September in North Texas took the phrase “Endless Summer” seriously. Unofficially, this September was the second hottest on record. Our day-night average temperature was 84.6 degrees. Only September 2019 was hotter with an average temperature of 85.5. DFW set a new record of 8 days at or above 100 degrees last month. The hottest temperature during the month was 110 degrees on Sept. 8. During the entire summer, we endured 55 days at or above 100 degrees, which was 4th behind the summers of 2011, 1980 and 1998.
Rainfall, as usual, was sparse. Two-tenths of an inch fell on Sept. 3rd, while .08” fell over the 11th, 12th, and 14th of the month. Another .29” fell on the 19th, resulting in a monthly total of .83”, far short of our normal September rainfall of 2.56”. That’s bad enough, but for the first nine months of the year DFW has recorded just 15.66” of rain, compared to our climatological norm of 27 inches of rain by now. The U.S. Drought Monitor paints North Texas in “extreme” drought, next to the most serious category of “exceptional” drought.
North Texas was trapped under a massive high-pressure ridge during most of August and September. When such a weather system moves in, the high pressure repels and deflects ordinary west-to-east storm systems far to the north. High pressure also forces cold air aloft down toward the surface, warming 3 degrees for every thousand feet it descends. It’s a powerful combination that perpetuates heat and drought until the seasonal shift in jet stream winds can finally overcome it.
Although rainfall was disappointing, North Texas had several outbreaks of severe weather. One bout of severe weather produced 1” hail in parts of Denton County, quarter-inch hail elsewhere, 60-mph winds at Robson Ranch and scattered wind damage across much of North Texas. Another round dropped golf ball hail on Krum.
Looking ahead, the developing El Nino in the Pacific is finally nearing the point where it can affect our weather. A deep trough in the northern jet stream and the increasingly moist subtropical pacific jet stream might combine to produce some significant rains for North Texas this month. In Texas, it’s not unusual for a drought to be broken by a flood. We’ve seen over 13” of rain during October and that’s just about how far behind we are on rainfall. Let’s hope we don’t make up the rainfall deficit all at once. Meanwhile, fire danger is still the most serious hazard in the here-and-now.
