The National Weather Service has produced a 3-day excessive rainfall map that show all of SE Texas under a moderate risk for flash flooding this week. “Moderate” means we have a 20-50% chance of exceeding flash-flooding guidance. Flash flooding occurs when short-duration, high-intensity rains exceed the drainage capacity in areas.
Issued Monday at 3AM Houston time by the National Weather Service.
Jeff Lindner, Harris County’s meteorologist, sees heavy rainfall and flash flood threats increasing through the week. “A flash flood watch will likely be required for portions of the area later today,” he said.
Chance of Thunderstorms 70% and Increasing
The National Weather Service predicts a 70% chance of thunderstorms for the Lake Houston Area through Tuesday night. The chance increases to 80% for Wednesday and Thurday. The chances decrease to 70% for Friday, 60% for Saturday and 40% for Sunday.
It is difficult to predict exact amounts of rainfall for any specific location, such as Lake Houston, that far in advance. However, conditions are in place to produce heavy rainfall. The main threat for today is slow moving storms that could produce street flooding this afternoon. But chances increase tomorrow, Wednesday and Thursday.
“This pattern will support heavy rainfall and flash flooding especially during the mid-week period. But really every day this week has potential,” says Lindner.
Space City Weather likens the conditions in place to those that produced the May 2019 floods in Kingwood.
Rainfall Amounts
Since yesterday, there has been no change. Models suggest a fairly high limit on potential totals. “As seen yesterday, this air mass is capable of excessive short term rainfall amounts. Widespread amounts of 4-8 inches will be likely over much of the area over the next 5 days with isolated totals of 10-12 inches or more. Short duration rainfall rates of 2-4 inches per hour will be possible leading to rapid urban flash flooding,” says Lindner.
Grounds in the Houston area are already wet and water supply lakes near full capacity. As of this morning, the City has started lowering Lake Houston by one foot. The SJRA is not releasing water from Lake Conroe.
From SJRA.net as of Monday 5/17/21 at 9am.
Lindner says that rises on area watersheds are likely given the widespread nature of this event. “It is certainly possible some watersheds will experience flooding at some point this week. Which watersheds potentially get hit the hardest remains uncertain…but the risk for flooding will be increasing,” he says.
Posted by Bob Rehak on Monday morning at 9 am, 5/17/21 based on information by HCFCD, NWS, and Space City Weather
1357 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/05/image002.gif?fit=800%2C561&ssl=1561800adminadmin2021-05-17 09:16:192021-05-17 09:16:28Monday AM: All SE Texas Now Under Moderate Risk for Flash Flooding This Week
Rain is winding down for today, but areas southwest of Houston along US59 received massive amounts today. Ganado in Wharton County reported 13.47 inches at one gage and 10.87 inches at another. Radar totals indicated 10-14 inches…much of that falling in a 4-6 hour period. According to Atlas 14, that’s a 100- to 200-year rain.
Atlas 14 Rainfall Frequency Chart for this area.
A Portent of Rainfall to Come
“This shows the capability of the air mass we will be dealing with nearly all week,” said Jeff Lindner, Harris County’s meteorologist. “Expect additional “big totals” over parts of the area through the week.”
Ganado is on US 59 between Victoria and El Campo in Wharton County, southwest of Houston.
Heaviest Rains Spreading Toward Houston Later This Week
The threat of heavy to excessive rainfall will continue for the next several days and spread northeast into the Houston area. The threat of flooding and flash flooding will increase during that time, according to Lindner’s Sunday afternoon update.
Lindner predicts that we should get a break tonight, but another wave approaches on Monday late morning into the afternoon. Expect another flare up of showers and thunderstorms. “We will likely see another break on Monday night and then additional showers and storms on Tuesday,” he says.
Wednesday-Thursday
Lindner is most concerned about Wednesday into Thursday. Another tropical air mass from the Bay of Campeche will surge into our area. Upper level winds will help lift the surface moisture into thunderstorms. Training of storms from SSW to NNE looks increasingly likely. “Potential formation of a coastal trough or weak surface low near the lower Texas coast will only help to further promote rainfall.” Given the fact that we’re still talking about forecasts three or four days out, Lindner doesn’t want to get too aggressive with rainfall total predictions just yet. But he says that models show an overall pattern favoring heavy rainfall and flash flooding.
Rainfall Amounts
Additional rainfall amounts on top of what has already fallen will average 4-8 inches over the region with isolated totals of 10-15 inches certainly possible. The expected widespread nature of the rainfall along with potential high hourly rainfall rates of 2-4 inches support rapid onset flash flooding and rises on area watersheds especially our river system as rainfall totals pile up over time. Creeks and bayous in urban areas will tend to respond to the short duration higher rainfall rates and will need to be monitored closely.
Posted by Bob Rehak on 5/16/2021at 6PM based on information from NWS, HCFCD, and Space City Weather.
