tower SE. (Severe thunderstorm warning NE Hall Co.-KGNC radio Storms moving NE at 40?). Made the decision to go for the storm to my south and leave the two sheared LP's.

4:37 063 1 super wide angle shot northwest of southernmost LP. N Lp is shrinking.

4:40 065 McLEAN- Overshoot on Cb SE. Backshearing anvil. (Road construction 1 lane road)

4:54 080 FM 1647S- Leaving LPs.

4:57 082 1 picture south of backsheared anvil on SE storm. Southern Lp to our north is strengthening with first vertical tower now reaching anvil level and another tower rising up on the back end. Storms are pulsing.

5:09 098 Rt. 83 S - Cb with backsheared anvil SSE.

5:10 1 wide angle and two super wide angles S.

5:12 102 Cloud base SE is in view. Wall cloud noted. Storm N is now starting its first backshear. Main tower leans back at anvil level. Lost sight of wall cloud SE due to heavy precip curtain.

5:20 112 WELLINGTON- 1 picture overhead of main storm tower and anvil.

5:22 113 East on FM 338. Small backshear on Cb distant N. Gustnado NE. Blowing dust east.

5:25 118 High base on Cb just north. Does have a beaver tail. (Severe Thunderstorm 10 N of Wheeler)

5:31 124 DODSON- Lots of blowing dust moving north into rain free base.

5:37 131 Rt. 30 N in Oklahoma. Lots of chasers, Al Moller, Doppler on Wheels

5:44 138 1 super wide angle shot of clear slot NE. Base has elongated to the west. NW winds. Stopped briefly to watch disorganized rotation at nose of clear slot NE.

5:51 138 Winds went calm. Base relatively flat. Classic supercell.

5:52 138. Heading north now to Rt. 9.

5:54 140 Rt. 9 East. Ch. 9 TV truck ahead.

5:56 142 Winds switched back to SE

5:57 VINSON- Lots of chasers around. Moving too slow. Stopping on roads. NW winds. Robert Willis, Roger Edwards, Rich Thompson

6:04 150 3 super wide angle shots of storm.

6:04 151 Greer County line. Stopped breifly. Took 2 pictures NE of storm. Occluding portion is NE.

6:07 152 Moving east again. North winds. Saw Chuck Roberts

6:08 153 REED- Storm has backwards C-shape with main updraft on northwest side, flank SW. 1 super wide angle overhead to finish out the roll. Mushy anvil. Stopped where white house had white picket fence. Took photos.

6:15 154 Leaving film site Rt. 9 east. Storm will not produce a tornado.

6:24 164 Rt. 283 N. Jogging for position. Encountering rain.

6:28 168 Rt. 9 E.

6:30 170 1 super wide angle of base E.

6:37 174 Stopped just west of Granite. Pea-marble hail. 2 horizontal and 1 vertical shot as well as others of hail. Took video of hail at 6:42pm. Grass in foreground.

6:52 180 GRANITE: Hail to one inch. Good hail video taken. Hail covers road but melts fast.

6:54 182 Rt. 9 east. Heavy rain. Pea to marble hail. Stopped at TOTAL station.

7:02 184 LONE WOLF-Cb distant north looks multi-cell and not as organized as this storm.

7:16 196 HOBART- Rt. 183 South. Trying to get back to some visibility. In heavy rain.

7:22 201 Took 4 pictures of storm SE with green grass in foreground and mountains in back. Not enough deep moisture - No definition to the base.

7:30 204 Stopped and talked with Gene Rhoden. Let Cb go. New Cb is developing to the west at interesection of outflow boundary (from Hobart storm) and the dryline.

7:45 204 Leaving site. Heading north to intercept storm that is now near Sayre. Heading north on Rt. 183. Stopped at rest area. Took several pictures of crepuscular rays emanating from behind towers and backsheared anvil to my west and also east of crown of Cb being lit by the sun. Strong SE winds. Storms are intensifying now.

8:00 210 HOBART- Rt. 9 west. Low cloud band (outflow boundary) intersects storm base NW.

8:07 217 Rt. 44 N. - Upper wave must be getting closer. Getting in to low clouds too much. Turned east and heading back to town for better viewing. Cb E still looks nice.

