Hurricane Harvey Jeff Lindner Meteorologist Harris County Flood - PowerPoint PPT Presentation

Hurricane Harvey Jeff Lindner Meteorologist Harris County Flood Control District

Landfall near Port Aransas 10:00 p.m. August 25 th Category 4 (130mph) First hurricane to strike TX since Ike (2008)

A Category 4 Hurricane With Epic Flood Forecasts had to separate the flood out of the • hurricane Hurricane conditions were a coastal bend concern • (surge/wind) Strong and consistent messaging for the upper coast • flood threat Most heard hurricane and prepared for a hurricane • Preparations paid off…just done for the wrong reason •

The Forecast

Forecasting Historic Events Comparison to previous events TS Allison • Hurricane Ike • Tax Day Flood (2016) • The Forecast Is that really going to happen • Can that really happen • Most people do not understand uncertainty or • probability Most people will verify with other sources • (message consistency is critical)

The Reality 30 inches

Harvey Smashes US Rainfall Records TX State Climatologist 1530 Billion gallons • Fill Astrodome 4790 times • Supply US water usage for 26 days •

Harris County Rainfall Statistics 1 Trillion gallons of water over 4-days (1,777 sq mi) • Would run Niagara Falls for 15 days • Fill the Astrodome 3200 times • 33.7 inches average Harris County rainfall over 4 days • 68% of Harris County yearly rainfall in 4 days • 69% of PMP • Max 4 day total: 47.40 in at Clear Creek at I-45 • 95% of PMP • PMP = probable Maximum Precipitation

The Flood Versus The Tornado Overlapping warnings • Which is more critical • at the time Call to action • statements How many warnings • are needed…at some point everyone knows things are bad

Understanding the Hydrology • Complex urban/rural hydrology • 22 watersheds each with different flooding types • 2 flood control reservoirs (Addicks/Barker) • 2 levees • Spillways (4) • Dam Releases (controlled vs. uncontrolled) • Lack of public understanding of how water flows, watersheds, reservoir operations

Addicks and Barker Watersheds

Inverness Forest Levee Event Date HWM Harvey 92.1 Allison (01) 86.9 4/18/16 86.9 11/14/98 85.4 10/49 89.8

Inverness Forest Levee

Addicks Reservoir Top 5 Pools Date Elevation Harvey 109.1 Apr 2016 102.65 Mar 1992 97.64 Apr 2009 97.08 Nov 2002 96.63

Addicks Reservoir N End Spillway

HCFCD Actions

Hydrographs vs. Inundation Map Most people don’t know their elevation Some people get this…most want a forecast for their address

HCFCD Actions (Media) Over 275 Interviews Local, national, world media 3 Daily Press Briefings (HCFCD/COE)

Communicating Complex Topics Use basic words, be calm, and confident • Answer the best you can what people want to know • How does it affect me • When will it affect me • What should I do • Have compassion and understanding • We will get through this • This will end • Relate if you can • If you don’t know say you don’t know •

HCFCD/NWS Coordination: NWS Chat 02:14:23] <nws-nikki.hathaway Plan is to issue a Flash Flood Emergency to include parts of Southern and Southwest Houston in Harris County and parts of Eastern Fort Bend County. [02:17:14] <water-jeff.d.lindner Lance I agree....with Flash Flood Emergency wording... [02:17:27] <water-jeff.d.lindner Brays rising very rapidly [02:21:28] <water-jeff.d.lindner Willow Waterhole going over banks [02:35:16]<water-jeff.d.lindner 4.56 inches over Meyerland [02:35:42]<nws-charles.roeseler Jeff, do you want warnings out for Brays? [02:38:17]<nws-katie.landry Jeff, going out with warning on Brays...Gessner eastward

NWS/HCFCD/MEDIA: NWS Chat [10:49:40]<water-jeff.d.lindner MEDIA/NWS : we need help getting this message out. Our message is for persons to not go into their attic, but instead get on the roof. Also if calling 911 stay on the line until it is answered [10:53:21]<media-britta.merwin Thanks Jeff we just passed that along. To my knowledge there are 2 spots this is occurring/possible I-10 between the loop and beltway due to hunting bayou and then down along the gulf freeway [10:53:41]<water-jeff.d.lindner Getting reports of water going into second story of houses and apartments complexes near Hobby Airport and lower Hunting Bayou near I-10 [10:53:55]<nws-molly.merrifield Britta- Also have reports of water in second story apartments in Dickinson

Harvey: Lessons Learned • Public comprehension of forecasted rainfall or historic events • Media/social media engagement • Plans and procedures • Partnerships matter!!! • Communication

Jeff Lindner 713-684-4165 jeff.lindner@hcfcd.org @jefflindner1