WKU Meteorology

We woke up in Pampa, TX with a difficult forecast ahead of us. Below is a surface composite from the morning. Isodrosotherms (green) showed rich moisture nosing into the central plains with dewpoints reaching into the upper 50’s in the Texas Panhandle. 500mb jet (yellow) showed southwest flow and was forecast around 40kts, which would provide ample upper-level support. The 850mb jet (orange) was forecast to be nearing 30kts out of the southern and increasing into the evening over the Texas Panhandle. The purple oval indicates where the greatest helicity was expected and the purple line in western New Mexico showed where the dryline was. Due to a diffuse dryline and lack of a frontal lifting system, we decided it best to monitor outflow boundaries from the morning precipitation. A target of Elkhart, KS was used to monitor these boundaries but decided it best to stop in Guymon, OK.

Composite Surface Analysis

Once we arrived in Guymon around 11 AM, we noticed an outflow boundary interacting with the dryline, leading to the initation of thunderstorms over southeastern Colorado. West of Campo, CO we stumbled upon a tarantula as well as a great display of mammatus clouds.

Big, Creepy Spider

Mammatus Clouds

We then departed for the southern end of a line segment to chase a storm near Dalhart, TX. As we approached the storm, we saw a great whale’s mouth cloud formation, as well as a shelf cloud. This storm produced a brief wall cloud, as well as a photogenic, sunlit hail shaft.

Whale’s Mouth

Shelf Cloud

Backlit Wall Cloud

Sun Rays Peaking Through Clouds

Hail Shaft

Dissipating Hail Shaft

We are staying the night in Dumas, TX and will likely be chasing in western Texas once again on Friday.

Today began bright and early in Gainesville, Texas. After a morning forecast discussion, we decided to head toward the town of Graham, TX. This would place us in a good area to await initiation of the storms that afternoon. For the first time in several days, the upper and lower atmosphere were beginning to show a more favorable environtment for severe weather. The 250mb winds (blue arrow) shifted from southerly to westerly as did the 500mb winds. The Low Level Jet (yellow arrow) also returned to played a helpful role today with 30 knot winds out of the southeast drawing moisture out of the gulf. This brought in greater than 60°F dewpoints (green line) over much of eastern Texas providing significant moisture for the region.  The greatest region of instability is highlighted in the orange half circle. This would eventually provide the necessary lift to produce the storms. The red box shows the target area of Graham, TX just to the east of Abilene.

After roughly a two hour drive from Gainesville to just south of Graham, we stopped for lunch at Subway and headed to a local park to eat and watch the sky for storms beginning to pop up. It was not long before we headed back to the gas station to Rain-X the windows and get gas in preperation for the chase. Around 2:30 pm we began to notice one cell to the north around Breckenridge.

For the first time on the trip, we were able to watch the this storm develope while we sat in a hotel parking lot. We saw it initiate out the front window of the van and were able to keep an eye on it on the radar until the decision was made to follow this storm. Very quickly after the storm formed, a severe thuderstorm warning was placed on it, quickly followed by a tornado warning. We chased this cell from just north east of Breckenridge, all the way to Stephenville for the night.

Due to the capping that did not erode until late in the afternoon, this cell was able to form and stay in a clean environment for longer before forming a line. Through much of the day, there was a lack of speed shear in the environment.  This caused the cell to be a high precipitation cell with a very closesly located updraft and downdraft. A tornado was confirmed by chaser, but we could not see it due to the curtains of rain surrounding the storm for most of the day.

Photo Courtesy of DJ Lipps

When we arrived in Stephenville for the night, the storm had lost its severe and tornado warnings. We unloaded our things and allowed the much weakend storm to pass over us in the van. Due to the substantial energy in the storm, lightning was striking well into the night and could be seen even when the storm was long gone.

Today we woke up in Altus, Oklahoma with the intentions of traveling south for the day’s chase. As seen in the composite map below, there was sufficient support for a good chase day. 500mb wind flow (blue arrow) was out of the southwest with a jet streak moving northeastward through Texas. 850mb wind flow (orange arrow) was out of the southeast with a low-level jet max also located in mid Texas. Plenty of moisture was located in Texas today as seen by the 60 degree dewpoint line (in green) extending as far west as the Abilene area. Likewise, the dry line (brown dash) was located just to the west of 60 degree dewpoints, providing a nice moisture gradient. The area of greatest of instability (dark blue circle) was located a tad east of Abilene and the area of greatest helicity (pink circle) was located to the south. With these factors in mind and better chasing terrain west of Dallas/Fort Worth, the Abilene area was chosen as the target city (red box). Simulated reflectivity models suggested a clustering of storms moving through this area around noon and SPC issued a moderate risk for east central Texas with Abilene in the enhanced risk area.

