Harvey has rapidly organized this morning and is just below hurricane strength. Based on atmospheric conditions and the system approaching a warm eddy associated with the very warm Gulf stream – rapid intensification is likely. This means that the intensity forecast for Harvey has been significantly increased. Harvey is now expected to make landfall as a major hurricane along the South Texas and the Coastal Bend coast – riviling the intnesity of Ike. We’re going to have to see a fairly fast ramp-up in coastal evacuations now that Harvey is forecast to make landfall with at least category 3 intensity. A life-threatening storm surge of 7 to 10 feet is expected in the northeast quadrant of the eye wall along with sustained winds over 115 MPH. This rapid intensification trend does not change the fact Harvey will likely stall over South/South-Central Texas this weekend into early next week. Widespread rain totals over 10 to 20 inches with localized amounts to 30 inches are expected – resulting in a widespread, devastating flood event in South Texas, the Coastal Plains, and Southeast Texas. Rain totals will have a sharp cut-off west of Harvey.

Key Messages:

1. Harvey has intensified quickly this morning, and is now forecast
to be a major hurricane at landfall, bringing life-threatening storm
surge, rainfall, and wind hazards to portions of the Texas coast.
Preparations to protect life and property should be completed by
tonight, as tropical-storm-force winds will first arrive in the
hurricane and storm surge warning areas on Friday.

2. A Storm Surge Warning is in effect for much of the Texas coast.
Life-threatening storm surge flooding could reach heights of 6 to 10
feet above ground level at the coast between the north entrance of
the Padre Island National Seashore and Sargent. For a depiction of
areas at risk, see the Storm Surge Watch/Warning Graphic at
hurricanes.gov.

3. Life-threatening flooding is expected across much of the Texas
coast from heavy rainfall of 12 to 20 inches, with isolated amounts
as high as 30 inches, from Friday through early next week. Please
refer to products from your local National Weather Service office
and the NOAA Weather Prediction Center for more information on the
flooding hazard.

4. The Potential Storm Surge Flooding Map is available on the NHC
website. This product depicts a reasonable worst-case scenario –
the amount of inundation that has a 10 percent chance of being
exceeded at each individual location. This map best represents
the flooding potential in those locations within the watch and
warning areas.

Tropical Storm Harvey Advisory Number 16
NWS National Hurricane Center Miami FL AL092017
1000 AM CDT Thu Aug 24 2017

…HARVEY QUICKLY STRENGTHENING AND FORECAST TO BE A MAJOR
HURRICANE WHEN IT APPROACHES THE MIDDLE TEXAS COAST…
…LIFE-THREATENING STORM SURGE AND FRESHWATER FLOODING EXPECTED…

 

SUMMARY OF 1000 AM CDT…1500 UTC…INFORMATION
———————————————–
LOCATION…24.0N 93.3W
ABOUT 365 MI…590 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 360 MI…580 KM SSE OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS…65 MPH…100 KM/H
PRESENT MOVEMENT…NNW OR 340 DEGREES AT 10 MPH…17 KM/H
MINIMUM CENTRAL PRESSURE…982 MB…29.00 INCHES

 

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for…
* Port Mansfield to San Luis Pass Texas

A Storm Surge Watch is in effect for…
* South of Port Mansfield Texas to the Mouth of the Rio Grande
* North of San Luis Pass to High Island Texas

A Hurricane Warning is in effect for…
* Port Mansfield to Matagorda Texas

A Tropical Storm Warning is in effect for…
* North of Matagorda to High Island Texas
* South of Port Mansfield Texas to the Mouth of the Rio Grande

A Hurricane Watch is in effect for…
* South of Port Mansfield Texas to the Mouth of the Rio Grande

A Tropical Storm Watch is in effect for…
* South of the Mouth of the Rio Grande to Boca de Catan Mexico

A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
during the next 36 hours in the indicated locations. For a
depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov. This is a life-threatening situation. Persons
located within these areas should take all necessary actions to
protect life and property from rising water and the potential for
other dangerous conditions. Promptly follow evacuation and other
instructions from local officials.

A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. A warning is typically issued
36 hours before the anticipated first occurrence of tropical-storm-
force winds, conditions that make outside preparations difficult or
dangerous. Preparations to protect life and property should be
rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.

A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations during the next 48 hours.

A Hurricane Watch means that hurricane conditions are possible
within the watch area.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area.

In addition, interests in southwestern Louisiana should continue to
monitor the progress of this system.

For storm information specific to your area in the United
States, including possible inland watches and warnings, please
monitor products issued by your local National Weather Service
forecast office. For storm information specific to your area outside
the United States, please monitor products issued by your national
meteorological service.

 

DISCUSSION AND 48-HOUR OUTLOOK
——————————
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Harvey was
located by an Air Force Reserve Hurricane Hunter aircraft near
latitude 24.0 North, longitude 93.3 West. Harvey is moving toward
the north-northwest near 10 mph (17 km/h). A turn toward the
northwest is expected later today, and Harvey’s forward speed is
forecast to slow down during the next couple of days. On the
forecast track, Harvey will approach the middle Texas coast on
Friday and make landfall Friday night or early Saturday, and then
stall near the middle Texas coast through the weekend.

Data from the Hurricane Hunter plane indicate that maximum sustained
winds have increased to near 65 mph (100 km/h) with higher gusts.
Rapid strengthening is forecast, and Harvey is expected to become a
major hurricane before it reaches the middle Texas coast.

Tropical-storm-force winds extend outward up to 90 miles (150 km)
from the center.

The minimum central pressure based on reconnaissance data is 982 mb
(29.00 inches).

 

HAZARDS AFFECTING LAND
———————-
RAINFALL:

Harvey is expected to produce total rain accumulations of
12 to 20 inches and isolated maximum amounts of 30 inches over the
middle and upper Texas coast through next Wednesday. During the same
time period Harvey is expected to produce total rain accumulations
of 5 to 12 inches in far south Texas and the Texas Hill Country to
central Louisiana, with accumulations of less than 5 inches
extending into other parts of Texas and the lower Mississippi
Valley. Rainfall from Harvey may cause life-threatening flooding.

STORM SURGE:

The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline. The water is
expected to reach the following heights above ground if the peak
surge occurs at the time of high tide…

N Entrance Padre Island Natl Seashore to Sargent…6 to 10 ft
Sargent to San Luis Pass…5 to 7 ft
Port Mansfield to N Entrance Padre Island Natl Seashore…5 to 7 ft
San Luis Pass to High Island…2 to 4 ft
Mouth of the Rio Grande to Port Mansfield…2 to 4 ft
High Island to Morgan City…1 to 3 ft

The deepest water will occur along the immediate coast near and to
the northeast of the landfall location, where the surge will be
accompanied by large and destructive waves. Surge-related flooding
depends on the relative timing of the surge and the tidal cycle, and
can vary greatly over short distances. For information specific to
your area, please see products issued by your local National Weather
Service forecast office.

 

WIND:

Hurricane conditions are likely within the hurricane warning
area late Friday or Friday night, with tropical storm conditions
expected to first reach the coast in the hurricane warning area
Friday.

SURF: Swells generated by Harvey are likely to affect the Texas,
Louisiana, and northeast Mexico coasts by Friday. These swells are
likely to cause life-threatening surf and rip current conditions.
Please consult products from your local weather office.