Many areas in East Texas received heavy rains in May and early June which led to widespread flooding. The Brazos River from central Texas, just north of Killeen and Temple TX, southeast to the western and southern suburbs of Houston has seen a significant amount of water with record levels near Houston.
Rainfall in May and early June
Several slow moving systems allowed for heavy rains across Texas in May and into early June. The event which led to the record levels on the Brazos River started in the last week of May with a nearly stationary upper level low. This slow moving upper level system allowed for several rounds of heavy rain to impact areas from Austin to Houston. A region of 10+ inches of rain occurred in the 24 hour period of May 26th to the 27th. Unfortunately, the rains continued and an additional 3 to 5+ inches fell into the 28th in the Houston area. This resulted in significant flash flooding which was sadly reminiscent to the flooding this area experienced over Memorial Weekend last year (2015). The additional rains into early June, further exacerbated the flooding situation especially in the Houston area.
In total for the 30-day period from May 5th to June 4th, a large part of central and east Texas saw 6 to 12 inches of rain (as shown in the red below) with several pockets seeing 18 to 20+ inches of rain (the purple and white areas).
Brazos River Flooding
Flooding occurred on the Brazos River from Central Texas to Houston. The Richmond River gage which is located in the southern suburbs of Houston reached a preliminary record flood height while the downstream gauge at Roshardon preliminary had the 3rd highest height on record. Both gages are owned and operated by the USGS, while the Brazos River Authority helps fund the gage at Roshardon. On June 1st, the USGS took a measurement at Richmond, during the crest, to determine the amount of flow (aka water in the river) and measured 104,000 cubic feet per second (cfs) with a stage of 54.64 feet.
The USGS also took a measurement at the Roshard on June 3 and measured 104,000cfs at a level of 52.46 ft.
These measurements are vital to the river forecast and flood warning process as they provide the data for the USGS to calculate the gauge specific rating curve at each location. The rating curve is the correlation between the amounts of water in the river (which is the data produced by the river models) to the river height (which is the data that is reported hourly and is what the National Weather Service bases River Flood warnings for communities to prepare and respond to the flood.) These correlations tend to shift from flood to flood due to sediment in the river as well as vegetation in along the banks and in the flood plain. So the measurements allow for real-time adjustments to improve the accuracy of the forecast both at the river gauge location as well as for downstream river forecast locations and communities.
Another resource is satellite imagery and drone footage that provides the broader bird’s eye view of the flooding. The image below from is an NASA Earth Observatory satellite image shows the flooding is upstream of the Richmond gage in the western suburbs of Houston.
The map below shows the locations of the satellite image in comparison to the river gages that experienced major flooding.
The major flooding levels are causing significant impacts for people in East Texas. Sadly, many homes and business have been flooded. While much attention has been focused on Houston, inundation upstream has impacted smaller communities and area farmers and ranchers. Unfortunately several ranchers were caught by surprise with the rising water, and cattle and horses were stranded. The NBC affiliate in the Dallas area recently had a story on the impacts.
The team at WxIntegrations will continue to provide relevant information and resources to help you better understand and prepare by incorporating weather impacts into your planning and response.