Storms had already started to fire early in the morning and we were unable to make the 2.5 hour drive from Altus to Abilene in time to intercept the cluster of storms. Instead, we drove southeast to position ourselves in front of the line of storms. On the way, we saw great mammatus formation on the front edge of the storm.

Tori Hampton

We stopped in Weatherford, TX to grab a quick lunch and proceeded south. The linear system started to break apart and multiple tornado vortex signatures were detected, one of which we followed to the outskirts of Granbury. We were unable to see any funnel cloud formation, however we did get some amazing pictures of the shelf cloud as it was moving toward us.

Tori Hampton

We stopped following the storms as they moved northeast into non-ideal chasing terrain. We decided to call it a day and head north to Gainesville, TX to stay the night.

We began the day in Garden City, Kansas after chasing in southeastern Colorado. The surface analysis shows observations from the morning just before we left to chase and also model outputs for convection parameters. The 250mb jet(yellow arrow) is coming out of the south west, the 500mb jet(light green arrow) and 850mb jet(dark green) are primarily out of the south. The analysis also shows the local vorticity max(red circle) over south central Oklahoma/northern Texas. This overlapped with the local helicity max(light green circle) which, with a little help from the dry line(light orange dashed line) could potentially cause enough lift to produce storms over the target area(red box). Dew points started off in the mid to upper 50s and lower 60s across the area of interest. With the upper level winds lacking the essential profile needed for good sheering, the dry line was our key factor for the target.

We departed Garden City, KS a little before 10am and were heading south towards Canadian, TX. We stopped in Hooker, OK where the group grabbed a bite to eat at the local Subway and gassed up. After heading more south towards the target we decided to stop and admire a wind farm outside of Borger, TX.

David Lipps Jr.

After about 20mins of observing them, we took off and continued to our target. Continuing the drive, we past a local landmark known as Palo Duro Canyon. We stopped in Silverton, TX to wait for the storms to initiate along the dry line. After tossing the football around for a bit and noticing nothing was really initiating we drifted more south to Turkey, TX. Here we sat for primarily the rest of the day waiting on initiation but due to lack of lift from the dry line, nothing was firing up. Blue skies dominated the area we were in other than a few passing clouds. Around 7pm, we made the decision that due to the lack of  lift we were going to head to our hotel located in Altus, OK, 110 miles away. We arrived at the hotel at 8:30pm.

Today we started our chase day in Limon, CO after chasing in Southeast Colorado the day before. The surface analysis below displays observations of the mornings conditions before the chase, as well as the parameters that model output was giving for the afternoon. The Surface analysis displays current morning dew points (green lines), 250 mb flow (blue arrow), 850 mb flow (yellow arrow),  greatest area of instability (purple box), greatest quantity of vertical velocity (X), and our target itself, which was Lamar, CO (red box). 250 mb winds were setting stage for a greater amount of upper level support in our area which there has been a lack if in previous forecast days. With the combination of the 250 mb flow and the 850 mb flow, the directional change in height of the winds gave the atmosphere a sheered profile in Southeastern Colorado. The dew points reached the mid 50 degree marks which is enough moisture in the high plains to produce severe thunderstorms. The greatest amounts of instability and vertical velocity were also located in the Southeastern Colorado region. With the parameters mentioned above, and outlying boundaries left from morning convection, Lamar, CO was chosen as our target for the day.

After sticking around the hotel in Limon, the group ate lunch on their own and left towards Lamar, CO around noon. Due to the lack of a capped environment, storm initiation was already occurring to the southwest of Limon. The group traveled south and closed in on a tornado warned storm just southwest of Arlington, CO. This storm had several reported funnels descend from a wall cloud, but none officially reached the ground.

Josh Durkee

After the many instances of poor road networks the group decided to keep proceeding eastward ahead of the line of storms and get fuel in Lamar. After fueling up, we went south and let the line of storms hit our van, where we experienced a gust front, heavy rain and pea sized hail. After letting the line pass in front of us, the group followed the storm east and noticed smaller cells forming on the southern end of the line of storms. We stopped just west of Las Animas, CO and viewed the storm as well as threw around the football.