8:10 220 HOBART - Stopped to take picts of anvil and Cb reflected in water puddles. (Severe Thunderstorm Warning for Elk City, golfball hail in Sayre moving NE at 40) Storm at Anadarko moving east at 35mph but going downhill. 2 vertical shots west. Third picture at 8:24. Horizontal shot 8:25.

8:33 225 Leaving Hobart moving east on Rt. 9. Chunky anvil. Main tower is vertical.

8:36 228 Rt. 183 North. Bands emerging and crisp crown. Flickers N.

8:42 235 Crossing into Washita county. Nice backshear on anvil.

8:44 238 ROCKY- Great looking Cb just NW. Lots of intercloud lightning.

8:48 242 Stopped on hill just southwest of Cordell. Took lots and lots of pictures on tripod. (Tornado Warning for our storm. Officer sees a funnel 5 SW of Bessie)

9:23 242 Rt. 183 N. Heading to Cordell

9:29 250 CORDELL-Rt. 152 East. Heading home.

9:36 256 Rt. 54 South

10:18 302 Rt. 62 E.

10:38 325 LAWTON- Stopped for gas and dinner.

11:00 325 LAWTON- Leaving town.


1:37 500 FLOWER MOUND-

Summary: Saw 2 LP's and 2 classic supercells today. Great structure shots taken including good hail video. Storms were high based and non-tornadic. Some possible reasons for this was the lack of deep moisture -a problem most of this season, and lack of storms turning right of the mean flow to enchance their storm relative inflow. The best storm of the day was the last one which developed around 7-7:30pm at the intersection of the outflow boundary of the previous storm and the dryline. Lesson to be learned is NEVER give up on the chase day until the last glimmer of light fades away.


May 1, 1997

by John Holsenbeck, NWS AMA

Todd Lindley (NWS AMA met aide), his girlfriend Hilary Oliver (West Texas A & M nursing student), and John Holsenbeck (NWS AMA met intern) chased Thursday, May 1st and encountered both the North Storm: the one that developed near Alanreed, TX and passed north of well as the West Storm: the one that developed just north of Erick, OK and passed over Sayre.

I am unable to give a detailed account of what happened since I have not had enough time (wife and job at NWS AMA) to review my video or get my pictures developed. I will try to get my pictures developed tomorrow (if they even turned out worth anything) and scanned onto the NWS AMA homepage soon and dub the Hi-8 video off tonight. Anyway, I would like to throw our "two cents" in.

The North Storm passed north of Wheeler and around 530 pm CDT brought us 3/4 inch hail just east of the community of Briscoe. While it was still northwest of Wheeler, it was quite artistic being a highly sheared LP storm with an incredible vault on the northeast through north side. This was probably the high point of the North Storm. As it moved east of the moist axis (which I agree was very narrow), the base rose considerably. Around 620 pm CDT we left this rapidly dying cell east of Roll, OK and decided to head back toward Clarendon.

Driving back south to Cheyenne, OK we could see the South Storm down near Mangum. We knew this was too far to get and wasn't worth it since it would continue to move toward lower instability. We stopped off in Cheyenne to get gas when we started to notice more towers going up from southwest through northwest. One tower went up northwest of Cheyenne, but got sheared to death. Another cell went up west-southwest of Cheyenne and was high-based, yet artisitic due to its highly sheared structure. While we were taking stills and video of this artistic storm, another updraft grew rapidly to our southwest. This would be the West Storm in the making.

Around 650 pm CDT an impressive series of stair-stepped cells formed to the west of the still-leaning main updraft leading us to think the West Storm was multi-cellular. However, we continued to drive south toward Sayre. During that time the storm became better organized with the main updraft much more vertical as well as the formation of an anvil. We attempted to drive south through Sayre, but felt it was too late and too unsafe - rain and hail core now in Sayre. So we turned around and headed back north of town a few miles to let it pass on by.

Some time passed when the rather weak pseudo-RFD slowly cleared out the rain and hail allowing us to see the rain-free base to the south- southeast. The base never really developed a wall cloud from our vantage point, but did have moderate rotation. The RFD continued its slow advancement scouring out the low clouds on the back side of the storm revealing huge updrafts towering up toward the anvil. We stayed there for awhile taking stills and video of the impressive updrafts. (I have to agree with Rich Thompson's observation that RFD's with Thursday's storms were lacking or at best mediocre).