1356 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/09/NOAA-Atlas-14-Rainfall-Rates-for-Kingwood.png?fit=976%2C828&ssl=1828976adminadmin2021-05-16 18:16:302021-05-16 18:16:33Wharton County Receives 13.47 Inches So Far Today
Jeff Lindner, Harris County’s meteorologist is predicting a wet week ahead for southeast Texas with frequent rounds of thunderstorms and heavy rainfall. He also predicts flooding and flash flood threats that will increase throughout the week.
National Weather Service 5-Day forecasted rainfall amounts as of Sunday morning.
Says Lindner, “A short wave is approaching the area this morning. Numerous showers and thunderstorms will develop over the area and continue through the day. Storms have already anchored over portions of Matagorda into Jackson Counties this morning. Flash flood warnings are currently in effect for that area and this will be the story this week.”
An upper level storm system over the southwest will eject several disturbances across Texas this week, according to Lindner. These disturbances will interact with a near constant flow of tropical moisture off the Gulf of Mexico to produce rounds of storms and heavy rainfall with each disturbance. Humidity levels throughout the Houston region range from 70% to above 90%.
Given the feed of moisture, the potential for slow moving and training storms, and high moisture levels, heavy to excessive rainfall will be possible.
Jeff Lindner, Harris County Meteorologist
Expect Heavy Rain Through End of Week
Heavy rain is likely from today through the end of the week. While it will not rain the entire time, there will be several rounds. Grounds will saturate and run-off will increase during the wet week ahead.
Today’s concern: slow storm motions currently being seen southwest of the city. Such storm motions and rainfall rates over urban areas could quickly lead to street flooding.
Main concern: Wednesday and Thursday. The main upper-level storm will move into Texas. Southeast Texas will develop very favorable conditions for rainfall. A steady stream of moisture and strongly divergent winds aloft will support training of lines and clusters of thunderstorms. However…
…There could be flooding and heavy rainfall at nearly any time from today through Friday.
Jeff Lindner, Harris County Meteorologist
Rainfall Amounts
Lindner thinks rainfall totals over the next 5 days will likely average 4-6 inches over the region with isolated amounts of 8-10 inches. Hourly rainfall rates of 1-3 inches will be possible under stronger storms. Rises on area rivers will certainly be possible given the widespread nature of this event along with the multiple rounds of heavy rainfall. While totals will be spread out some over time, the concern of short term excessive rainfall rates resulting in flash flooding is possible in this pattern. Get out the galoshes. It’s going to be a wet week ahead.
Lake Report
At this hour, Lake Conroe is not releasing water and the lake is at its normal level of 201 feet above sea level.
This could get interesting. Lake Conroe is full and if you look closely at the rainfall map above, you will see that the NWS is predicting some of the heaviest rainfall for our area to be upstream from Lake Conroe.
Posted by Bob Rehak on 5/16/2021
1356 Days since Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/05/image001.gif?fit=800%2C561&ssl=1561800adminadmin2021-05-16 09:56:152021-05-16 18:15:58Wet Week Coming: 4-6 Inches Likely for Region, 8-10 Possible
Monday AM: All SE Texas Now Under Moderate Risk for Flash Flooding This Week
The National Weather Service has produced a 3-day excessive rainfall map that show all of SE Texas under a moderate risk for flash flooding this week. “Moderate” means we have a 20-50% chance of exceeding flash-flooding guidance. Flash flooding occurs when short-duration, high-intensity rains exceed the drainage capacity in areas.
Jeff Lindner, Harris County’s meteorologist, sees heavy rainfall and flash flood threats increasing through the week. “A flash flood watch will likely be required for portions of the area later today,” he said.
Chance of Thunderstorms 70% and Increasing
The National Weather Service predicts a 70% chance of thunderstorms for the Lake Houston Area through Tuesday night. The chance increases to 80% for Wednesday and Thurday. The chances decrease to 70% for Friday, 60% for Saturday and 40% for Sunday.
It is difficult to predict exact amounts of rainfall for any specific location, such as Lake Houston, that far in advance. However, conditions are in place to produce heavy rainfall. The main threat for today is slow moving storms that could produce street flooding this afternoon. But chances increase tomorrow, Wednesday and Thursday.
“This pattern will support heavy rainfall and flash flooding especially during the mid-week period. But really every day this week has potential,” says Lindner.
Space City Weather likens the conditions in place to those that produced the May 2019 floods in Kingwood.
Rainfall Amounts
Since yesterday, there has been no change. Models suggest a fairly high limit on potential totals. “As seen yesterday, this air mass is capable of excessive short term rainfall amounts. Widespread amounts of 4-8 inches will be likely over much of the area over the next 5 days with isolated totals of 10-12 inches or more. Short duration rainfall rates of 2-4 inches per hour will be possible leading to rapid urban flash flooding,” says Lindner.
Grounds in the Houston area are already wet and water supply lakes near full capacity. As of this morning, the City has started lowering Lake Houston by one foot. The SJRA is not releasing water from Lake Conroe.
Lindner says that rises on area watersheds are likely given the widespread nature of this event. “It is certainly possible some watersheds will experience flooding at some point this week. Which watersheds potentially get hit the hardest remains uncertain…but the risk for flooding will be increasing,” he says.
