Case Review: April 19, 2023 Thunderstorm Gap

A gap between thunderstorms complexes was the only opening in the convection to allow air traffic to funnel through safely.

Kenneth Podrazik

Synopsis: On the afternoon of April 19, 2023, a strong low pressure system transitioned across Nebraska and dragged a cold front and dryline through Kansas and Oklahoma. Out ahead of the surface low, a warm front extended eastward through Iowa, practically along the Interstate 80 corridor. This synoptic setup resulted in numerous strong to severe thunderstorms from eastern Nebraska, much of Iowa, southward into central and eastern Kansas and Oklahoma. Storms quickly developed after 4 p.m. CT near the low pressure system and then began to develop along the cold front/dryline after 5 p.m. in central to eastern Kansas. Thunderstorms developed over central Oklahoma late in the afternoon and began to spread/expand northward into far southern Kansas. The combination of a line of storms developing over central Kansas northward and the cluster of storms migrating north out of Oklahoma, caused for a significant squeeze in airspace over southeast Kansas.

At 2:45 p.m. CT, the Storm Prediction Center issued Mesoscale Discussion  #560  for thunderstorm development late in the afternoon.

Animation of the surface analysis from late April 18th to early April 20th.

GOES-East meso-sector Channel 13 Infrared Imagery showing the gap closing quickly in southeast Kansas. This is a 30 minute loop consisting of 1-minute increments from 01:21 UTC to 01:51 UTC (8:21 p.m. CT to 8:51 p.m. CT). The small gap in southeast Kansas closed to roughly 30 miles wide, but storms began to weaken and break apart along the Oklahoma and Kansas border toward the end of the loop. This allowed some extra space for aircraft to funnel through the convection.

LightningCast (60-min probability) provided nice lead time in the gap closing between the two thunderstorm complexes in southern Kansas. The shortest distance between the two storms was roughly 30 miles wide towards the end of this IR loop.

FlightAware images captured an hour apart showing the amount of traffic and the thunderstorm gap closing. An hour apart Image on left is at 7:39 p.m. CT. Image on the right is at 8:39 p.m. CT. Images courtesy of FlightAware.

At 8:41 p.m. CT, image capturing air traffic funneling through the gap in thunderstorms in southeast Kansas. Image courtesy of FlightAware.

Air traffic funneling through the break in the line of thunderstorms. An hour difference 8:29 p.m. CT vs 9:28 p.m. CT and traffic continues to funnel through the break in the storms. Images courtesy of FlightAware.

This video shows PDARS of the air traffic funneling around thunderstorms activity. The Performance Data Analysis and Reporting System (PDARS) is a FAA system that collects flight track data across the NAS. The video begins at 20:00 UTC ending at 06:00 UTC on the 20th and shows 1-minute increments of any air tracks above 23,000 feet that traveled through ZKC ARTCC.

A zoomed in look at the PDARS for sector 2 in southeast Kansas. Even with a fairly large airspace, this video shows the complexity with the air traffic diverting around thunderstorms and shrinking or constricting the airspace.

At 2:45 p.m. CT, the Storm Prediction Center issued Mesoscale Discussion  #560  for thunderstorm development late in the afternoon.

Animation of the surface analysis from late April 18th to early April 20th.

GOES-East meso-sector Channel 13 Infrared Imagery showing the gap closing quickly in southeast Kansas. This is a 30 minute loop consisting of 1-minute increments from 01:21 UTC to 01:51 UTC (8:21 p.m. CT to 8:51 p.m. CT). The small gap in southeast Kansas closed to roughly 30 miles wide, but storms began to weaken and break apart along the Oklahoma and Kansas border toward the end of the loop. This allowed some extra space for aircraft to funnel through the convection.

LightningCast (60-min probability) provided nice lead time in the gap closing between the two thunderstorm complexes in southern Kansas. The shortest distance between the two storms was roughly 30 miles wide towards the end of this IR loop.

FlightAware images captured an hour apart showing the amount of traffic and the thunderstorm gap closing. An hour apart Image on left is at 7:39 p.m. CT. Image on the right is at 8:39 p.m. CT. Images courtesy of FlightAware.

At 8:41 p.m. CT, image capturing air traffic funneling through the gap in thunderstorms in southeast Kansas. Image courtesy of FlightAware.

Air traffic funneling through the break in the line of thunderstorms. An hour difference 8:29 p.m. CT vs 9:28 p.m. CT and traffic continues to funnel through the break in the storms. Images courtesy of FlightAware.