The High Plains, Front Range and Rockies Superstorm June 14-17 1965

One of the worst floods in Colorado State history occurred on June 15-18, 1965, with 28 people losing their lives. Total damage was about $540,000,000. The hardest hit counties were Weld, Denver, Adams, Larimer, Morgan, Lincoln, Arapahoe, Elbert, El Paso, Teller, Park, Fremont, Otero, Baca, and Prowers. Extensive flooding occurred in the mountains and foothills of New Mexico. The hardest hit area was Colfax county around Raton and Las Vegas. Total damage exceeded $5,000,000. Flash flooding occurred in Wyoming with at least 1 fatality. Dodge City experienced it's worst river flood of record on June 19 in spite of negligible rainfall in the Dodge City area. Here are some links that detail the sequence of flooding events as well as rain amounts and riverflow.

Severe storms occurred up and down the front range and foothills from Ruidoso, NM to Casper and Worland, WY. Although storm reports were not sought after in the 1970s, there were several reports of very large hail.

Tornadoes occurred on the 14th, 15th 16th and 17th. Most of these were in sparsely populated areas and some surely went unreported or unseen. After I made the above severe weather maps, I searched the Douglas Budget and documented a tornado and baseball sized hail that occurred on June 15. This tornado or hailstorm is not included in the national severe storm databases. Here is a map that details the severe storm events on June 14 and 15. The tornado paths for the 16th can be found here.

Late on June 13 and early on June 14, 1965, low level upslope flow pushed moisture onto the front range. Two frontal boundaries were present by the 22 UTC June 14. The northern front extended from southern Colorado across Oklahoma and Arkansas. The southern front extended up and down the front range into New Mexico and Texas. Very unstable conditions existed along the length of the front range, with the highest instability further north in Colorado and Wyoming.

The 00z June 15 500mb chart showed a deep trough in the western US with moderate mid level flow as far east as the front range of Colorado. The 6km flow (close to 400mb at Denver) was 40kts, which is fairly strong by eastern Colorado standards in mid June. It was fairly cold aloft for mid June with 400mb temperatures from -22 to -24C and 300mb temps from -38C to -40C. 700mb temps were 15C at Albuquerque, +13C at Denver and slightly cooler further north in Wyoming. Approximate soundings for Douglas, WY and Fort Collins, CO showed moderate to high surface based CAPE from 2300 to 2800 j/kg. Tornadoes occurred 3 to 5 miles west of Loveland and southeast of Douglas, WY.

The surface observation form Fort Collins makes reference to the tornado that occurred west of Loveland that lasted for 15 minutes. The capping inversion was obviously much weaker in the foothills and mountains southwest of Fort Collins where the storm developed. The storm probably initiated on the edge of the mountains west or southwest of Loveland. Given the sw to wsw mid level flow, the storm probably moved to the ene or east.

Tornadoes also occurred near Douglas, WY and at Colorado Springs. Baseball sized hail fell in Colorado Springs. The tornado occurred at Peterson Field in Colorado Springs.

The theta-e was higher at Las Vegas than at Chanute, even though the T/TD were 4F/19F higher at Chanute. This is because elevated heating resulted in a potential temperature of 108F at Las Vegas. This offsets the moisture deficit at Las Vegas. The highest theta-e was at Colorado Springs where the T/TD were 11F and 13F lower than at Mcalester, OK.

22 UTC	Elev(ft)	Pres.(mb)	SLP(mb)	T(F)	Td(F)	MR(g/kg)	theta(F)	theta-e(K)
Las Vegas	6800	788	1002	71	47	8.8	108.3	343.4
Colo. Springs	6140	806.8	1004	75	57	12.5	108.9	355.0
Denver	5300	830	1003.6	73	55	11.3	102	347.0
Chanute	950	975	1010	75	66	14.2	78.9	340.9
Mcalester	487	988	1007.6	86	70	16.2	87.9	352.6

On June 15, 1965 , a tornado was observed by a weather research team at Colorado State University. The surface observation sheet from Fort Collins indicated that a weather research team witnessed a tornado 8 miles west of Fort Collins at 413 pm.

A major hailstorm occurred in the northern suburbs of Las Vegas, NM and Sapello, NM with hail up to 3" in diameter.

A cooperative observer 32 miles west of Cheyenne reported that a tornado tore up some timber but hit no structures. This tornado was probably located near Vedauwoo at 8400 ft. Officially, there is a tornado listed near Hecla (20 west of Cheyenne), but nothing further west near Vedauwoo.

A tornado destroyed thousands of valuable trees at the Dick Hornbuckle ranch 40 miles north of Gillette, WY. Some of these trees were ancient and 5 ft in diameter. Two trailer houses were demolished. A man suffered broken ribs. Baseball sized hail remained until the next day. Tangled masses of downed trees were all that remained of these trees that served as a winter cattle shelter for years.

