Good to have the Pearl Harbor Day flooding in the rear-view mirror. And good that the worst predictions did not come true. So what happened? Did we just get lucky? Or did something go right for a change? It might have been a little of both.
Here’s what I know at 8 p.m. on Saturday night, about when the flood was expected to crest and flood multiple neighborhoods.
Lake Conroe Releases Have Peaked
According to Jace Houston, General Manager of the SJRA, releases from the Lake Conroe dam have likely peaked. The current release rate of 8181 cfs falls far short of previous floods and short of 9,000 to 11,000 cfs release rates predicted earlier.
Less Rain than Expected
That’s because we got less rainfall than predicted. Most of the area, including Lake Houston and upstream from Lake Conroe, received about 4.5 inches or less instead of the 8 to 10 predicted earlier. And rain was fairly spread out over time. The heaviest rainfall seems to have happened in The Woodlands with some gages approaching 6 inches.
Aggressive Pre-Release by City
Finally, the City of Houston started releasing water from the Lake Houston Dam two days in advance of the storm. They took the lake level down two feet before the storm and kept releasing water during the storm. Had it not been for that, homes along the shoreline would almost certainly have flooded.
Looking across the flood-swollen San Jacinto at the US Army Corps of Engineers’ Command Site. Had the City not pre-released more than 2 feet of water from Lake Houston, this site would have been inundated.
Trending Steady or Down
At this moment, every stream gage that the SJRA reports upstream from the Lake Houston area is trending down. The peak has passed.
Harris County Flood Control shows that the gages at US59, West Lake Houston Parkway and FM1960 also appear to have peaked.
A photographic tour of the Kingwood area this afternoon showed that the river came out of its banks at River Grove Park and US59 and was on the verge of coming out in many other places. Surprisingly, I saw no flooded homes, not even on Marina Drive in Forest Cove. However, I did hear of many affected by street flooding, especially upstream in Montgomery County.
Still Much Mitigation Work to Do
Ben’s Branch by the Enclave and Kingwood Library had standing water. That should be a reminder that the County needs to make cleaning out this stream a high priority.
One final point. Late this afternoon, I noticed a huge difference between the gages upstream and downstream from the dredging.
At 59, the West Fork exceeded its banks and peaked at 52 feet.At West Lake Houston Parkway, the river was well within its banks and peaking around 45 feet.At FM1960 the river was still well within banks and peaking at 44 feet.
Normally, these gages all read the same elevation. One can partially attribute the differences to spreading of the river. However one must also consider the huge blockages in the river that the Corps has not yet removed. At the moment, one of the biggest is just downstream from River Grove Park. Another, the mouth bar, blocks the river between Kings Point and Atascocita Point.
Even during a flood, the mouth bar (in the middle of this picture) stands out of the water by several feet and blocks the mouth of the West Fork. Water must make its way past this blockage through narrow passages on either side of it. It backs water up throughout the Humble/Kingwood area.Here’s what the mouth bar looks like from the air, right after Harvey, before grass started growing on it. The area around it averages 1-3 feet deep. The deepest parts of the narrow channel reach 5 feet deep.
The Lake Houston Area lucked out this time due to aggressive action by City officials, a conservative release rate by the SJRA and the kindness of Mother Nature. I hope we don’t press our luck and assume that these blockages make no difference. They do. We need to remove them.
Posted by Bob Rehak on 12/8/2018
466 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2018/12/CommandSiteNearlyFlooded.jpg?fit=1500%2C1000&ssl=110001500adminadmin2018-12-08 20:46:402018-12-08 21:33:30Whew! Luck and Aggressive Action Avert Major Flooding
Below is a list of historic crests on the West Fork at the 59 bridge. If the current flood crests at 54 feet, it will be the tenth highest in the last 25 years. Scroll down the list for floods you remember. For instance, did you flood in the Memorial or Tax Day floods?
The Memorial Day flood of 2015 on the West Fork crested at about the same height as this flood is expected to crest – 54 feet. However, that was lower than a flood in 2016, also near Memorial Day that crested at about 62 feet.
This flood will be about three feet lower than the Tax Day flood in 2016. And about 2.5 feet higher than the Good Friday flood this year.
Apply some judgment to all these numbers. New blockages downstream, such as the mouth bar, could back water up compared to what it used to be. New development upstream could also. hasten the convergence of water and increase flood levels. And it’s not just how much water falls, it’s how fast it falls.
