BULLETIN
Hurricane Laura Intermediate Advisory Number 28A
NWS National Hurricane Center Miami FL AL132020
700 PM CDT Wed Aug 26 2020
…WINDS INCREASING AS EXTREMELY DANGEROUS HURRICANE LAURA TAKES AIM
AT THE NORTHWEST GULF COAST…
…CATASTROPHIC STORM SURGE, EXTREME WINDS, AND FLASH FLOODING
EXPECTED ALONG THE NORTHWEST GULF COAST TONIGHT…
SUMMARY OF 700 PM CDT…0000 UTC…INFORMATION
———————————————-
LOCATION…28.4N 92.9W
ABOUT 120 MI…190 KM S OF LAKE CHARLES LOUISIANA
ABOUT 120 MI…190 KM SSE OF PORT ARTHUR TEXAS
MAXIMUM SUSTAINED WINDS…150 MPH…240 KM/H
PRESENT MOVEMENT…NNW OR 330 DEGREES AT 15 MPH…24 KM/H
MINIMUM CENTRAL PRESSURE…940 MB…27.76 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:
None.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for…
* Freeport Texas to the Mouth of the Mississippi River
A Hurricane Warning is in effect for…
* San Luis Pass Texas to Intracoastal City Louisiana
A Tropical Storm Warning is in effect for…
* Sargent Texas to San Luis Pass
* East of Intracoastal City Louisiana to the Mouth of the
Mississippi River
A Hurricane Watch is in effect for…
* East of Intracoastal City to west of Morgan City Louisiana
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.
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. Preparations to protect life
and property should be rushed to completion.
A Hurricane Watch means that hurricane conditions are possible
within the watch area.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
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 OUTLOOK
———————-
At 700 PM CDT (0000 UTC), the eye of Hurricane Laura was located
near latitude 28.4 North, longitude 92.9 West. Laura is moving
toward the north-northwest near 15 mph (24 km/h). A turn toward the
north is expected overnight, and a northward motion should continue
on Thursday. A northeastward to east-northeastward motion is
expected Thursday night and Friday. On the forecast track, Laura
will approach the upper Texas and southwest Louisiana coasts this
evening and move inland within that area tonight. The center of
Laura is forecast to move over northwestern Louisiana tomorrow,
across Arkansas Thursday night, and over the mid-Mississippi Valley
on Friday.
Reports from a NOAA Hurricane Hunter aircraft indicate that the
maximum sustained winds have increased to near 150 mph (240 km/h)
with higher gusts. Laura is an extremely dangerous category 4
hurricane on the Saffir-Simpson Hurricane Wind Scale. Some
additional strengthening is possible tonight before Laura reaches
the northwest Gulf coast overnight. Rapid weakening is expected
after Laura moves inland.
Hurricane-force winds extend outward up to 60 miles (95 km) from
the center and tropical-storm-force winds extend outward up to 205
miles (335 km). A sustained wind of 48 mph (78 km/h) was recently
reported at Cypremort Point, Louisiana, on Vermilion Bay.
The minimum central pressure estimated from NOAA Hurricane Hunter
aircraft observations is 940 mb (27.76 inches).
HAZARDS AFFECTING LAND
———————-
Key messages for Laura can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC.
Storm surge and tropical-storm-force winds will arrive within the
warning areas well in advance of Laura’s center. All preparations
to protect life and property should be rushed to completion in the
next few hours.
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 could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide…
Johnson Bayou LA to Rockefeller Wildlife Refuge including Calcasieu
Lake…15-20 ft
Sea Rim State Park TX to Johnson Bayou LA including Sabine
Lake…10-15 ft
Rockefeller Wildlife Refuge to Intracoastal City LA…10-15 ft
Intracoastal City LA to Morgan City including Vermilion Bay…8-12
ft
Port Bolivar TX to Sea Rim State Park…6-9 ft
Morgan City LA to Mouth of the Mississippi River…4-7 ft
Freeport TX to Port Bolivar including Galveston Bay…2-4 ft
Mouth of the Mississippi River to Ocean Springs MS including Lake
Borgne…1-3 ft
Lake Pontchartrain and Lake Maurepas…1-3 ft
The deepest water will occur along the immediate coast near and to
the right of the landfall location, where the surge will be
accompanied by large and destructive waves.
Unsurvivable storm surge with large and destructive waves will cause
catastrophic damage from Sea Rim State Park, Texas, to Intracoastal
City, Louisiana, including Calcasieu and Sabine Lakes. This surge
could penetrate up to 40 miles inland from the immediate coastline,
and flood waters will not fully recede for several days after the
storm.
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 expected in the hurricane warning
area tonight and Thursday, with catastrophic wind damage expected
where Laura’s eyewall moves onshore tonight. Tropical storm
conditions are moving onshore along the coast of Louisiana within
the tropical storm warning area and are expected to spread
northwestward within the warning areas this evening.
Hurricane-force winds and damaging wind gusts are also expected to
spread well inland into portions of eastern Texas and western
Louisiana early Thursday.
RAINFALL: From this evening through Friday, Laura is expected to
produce the following rainfall totals:
Across the northwestern Gulf Coast from far southwest Louisiana and
the Golden Triangle of Southeast Texas: 8 to 12 inches with isolated
totals of 18 inches.
Across central and the rest of western Louisiana into far eastern
Texas: 5 to 10 inches with isolated totals of 15 inches.
Across much of Arkansas: 3 to 7 inches with isolated totals of 10
inches.
This rainfall will cause widespread flash and urban flooding, small
streams and creeks to overflow their banks, and minor to moderate
freshwater river flooding.
By Friday into Saturday, Laura is expected to produce the following
rainfall totals:
Across the mid-Mississippi and portions of the Tennessee Valley,
Lower Ohio Valley, and central Appalachians: 2 to 4 inches with
isolated maximum amounts of 6 inches.
This rainfall may lead to flash and urban flooding and rapid rises
on small streams.
Across the Mid-Atlantic Region: 1 to 3 inches.
TORNADOES: Several tornadoes are expected this evening through
tonight over Louisiana, far southeast Texas, and southwestern
Mississippi. The risk for a few tornadoes will continue into
Thursday across Louisiana, Arkansas, and western Mississippi.
SURF: Swells produced by Laura are affecting the U.S. Gulf coast
from the west coast of Florida to Texas and northeastern Mexico.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local
weather office.