Hurricane Harvey Local Statement Advisory Number 18
National Weather Service Austin/San Antonio TX AL092017
431 PM CDT Thu Aug 24 2017

This product covers SOUTH CENTRAL TEXAS

Hurricane Harvey expected to bring a life-threatening heavy rainfall
event across South Central Texas

NEW INFORMATION

• CHANGES TO WATCHES AND WARNINGS:
• None

• CURRENT WATCHES AND WARNINGS:

• A Tropical Storm Warning is in effect for Atascosa, Bastrop,
  Bexar, Caldwell, Fayette, Gonzales, Guadalupe, Lavaca, and
  Wilson

• A Hurricane Warning is in effect for De Witt and Karnes

• STORM INFORMATION:

• About 450 miles south-southeast of Austin TX or about 370 miles
  southeast of Cuero TX
• 24.7N 93.9W
• Storm Intensity 85 mph
• Movement North-northwest or 330 degrees at 10 mph

SITUATION OVERVIEW

Harvey continues to strengthen and is now a Category One Hurricane.
Harvey is still moving slowly northwestward in the Gulf of Mexico. This
northwestward movement is expected to continue and Harvey should
approach the Texas coast late Friday into Saturday. Confidence
continues to increase for tropical storm winds and a significant heavy
rainfall event across South Central Texas beginning Friday afternoon
and continuing through Tuesday. Flash flooding and river flooding
continue to be the main concerns, mainly within the Tropical Storm
Warning and Flash Flood Watch areas.

Hurricane Harvey will produce a life-threatening heavy rainfall event.
Storm total rainfall amounts from Friday through Tuesday could be in
the 10 to 20 inch range along and east of Interstate 35 with isolated
totals in excess of 25 inches possible over areas south of Interstate
10 as Harvey is expected to stall over the area. Devastating mainstem
river flooding is possible east of Interstate 35 and south of
Interstate 10.

Additionally, hurricane force winds of 70 to 80 mph will be possible
for the counties within the Hurricane Warning, while 40 to 50 mph
winds with some gusts to 60 mph will be possible for areas within the
Tropical Storm Warning. The timing of these winds look to arrive Friday
night through Saturday morning. There is a low risk of brief tornadoes
east of Interstate 35 and south of Interstate 10 Friday evening into
the weekend associated with tropical rain bands.

POTENTIAL IMPACTS

• FLOODING RAIN:
  Protect against life-threatening rainfall flooding having possible
  devastating impacts across areas east of Interstate 35 and south of
  Interstate 10. Potential impacts include:
• Extreme rainfall flooding may prompt numerous evacuations and
  rescues.
• Rivers and tributaries may overwhelmingly overflow their banks
  in many places with deep moving water. Small streams, creeks,
  canals, arroyos, and ditches may become raging rivers. In
  mountain areas, deadly runoff may rage down valleys while
  increasing susceptibility to rockslides and mudslides. Flood
  control systems and barriers may become stressed.
• Flood waters can enter numerous structures within multiple
  communities, some structures becoming uninhabitable or washed
  away. Numerous places where flood waters may cover escape
  routes. Streets and parking lots become rivers of raging water
  with underpasses submerged. Driving conditions become very
  dangerous. Numerous road and bridge closures with some weakened
  or washed out.

Protect against life-threatening rainfall flooding having possible
limited to extensive impacts across areas along and east of the
Interstate 35 Corridor.

• WIND:
  Protect against life-threatening wind having possible devastating
  impacts across areas in the Tropical Storm and Hurricane Warnings
  mainly east of Interstate 35. Potential impacts in this area include:
• Structural damage to sturdy buildings, some with complete roof
  and wall failures. Complete destruction of mobile homes. Damage
  greatly accentuated by large airborne projectiles. Locations
  may be uninhabitable for weeks or months.
• Numerous large trees snapped or uprooted along with fences and
  roadway signs blown over.
• Many roads impassable from large debris, and more within urban
  or heavily wooded places. Many bridges, causeways, and access
  routes impassable.
• Widespread power and communications outages.

Also, protect against life-threatening wind having possible limited
to extensive impacts across areas along and east of the Interstate 35
Corridor.

• TORNADOES:
  Protect against a tornado event having possible limited impacts across
  areas within the Tropical Storm and Hurricane Warnings. Potential
  impacts include:
• The occurrence of isolated tornadoes can hinder the execution
  of emergency plans during tropical events.
• A few places may experience tornado damage, along with power
  and communications disruptions.
• Locations could realize roofs peeled off buildings, chimneys
  toppled, mobile homes pushed off foundations or overturned,
  large tree tops and branches snapped off, shallow-rooted trees
  knocked over, moving vehicles blown off roads, and small boats
  pulled from moorings.

Elsewhere across SOUTH CENTRAL TEXAS, little to no impact is
anticipated.

PRECAUTIONARY/PREPAREDNESS ACTIONS

• OTHER PREPAREDNESS INFORMATION:
  |Now is the time to bring to completion all preparations to protect
  life and property in accordance with your emergency plan.

Check-in with your emergency points of contact among family, friends,
and workmates. Inform them of your status and well-being. Let them know
how you intend to ride out the storm and when you plan to check-in
again.

In emergencies it is best to remain calm. Stay informed and focused
on the situation at hand. Exercise patience with those you encounter.
Be a Good Samaritan and helpful to others.

If relocating to a nearby shelter or to the home of a family member
or friend, drive with extra caution, especially on secondary roads.
Remember, many bridges and causeways will be closed once higher winds
arrive. Also, if you encounter water covering the road, seek an
alternate route. Always obey official road signs for closures and
detours.

Closely monitor NOAA Weather radio or other local news outlets for
official storm information. Be ready to adapt to possible changes to
the forecast.

• ADDITIONAL SOURCES OF INFORMATION:
• For information on appropriate preparations see ready.gov
• For information on creating an emergency plan see getagameplan.org
• For additional disaster preparedness information see redcross.org

NEXT UPDATE

The next local statement will be issued by the National Weather
Service in Austin/San Antonio TX around 11 PM CDT, or sooner if
conditions warrant.