Recent Crests (1) 49.51 ft on 07/05/2018 (2) 51.66 ft on 03/29/2018 Good Friday (3) 49.46 ft on 02/26/2018 (4) 69.18 ft on 08/29/2017 Harvey (5) 61.95 ft on 05/29/2016 (6) 57.32 ft on 04/21/2016 Tax Day (7) 50.11 ft on 06/21/2015 (8) 53.65 ft on 05/29/2015 Memorial Day (9) 49.56 ft on 05/18/2015 (10) 50.54 ft on 05/14/2015 (11) 49.58 ft on 03/13/2015 (12) 49.92 ft on 05/28/2014 (13) 52.09 ft on 07/14/2012 (14) 50.10 ft on 10/30/2009 (15) 50.10 ft on 04/28/2009 (16) 49.70 ft on 11/13/2008 (17) 62.80 ft on 09/14/2008 (18) 50.20 ft on 01/17/2007 (19) 51.40 ft on 10/17/2006 (20) 51.10 ft on 10/17/2006 (21) 49.60 ft on 05/02/2004 (22) 50.60 ft on 02/14/2004 (23) 55.80 ft on 11/07/2002 (24) 53.90 ft on 10/29/2002 (25) 55.30 ft on 06/10/2001 TS Allison (26) 60.10 ft on 11/15/1998 (27) 55.10 ft on 10/20/1998 (28) 54.20 ft on 10/19/1998 (29) 46.90 ft on 02/22/1998 (30) 52.40 ft on 01/08/1998 (31) 67.30 ft on 10/18/1994 ’94 Flood (32) 49.82 ft on 03/04/1992 (33) 51.72 ft on 06/27/1989 (34) 55.60 ft on 05/18/1989 (35) 50.46 ft on 11/26/1987 (36) 50.10 ft on 06/13/1987 (37) 42.20 ft on 08/23/1986 (38) 53.20 ft on 11/26/1985 (39) 51.80 ft on 10/26/1984 (40) 46.00 ft on 02/13/1984 (41) 54.00 ft on 05/23/1983 (42) 50.60 ft on 05/14/1982 (43) 50.10 ft on 09/01/1980 (44) 55.70 ft on 04/19/1979
5th Wettest December 7th on Record
According to Matt Lanza at Space City Weather, Houston officially had 4.31″ of rain on Friday, making December 7, 2018 the 5th wettest December day on record in the city, going back to the late 1800s. It was also our wettest single day since August of 2017, which we all know was during Hurricane Harvey.
Posted by Bob Rehak on 12/8/2018
466 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2018/12/Screen-Shot-2018-12-08-at-7.20.36-AM-copy.jpg?fit=1500%2C837&ssl=18371500adminadmin2018-12-08 07:31:592018-12-08 07:32:05Putting a 54-Foot Flood in Historical Perspective
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.
West Fork:
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.
The West Fork reached it’s low point around 4 p.m. this afternoon after the City lowered the Lake to 40.75 feet. Flood gates remain open at the Lake Houston dam. Regardless, the West Fork is now expected to crest at around 54 feet on Monday afternoon and not return to its banks for several days.Near Real Time Inundation Map from HarrisCountyFWS.org. Check the site periodically for latest updates.
This will be the inundation with a stage of 52.0 ft at US 59
East Fork:
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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2018/12/image001-1.png?fit=600%2C465&ssl=1465600adminadmin2018-12-07 20:01:502020-01-17 10:16:24West Fork Forecast to Flood up to 54 Feet
Whew! Luck and Aggressive Action Avert Major Flooding
Good to have the Pearl Harbor Day flooding in the rear-view mirror. And good that the worst predictions did not come true. So what happened? Did we just get lucky? Or did something go right for a change? It might have been a little of both.
Here’s what I know at 8 p.m. on Saturday night, about when the flood was expected to crest and flood multiple neighborhoods.
Lake Conroe Releases Have Peaked
According to Jace Houston, General Manager of the SJRA, releases from the Lake Conroe dam have likely peaked. The current release rate of 8181 cfs falls far short of previous floods and short of 9,000 to 11,000 cfs release rates predicted earlier.
Less Rain than Expected
That’s because we got less rainfall than predicted. Most of the area, including Lake Houston and upstream from Lake Conroe, received about 4.5 inches or less instead of the 8 to 10 predicted earlier. And rain was fairly spread out over time. The heaviest rainfall seems to have happened in The Woodlands with some gages approaching 6 inches.
Aggressive Pre-Release by City
Finally, the City of Houston started releasing water from the Lake Houston Dam two days in advance of the storm. They took the lake level down two feet before the storm and kept releasing water during the storm. Had it not been for that, homes along the shoreline would almost certainly have flooded.
Trending Steady or Down
At this moment, every stream gage that the SJRA reports upstream from the Lake Houston area is trending down. The peak has passed.
Harris County Flood Control shows that the gages at US59, West Lake Houston Parkway and FM1960 also appear to have peaked.