Around 800 pm CDT we decided to head northeast to Elk City - we were thinking that the storm motion was northeast. However, we were wrong; the storm was moving east. So we decided to take a route to the south just west of Elk City. We took exit #34 off of I-40 and headed south through the community of Merritt. We were about a mile north of OK Hwy 152 when we passed this barn on the east side of the road that had sustained some light wind damage. About 1/2 mile down the road Todd decided to turn around and go back. He said that there were people walking across the road toward the barn. We returned to the barn and met up with a couple that owned the barn who lived in a house to the northwest and just across the road from the barn. They said they had heard the wind make some howling sounds and looked out and saw a tornado hit their barn across the road. Some tin and 2x4 rafters lay scattered to the northwest across the yard of the couple's home. They said that it was the fourth tornado that had crossed their property during the 20 years they had lived there. I then made a call to NWS Norman about the possible tornado.

I personally can not say for sure if it was a tornado or not since the damage was at best F0 and no other structures were hit - there weren't any other structures. We never saw a tornado. It very well could have been strong inflow winds underneath the storm's inflow jet. This would, also, give good reason for the debris thrown to the northwest. Anyway, we finally left and headed down to OK Hwy 152 to get a few parting shots and video before we headed back to Clarendon. By this time it was after 900 pm CDT.

Michael Watts (E-mail asks: "Were there any power lines snapped north of Cordell? I haven't seen any damage survey results of course, but at 9:10 pm I did see a bright flash from what I assumed to be a snapped line north of town. I was further south, on 152, shooting wide-angles of the lightning and structure. This isn't conclusive in any way, but I've seen it happen with tornadoes several other times.


Why were the May 1, 1997 supercells non-tornadic?

Brian Curran wrote: "Yesterday morning, I noticed an area of potentially cool theta-e air parked over southern Arkansas/northern Louisiana. I didn't think anything of it; my vision would have this air being pulled into central Oklahoma as the wind field adjusted to the lee cyclogenesis over eastern Colorado. Sure enough, there was a narrow slot of quality theta-e air along the warm front; to the east was the air with its source over southern Arkansas/northern Louisiana. Once the supercells went into this lower CAPE [convective available potential energy, an overall measure of instability] air, they died. The MCS [mesoscale convective system] which churned through Oklahoma Friday morning laid out a nice outflow boundary... rather, a ducted low level gravity wave...that really hosed the wind field across north Texas Friday morning. The balance between shear and buoyancy (in a 2D sense, anyway) was tilted toward shear as the storms moved into the potentially cooler air. This in turn caused the outflow to race ahead of the MCS, which in turn was ducted underneath a rather wicked cap across northwest Texas Friday morning. I don't think I could have envisioned this scenario 36 hours ago; for every paradigm, there's an exception. Such is life in a nonlinear environment. What lessons does this teach the chase forecaster? ALWAYS look upstream and envision the source region for parcels arriving in your target area. Sometimes modification will help; other times it will hurt. Furthermore, consider the balance between shear and buoyancy with regards to the expected storm type. A decrease in buoyancy holding shear constant can cause a linear system to "gust out". Increasing buoyancy while holding shear constant can result in interesting things, such as a squall line morphing into supercells on April 26, 1984."

