September 2018 may go down as one of the wettest months on record for the state of Texas, following heavy storms late in the month. September’s totals follow record-breaking rainfall in recent years, including storms that brought large-scale flooding over the summer of 2015.
Texas State Climatologist John Nielsen-Gammon said the official records for rainfall for September should be certified within the next few days. Upon first glance, Nielsen-Gammon said, September will likely be the second or third wettest month on record, following May 2015 and August 2017.
“The fact that the wettest three months on record have happened in the past four years is certainly eye-catching,” he said in a phone interview Monday. Nielsen-Gammon did not give details on exactly how much rain fell in September across the state.
This comes three years after the region saw record-breaking rains over the summer of 2015 that lead to Lake Texoma cresting the spillway of the Denison Dam, setting a record for lake height at the same time.
Officials with the National Weather Service’s Fort Worth office said the Sherman co-op weather station received 10.51 inches of rain, with about eight inches falling over a 48-hour period on Sept. 21 and 22. The same storm system inundated the Dallas-Fort Worth area, leading to flooding in some areas and a swell along the Trinity River.
Meteorologist Matt Staley said the same weather station would normally see an average of 3.59 inches of rain for the month.
This put last month as the fifth wettest September on record for the Sherman weather station, with September 1980 taking the top spot with 12.91 inches. When looking at all months, September was the 33rd wettest month on record for the Sherman-Denison area with nearly half the 22 inches that were recorded in Oct. 1981. Jason Dunn, another meteorologist with the NWS, said he could not comment on the statewide totals for the month of September, noting the focus of the Fort Worth office on the North Texas region.
“It does tend to be wetter than the summer months, but not a wet as October,” Staley said.
Staley said the late September rain came as a cold front stalled over North Texas and Southern Oklahoma. This system mixed with moisture-rich air moving north from the Gulf of Mexico. As the system stalled, it was given plenty of opportunity to inundate the region with heavy rainfall, he said.
Staley said the system did not seem to be affected by larger-scale trends generated by El Niño or La Niña, adding that cold fronts are known to enter the region in late August and early September. However, Staley said that weather patterns are beginning to trend toward El Niño patterns.
If El Niño patterns — which are caused by warmer temperatures of waters in the Pacific — do emerge, it could lead to a wetter, more mild winter for Texoma.
Nielsen-Gammon agreed that September’s weather seems unrelated to other patterns for recent weather. Likewise, he said he doesn’t think that the weather in the late summer months is a precursor to fall. However, he said the weather over the next few months could set the stage for rainfall and conditions to come during the winter months.
Nielsen-Gammon also agreed that recent weather is trending toward El Niño patterns.
Staley said October had a wet start in Texoma, with the NWS recording 1.29 inches of rain for the area as of Monday afternoon. Despite an average rainfall of 5.29 inches for the month, Staley said long-range predictions call for the month to be slightly wetter than average. Staley said recent wet weather is likely to continue with rain is expected to remain in the forecast throughout the week.