Conclusion
NWS Storm Reports
During severe weather events, the NWS collects observations of damaging wind gusts, large hail, and tornadoes for the Storm Reports Database. In some instances, these observations are captured by automated weather stations. But far more frequently, the observations are reported by law enforcement officers or the general public. This valuable data improves official warnings and helps reduce weather-related injuries.
The storm reports for the 24-hour period ending at 7:00 am CDT (1200 UTC) on Sunday, July 24, 2022 are shown on Figure 25. There were 96 reports of damaging wind gusts (designated by a “W” on Figure 25) across Wisconsin during the three rounds of storms. In addition, there were several reports of large hail (“H”) and a couple of tornadoes (“T”).
Marine Observations
With the exception of the previously discussed 62 knot gust at station CHII2 near Chicago, observed gusts in the southern and central portion of Lake Michigan ranged from 30 to 45 knots. Many boats encountered higher gusts, but the majority of the reports from the fleet were consistent with the data from a variety of NDBC stations in the area.
Observations of high winds in the marine environment are not included in the NWS storm report database. In addition, it is relatively rare for damaging wind gusts to be observed by the automated weather stations found on breakwalls, lighthouses, and offshore platforms. The reasons are twofold and related.
First, the number of stations on each lake is relatively low (Figure 33). For example, there are less than fifty stations monitoring Lake Michigan’s 1,600 miles of shoreline and 22,000 square miles of surface area. Of the fifty stations, only two platforms are located in the offshore environment. Furthermore, the modest number of stations tend to be clustered around major cities which leaves considerable distances between sites in less populated areas.
Second, thunderstorm downdrafts are compact and relatively short-lived. While they may pack a fearsome punch, they typically affect a relatively small area. A great example of the localized nature of a thunderstorm downdraft occurred near Sheboygan, Wisconsin around 7:00 pm CDT (00 UTC) on July 23rd. The NWS received a credible report of a 65 knot gust near the lakefront. Although less than mile from this observation, NDBC station SGNW3 (Sheboygan lighthouse) recorded a gust of only 28.6 knots. The sparse nature of the observation network, combined with the behavior of thunderstorm downdrafts, means that most damaging gusts on the water are not recorded.
Looking Forward to 2023
In total, thunderstorms raged across the central and southern portions of Lake Michigan for more than eleven hours. There were countless reports of damage to sails and rigging from the persistently high winds and several boats were forced to retire. Fortunately, there were no serious injuries. Few sailors could recall such a relentlessly stormy Chicago Mac. It is hard to imagine that the 2023 Chicago Mac could be as stormy as 2022, but we’ll see what Mother Nature has in mind.
