July 20th, 2023 Severe Thunderstorm Outbreak

Pikes Peak tornado, destructive hail, and destructive winds across the eastern mountains and eastern plains.

National Weather Service - Pueblo, Colorado

July 27, 2023

On July 20th, 2023, southern Colorado experienced a high impact severe weather event that led to 1 confirmed tornado on the west side of Pikes Peak in Teller County. In addition, many reports of large destructive hail and damaging winds developed over the adjacent and eastern plains of southern Colorado. The following ArcGIS StoryMap will cover the meteorology of the event.

The Large Scale Set-up and General Outlook

To start this story, we'll talk about the large scale set-up then bring it down to the small scale and talk about contributing factor observed throughout the event.

6:00AM July 20th, 2023

300hPa - A closed high was located over central New Mexico and a broad trough was located over the Midwest. In this synoptic setup, high pressure overhead allowed for efficient diurnal wind fluctuations, which provided the lower Arkansas River Valley with east to southeasterly winds at the surface, an orientation favorable for upslope flow up the Arkansas River Valley and the eastern mountains.

6:00AM July 20th, 2023

700hPa - A distinct shortwave trough was found over northwestern Colorado, providing lift to initiate thunderstorms over the mountains in the early afternoon. Another notable feature was a closed low over Lake Superior and its associated trough which extended southwesterly towards Nebraska and Kansas.

6:00AM July 20th, 2023

Surface: A notable surface high was located over Wyoming and Nebraska. A cold front was located over Nebraska using the surface winds. Some manipulation of temperatures was noted due to fog development over Kansas at this time, so the best indicator for front location was its location along the surface high and the winds.

In Colorado, the presence of moisture can make or break a severe weather day. That was the case in this event, with the following dewpoint temperatures observed at 6:00AM: Pueblo - 60F, La Junta - 64F, and Lamar - 64F. Some notable upper 60s dewpoints were located in western Kansas.

The Storm Prediction Center in Norman, Oklahoma issued an Enhanced Risk for severe weather over the far eastern plains, a Slight Risk for the I-25 Corridor, and a Marginal Risk for portions of our eastern Mountains.

Severe hail probabilities were rated at 15% with a hatched area indicating the potential for destructive hail

Severe wind probabilities were rated at 30% with a hatched area indicating the potential for destructive winds

The Pikes Peak Tornado

So what started the thunderstorms over Teller County that eventually led to a confirmed tornado on the west side of Pikes Peak? The animated GIF on the right illustrates surface moisture convergence in the blue contours which shows that there was moisture at the surface. There is a distinct trend of moisture heading from the northeastern plains of Colorado towards Park County where thunderstorms developed. There seem to be two factors at play for the initial convection initiation:

1) Early morning thunderstorms produced an outflow boundary forcing moist air towards Teller County

Thunderstorms in northeastern Colorado at 8am MDT on July 20, 2023

2) A shortwave trough passed overhead aiding in convection initiation (as seen in previous section)

At roughly 1:30PM on July 20th, 2023, thunderstorms developed over Park County. The thunderstorm quickly developed rotation. The thunderstorm entered Teller County where it only continued to intensify.

When thunderstorms entered Teller County they entered an atmosphere with roughly 2000 J/kg of surface based CAPE, between 40 and 50kts of 0-6km bulk shear, and the hodographs at 2PM indicated a favorable shear profile for right moving supercells.

Surface Based CAPE and Surface Based CIN at 2PM MDT on July 20th, 2023

RAP Derived SkewT Diagrams at 2PM MDT on July 20th, 2023

0-6km Bulk Shear at 2PM on July 20th, 2023

RAP Derived Hodographs at 2PM MDT on July 20th, 2023

At 1:58PM the NWS in Pueblo issued a Tornado Warning for the tornadic supercell. The image on the right illustrates what NWS Pueblo warning forecasters observed when issuing the Tornado Warning from KFTG (NWS Boulder's radar). The velocity couplet on the right side of the image indicated strong rotation at the lowest levels. The reflectivity pattern on the left side of the image does show a hook echo. Below is an incredible image of what the supercell looked like from near the peak of Pikes Peak. Image courtesy of Jessica Kellogg, a realtor in Colorado.