The Denver sounding from 12 UTC June 15 had a loaded gun appearance with rich moisture up to 700mb. With surface heating, strong instability would be present. The 500mb chart showed 40kts as far east as Denver and Albuquerque with fairly cool 500mb temperatures. The 700mb chart featured a warm plume covering the southern Rockies.

The 19 UTC surface chart showed 2 areas of moist upslope flow--one in New Mexico and the other in northeast Colorado back to the front range. The 00 UTC surface chart is here.

The approximate sounding for Las Vegas, NM for 21 UTC showed 2500 j/kg CAPE, with a freezing level of 8400 ft AGL and web-bulb zero height of 6000 ft AGL.

The mid to high level flow became more meridional by 00 UTC June 16 as seen on the 500mb, 400mb, 300mb and 200mb charts. The leading edge of the stronger flow was right along the front range. This would remain the case through June 17. All these charts are valid at 00 UTC June 16.

The 700mb chart showed a warm plume extending from Old Mexico to Albuquerque to southern Wyoming. So how was I able to analyze >+14C 700mb temperatures at Eagle, Aspen, Alamosa, and Rawlins despite the lack of supporting 700mb observations? I found the temperatures and surface pressures at 19 UTC (local noon) or 22 UTC from the observation sheets and lifted these values up the dry adiabats to 700mb. 700mb was actually in the moist layer at Laramie, WY. So there was a sharp gradient in 700mb temperatures between Rawlins and Laramie.

The T/TD were 18F and 13F higher at Tulsa compared to Las Vegas but the theta-e was slightly higher at Las Vegas. The T/TD were 9F/12F lower at Denver compared to Ardmore but the theta-e was slightly higher at Denver. The potential temperature at Santa Fe was 111F. This makes up for the lack of moisture(mixing ratio 9.5 g/kg) as the theta-e was higher than at Tulsa (T/TD of 84F/66F). So even though the mixing ratio was 47% lower at Santa Fe, and the temperature 8F lower than at Tulsa, the theta-e was actually higher at Santa Fe since the potential temperature was 111F.

19 UTC	Elev(ft)	Pres.(mb)	SLP(mb)	T(F)	Td(F)	MR(g/kg)	theta(F)	theta-e(K)
Santa Fe	6350	800	1002	76	49	9.5	111.2	346.9
Las Vegas	6760	789	1004	66	53	11	102.8	346.7
Denver	5300	830	1003.4	75	60	13.5	104.2	355.3
Mcalester	487	988	1010.8	86	70	16.2	85.8	353
Tulsa	600	988	1011.9	84	66	14	86.9	345.6
Ardmore	750	983	1009.9	83	72	17.4	85.7	354.8
Waco	500	990	1007.8	92	67	14.5	93.6	351.4

An approximate sounding for Laramie for most unstable late afternoon conditions shows about 2600 j/kg CAPE and strong 0-3 km vertical wind shear. The theta-e was higher at Laramie and Las Vegas than Tulsa despite the temperature and dewpoint being much lower. So even through the mixing ratio was 25% lower at Laramie than Tulsa, the potential temperature was 19F higher at Laramie. The freezing level at Laramie was about 6000 ft AGL and wet bulb zero height 4000 ft AGL.

00 UTC	Elev(ft)	Pres.(mb)	SLP(mb)	T(F)	Td(F)	MR(g/kg)	theta(F)	theta-e(K)
Laramie	7200	772	1000	66	53	11.2	106.3	349.7
Las Vegas	6800	789	1004	60	57	12.8	96.6	348.1
Mcalester	487	984	1010.1	81	71	16.8	83.5	351.5
Tulsa	600	987	1011.9	82	66	14	86.9	343

Very strong upslope flow on the 16th resulted in very high surface dewoints along the front range from Las Vegas, NM to Pueblo and Colorado Springs. On June 16, 1965 several tornadoes occurred along and west of the urban corridor in Colorado. On this day, hail to golfball size and greater occurred at Holman, NM (elev. 7800 ft) which is 32 miles northwest of Las Vegas in the foothills of the southern Rockies. Hail to 1.5" fell at Black Lake NM (elev. 8600 ft). I plotted the 20 UTC surface observations on a terrain map as well.

The 20 UTC surface map showed strong southeast winds advecting moisture onto the front range. The T/TD at Colorado Springs (elevation 6180 ft.) were 64F/60F. At Dallas the dewpoint was 70F. But since a 60F dewpoint at COS has the same amount of moisture as a 66F dewpoint at Dallas, the mixing ratio at Fort Worth was only 16% higher than at COS. The surface temperature at Dallas was 85F compared to 64F at Colorado Springs. However, the potential temperature was much higher at Colorado Springs--96.9F versus 85.8F. Therefore, the surface theta-e was higher at COS(351.6K versus 350.8K). Even though COS and Vichy(VIH) had about the same T/TD, the theta-e was much higher at COS owing to a MUCH higher potential temperature and somewhat higher mixing ratio. The theta-e at COS was also higher than at Dodge City, mostly due to the huge difference in potential temperature.