Rich Thompson: "I don't have a good explanation. It's probably a combination of several factors: When the storm was most intense and in the axis of decent instability (near Tx/OK border), there was no evidence of a RFD (rear flank downdraft). This was probably due to all the rain falling well northeast of the mesocyclone. By the time the storm developed an RFD, it was moving into a more stable environment, thus the RFD disrupted the low-level structure (went from solid updraft to a narrower "horse shoe") instead of a strong low-level occlusion. There was some half decent cloud base rotation during the first RFD attempts, but nothing persisted more than a few minutes and the majority of the updraft remained along the trailing gust front. We were probably just the "victims" of poor timing. The second storm had even more going for it shear-wise since began along the outflow boundary from the first storm (and the low level jet increased to 85 kt at 2 k ft!), but again low-level theta-e wasa problem. Both storms (especially the second) probably would have produced tornadoes with about 1000-1500 j/kg more surface CAPE when they developed RFDs. The first storm was indeed a supercell with a flared base, 45kt surface inflow, striations, sort of a beaver's tail, etc. As soon as it began to develop decent cloud base rotation and RFD attempts, it began to move east of the best instability. From Greer Co. eastward, the shear dominated the storm and eventually killed it. Farther west, we chased another supercell that developed along the trailing boundary from the first. It quickly developed a similar barber pole appearance, but there just seemed to be too much shear (for the instability) to expect much of a hose threat. The storm stayed quite organized for a couple of hours, and we drove right into the southeast side of the hook with the only tornado warning of the evening. Again, lots of nice structure, but no confirmed tornadoes. Seems to me that the storms formed a little too early, orthat we just didn't have a wide enough instability axis. It probably all comes back to the last minute return flow. A nice overall chase, but I'm still surpised there weren't any tornadoes. Blame this one on Roger Edwards!"

Al Moller: "The storms simply outran the good low-level air by moving east of the warm front. Thus, a bad balance of shear and instability likely shut the tornado potential down. The inflow was significantly cooler in (non-tornadic) Oklahoma than across the border. We (Jesse Moore, Martin Lisius, and myself) also chased the Memphis to Hobart storm and the secondary supercell that blew up to the first storm's west-northwest. Mike Foster had an interesting observation from his non-chasing desk yesterday, in reference to some of us, who on Wednesday thought there might be warm-frontal storms south of Childress on Thursday. When one looks at Thursday's visible satellite loop, there is no southern New Mexico high-based mountain cumulus and/or wave clouds during the day (a rare event), mainly south of a 35 degree north latitude. If you run a straight line east-northeast from the southern edge of the New Mexico mountain convection, it pretty much runs into the southern-most storm (the Palo Duro/Memphis TX storm). Nothing formed south of that complex. Thus, the cap (and probably the subsidence area south of the polar jet) in New Mexico more or less "pointed" to the southern end of potential convective development further east-northeast. This is food for thought, especially with tight, strongly dynamic systems, as to how far south "chasable" weather may occur. Of course, like everything else this is not a hard and fast rule, for sooner than later it will be broken! It turns out that Bob Johns' slight risk early Thursday (which ended near the Red River) was a good one. The later, further southward extending, moderate risk (which I would have agreed with, from what I saw of the morning data) didn't pan out. One thing that chasing has taught me is that I am never satisfied with my expertise in severe weather forecasting. About all that I can do is make a forecast, and (hopefully) have the sense to make acute observations (e.g., M. Foster's observation from above) and thereafter adjust my forecast. Because of my perceived mediocrity, I prefer to forecast a "zone" of potential (rather than a point), or maybe even several "zones". So, if I get to my forecast area and nothing happens (imagine that!), I will start thinking of other zones of severe storm potential, and whether or not I can reach the alternate area, should something develop."

