Hurricane Harvey’s winds are weakening this morning over the Coastal Plains and eastern sections of South-Central Texas. Maximum sustained winds are estimated to be near 100 MPH, although that might be a bit generous based on recent surface observations. The center of Harvey is located 30 miles southwest of Victoria or 105 miles southeast of San Antonio. We’ll continue to winds wind-down and Harvey should be below hurricane strength later today. That’s the good news with this forecast, but there is considerable bad news.
Harvey will not be moving much over the next five days from its present location. At most, we might see Harvey perform a small loop across the Coastal Plains. The low pressure associated with Harvey will remain intact, providing plenty of lift to support bands of prolifically heavy rain.
Wind fields east of Harvey will be favorable for rotating thunderstorms capable of producing brief tornadoes through at least Monday across Southeast Texas. A tornado watch is in effect with several tornado warnings this morning. Expect this issue to continue for the next three days – or through at least Monday.
Specific 12-hourly rainfall forecasts will depend on the location of Harvey’s bands of thunderstorms. It won’t rain at a given location all the time over the next five days, but don’t let that deceive you about the seriousness of the event. Rainfall rates will be ridiculous – exceeding four inches per hour in some cases. We’ll see plenty of training thunderstorms and lots of widespread heavy rainfall over the next five days. With a strong agreement in weather models here is the latest National Weather Service’s precipitation total forecast through Wednesday.
Per the Weather Prediction Center, there is a high risk of flash flooding across Southeast Texas, the Coastal Plains, Middle Texas Coast, extending west to near Interstate 35 in South-Central Texas. Like a severe weather outlook, a high risk is fairly rare. There is a high risk of flash flooding on Sunday and Monday over the same areas – something that has never been seen before from the Weather Prediction Center… because they’ve never issued a ‘high risk’ of flooding three days out until yesterday.
Here is the full 4 AM advisory from the National Hurricane Center on Harvey. I’ll be getting a few hours of shut-eye so our feeds will be quiet for a bit. You can expect my next activity to be around 10 AM.
Hurricane Harvey Advisory Number 24
NWS National Hurricane Center Miami FL AL092017
400 AM CDT Sat Aug 26 2017
…HARVEY MOVING SLOWLY INLAND OVER SOUTH TEXAS…
…CATASTROPHIC FLOODING EXPECTED OVER THE NEXT FEW DAYS DUE TO
SUMMARY OF 400 AM CDT…0900 UTC…INFORMATION
ABOUT 30 MI…50 KM SW OF VICTORIA TEXAS
ABOUT 105 MI…170 KM SE OF SAN ANTONIO TEXAS
MAXIMUM SUSTAINED WINDS…100 MPH…155 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 6 MPH…9 KM/H
MINIMUM CENTRAL PRESSURE…963 MB…28.44 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The Hurricane Warning and Storm Surge Warning have been
discontinued south of Baffin Bay. The Hurricane Warning north of
Port O’Connor to Sargent has been changed to a Tropical Storm
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for…
* Baffin Bay to High Island Texas
A Hurricane Warning is in effect for…
* Baffin Bay to Port O’Connor Texas
A Tropical Storm Warning is in effect for…
* North of Port O’Connor to High Island Texas
A Storm Surge Warning means there is a danger of life-threatening
inundation from rising water moving inland from the coastline 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.
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. Preparations to protect life and
property should already be complete.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning.
Interests in southwestern Louisiana should continue to monitor the
progress of this system.
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
DISCUSSION AND 48-HOUR OUTLOOK
At 400 AM CDT (0900 UTC), the eye of Hurricane Harvey was located
by NOAA Doppler radar near latitude 28.5 North, longitude 97.2 West.
Harvey is moving toward the northwest near 6 mph (9 km/h). Harvey
is expected to slow down through the day and meander over
southeastern Texas through the middle of next week.
Doppler radar data indicate that maximum sustained winds have
decreased to near 100 mph (155 km/h) with higher gusts. Additional
weakening is forecast, and Harvey is likely to become a tropical
storm later today.
Hurricane-force winds extend outward up to 35 miles (55 km) from the
center, and tropical-storm-force winds extend outward up to 140
miles (220 km).
The estimated minimum central pressure is 963 mb (28.44 inches).
Almost 10 inches of rain have already been reported at a few
locations in southeastern Texas.
HAZARDS AFFECTING LAND
RAINFALL: Harvey is expected to produce total rain accumulations of
15 to 30 inches and isolated maximum amounts of 40 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 15 inches in far south Texas and the Texas Hill Country over
through southwest and central Louisiana. Rainfall of this magnitude
will cause catastrophic and 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…
Port Aransas to Port O’Connor…6 to 12 ft
Port O’Connor to Sargent…6 to 9 ft
Sargent to Jamaica Beach…4 to 6 ft
Baffin Bay to Port Aransas…3 to 6 ft
Jamaica Beach to High Island…2 to 4 ft
Mouth of the Rio Grande to Port Mansfield…1 to 3 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 occuring inland from the coast
within Harvey’s eyewall, and hurricane-force winds, especially in
gusts, are still possible near the middle Texas coast for the next
several hours. Tropical storm conditions are occurring in other
portions of the hurricane and tropical storm warning areas.
Tropical storm conditions are likely to persist along portions of
the coast through at least Sunday.
SURF: Swells generated by Harvey are affecting the Texas,
Louisiana, and northeast Mexico coasts. These swells are likely to
cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.
TORNADOES: Tornadoes are possible today and tonight near the middle
and upper Texas coast into far southwest Louisiana.