The following is the forecast for the San Jacinto River basin including the West and East Forks and the mainstem below Lake Houston, as of about 8:30 p.m. Friday evening. Some forecasters believe rainfall, runoff and flooding could go higher. This post has already been updated once.
Major flooding forecast. Some uncertainty remains. Forecast could go a few feet higher. Jeff Lindner, Harris County meteorologist warns Northshore, Belleau Woods, Rivercrest, and Forest Cove will likely flood into early next week. Even elevated structures will be cut-off for several days.
Lake Conroe is currently releasing 2121 cfs as of 7 p.m. Friday. This is a small fraction of the expected flows along the West Fork.
This will be the inundation with a stage of 52.0 ft at US 59
NWS forecasts minor to moderate flooding along the East Fork at FM 1485. At 62 ft FM 1485 west of the river bridge will be impacted.
Mainstem below Lake Houston:
A rise to near flood stage is currently expected. A few low lying roads near the river could be flooded.
Overnight Rain Forecast
Lindner says, “Widespread rainfall of 1-2 inches has occurred over much of the area this afternoon with isolated totals of 3-4 inches over southern Walker and extreme northern Montgomery Counties.”
“Surface low is deepening northwest of Harris County and suggests increasing potential for heavier showers and thunderstorms. They will train from WSW and SW to the ENE and NE. Rainfall will continue to pile up at the rate of .5 to 1.5 inches per hour this evening and much of what is now falling is directly running off,” says Lindner.
The National Weather Service and Lindner expect areas along and NW of US 59 will receive the most sustained rainfall this evening.
Impact of Lake Lowering
Luckily for the Humble Kingwood Area, the City of Houston reduced the level of Lake Houston more than the 18″ they originally projected. As of this afternoon, the Lake was down to 40.5. That should give us some cushion against flooding.
Said City Council Member Dave Martin, “The gates at Lake Houston continue to remain open and will be adjusted as needed to allow for even more water to be released should that be necessary. In response to the lowering of Lake Houston, the West Fork of the San Jacinto River near Highway 59 has also lowered by 2 feet providing additional capacity in the river.
Expected SJRA Release Rates
According to Martin, the SJRA currently estimates that releases from Lake Conroe might peak at 9,000 to 11,000 cfs sometime over the weekend based on current forecasts. These amounts are relatively small in comparison to the rain events that our area saw during July 4, 2018 and Memorial Day 2016.
If you live in a low-lying area, monitor rainfall and water-level trends by visiting these web sites throughout the weekend.
Posted on 12/7/2018 by Bob Rehak based on info from Harris County & COH
465 Days since Hurricane Harvey.