The National Weather Service just issued a FLASH FLOOD WARNING FOR OUR AREA. Extreme rainfall rates of 3-6 inches per hour could lead to extensive and rapid onset flash flooding. This flash flooding will be possible over the Humble, Kingwood, Huffman, Crosby areas if a line of thunderstorms progresses slightly more to the SSE over the next few hours.
Given saturated grounds and already high water levels in E/NE Harris County these sort of rainfall totals would result in significant run-off and flash flooding.
Travel is strongly discouraged in the Flash Flood Warning and Flash Flood Emergency areas.
Overnight, the remnants of TS Imelda continued to shift north. The heaviest rainfall occurred north and east of Houston. The East Fork of the San Jacinto is at flood stage at Splendora and New Caney. The NWS has issued multiple flood warnings for that area.
A band of intense rainfall with rates of 3-5 inches per hour continues from Conroe to Porter to Liberty to Winnie.
Conroe Airport recorded 5.16 inches of rain in the last hour.
This band of intense rainfall will move into the NE portions of Harris County over the next hour impacting areas around Kingwood, Humble, Huffman, and Crosby.
Flash flood warnings for much of the NE Houston, SE Montgomery County and W Liberty County that had been due to expire this morning have been extended to this evening.
Intense rainfall rates will result in rapid onset urban flash flooding. It is already in progress in SE Montgomery County.
West Fork and Lake Conroe Well Within Banks
Overnight, the West Fork of the San Jacinto at the SH99 (Grand Parkway) received another three inches of rain.
Lewis Creek on Lake Conroe received two inches in the last couple of hours.
Lake Conroe is now at its seasonal lowering target of 199 feet (actual reading is 198.88). Until now, the lake had been about a half a foot lower than its target due to evaporation. Despite the rain, Lake Conroe is still two feet below its normal level of 201 feet. That means an additional two feet of buffer remains before the lake reaches its normal level. Another two feet remains beyond that before the lake would have to open its gates.
The West Fork at US59 is at 43.5 feet, a little up, but still six feet from coming out of its banks.
Currently Lake Conroe is still releasing 0 cubic feet per second. I.e., NOTHING.
East Fork Getting Hammered
Over on the East Fork, it’s a much different story. The storm has hammered that area all night.
- Caney Creek at FM2090 received 12 inches in the last 24 hours and almost 6 inches in the last six hours. And 4.5 inches between 6 and 7 am.
- The East Fork at New Caney has risen 18 feet since yesterday and will continue rising. It is currently at 62.78 feet.
- FM1485 is now under water and closed.
- Peach Creek at Splendora rose 10 feet since yesterday.
- The East Fork at 2090 received more than 14 inches of rain in the last 24 hours, more than 8 of those inches falling overnight. As a result, the stream rose another six feet since 2 a.m. Flooding is now likely.
Lake Houston Up Slightly
Lake Houston is at 42.78 feet. Normal is 42.38. As East Fork rains descend into the lake, we can expect a rise. How much depends on the amount of rain this morning across the region.
The remnants of Tropical Depression Imelda should continue to drift slowly north today as extremely warm and moist air flows into Southeast Texas.
This moisture will feed the development of slow moving and training thunderstorms with rainfall rates of 3 to 5 inches per hour.
A persistent swath of storms across Eastern Montgomery, Liberty and Chambers county should wobble north then south early this morning.
Storms should continue to expand and develop further to the west as far out as the College Station by mid to late morning. Eventually a band of rainfall should develop and amounts across the band of 3-5 inches should be common with isolated amounts near 10 inches while outside of the band heavy rainfall may be more scattered in nature with amounts of only 1 to 2 inches.
The heavy rains will not only cause street flooding but with the elevated river and bayou levels more river flooding is likely to occur. The flash flood watch may need to be extended this evening. The flood threat may begin to shift further north tonight toward the Madisonville and Huntsville and Crockett areas.
Worst to East; Consider Yourself Lucky
As bad as this sounds, it could be worse. Areas east of us received an incredible 17.24 inches of rainfall in 6 hours near HWY 124 with a storm total nearing 28 inches. Catastrophic flooding is in progress along I-10 between Winnie and Beaumont.
DO NOT Travel. Wait until the threat of high water has passed.
Turn Around, Don’t Drown®: Do not drive through flooded areas. If you see water covering the road, do not attempt to cross it. Only a few inches of water can float a vehicle . If you find yourself in a dangerous situation where your vehicle is taking on water, get out of the vehicle, get to a higher position, and call 911.
Monitor Official Sources for Current Information: Harris County Flood Warning System (harriscountyfws.org), Houston TranStar (houstontranstar.org), and the National Weather Service Houston/Galveston Forecast Office (weather.gov/hgx).
Monitor Stream, Bayou, and Creek Conditions: Rain may move repeatedly across the same area, causing creeks and bayous to rise and possibly exceed their banks. Stay informed of current conditions and avoid traveling near creeks and bayous.
Avoid Traveling during Periods of Heavy Rain: Rain can reduce visibility and prevent you from seeing the road ahead, which could lead to accidents.
Posted by Bob Rehak at 7:30 a.m. on 9/19/2019
751 Days after Hurricane Harvey