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

                                                                                                        by Jonathan D. Finch

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                        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. Extensive flooding also
                        occurred downstream in Kansas on June 18-19. Dodge City experienced its worst river flood of record on the 19th. Here
                        are some links that detail the sequence of flooding events as well as rain amounts and riverflow.
                        Flood Summary
                        South Platte Flood

                        Larkspur Flooding                  

                        Deer Trail Flooding

                        Detailed  report on the 1965 flood

                        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.  I just added more severe weather information here for the 14th and 15th. There
                        was an undocumented tornado north of Douglas on June 15 that I found in the Douglas Budget. The tornado paths                   
                        can also be found here for the 16th.

June 14

                        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 show moderate to high surface based
                        CAPE from 2500 to 3500 j/kg. Tornadoes occurred 3 to 5 miles west of Loveland and southeast of Douglas, WY. 
                        The surface observation form from Fort Collins makes reference to the the tornado that occurred west of Loveland that
                        lasted for 15 minutes. The approximate sounding for Fort Collins showed 2800 j/kg surface based CAPE. 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. 

                        The other upper air charts are    850mb     700mb     200mb


                        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 T 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.

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

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
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

June 15


                        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 tornado occurred 32 miles west of Cheyenne (elev. 8200ft) or about 15 miles southeast of Laramie, tearing up some
                        timber, but hitting no structures. Another tornado occurred 25 miles west of Cheyenne.

                        A tornado and baseball sized hail occurred about 40 miles north of Douglas near the Cheyenne river. This tornado
                        is not listed in any storm databases.  The surface observations at Douglas, WY are here. My approximate sounding
                        for Douglas, WY during the late afternoon shows about 3000 j/kg surface based CAPE. Of course the shear was good
                        with ese low level winds veering to the south or southwest with increasing speeds. The wet-bulb zero was around 7700ft AGL.

                        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 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 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 has become more meridional by 00 UTC June 15 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 other 00 UTC upper air charts are: 850mb    700mb

                        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 Ardmore. 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
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 6000ft 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

June 16

                   Very strong upslope flow on the 16th resulted in very high surface dewpoints 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. 7800ft) 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). The 500mb charts at 12Z and 00Z showed southerly flow up
                        and down the western high plains.  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. 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 12 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. The 850mb chart showed backed winds along the high plains with
                        rich 850mb dewpoints. 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 00 UTC sounding from Denver was convectively contaminated. The 00 UTC June 16  500mb, 400mb, 300mb and 200mb
                        charts still showed the leading edge of the stronger flow along the front range.  

                        The approximate sounding for Colorado Springs at 20 UTC shows about 3200 j/kg surface based CAPE.                     

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

June 17

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.
On June 17, 1965 several tornadoes occurred 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.  A topographic map with surface observations at 19 UTC can be found here.

                        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.
                   The approximate sounding for Pueblo for 18 UTC June 17 shows 4400 j/kg surface based CAPE.

18 UTC Elev(ft) Pres.(mb) SLP(mb) T(F) Td(F) MR(g/kg) theta(F) theta-e(K)
Las Vegas 6800 795
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

                        By 21 UTC on June 17, 1965, just before a tornado hit at 7300ft 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.

                        The approximate sounding for Las Vegas for 21 UTC June 17 showed 3600 j/kg CAPE.

                        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 around +12 C.

21 UTC Elev(ft) Pres.(mb) SLP(mb) T(F) Td(F) MR(g/kg) theta(F) theta-e(K)
Las Vegas 6800 793
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