KSNF— September, 2022 ended up being an abnormally dry and hot month in the Four State area.
The weather pattern that was in control throughout the month was perfect for limiting rainfall and producing excessive heat. In the upper levels of the atmosphere, a large ridge of high pressure formed across the central United States. Higher atmospheric pressure leads to descending air, and as the air drops closer to the surface, it warms due to compression from the weight of air at higher levels. Warming air leads to drying air, and it is very difficult to get a rain-producing cloud to form within the realm of a massive upper-level ridge like the one that developed in September.
The problem was exacerbated by a persistent westward extension of the sub-tropical high, also known as the Bermuda high; which typically occupies the eastern third of the nation during the summer months. This high-pressure system expanded west across the entire Gulf of Mexico; the primary source of lower-level moist air that feeds rain-producing storm systems across the central and eastern U.S.
Because of the alignment of this large pressure system, the Gulf was effectively shut down as a moisture source for an extended period as almost all of this rich, tropical moisture was carried out to the west across Southern Texas and the climatologically favored, monsoonal region that we know as “the desert” southwest. Of course, the American monsoon is partly a product of this flow pattern but it would have been beneficial if the sub-tropical high had periodically weakened, which would have allowed at least some moisture to flow northward through eastern Texas and Louisiana. This deeper moisture would have been available for lifting into beneficial, drought-busting rainfall for the four cool fronts that passed through the Four States in September. It was not, and so the month ended up being the fourth driest on record at Joplin and the fifth driest at Chanute.
Large sections deteriorated from the severe drought category at the beginning of September, into extreme and exceptional drought categorization by the end of the month. Evaporation was at a maximum with almost unabated insolation. Intense heating in the dominant Bermuda high-pressure regime produced a heat wave for the meteorological history books. Weather data has been collected for more than a century at Joplin, where high-temperature records fell on three occasions during the latter half of the month.
Chanute also broke long-standing records for the month of September four times when the mercury topped out above 100 degrees. It was definitely an extremely warm month—some would call it hot! Decreasing solar energy as we move forward through Fall is helping us forget about the 2022 heat wave with most pleasant highs in the 60s and lows in the 40s. However, we are still waiting for more frequent, moderate to heavy, rain-producing frontal systems.
We will need more than just a few of these to pull us out of our historic drought.