May 4-5 1950 Tornadoes, Blizzard, Duststorm and Windstorm

Overview

                        On May 4-5, 1950 an interesting case of cyclogenesis occurred over the plains states. All types of  extreme weather
                        occurred with this system including blizzard conditions, tornadoes, a duststorm and high winds. A powerful shortwave
                        trough ejected northeast across the plains in negative tilt fashion. Strong surface cyclogenesis occurred with the surface low
                        deepening from 985mb around midday May 4th to 974 mb by midday May 5th. Several strong tornadoes occurred between
                        02 GMT and 06 GMT, with a tornado at 330 am. A blizzard began in eastern Colorado around 3 GMT May 5 and spread
                        north-northeast into western Nebraska, South Dakota and North Dakota by May 5th. A windstorm occurred across northern
                        Missouri and Iowa on May 5th.

Detailed Synoptic Sequence of Events

                        The 15 UTC May 4 500mb chart showed a deep trough over the southwest US with strong flow across the plains states.
                        The 700mb chart showed a tight baroclinic zone from NM/AZ into Colorado and Wyoming. The 700mb 0C line stretched
                        from western NM to east of Denver to west of Rapid City.

                        At 1930 UTC, a surface low(985mb) was located in southern CO with a warm front east to southern Kansas. Keep in mind
                        that sea level pressure values can be suspect at higher elevations. For example, the SLP was way out of whack at places like
                        Alamosa, CO, Limon, CO and Colorado Springs for years. A cold front stretched  south from the low to west of Santa Fe
                        and east of Rodeo, NM. The surface dryline extended from just west of Midland, TX to just east of Lubbock to east of Gage,
                        OK to just east of Hutchinson, KS. The cold front was charging east around 45 to 53 mph.

                       At 2230 UTC a strong "pacific" cold front was charging east into eastern NM. The surface dryline stretched from east of
                        Dodge City to just east of Clarendon, TX to east of Midland, TX. The northern end of the dryline was clearly retreating
                        westward. The minimum pressure in the sfc low was about 984 ot 985 mb which was relatively unchanged from 1930
                        UTC. The cold front was charging east at 45 to 53 mph. This speed remained almost constant through the afternoon and
                        evening hours as it moved into the Texas Panhandle and western Oklahoma. The warm front was moving north over
                        central and western Kansas as can be seen in the surface observations from Dodge City, Garden City and Salina.

                        By 0130 UTC the minimum value of surface pressure was about 983 to 984mb in far southwest Kansas. The surface
                        pacific cold front stretched south from the low to just east of Amarillo to just west of Lubbock to east of Wink, TX. The
                        dryline was still retreating westward and stretched from west of Dodge City to west of Perryton, TX to just east of Lubbock.
                        Surface observations from Gage, Dodge City and Clarendon, TX show the retreating dryline. Note that the cold front
                        had almost overtaken the dryline in west Texas and the Texas panhandle. Snow was falling across Wyoming and the front
                        range of Colorado.

                         The 0330 UTC surface chart showed the surface low north of Garden City(983mb) with the cold front extending south
                         to Gage and Childress and to near Sanderson, TX. Snow was falling across the Nebraska panhandle, Wyoming and
                         central and northeast Colorado. The warm front progressed as far north as Russell by this time.

                        The 03 UTC 500mb chart showed an intense shortwave trough located over the southern Rockies, with a lowest 500mb height
                        of 542dm over Colorado. The 700mb chart showed the strong baroclinic zone marching eastward into the Texas panhandle
                        behind the pacific cold front. 700mb temps were very high by early May standards with +13C at Oklahoma City and +16 at
                        Fort Worth.