Melissa Moore

Melissa Moore

After watching the storms just before sunset, we drove about 120 miles east to our hotel for the night in Garden City, KS. But before going to bed, we enjoyed a fabulous supper at Las Margaritas, a Mexican restaurant in Garden City.

Day 4 of the trip began in Guymon, OK after traveling from Alpine, TX the day before. Guymon put us about 6 hours away from the potential target areas.  The surface analysis below shows isodrosotherms (green), 500mb flow (yellow), 850mb flow (orange), greatest area of helicity (purple), greatest area of instability (blue), 500mb vortmax (black x), and forecasted target area in red. 500mb winds out of the southwest were forecast to assist in upper level support and this combined with 850mb winds, out of the southeast, generated part of shearing wind profile over eastern Colorado. Dew point temperatures reached only into the fifties, but due to high elevation, less moisture is necessary for severe weather development. The low dewpoints also assisted in keeping the storms LP (low precipitation). The greatest area of instability was in SE Colorado and the greatest helicity values were in eastern Colorado. These parameters along with the upsloping flow and mesoscale considerations along the front range of the Rockies resulted in Limon, CO being our target area.

After eating lunch at Oscar’s in Limon, CO, we drove south to Punkin Center to find a view for storm initiation (below). From this location we viewed multiple cells fire and dissipate after a few minutes. However, the blue skies and sunshine were a nice break from the foggy mornings of the past few days. Storms struggled to maintain so after a couple of hours we decided to head to Hugo, CO. From here we were able to monitor two potential areas of storm development. Both the HRRR and NAM-4k painted development near Limon around 21z. This didn’t pan out and we ended up playing a game of football pig at a local park.

Colton Lindsey

Around 6pm a cell was able to develop slight rotation so we decided to ditch the park and intercept it. Although the storm was not impressive on radar, it eventually produced some decent supercell structure. While chasing the storm we were able to stop and capture great images of it’s lifecycle.

Colton Lindsey

The radar image below shows our location relative to the picture above.

Radar screenshot by John Thomas

Josh Durkee

Colton Lindsey

Jacob Wilkins

After this supercell began to dissipate we decided to leave it and head east to observe other cells. One of these being a low precipitation supercell, pictured below.

Jacob Wilkins

We attempted to grab a few lightning photos at dusk but strikes were sparse so we decided to head back to our hotel in Limon, CO to prepare for tomorrow.

After a successful first day of chasing, during which we analyzed and documented one of two supercells in the panhandle of Texas, we stayed the night in Childress, TX to analyze data for Wednesday. We woke up Wednesday morning and determined we needed to move further south where a cold front was moving south, intersecting a dryline in southwest Texas. Below is the composite map based on 12z observations.

May 20, 2015 12z Composite Map

Flow aloft remained rather weak as mid level ridging was noted across the entire region. However, the cold front and dryline intersection was located in a moist and unstable atmosphere conducive for robust updrafts in thunderstorms. While the magnitude of the shear was not great, the directional wind shear in the low levels was conducive for multicell and supercell development.

Cells trying to form over Fort Stockton, TX

Click the image below to view a time lapse of cells trying to form around Fort Stockton, TX between 3:15 PM and 4:10 PM. 

As we moved toward the region, cells began developing along the cold front, just as forecast. However, these cells quickly became elevated as the cold front cut underneath them. Thus, we headed further south toward Fort Stockton, TX to wait for initiation closer to the dryline and cold front intersection point. Shortly after 4 PM, we left Fort Stockton, TX in order to get a better view of a small, developing supercell. We got as close as 4 to 5 miles from the storm where the base and inflow were clearly visible.

KMAF Radar valid at 4:47 PM depicts a supercell north of Fort Stockton, TX

Supercell north of Fort Stockton, TX

Supercell north of Fort Stockton, TX

As this storm got closer to our location we moved to the east to get in better position. However, by this time the storm began to grow, as well as lose some structure. A hail core remained stationary over I-10, limiting our progress to the east. Around 6 PM, we decided to drive southeast as the storm began to make a right turn. At this time a wall cloud was reported on the storm, however we could not see it due to precipitation in between us and the storm. We called the chase off shortly after and have staged for Thursday in Alpine, TX, which is at an elevation of around 4,500 feet.

Topography surrounding Alpine, TX

Google Earth image of Alpine, TX

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