Isaias, advisory 7

000
WTNT34 KNHC 080854
TCPAT4
 
BULLETIN
Hurricane Isaias Advisory Number   7
NWS National Hurricane Center Miami FL       AL092026
400 AM CDT Thu Oct 08 2026
 
...NOAA HURRICANE HUNTERS INDICATE THAT ISAIAS CONTINUES TO
INTENSIFY...
...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND 
DAMAGING WINDS ALONG THE WARNING AREA OF THE GULF COAST SHOULD BE 
RUSHED TO COMPLETION TODAY...
 
 
SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...23.3N 91.2W
ABOUT 170 MI...270 KM NW OF PROGRESO MEXICO
ABOUT 420 MI...680 KM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...ENE OR 60 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES
 
 
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
 
None.
 
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
 
A Storm Surge Warning is in effect for...
* Mouth of the Mississippi River to the Steinhatchee River, FL
 
A Hurricane Warning is in effect for...
* Ocean Springs, MS to the Bay/Gulf County Line, FL
 
A Tropical Storm Warning is in effect for...
* Jefferson/Plaquemines Parish Line, LA to west of Ocean Springs, MS
* East of Bay/Gulf County Line to Aucilla River, FL
 
A Storm Surge Watch is in effect for...
* Steinhatchee River to Yankeetown, FL
 
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. For
a depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov.
 
Interests in the Yucatan Peninsula of Mexico and elsewhere along the
U.S. northern Gulf Coast should closely 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 OUTLOOK
----------------------
At 400 AM CDT (0900 UTC), the eye of Hurricane Isaias was located by 
NOAA Hurricane Hunter aircraft near latitude 23.3 North, longitude 
91.2 West. Isaias is moving toward the east-northeast near 9 mph  
(15 km/h). A turn toward the northeast is expected later today 
followed by a turn northward on Friday. On the forecast track, 
Isaias is expected to pass to the north of the Yucatan Peninsula 
later today and make landfall along the U.S. northern Gulf Coast 
within the warning area late Friday or early Saturday.
 
Maximum sustained winds have increased near 80 mph (130 km/h) with
higher gusts. Additional strengthening is expected through early
Friday, and Isaias should remain a strong hurricane as it approaches
the northern Gulf Coast on Friday night.
 
Hurricane-force winds extend outward up to 15 miles (30 km) from the
center and tropical-storm-force winds extend outward up to 90 miles
(150 km).
 
The estimated minimum central pressure measured recently by NOAA 
Hurricane Hunter dropsonde data 979 mb (28.91 inches).
 
 
HAZARDS AFFECTING LAND
----------------------
Key messages for Isaias can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC.
 
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...
 
Ocean Springs, MS to Indian Pass, FL...5-7 ft
Mobile Bay...5-7 ft
Mouth of the Mississippi River, LA to Ocean Springs, MS...3-5 ft
Indian Pass, FL to Steinhatchee River, FL...4-6 ft
Steinhatchee River, FL to Yankeetown, FL...2-4 ft
Lake Pontchartrain...1-3 ft
 
The deepest water will occur along the immediate coast near and to
the east of the landfall location, where the surge will be
accompanied by large and dangerous 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.
 
For a complete depiction of areas at risk of storm surge inundation,
please see the National Weather Service Peak Storm Surge Graphic,
available at hurricanes.gov/graphics_at4.shtml?peakSurge.
 
WIND: Hurricane conditions are expected within the Hurricane Warning
area Friday night into early Saturday, with tropical storm
conditions beginning on Friday. Tropical storm conditions are
expected in the warning areas on Friday and Friday night.
 
Gusty winds are possible in portions of the Yucatan Peninsula later
today.
 
RAINFALL: Isaias is expected to produce rainfall amounts of 1 to 3
inches through today across coastal portions of the eastern Bay
of Campeche with isolated higher amounts possible in the states of
Campeche and western Yucatan.
 
From Friday through the weekend, the system is expected to produce
rainfall amounts of 3 to 7 inches, with localized totals up to 10
inches, across the central U.S. Gulf Coast extending from far
southeastern Louisiana to the Florida Panhandle. Rainfall amounts of
1 to 3 inches, with localized amounts up to 5 inches, are possible
across much of the Southeast as far north as the Tennessee Valley
and the Carolinas. Flash and urban flooding, along with isolated
river flooding, will be possible.
 
For a complete depiction of forecast rainfall associated with
Isaias, please see the National Weather Service Storm Total Rainfall
Graphic available at hurricanes.gov/graphics_at4.shtml?rainqpf and
the Flash Flood Risk graphic at
hurricanes.gov/graphics_at4.shtml?ero
 
TORNADOES: Isolated tornadoes will be possible Friday night in 
coastal areas of Alabama and the Florida Panhandle and far 
southwestern Georgia. The tornado threat will continue Saturday for 
eastern Alabama, Georgia and northern Florida.
 
SURF: Swells will affect the western and northern portions of the 
Yucatan Peninsula beginning later today and spread northward toward 
the Gulf Coast on Friday. These swells are likely to cause 
life-threatening surf and rip current conditions. Please consult 
products from your local weather office.
 