                        The central value of the of the surface low did not change from 2230 UTC to 0330 UTC, but cyclogenesis may still been
                        occurring during this time. When lows initially move away from the western high plains, the downslope weakens and this
                        tends to result in higher surface pressures. So we had 2 competing factors going on during the evening hours. The loss of
                        downslope flow tended to result in higher surface pressures while cyclogenesis tended to lower the surface pressures.
                        However, the central value of the low started dropping markedly after 0330 UTC. This is because the lack of downslope
                      had already been accounted for so that cyclogenesis actually resulted in lower surface pressures. In other words, lows
                        on the western high plains tend to be "artificially" low--not completely due to the dynamics. Downslope flow leads to
                        adiabatic warming which leads to lower surface pressures. Also note that even when the surface low was pulling away
                      from the rockpile, a weak low remained up against the higher terrain of southeast Colorado.

                        At 0630 UTC the surface low was down to 982 or 983mb and located just southwest of Russell, KS. Moderate to
                        heavy snow and blowing snow were occurring as far south as La Junta, CO.

                        At 0830 UTC the surface low was down to about 981 mb with a trailing pacific cold front into central OK and
                        north Texas. Blizzard conditions had spread as far east as Goodland, KS. But it was still raining at North Platte
                        and Hayes Center, NE. The rain-snow line extended almost due north-south from Philip, SD to east of Goodland, KS.

                        At 1330 UTC the surface chart showed an occluded low(976mb) between Grand Island and Lincoln, NE. Blizzard or
                        near blizzard conditions were occurring as far east as Kearny, NE, as far north as Mobridge, SD and as far west as
                        Sidney, NE and Goodland, KS.


                        The 15 UTC May 5 500mb chart showed an intense 500mb shortwave trough ejecting ne/nne into the central and
                        northern plains. The 500mb height at Omaha had dropped from 565dm to 533dm in 12 hours. Note the strong
                        500mb height gradient across Iowa.

                        By 1830 UTC the surface low had deepened to 974mb just to the west of Sioux Falls, SD. Snow was falling as far
                        south of as Burwell, NE(sw of the surface low) and as far north as Minot, ND. Note the very high winds across Iowa.

Duststorm

                        A duststorm occurred during the afternoon and evening hours across eastern NM and west Texas. High winds from
                        40 to 70 mph occurred well behind the dryline and ahead of the pacific cold front, with visibilities as low as 1/4 mile.
                        Surface observations from Dalhart, Tucumcari and Roswell demonstrate this. The worst part of the duststorm, as is typical,
                        occurred behind a strong north-south oriented pacific cold front. Surface observations for several sites across the
                        region show visibilities from a half of a mile to near zero. Surface winds were as high as 50 to 60 mph. West winds gusted
                        to 120 mph at Guadalupe Pass, TX.

Tornadoes

                        Several significant tornadoes occurred across parts of Oklahoma, Texas, and Kansas. The first tornado of the
                        evening developed in the far eastern Texas Panhandle and moved to 3 miles northwest of Shattuck. The time of
                        this tornado is very suspicious. I think the time on this tornado is off by 2 hours. The time given in "Significant Tornadoes"
                        by Tom Grazulis is 630 pm and the observations at Gage, OK(just east of the tornado) did not show lightning until 842 pm.
                        Of course it is possible to have a tornado without lightning as the storm approaches, but not likely. So it is not clear which
                        tornado occurred first on this evening, the Shattuck tornado or the Perryton tornado.

                         A tornado cut a half-block path through Perryton, TX around 830 pm. Several homes and a large warehouse were
                        destroyed. I am trying to gather more details about this strong tornado from local newspapers. "Significant Tornadoes"
                        shows 1 fatality and 13 injuries with this tornado. The storm that hit Perryton obviously developed southwest or
                        south-southwest of town. Given that the dryline retreated past Perryton around 730 pm and that the cold front
                        overtook Perryton around 830 pm(around the time of the tornado), I am speculating that this tornadic storm
                        developed as the cold front encountered the dryline southwest of Perryton around 8 pm.

At 930 pm a tornado moved NNE from 3 miles west to 6 miles north of Carter in Beckham county, OK. 20 farms were
hit. One home was destroyed on highway 34.