20 UTC	Elev(ft)	Pres.(mb)	SLP(mb)	T(F)	Td(F)	MR(g/kg)	theta(F)	theta-e(K)
Las Vegas	6800	788	1004	72	53	10.6	110.5	350.4
Vichy, MO	1000	980	1020.5	73	52	8.5	76.1	323
Colo. Springs	6140	808	1008.0	64	60	13.9	96.9	351.6
Dodge City	2600	927	1017.4	68	67	15.5	79.5	345.0
Dallas	487	994	1015.2	85	70	16.1	85.8	350.8

Here is an terrain map with a depiction of the strong upslope on the windward side of Pikes Peak and the training of storms to the N/NNE that lead to 6" to 14" rain amounts in Larkspur, Palmer Lake and south of Castle Rock. Creeks in the region flooded and caused major flooding in Denver with $250,000,000 damage. The 700mb flow was backed to the sse in the morning. Its is obvious from this 700mb chart that the warm sector extends only as far north as southern Wyoming. This limited the northern extent of severe weather that day. The 850mb chart showed backed winds along the high plains with rich moisture. The 500-200mb flow had become more meridional with the leading edge along the front range at 12 UTC. 500mb, 400mb, 300mb and 200mb.

The evening (00 UTC) sounding from Denver was convectively contaminated. The 00 UTC June 17 500mb, 400mb, 300mb and 200mb charts still showed the leading edge of the stronger flow along the front range. The 700mb chart featured strong 30-40kt flow from New Mexico into Colorado. The approximate sounding for Colorado Springs at 20 UTC shows about 3200 j/kg surface based CAPE.

On June 17, 1965 several tornadoes occured along the front range in Colorado. Howling upslope flow at 30 to 40kts resulted in extremely high surface dewpoints at Colorado Springs. The T/TD at Pueblo was 72F/66F at 18 UTC. This is about as high as the dewpoint ever gets at 4700ft. In fact, a 66F dewpoint at Pueblo has nearly the same mixing ratio as a 71F dewpoint at Dallas, TX. The T/Td at Dallas and Port Arthur were 83F/71F and 87F/72F respectively. The theta-e was higher at Pueblo than at Dallas and Port Arthur despite the much lower temperature. The mixing ratio was about the same at all 3 locations. So elevated heating was crucial. Despite the T/TD being 20F/14F lower at LVS compared to Port Arthur, the theta-e was still slightly higher at Las Vegas.

18 UTC	Elev(ft)	Pres.(mb)	SLP(mb)	T(F)	Td(F)	MR(g/kg)	theta(F)	theta-e(K)
Las Vegas	6800	795	1012	67	58	13.2	102.6	353.1
Pueblo	4726	856.7	1013.6	72	66	16.2	96	358.2
Port Aurthur	20	1017.0	1017.8	87	72	16.8	84.4	352.2
Dallas	487	1002.9	1020.1	83	71	16.5	82.6	350.0

The 12 UTC 500mb chart showed fairly strong (50 to 60 kts) flow with cool temperatures (-10 to -12C). The upper flow was still meridional with the 400, 300 and 200mb jet axis from western AZ into Utah and western WY. 700mb temperatures had cooled off to 7C at Denver since the moist layer deepened. Of course, this cooling was partly diurnal in nature.

By 21 UTC on June 17, 1965, just before a tornado hit at 7300 ft elevation near Mora, NM, the theta-e at Las Vegas was up to 356.9K. The theta-e at Tulsa was MUCH lower despite the temperature being 9F higher and dewpoint 1F higher. The mixing ratio at Tulsa was much lower than at Las Vegas even though Tulsa's dewpoint was higher. The theta-e was higher in Las Vegas than at Port Arthur even though the temperature was 18F lower and dewpoint 14F lower.

21 UTC	Elev(ft)	Pres.(mb)	SLP(mb)	T(F)	Td(F)	MR(g/kg)	theta(F)	theta-e(K)
Las Vegas	6800	793	1009	72	58	13.2	108.4	356.9
Tulsa	670	997.5	1021.7	81	59	10.8	81.4	332
Pueblo	4726	853.7	1009	81	63	14.6	106	360
Houston	60	1013.4	1015.8	88	75	18.7	86	359
Port Arthur	20	1014.7	1015.8	90	72	16.8	84.4	352.2
Waco	500	998.5	1016.6	93	65	13.4	93.2	347.9

The 00 UTC June 18th upper air charts showed fairly strong mid to high level flow(500, 400, 300, 200mb) along the front range. 700mb temps were still +12 to +13C in Colorado and New Mexico.