Here is an image taken from Jessica Kellogg, a realtor in Colorado, who was driving up the Pikes Peak Highway during the event.

Image from Rob Hoff, taken from I-25 and Cimarron in Colorado Springs at 2:04PM

The NWS in Pueblo worked with Teller County Emergency Management and the management team of Pikes Peak America's Mountain to conduct a damage survey on 7/21/23. The NWS determined the tornado was an EF-1 tornado with estimated peak wind speeds of 108 MPH. The tornado was on the ground for roughly 8 minutes and had a max width of 75 yards.

Here are some images from the damage survey

Hail over Colorado Springs

The supercell then tracked over the city of Colorado Springs. The largest hail stone reported was 2.5" by a trained spotter at 2:25PM just north of downtown Colorado Springs.

Hail pictures were provided from Matt Manillo (Center) and Rob Hoff (Right).

Fremont County Hail

A similar environment existed over Fremont County, which created around 2 inch hail near Canon City. The photo below was provided from Dave and Jackie Jones

Base Reflectivity on the left side and 2" hail that the storms produced. Hail image provided by Dave and Jackie Jones.

The Eastern Plains

4PM - 8PM Two distinct complexes of thunderstorms interacted with each other over the eastern plains during the afternoon. Thunderstorms developed over the southern Sangre de Cristo Mountains traveled from the southwest to the northeast and the complex of thunderstorms that developed over Pikes Peak (previously mentioned) traveled from the northwest to southeast. The two complexes merged over Crowley County and produced destructive hail and damaging winds. The NWS in Pueblo issued a Tornado Warning for the area north of Cheraw, Colorado, but there was no confirmation of the tornado.

The environment was primed for the continuation of severe weather as the thunderstorms traveled to the southeast. Below are some images of the environment at around 5PM, when thunderstorms developed over Crowley, Otero, Las Animas, and Bent Counties. The following analysis (see below) will be from the left to right. The surface based CAPE values had around 2000 to 3000 J/kg with around 75 J/kg of CIN (first image), the 0-6km bulk shear values (second image) indicated values around 50 to 55kts, the Skew-T diagrams (3rd image) show steep lapse rates aloft due to dry air aloft allowing the air to efficiently cool with altitude, the hodograph (4th image) show a curved hodograph favoring right moving supercells (this is a visualization of wind direction from the second image), and lastly the supercell composite parameter (5th slide) of roughly 16, which is quite high.

From left to right: Surface based CAPE and CIN, 0-6 km effective bulk shear, RAP derived Skew-T diagrams, RAP derived Hodographs, and supercell composite parameter.

Large hail was once again observed in Crowley County and over Manzanola, Colorado. Photos Courtesy of Chris Incinias and Shurrel Ramsey.

Base reflectivity from 4:54PM to 5:21PM (left), large hail in Fowler, Colorado (photo courtesy of Shurrel Ramsey), and large hail in Manzanola, Colorado (photo courtesy of Chris Encinias).

Baca County

8PM Onward: The intensity of thunderstorms ramped up as the the complex of thunderstorms began to enter into Baca County. There were three distinct supercells that formed in a line as they were propagating to the southeast. Extensive damage was recorded due to very strong rear flank downdraft winds. There were tornado warnings issued for the supercells, but after conducting a damage survey, it was conclusive that the damage was due to straight-line winds ranging from 80 to 100 MPH. There was 3,000 J/kg of surface based CAPE, 55 to 60kts of 0-6km effective bulk shear, a curved hodograph favoring right moving supercells, and the supercell composite parameter reached around 20. When the thunderstorms entered the previously described environment, they were forced to organize themselves into a supercellular manor again.

Base Reflectivity and Storm Relative Motions Velocity

From right to left: Surface based CAPE, 0-6km Effective Bulk Shear, RAP derived Hodographs, and Supercell Composite Parameter.

The NWS in Pueblo worked with Baca County Emergency Management to conduct a damage survey on July 22nd, 2023. The images below show the results from the survey, including a damage swath from the rear flank downdraft damage from wind gusts ranging from 80 to 100 MPH.

Images from the damage survey conducted on July 22nd, 2023

Service from NWS Pueblo

The NWS provided multiple briefings to our partners via Google Meet the day before the event (7/19/23) and the day of the event (7/20/23). There were multiple updates via social media, which can be seen below.