A depiction of rip current risk for the United States can be found
at: hurricanes.gov/graphics_at4.shtml?ripCurrents
 
 
NEXT ADVISORY
-------------
Next intermediate advisory at 700 AM CDT.
Next complete advisory at 1000 AM CDT.
 
$$
Forecaster Papin
 

000
WTNT44 KNHC 080856
TCDAT4
 
Hurricane Isaias Discussion Number   7
NWS National Hurricane Center Miami FL       AL092026
400 AM CDT Thu Oct 08 2026
 
Right after the previous advisory, Air Force Reserve hurricane 
hunter aircraft launched a dropsonde in the southwest quadrant of 
the storm, finding a 150 m boundary layer average wind of 76 kt, 
which was the basis for upgrading Isaias to a hurricane at 0330 UTC. 
Since that time, a NOAA-P3 aircraft has taken over the in-situ 
sampling of the hurricane, finding that Isaias continues to 
intensify. The Tail Doppler Radar (TDR) swaths still indicate some 
northward tilt with height, likely an impact of moderate westerly 
vertical wind shear that continues to impinge on the circulation, 
though the circulation is more aligned than in yesterday's mission. 
The peak TDR winds were up to 80 kt on the 500 m level, and 
experimental data that reduces the peak TDR winds to the 10 meter 
level support a maximum sustained wind of 70 kt this advisory.
 
Aircraft fixes indicate that Isaias continues to maintain a
east-northeastward heading at 060/8 kt. The most critical steering
feature is a subtropical ridge centered east of the Bahamas that is
building westward, leading to an enhancement of environmental
southerly flow over the eastern Gulf. At the same time, a mid-level
trough stretched across the northern Gulf coast will be reinforced
by another impulse digging in from the Rocky Mountains, leading to a
more amplified short-wave over east Texas. The net effect of these
synoptic features should result in Isaias making a turn to the
northeast and the north over the next 24-48 h. The guidance this
cycle has not changed appreciably since the previous cycle, and
there continue to be across-track differences between the further
west physics-based models, and further east AI/Machine
Learning-based models. The NHC track forecast remains very close to
the prior one, and continues to lead more on the Google DeepMind
ensemble mean (GDMI) and HFIP Corrected Consensus Approach (HCCA)
track aids, which have been our best performing track guidance this
year.  As mentioned previously, after Isaias moves inland, the
guidance is showing a more subtle westward shift as Isaias is
captured by the short wave trough to its west, leading in the
formation of a potent cutoff low over the Tennessee valley as the
tropical cyclone becomes post-tropical.
 
The intensity forecast continues to be somewhat tricky. Isaias has 
been trying to become better vertically aligned despite dealing with 
around 20 kt of westerly vertical wind shear, and an eyewall keeps 
coming and going in aircraft fixes. Other environmental factors (30 
C sea-surface temperatures, sufficient deep-layer moisture) are 
quite favorable. Because the shear is not forecast to increase 
appreciably for the next 24 h, and because the hurricane has been 
intensifying despite the shear, significant intensification is still 
shown in the short-term, making Isaias just shy of major hurricane 
intensity in 24 h. This part of the intensity forecast is on the 
higher end of the guidance, close to the HCCA and GDMI intensity 
aids. In the final 12-24 h before Isaias makes landfall on the north 
Gulf coast, vertical wind shear ramps up to 40-50 kt, and this will 
likely impart some weakening. However, at the same time, the 
hurricane's wind field may become broader and more asymmetric as it 
begins to interact with the short-wave trough capturing it from the 
west. Regardless, Isaias is expected to remain a dangerous hurricane 
through landfall, and gusty winds are expected well inland after 
landfall given the anticipated expansion of the wind field and 
accelerating forward speed of the storm.
 
Key Messages:
 
1. Isaias is expected to strengthen and be a strong hurricane when
it approaches the northern Gulf Coast on Friday. A life-threatening
storm surge is expected along a portion of the northern Gulf Coast,
and a Storm Surge Warning remains in effect from the Mouth of the
Mississippi River to Steinhatchee, Florida. Residents in the warning
area should follow advice given by local officials and evacuate if
told to do so.
 
2. Damaging hurricane force-winds are expected over portions of the
Florida Panhandle, southern Alabama, and southern Mississippi, and a
Hurricane Warning remains in effect from Ocean Springs, Mississippi
to the Bay/Gulf County Line, Florida. Residents in these areas
should prepare for the possibility of long-duration power outages.
 
3. Isaias will bring areas of heavy rainfall to the central U.S.
Gulf coast and much of the Southeast Friday into the weekend. Flash
and urban flooding, along with isolated river flooding, will be
possible.
 
4. Isaias could bring gusty winds and areas of heavy rain to the
western portion of the Yucatan Peninsula through today. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/0900Z 23.3N  91.2W   70 KT  80 MPH
 12H  08/1800Z 24.2N  90.0W   85 KT 100 MPH
 24H  09/0600Z 25.9N  88.6W   95 KT 110 MPH
 36H  09/1800Z 28.4N  87.6W   90 KT 105 MPH
 48H  10/0600Z 31.0N  87.6W   55 KT  65 MPH...INLAND
 60H  10/1800Z 33.7N  88.5W   30 KT  35 MPH...POST-TROP/INLAND
 72H  11/0600Z 36.0N  88.7W   25 KT  30 MPH...POST-TROP/INLAND
 96H  12/0600Z...DISSIPATED
 
$$
Forecaster Papin