Robert Prentice: "I intercepted the SW OK supercell at Mangum. At this point is was a classic/LP supercell hybrid with a striated, barrel-shaped updraft and a significant (but not overwhelming) precipitation core well displaced to the northeast by about 5-15 miles. The updraft resembled 5/31/90 Waka/Spearman, Texas tornadic supercell, though not as physically large. As the northeast side of the updraft approached the northwest side of Mangum, I observed persistent moderate rotation at cloud base. Then the storm occluded and became disorganized. When it finally reorganized in Kiowa County, it was a struggling, high-based supercell with a laminar base and flanking line and a strongly sheared-over updraft. What I speculate happened was this. Keep in mind I don't know much about the storm before Mangum, except what I have heard and seen from the ADAS (OK Mesonet objective Analysis) Homepage. At 3pm, the dryline extended from Dumus-Amarillo-Hall Co-Lubbock. The dryline was bowing eastward into the southeast Panhandle around Hall Co. Meanwhile a warm front extended northwest/southeast from a triple point near Amarillo. These boundaries were well-defined by cumulus/towering cumulus (as seen on visible satellite images). Apparently the storm formed around 4-5pm in the warm sector along the dryline bulge in Hall Co. Even though the storm had great low-level inflow and sufficient instability, it never produced a tornado. Its best attempt at producing a tornado was when it crossed the warm front (baroclinic zone) at Mangum around 6:30pm. You would think that even in the strong shear environment, the supercell would have had enough time to organize (~2 hours?) (see Brooks, et al.) and produce a tornado. Erik Rassmussen (VORTEX) has emphasized just how quickly strong low-level rotation can occur within an updraft around these baroclinic (temperature) zones. Storm chaser's have know this for many years and (mainly) informal scientific literature has discussed the importance of baroclinic boundaries. However, mesocyclonic tornado formation seems to be tied to the Rear Flank downdraft (RFD). VORTEX cases have show that strong vorticity generation along the storm-generated Forward Flank Downdraft (FFD) is really not occurring. The latest thinking from Erik is we must learn more about the Rear Flank Downdraft, before we can unlock all the secrets of tornado formation. This is going to be tough to do since, ground-based probe observation are insufficient (may occur just above the surface) and with virtually no scatterers, radar is insufficient. Erik has said it may take near-storm LIDAR observations to study the RFD. Brooks and Doswell wrote a great paper about atmospheric parameters used to distinguish between tornadic and non-tornadic supercells. It is probably available through their homepages. To summarize, they think there is a delicate balance between storm-relative helicity, the max mixing ratio [~dewpoint] in the low-levels, and the minimum storm-relative wind (at any point) in the mid-levels. Rich Thompson has done a great deal of study, particularly on the last parameter (storm relative winds) and its ability to predict tornadic versus non-tornadic supercells. He even has PC Gridds macros to utilize Brooks and Doswell's technique in an operational SPC (Storm Prediction Center) environment. A few of the SPC forecasters will now try to distinguish tornadic versus non-tornadic supercells in their discussions/outlooks. A lot of this goes back to trying to predict supercells with strong RFD potential. Many scientists and chasers think this is tied to the strength of the storm-relative, mid-level wind, but without hard scientific observations about how the RFD forms and evolves, we don't know for sure. The next major goal for VORTEX may be RFD studies. So a possible reason the supercells did not produce tornadoes could have been related to RFD generation problems. I did not observe a well-defined clear slot with the Mangum supercell until it was a high-based storm in Kiowa County. Why did the storm slowly die after Mangum? It crossed the warm front and moved into cooler, drier, more stable air. That would also explain the high cloud base. At least I got some pretty video (for later time lapse) and stills from an abandoned cobblestone farm house in central Kiowa County. It died to my east-northeast in southern Caddo county as the updraft got completely sheared over around sunset. I never knew about the "new supercell" which moved east-northeast from Hobart (unless that was it and I got completely turned around!)."

Dave Gold: "I was afraid for a while there that the narrowness of the theta-e ridge was going to be the quick death of the nice Wellington barberpole. Around 22Z, it seemed to lose a lot of intensity judging by Frederick 1 and 2.4 km reflectivity, but soon afterward really intensified near Dodson, TX, and became a flared flying eagle with WER (weak echo region), notch, and mid-level meso. The storm never did show any signs of a good low-level meso, though... ...and that explains it. In addition to the Edwards Factor, it seemed that there was just a bit too much shear for the given instability. Vici wind profiler showed horrendous low-level shear and 50 kt mid-levels while the 00z OUN (Norman, OU) sounding showed garbage low-level theta-e. A bit more time for moist return to broaden the theta-e axis and you likely would have had a real tornado show."

Tim Vasquez: "Before we intercepted the storm (near Dodson TX), the Wellington TX flanking line towers were well-separated (I have time lapse illustrating this). For the rest of the evening, it appeared to me that the storm's behavior and features were going through cycles on the order of 8-15 min (hard tops, soft tops, hard tops, soft tops, for instance). It suggests line-multicell characteristics and this "pulsing" would have to be detrimental to continued evolution into a tornado producer, in spite of the great shears. Shouldn't a supercell have at least a quasi-steady updraft? I definitely agree with the statement about the poorer theta-e's over Oklahoma. The moisture axis was very narrow and was locked over San Angelo to the eastern Panhandle most of the day. Anyone notice how the storm bases kept rising as you went east?"

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