Posted by Bob Rehak on Monday morning at 9 am, 5/17/21 based on information by HCFCD, NWS, and Space City Weather
1357 Days since Hurricane Harvey
Wharton County Receives 13.47 Inches So Far Today
Rain is winding down for today, but areas southwest of Houston along US59 received massive amounts today. Ganado in Wharton County reported 13.47 inches at one gage and 10.87 inches at another. Radar totals indicated 10-14 inches…much of that falling in a 4-6 hour period. According to Atlas 14, that’s a 100- to 200-year rain.
A Portent of Rainfall to Come
“This shows the capability of the air mass we will be dealing with nearly all week,” said Jeff Lindner, Harris County’s meteorologist. “Expect additional “big totals” over parts of the area through the week.”
Ganado is on US 59 between Victoria and El Campo in Wharton County, southwest of Houston.
Heaviest Rains Spreading Toward Houston Later This Week
The threat of heavy to excessive rainfall will continue for the next several days and spread northeast into the Houston area. The threat of flooding and flash flooding will increase during that time, according to Lindner’s Sunday afternoon update.
Lindner predicts that we should get a break tonight, but another wave approaches on Monday late morning into the afternoon. Expect another flare up of showers and thunderstorms. “We will likely see another break on Monday night and then additional showers and storms on Tuesday,” he says.
Wednesday-Thursday
Lindner is most concerned about Wednesday into Thursday. Another tropical air mass from the Bay of Campeche will surge into our area. Upper level winds will help lift the surface moisture into thunderstorms. Training of storms from SSW to NNE looks increasingly likely. “Potential formation of a coastal trough or weak surface low near the lower Texas coast will only help to further promote rainfall.” Given the fact that we’re still talking about forecasts three or four days out, Lindner doesn’t want to get too aggressive with rainfall total predictions just yet. But he says that models show an overall pattern favoring heavy rainfall and flash flooding.
Rainfall Amounts
Additional rainfall amounts on top of what has already fallen will average 4-8 inches over the region with isolated totals of 10-15 inches certainly possible. The expected widespread nature of the rainfall along with potential high hourly rainfall rates of 2-4 inches support rapid onset flash flooding and rises on area watersheds especially our river system as rainfall totals pile up over time. Creeks and bayous in urban areas will tend to respond to the short duration higher rainfall rates and will need to be monitored closely.
Make sure you bookmark this page and consult it frequently throughout the week: Harris County Flood Warning System.
Posted by Bob Rehak on 5/16/2021 at 6PM based on information from NWS, HCFCD, and Space City Weather.
1356 Days since Hurricane Harvey
Wet Week Coming: 4-6 Inches Likely for Region, 8-10 Possible
Jeff Lindner, Harris County’s meteorologist is predicting a wet week ahead for southeast Texas with frequent rounds of thunderstorms and heavy rainfall. He also predicts flooding and flash flood threats that will increase throughout the week.
Upper Level Disturbances Meet Tropical Moisture Inflow
Says Lindner, “A short wave is approaching the area this morning. Numerous showers and thunderstorms will develop over the area and continue through the day. Storms have already anchored over portions of Matagorda into Jackson Counties this morning. Flash flood warnings are currently in effect for that area and this will be the story this week.”
An upper level storm system over the southwest will eject several disturbances across Texas this week, according to Lindner. These disturbances will interact with a near constant flow of tropical moisture off the Gulf of Mexico to produce rounds of storms and heavy rainfall with each disturbance. Humidity levels throughout the Houston region range from 70% to above 90%.
Expect Heavy Rain Through End of Week
Heavy rain is likely from today through the end of the week. While it will not rain the entire time, there will be several rounds. Grounds will saturate and run-off will increase during the wet week ahead.
Today’s concern: slow storm motions currently being seen southwest of the city. Such storm motions and rainfall rates over urban areas could quickly lead to street flooding.
Main concern: Wednesday and Thursday. The main upper-level storm will move into Texas. Southeast Texas will develop very favorable conditions for rainfall. A steady stream of moisture and strongly divergent winds aloft will support training of lines and clusters of thunderstorms. However…
Rainfall Amounts
Lindner thinks rainfall totals over the next 5 days will likely average 4-6 inches over the region with isolated amounts of 8-10 inches. Hourly rainfall rates of 1-3 inches will be possible under stronger storms. Rises on area rivers will certainly be possible given the widespread nature of this event along with the multiple rounds of heavy rainfall. While totals will be spread out some over time, the concern of short term excessive rainfall rates resulting in flash flooding is possible in this pattern. Get out the galoshes. It’s going to be a wet week ahead.
Lake Report
At this hour, Lake Conroe is not releasing water and the lake is at its normal level of 201 feet above sea level.
This could get interesting. Lake Conroe is full and if you look closely at the rainfall map above, you will see that the NWS is predicting some of the heaviest rainfall for our area to be upstream from Lake Conroe.
Posted by Bob Rehak on 5/16/2021
1356 Days since Harvey