A photographic tour of the Kingwood area this afternoon showed that the river came out of its banks at River Grove Park and US59 and was on the verge of coming out in many other places. Surprisingly, I saw no flooded homes, not even on Marina Drive in Forest Cove. However, I did hear of many affected by street flooding, especially upstream in Montgomery County.
Still Much Mitigation Work to Do
Ben’s Branch by the Enclave and Kingwood Library had standing water. That should be a reminder that the County needs to make cleaning out this stream a high priority.
One final point. Late this afternoon, I noticed a huge difference between the gages upstream and downstream from the dredging.
Normally, these gages all read the same elevation. One can partially attribute the differences to spreading of the river. However one must also consider the huge blockages in the river that the Corps has not yet removed. At the moment, one of the biggest is just downstream from River Grove Park. Another, the mouth bar, blocks the river between Kings Point and Atascocita Point.
The Lake Houston Area lucked out this time due to aggressive action by City officials, a conservative release rate by the SJRA and the kindness of Mother Nature. I hope we don’t press our luck and assume that these blockages make no difference. They do. We need to remove them.
Posted by Bob Rehak on 12/8/2018
466 Days since Hurricane Harvey
Putting a 54-Foot Flood in Historical Perspective
Below is a list of historic crests on the West Fork at the 59 bridge. If the current flood crests at 54 feet, it will be the tenth highest in the last 25 years. Scroll down the list for floods you remember. For instance, did you flood in the Memorial or Tax Day floods?
The Memorial Day flood of 2015 on the West Fork crested at about the same height as this flood is expected to crest – 54 feet. However, that was lower than a flood in 2016, also near Memorial Day that crested at about 62 feet.
This flood will be about three feet lower than the Tax Day flood in 2016. And about 2.5 feet higher than the Good Friday flood this year.
However, we will be about 15 feet below Harvey.
Remember: Things Change
Apply some judgment to all these numbers. New blockages downstream, such as the mouth bar, could back water up compared to what it used to be. New development upstream could also. hasten the convergence of water and increase flood levels. And it’s not just how much water falls, it’s how fast it falls.
Recent Crests
(1) 49.51 ft on 07/05/2018
(2) 51.66 ft on 03/29/2018 Good Friday
(3) 49.46 ft on 02/26/2018
(4) 69.18 ft on 08/29/2017 Harvey
(5) 61.95 ft on 05/29/2016
(6) 57.32 ft on 04/21/2016 Tax Day
(7) 50.11 ft on 06/21/2015
(8) 53.65 ft on 05/29/2015 Memorial Day
(9) 49.56 ft on 05/18/2015
(10) 50.54 ft on 05/14/2015
(11) 49.58 ft on 03/13/2015
(12) 49.92 ft on 05/28/2014
(13) 52.09 ft on 07/14/2012
(14) 50.10 ft on 10/30/2009
(15) 50.10 ft on 04/28/2009
(16) 49.70 ft on 11/13/2008
(17) 62.80 ft on 09/14/2008
(18) 50.20 ft on 01/17/2007
(19) 51.40 ft on 10/17/2006
(20) 51.10 ft on 10/17/2006
(21) 49.60 ft on 05/02/2004
(22) 50.60 ft on 02/14/2004
(23) 55.80 ft on 11/07/2002
(24) 53.90 ft on 10/29/2002
(25) 55.30 ft on 06/10/2001 TS Allison
(26) 60.10 ft on 11/15/1998
(27) 55.10 ft on 10/20/1998
(28) 54.20 ft on 10/19/1998
(29) 46.90 ft on 02/22/1998
(30) 52.40 ft on 01/08/1998
(31) 67.30 ft on 10/18/1994 ’94 Flood
(32) 49.82 ft on 03/04/1992
(33) 51.72 ft on 06/27/1989
(34) 55.60 ft on 05/18/1989
(35) 50.46 ft on 11/26/1987
(36) 50.10 ft on 06/13/1987
(37) 42.20 ft on 08/23/1986
(38) 53.20 ft on 11/26/1985
(39) 51.80 ft on 10/26/1984
(40) 46.00 ft on 02/13/1984
(41) 54.00 ft on 05/23/1983
(42) 50.60 ft on 05/14/1982
(43) 50.10 ft on 09/01/1980
(44) 55.70 ft on 04/19/1979
5th Wettest December 7th on Record
According to Matt Lanza at Space City Weather, Houston officially had 4.31″ of rain on Friday, making December 7, 2018 the 5th wettest December day on record in the city, going back to the late 1800s. It was also our wettest single day since August of 2017, which we all know was during Hurricane Harvey.
Posted by Bob Rehak on 12/8/2018
466 Days since Hurricane Harvey
West Fork Forecast to Flood up to 54 Feet
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.
West Fork:
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
East Fork:
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.