The Katy and Fulshear area faces a slight risk of excessive rainfall starting Wednesday, Sept. 30, as a slow-moving weather system pushes heavy rain across Southeast Texas.
The National Weather Service Houston/Galveston office said Sunday, Sept. 27, that periods of heavy rain are possible starting Wednesday, with peak chances on Thursday, Oct. 1, and Friday, Oct. 2. An Excessive Rainfall Outlook map posted with the forecast placed the northwestern portion of the Houston/Galveston region, which includes Katy and Fulshear, in the slight-risk category. The rest of the region falls under a marginal risk.
Thursday looks like the wettest day across the region. The weather service put the probability of more than an inch of rain at 50% to 60% for the Houston area that day, compared with 20% to 35% on Wednesday and 30% to 40% on Friday. The chance of topping two inches is 30% to 45% on Thursday, according to NWS data reported by the Houston Chronicle.
The National Blend of Models projects 2 to 4 inches of cumulative rainfall through Friday, Oct. 2, according to the Chronicle.
Forecasters cautioned that exact totals remain uncertain. The weather service said in a forecast bulletin that confidence in a wetter pattern is increasing but that confidence on timing, coverage and amounts remains low. The agency urged residents to prepare for impacts rather than fixate on specific totals.
A deepening trough of low air pressure over the western United States is expected to combine with Gulf moisture and atmospheric moisture tied to Hurricane Polo, driving the unsettled pattern, according to the Chronicle.
Local flood history
On Sept. 3, the weather service issued a Flood Watch for the Katy and Fulshear area, warning of saturated ground and an additional 2 to 4 inches of rain with localized totals above 6 inches.
The Grand Parkway has also shown vulnerability. In July, the Fort Bend County Precinct 1 Constable's Office posted an advisory on X about water ponding on the inside lanes of SH 99 north of Westpark during a rain event.
Southeast Texas has been dealing with drought. More than 42% of the region was classified as abnormally dry in a recent U.S. Drought Monitor update reported by the Chronicle, and severe drought had expanded from 4.8% to about 9.7% of the region.
What to watch
The weather service said it will provide updated forecasts as confidence increases. Residents in flood-prone areas should monitor the NWS Houston/Galveston forecast page for watches and warnings. Fort Bend County's Office of Emergency Management had not issued a statement about the expected rain as of Sunday afternoon.
