Thunderstorm Impacts on Air Traffic Control
Across the NAS, thunderstorms impact aviation considerably resulting in diversions, delays, and cancellations. These are some examples.
The basic breakdown of air traffic control across the NAS (National Airspace System). The National Weather Service - CWSUs (Center Weather Service Units) are fully embedded within the ARTCC and provide day-to-day weather support to ATC and Traffic Managers. CWSUs also provide weather support to TRACONs and Towers within the Center's airspace.
The TCF is a thunderstorm forecast coordinated by AWC, CWSUs, FAA Command Center, and Airlines. Thunderstorm forecasting for aviation can be extremely challenging and causes significant impacts on aviation each convective season. The primary goal of this research is to provide NWS meteorologists with a greater understanding of these thunderstorm impacts and how to better serve the aviation community.
The NAS broken up by the FAA ARTCCs and their respective airspace sizes in square miles. There are 21 ARTCC (and CWSUs) that cover the entire NAS.
ZKC airspace is broken up into 6 areas and each area is sectorized by altitude; Low, High, and Super High. Low Altitude covers aircraft below 24,000 feet while High and Super High altitudes cover aircraft above 24,000 feet and 37,000 feet respectively. There are times when air traffic is slow and sectors can be combined, which is typical for the High and Super High sectors.
A detailed breakdown of ZKC Airspace that includes the TRACONs and Towers within the Center's airspace.
More on sectors within ZKC airspace. As mentioned above, each area is divided into sectors from low, high, and super high. Subsequently, these sectors are broken into smaller sectors and given a specific number. In the two case studies, March 5th and April 12th, 2022, the PDARS data from Praire sectors 06 and 20; Flint Hills sectors 02 and 27; and Ozark sectors 28 and 30 will be analyzed.
March 5, 2022: Severe Weather Outbreak and Impacts on ZKC Airspace
Storm Prediction Center Day 1 Severe Weather Outlook: 1630 UTC Update
On March 5, 2022, a major severe weather outbreak occurred across the Midwest. Severe storms broke out over Iowa resulting in multiple tornadoes during the afternoon hours. By the evening, a line of storms formed and extended as far south as northeast Oklahoma. The line of storms caused a significant impact on air traffic across the central portion of the country with multiple routes being diverted south of the line.
Radar loop from March 5, 2022. Loop begins at 2 PM CST and end at 9 PM CST. The only difference between the animations is the loop on the left is zoomed into central ZKC airspace to show a bit more detail.
PDARS for ZKC Ozark Area - Sector 28. This is an aircraft count that is sparse out in 15-minute bins for Sector 28. The MAP or Monitor Alert Parameter is the threshold for a specific sector designed to help FAA ATC and Traffic Management in organizing air traffic throughout the day. For planned routes, it helps them foresee potential busy sectors and thus could re-route, slow traffic, or change attitudes to help mitigate congestion in the air.
PDARS for ZKC Ozark Area - Sector 28. Although this data shows it only reached or just barely topped the MAP number, but remained steadily busy for a couple of hours. With numbers close to the MAP, it still remains a concern as things could change in an instant. For instance, further thunderstorm development or possibly an in-flight emergency may occur and tip these numbers above the MAP. When thunderstorms cause deviations, such as the case from March 5th, it overloads a sector with unplanned aircraft.
PDARS for ZKC Flint Hills Area - Sector 02. This sector was overloaded on several occasions throughout the evening.
The above image shows where Ozark Sector 28 is located and the aircraft captured at 00:48 UTC. The chart shows the comparison between Sectro 28 and Sector 32. One could guess where the thunderstorms were occurring based on the aircraft count. There was even a roughly 30-minute period in Rivers Sector 32 where there were aircraft above 24,000 feet.
Showing the location of Rivers Sector 32 and the aircraft at 00:48 UTC.
The YouTube video above is PDARS data exhibiting aircraft AOA 24,000 feet for traffic throughout ZKC airspace. Data is 1-minute time frames sped up to show the impacts of thunderstorms.
Another way to view PDARS is by looking at the Minutes Exceeding MAP. In Ozark Sector 28, there was almost a 30 minute window where the aircraft count exceeded the MAP for this particular sector. The idea behind the MAP is to insure safety of aircraft and quality of service provided by the ATC.
The TCF for March 5, 2022. TCF forecast coordination begins March 1st and ends October 31st each year. This was the first large-scale event of the 2022 convective season and certainly started with a bang that season. As you can see, the TCF could have been stretched further south to cover the line of storms which is outlined in the black box. The TCF could also have included greater coverage as well as higher tops. Note: I (Kenny Podrazik) was part of this TCF coordination and I certainly missed the "ball" on this forecast. These are the 4-hour and 8-hour forecasts and not shown is the 6-hour. Assessing thunderstorm forecast verification is an amazing learning tool and is a huge part of growing as a meteorologist. The TCF is widely used by the FAA for planning routes throughout the NAS each day and our input (as NWS meteorologists) has a large impression on air traffic management.
April 12, 2022 Severe Weather Event and Impacts on ZKC Airspace
SPC Severe Weather Outlook for April 12, 2022
A line of thunderstorms developed along a cold front on April 12, 2022. The line of storms extended from western Iowa southwest through central to eastern portions of Kansas and into northwest Oklahoma.
Learning from the March 5th case, the TCF handled the line of storms very well with the right amount of coverage, timing, and location. Even so, the line of thunderstorms still extended further south than forecast resulting in diversions across southwest Kansas and northwest Oklahoma.
A sharp cold front and area of low pressure developed a line of thunderstorms from southern Minnesota southwest through Kansas into northwest Oklahoma. The caveat to this event was the cluster of thunderstorms over Arkansas which caused diversions northward into ZKC airspace. This resulted in a funnel of aircraft through Missouri and southeast Kansas/northeast Oklahoma.
PDARS for Prairie Area Sector 06 shows they were extremely busy for several hours on April 12, 2022.
Low, High, and Super High Sector breakdown for Prairie.
The chart shows PDARS Aircraft Count Comparison for Prairie Sector 20 vs. 06. Sector 20 was extremely busy early in the event before the thunderstorms forced air traffic further south into Sector 06.
Aircraft Count for Flint Hills Sectors 27 and 02.
TCF for April 12, 2022. 4-hour TCF issued 2300 UTC valid at 0300 UTC and the 8-hour issued 1900 UTC valid at 0300 UTC. Very well done forecast, but still with that extra 100 miles of airspace uncovered from TCF, FAA traffic management planned routes through that airspace and thus diversions occurred because the line developed further south.
For additional PDARS examples and thunderstorms, view this playlist: https://youtube.com/playlist?list=PLfrNiXgWJCqyyuQhWCPyC870FOhli2bf5&si=KWQlHvu-u6-qV8hg
StoryMap completed by Kenny Podrazik - National Weather Service - ZKC
