Unlimited
Potential

Hurricane Harvey

UPDATE: 9:00AM 8-25-17

by Craig W. Kalkomey PE, CFM
Department Manager, Hydrology and Hydraulics
Jones|Carter

Overnight, Hurricane Harvey was upgraded to a Category 2 Hurricane with maximum sustained winds of 110 MPH. Harvey is currently expected hit landfall as a strong Category 3 Hurricane (maximum sustained winds of 130 MPH) somewhere between Corpus Christi and the Matagorda Bay. Conditions still appear to be favorable for continued intensification up to landfall and Harvey exhibits a classic well defined hurricane on both satellite and radar images.

Hurricane Harvey

Harvey continues to move in a northwesterly direction at 9 to 10 MPH. There has been little change in the track overnight and is still anticipated to hit land around the middle section of the Texas coast. There continues to be a forecasted slowing of Harvey as he nears the coast and moves inland. It is possible that Harvey will stall near or just west of Matagorda Bay over the weekend and then slowly move in an east northeast direction across southeast Texas early next week.

Hurricane Harvey

Rainfall

Rainfall estimation for the greater Houston area increased last night. Widespread rainfall amounts of 15-25 inches with isolated totals of 30 inches are possible, especially if Harvey stalls and slowly drifts across our area. Please note that these totals are for the duration of the storm. The forecasts are showing 15 to 25 inches over the next 5 to 7 days with the majority failing in the next 3 to 4 days. Like all major storm events, there is still some uncertainty in the exact times, locations, and volumes. Based on some of the National Weather Service forecasts, below is high level estimate of the average rainfall potentials for the Greater Houston Area:

  • Friday 7 AM through Sunday 7 AM (2 Day Outlook Total):  7 to 10 inches
  • Friday 7 AM through Monday 7 AM (3 Day Outlook Total):  10 to 15 inches
  • Friday 7 AM through Wednesday 7 AM (5 Day Outlook Total):  15 to 25 inches

Hurricane Harvey

You can check the status of streams in Harris County at https://www.harriscountyfws.org/. In addition, as rain starts to fall, the National Weather Service West Gulf River Forecast Center may start releasing river flood forecasts, which can be found https://www.weather.gov/wgrfc/.

Wind

As Harvey approaches land, our chances of seeing heavy winds start to decrease. As of this morning’s forecasts our probabilities are:

  • 60 – 80% Chance of Tropical Storm Force Winds (> 39 MPH @ 1 minute average)
  • 10 – 30% Chance of 50-Knot Winds (> 58 MPH @ 1 minute average)
  • 0 – 20% Chance of Hurricane Force Winds (> 74 MPH @ 1 minute average)

UPDATE: 6:00PM 8-24-17

by Craig W. Kalkomey PE, CFM
Department Manager, Hydrology and Hydraulics
Jones|Carter

As many of you are aware, at noon today Harvey was officially upgraded to a Category 1 Hurricane with maximum sustained winds of 85 MPH. As shown on the forecast, Harvey may continue to move in a northwesterly direction making landfall early Saturday morning. Harvey may continue to strengthen and is predicted to hit landfall as a Category 3 Hurricane with maximum sustained winds of 125 MPH.

Harvey map update

Rainfall

Rain and wind have become major concerns for the storm. As of this afternoon, forecasts are still predicting widespread rainfall amounts between 10 and 15 inches with isolated areas of 20 to 30 inches over the next several days. Rainfall of this magnitude could result in widespread flooding of rivers, creeks, and bayous as well as flash flooding where local rainfall rates may exceed 2-4 inches per hour.

At this moment, there are no active flood warnings for the Brazos River from Hempstead to the coast (outside of the storm surge). Based on the rainfall amounts, this could change over the course of the weekend. We may see a rise in the Brazos River, but its maximum height will depend on the final rainfall amount, duration, and location. Regardless of what the Brazos River does, this amount of rainfall could easily create high water events on Bessie’s Creek, Jones Creek, and Oyster Creek, as well as many other creeks, channels, and ponds.

Wind

The Greater Houston Area could see wind speeds between 60 and 100 MPH. These winds could cause considerable damage to sturdy buildings. Some roads could become impassable from large debris and/or flooding. As a reminder, please remember to secure any outdoor items that could be impacted by winds. Any items left outside could become projectiles causing damage to homes or injury to people.


by Erich M. Peterson. P.E.
Vice President, Municipal & District Services
Jones|Carter

As you may have heard, the threat of the tropical wave known as Harvey developed into Tropical Storm Harvey late Wednesday night, and as of 12 PM today, The National Hurricane Center has upgraded Harvey to a hurricane. Below are the official warnings that have been issued.

From KHOU:

A Hurricane Warning is in effect for Matagorda and Jackson Counties.

A Hurricane Watch is in effect for Brazoria County.

A Tropical Storm Watch is in effect for Austin County, Colorado County.

A Tropical Storm Warning is in effect for Brazoria County, Chambers, Fort Bend County, Galveston County, Harris County, Waller County, Wharton County.

Preparation is crucial for effects from both hurricanes and tropical storms. A quick look back in history shows that tropical systems have produced devastating rainfall amounts before:
– TS Allison: 28.5 inches in 12 hrs (NE Harris County)
– TS Claudette: 43.0 inches in 24 hrs (Alvin, TX)
– TS Amelia (1978): 50.0 inches (72 hrs) over Medina and Kerr Counties
– Unnamed (1921): 36.40 inches (18 hrs) Thrall, TX

Below is the latest prediction from the Weather Channel for the expected path, as well as the latest summary from Harris County Flood Control.

Tropical Storm Harvey

“River, creek, bayou, and flash flooding would be a given with [rain] of this magnitude. Unlike so many of the flood events we deal with across this area where isolated areas get the very high totals…the potential here is for a very large area to see excessive amounts of rainfall.

Preparations should include the potential for loss of power and prolonged excessive rainfall and flooding along with prolonged high coastal tides. Some areas near the coast may become cut-off as early as Friday.

Significant rises on area rivers, creeks, and bayous is a real threat and residents living in flood prone areas should be prepared for rising water and potentially significant flooding.” –Kirk Hooper, P.E., Infrastructure Support Manager, Harris County Flood Control District

Harvey Magnitude Harvey Path 1

As far as personal safety, please remember the old saying “Hide from the wind, Run from the water”.  If you are driving during the storm for some reason, use caution as you approach standing water or rushing water.  It does not take very much water to sweep a car or truck off the road, and it does not take a very deep pool of water to stall a car out.  Remember to secure any outdoor items that could be impacted by winds. Any items left outside could become projectiles causing damage to homes or even injury to people. When possible, bring all items in doors.

Are you prepared for Harvey? For Hurricane Preparedness resources check here.

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