Forecast keeps Texoma out of the 100s after Sunday storms flood Denison road

The National Weather Service forecast North Texas afternoons to stay short of 100 degrees, with highs in the lower to middle 90s through much of the week, the agency's Fort Worth office said in its Sept. 20 discussion. The break follows Sunday evening thunderstorms that brought flash flooding to Denison, according to a weather service preliminary storm report.

For Grayson County, which takes in Sherman and Denison, the Sept. 21 forecast called for a high near 92 degrees Tuesday and 93 Wednesday, with overnight lows around 69 both Monday and Tuesday nights. The discussion covers much of the week and does not declare the season's triple-digit weather finished.

The storms crossed the region the evening of Sept. 20. At 6:27 p.m. the weather service office in Norman flagged a strong cell near Achille carrying torrential rain and radar-indicated gusts of 50 to 55 mph, listing Denison, Durant, Colbert and Lake Texoma among the places in its path. Emergency management reported a road near Owens and Lamar streets impassable at 6:20 p.m., with a possible water rescue, and the police department parking lot flooded 20 minutes later, the preliminary storm report shows.

| Forecast and rainfall | |

|---|---|

| Grayson County Tuesday, Wednesday highs | 92°F, 93°F |

| Grayson County Monday, Tuesday night lows | 69°F |

| Collin County Tuesday, Wednesday highs | 96°F, 94°F |

| North Texas departure from normal | about 5–10°F above |

| Denison 0.8 ENE rainfall | 4.26 in. |

| Pottsboro 7.1 WNW rainfall | 0.19 in. |

| Period measured | 24 hours ending about 7 a.m. Sept. 21 |

Rain fell unevenly. A volunteer gauge just east of Denison caught about four and a quarter inches in the 24 hours ending around 7 a.m. Monday, while one west of Pottsboro measured less than a quarter inch, per the CoCoRaHS totals the weather service publishes. The agency calls those readings supplemental and unofficial, and they speak for single gauges rather than for a whole town.

The turn in the weather came behind a weak cold front and the drier air trailing it. With dew points expected in the 50s and lower 60s later in the week, forecasters said heat-index values should sit near or below the actual air temperature.

Highs in the 90s still run roughly 5 to 10 degrees above normal across North Texas for the first week of astronomical fall, the weather service said. Grayson County sits on the cooler side of the pattern: the same forecast put Collin County four degrees warmer Tuesday and one degree warmer Wednesday.

Weather service records show how long a hot spell can run in this part of the state. Wichita Falls logged 100 days at or above 100 degrees in 2011 and did not record its last triple-digit high until Sept. 13. The same date in 1976 brought more than five inches of rain to that area, with water reaching homes near Holliday and McGrath creeks.

NOAA's 2022 Texas climate summary, drawn from observations through 2020, reported statewide temperatures up almost 1.5 degrees since the early twentieth century and days with at least three inches of rain well above their historical average from 2015 through 2020. Those findings are statewide and say nothing about the cause of Sunday's storm.

The Sept. 21 discussion called for mostly dry weather from midweek on, with the next chance of rain late in the coming weekend or early the following week.