At 945 pm a tornado hit Fort Supply, OK which is 12 miles NW of Woodward. 12 homes, 4 businesses and a warehouse
were torn apart. One home was reportedly leveled.

                        At 1110 pm a tornado moved NNE from Zook, Kansas in Pawnee county to 5 miles NW of Great Bend. The path of this
                        tornado is shown here. I estimated that the tornado moved North-25 deg E. 11 homes were destroyed near Zook with
                        near F5 damage to 2 homes. 66 of the 100 units at Barton Courts(northwest of Great Bend) were rendered unlivable.
                        Rural property damage was greatest at "Ray" in eastern Pawnee county. Prior to this tornado, thunderstorms moved across
                      Russell based on the original surface observations from Russell. Gusty north winds and falling temperatures occurred at
                        Russell between 9 pm and 10 pm. Thus, it is likely that outflow from storms north of Great Bend in the evening left out a
                        boundary(front or outflow boundary). Storms either developed along this boundary and became quickly tornadic or storms
                        developed when the front met the dryline and eventually encountered the surface boundary (becoming tornadic). The latter
                        scenario seems more likely in my opinion. A map showing the position of the front/outflow boundary that may have helped
                        cause this violent tornado can be found here.

                        At 330 am, a tornado moved NNE from 2 miles N of Holton, KS and passed 2 N of Whiting and 3 S of Hiawatha.
                        2 homes and 13 barns were destroyed. Nine homes and 8 barns were damaged north of Whiting with all 5 injuries
                        occurring in this area.

                        The surface based CAPE for the evening tornadoes was very high. Using a T/TD af 76F/65F at Perryton(886mb)
                        and 700,500,400,300 and 200 mb temps of 10C,-12C, -23C, -38C and -56Cyields 4000 j/kg CAPE and lifted
                        index of -11.

These storms undoutbedly moved very rapidly to the NNE or NE at perhaps 50 to 60 mph.

Blizzard

                        Blizzard to near blizzard conditions occurred from eastern Colorado, across far northwest Kansas and into much
                        of central and western Nebraska, south Dakota and North Dakota. Surface observations showing the heavy
                        snow at several locations can be found here. A map of snowfall can be found here. At least a 3 hour burst of
                        moderate to heavy snow occurred at Kearny, NE(elev. 2200ft), with accumulating snow at Lexington, NE(2400ft). This
                        is a rare occurrence this far south at such low elevations. North Platte received 6 inches of snowfall with a max
                        snow depth of 4.5" due to melting. 5 inches occurred at Hayes Center, NE. Goodland reported 4 inches of snow.
                        The heaviest snow amounts occurred in Cherry, Brown and Cheyenne counties in Nebraska, northward into
                        central SD and southern ND. Another snowstorm occurred on May 6 but totals from this storm are not included.
                        Some areas of SD/ND had 17 to 22 inches of snow from both of these storms combined.

Windstorm


                        A windstorm occurred across much of Iowa on May 5. Surface observations showed wind gusts as high as 100 mph
                        at Ames, 90 mph at Des Moines, and 87 mph at Mason City. Other sites did not record peak wind gusts but recorded
                        winds of 78 mph at Iowa City, 67 mph at Lamoni and 77 mph at Waterloo. Blowing dust reduced visibilities to 1/2 mile
                       at Lamoni, 2 miles at Iowa City and 2 miles at Mason City.

I called the Des Moines Register and they were able to read me an article from the paper concerning this windstorm. Here
are some details:

                        Prelim damage total was still being assessed and was in the millions
                      $200,000 damage to Iowa Power and light system in DSM.
                        Trees fell and smashed cars
                        Windows blown out
                        many power lines down.
                        flood lights blown over at the Baseball park.
                        roofs blown off
                        lots of trees down
                        chimney blown off
                        drake univ billboard blown down
                        a man electrocuted in des moines
                        5th grader killed when Cupola?? of a building fell on him
                        33 yr old Madrid Grocer struck and killed by falling light tower at the baseball field