Jeff Lindner, Director of Hydrologic Operations and Division Meterologist for Harris County Flood Control, just issued this warning”
“Multiple rounds of thunderstorms with heavy rainfall and some severe weather likely today into tonight.”
“Large cluster of thunderstorms with heavy rainfall extends from near Sealy to College Station and is moving eastward and will overspread much of the region N of I-10 over the next several hours. A second…powerful…bow echo with 70-80mph is rapidly approaching Corpus Christi and the coastal bend and may impact the Matagorda Bay area later this morning.”
“Active pattern will remain in place as several disturbances and a weak cold front move across the area today and tonight and into Saturday. Rounds of thunderstorms will produce heavy rainfall and isolated severe weather. Main severe threats today will be mainly west of I-45 and some of the storms this morning over south-central TX have shown some weak rotation.”
“Expect the current round of storms to move across the area between now and 1-2pm followed by a brief break and then another…potentially stronger round this evening into the overnight period.”
“Rainfall amounts of 1-3 inches will be possible today into early Saturday with isolated higher totals. In fact some of the higher resolution models are showing isolated amounts up to 4-5 inches under training bands today and tonight. Air mass is certainly moist and will be able to support some 1-2 inch per hour rainfall rates which will lead to street flooding.”
River Forecast
“Area rivers are responding to the recent heavy rainfall and will remain elevated and in flood (Trinity). Additional rains today and tonight and then again next week will only increase rises. The area river and hydro situation is starting to become worrisome given the potential for this pattern to maintain for the next 1-2 weeks.”
Posted by Bob Rehak on April 3, 2019
612 Days since Hurricane Harvey
00adminadmin2019-05-03 09:41:282019-05-03 09:41:53Possible Street Flooding Today
Flash flooding and flooding will be possible Wednesday into Thursday. A band of heavy rainfall may form Wednesday morning from College Station to Crockett and heavy rainfall may continue to occur through the day. Gulf moisture will also move into the area and cause additional rainfall mainly east of I-45.
Southeast Texas has already had rainfall the last seven days which will cause any additional rainfall to runoff. Isolated thunderstorms may cause brief heavy rainfall of 1 inch an hour. Overall areas in the watch may get 2 to 3 inches of rainfall with isolated bands of 4 inches.
Potential Flood Impacts
In urban areas, street flooding and flooding of underpasses and typical low lying areas can be be expected. Bayous and creeks may have rapid rises and could reach out of banks. Rural low lying areas, low water crossings and poor drainage areas may flood. Rises on area rivers can be expected and this could extend river flooding that is on going.
PRECAUTIONARY/PREPAREDNESS ACTIONS
A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation. You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.
Additional Guidance from Harris County Flood Control
Jeff Lindner, Harris County Flood Control’s meteorologist added this:
Widespread rainfall…some heavy…will lead to rises on area watersheds and potentially some flooding of creeks and rivers.
Upper level storm system is digging into the SW US and will impact the state for the next 24-36 hours.
As moisture increases from the SSW this evening, light rain and showers will develop and spread NNE into the area. A secondary front from roughly Lake Livingston to Columbus will likely remain stationary and be the focus for rainfall production tonight into early Wednesday in that region. Expect numerous showers and thunderstorms to develop by midday along the coast and inland south of the stalled inland front…this rainfall will likely become heavier in nature and slightly more convective with potentially higher rainfall rates. Upper level system will move across the area early Thursday with rains continuing before dry WNW winds sweep across the area in the afternoon ending rainfall.
Rainfall Amounts
Widespread rainfall of 2-3 inches looks likely over much of the area with isolated totals of 4-5 inches. Some fairly decent agreement in the models today with respect to two rainfall maximums over the area…the first over our NW/N counties tonight in Wednesday and then a second Wednesday afternoon into Thursday morning from Houston ENE toward Liberty and then NE toward Lake Livingston. WPC has expended the slight risk of excessive rainfall exceeding flash flood guidance to include a larger part of SE TX. Think maximum hourly rainfall rates will be on the order of .5 to 1.25 inches which most urban areas will be able to handle. Overall fairly long duration of rainfall over a fairly large area will lead to significant amounts of run-off especially into area river systems as well as the creeks in northern Harris County.
Flash Flood Guidance
Flash Flood Guidance for the area is between 3.0-4.4 inches for 6-hrs which seems high and a review of soil saturation levels via the NASA SPORT webpage shows saturation levels of 65-70% over much of the area…or you can walk in the yard and quickly tell that the ground is still very wet from the rainfall on Sunday. Think much of what falls is going to run-off given how wet the ground is and widespread amounts of dormant vegetation.
Several watersheds are still high from the rainfall last Thursday and rainfall of this magnitude will likely result in renewed rises on nearly all watersheds. Main concern will be the Trinity and San Jacinto basins, along with the Navasota and Brazos. In Harris County, significant rises on Spring, Cypress, Little Cypress, Willow, Cedar, and the creeks that feed into Addicks and Barker Reservoirs are likely. Will also include lower Greens (east of US 59) and Halls, Hunting. Some of these watersheds may rise to levels that would impact low lying areas and roadways near the creek or bayou.
Flooding Probable on East and West Forks
Flooding on both the East and West Forks of the San Jacinto River (low lands and streets) certainly looks probable. At this time the threat for significant creek and bayou flooding as well as any flooding of structures is low.
Current thinking is that watersheds will see similar responses to last Thursday morning…although a few may see higher levels since they will be starting at higher current flows versus last Thursday.
Think hourly rainfall rates will be low enough to prevent widespread street flooding, but street flooding in areas of poor drainage and in rural areas where roadside ditches or small creeks spill onto the roadway will be possible.
Posted by Bob Rehak on 1/1/2019
480 Days Since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/01/Balcom_25.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-01-01 18:30:232019-01-01 18:30:29Flash Flood Watch Issued from 6 a.m. Wednesday to Noon Thursday
