From Jeff Lindner:
Flood Watch issued for much of SE TX until Wednesday evening.
Combination of increasing Gulf moisture, lift from an upper level trough over the region, and slow/training storm motions will produce a threat for heavy to excessive rainfall early this evening and then again late tonight into Wednesday.
Heavy rainfall is currently ongoing over portions of Montgomery County with scattered to numerous showers and thunderstorms developing over much of the area west of I-45 and north of I-10. Ongoing activity should begin to weaken and dissipate by mid evening with the loss of heating, but rainfall amounts over the next 3-5 hours of 2-4 inches in an hour or less will be possible with the heavier storms.
Late tonight into Wednesday the trough axis and lift will slowly sag southward toward the I-10 corridor and this combined with low level speed convergence near the coast late tonight will result in the development of thunderstorms that slowly progress inland. These storms will have the potential to produce rainfall rates of 3-5 inches per hour which is raising the flash flood risk for early Wednesday along and south of the I-10 corridor. It is possible that much of this activity could remain near the coast or just offshore, but it is close enough to warrant a close watch.
Additional rainfall amounts of 2-4 inches can be expected over much of the area with amounts of 4-6 inches south of I-10. Would not be surprised to see an isolated 10 inch amount somewhere given the air mass in place and the amounts that have happened in central and SW TX today. Some of these higher amounts are also supported on the recent HREF guidance, especially near the coast.
Flash flooding will be possible under the heavy rain cores as well as quick rises on area creeks and bayous.
East Fork of the San Jacinto River:
Heavy rainfall yesterday and again today will produce a significant rise along the river from above Cleveland to Lake Houston starting on Wednesday and lasting into late this week. The river will rise above flood stage late Wednesday at FM 1485 and above moderate flood levels on Thursday. Low lying roads near the river will be impacted and FM 1485 will potentially be overtopped. The current forecast for the river is well below levels experienced in May of this year.
Jeff Lindner
Director Hydrologic Operations Division/Meteorologist
Harris County Flood Control District
9900 Northwest Freeway | Houston, Texas 77092
346-286-4000 (main) | 346-286-4165 (direct) | 281-924-2091 (cell)
jeff.lindner@hcfcd.org | Twitter: @jefflindner1
