Isaias, advisory 3

000
WTNT34 KNHC 070852
TCPAT4
 
BULLETIN
Tropical Storm Isaias Advisory Number   3
NWS National Hurricane Center Miami FL       AL092026
400 AM CDT Wed Oct 07 2026
 
...DEPRESSION BECOMES TROPICAL STORM ISAIAS...
...FORECAST TO RAPIDLY STRENGTHEN OVER THE NEXT COUPLE OF DAYS...
 
 
SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...22.0N 94.1W
ABOUT 285 MI...460 KM W OF PROGRESO MEXICO
ABOUT 580 MI...935 KM SW OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...ENE OR 75 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES
 
 
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
 
Interests in the Yucatan Peninsula of Mexico and the U.S. northern
Gulf Coast should closely monitor the progress of this system.
 
Hurricane Watches will likely be required for a portion of the U.S.
northern Gulf coast later today.
 
 
DISCUSSION AND OUTLOOK
----------------------
At 400 AM CDT (0900 UTC), the center of Tropical Storm Isaias was 
located near latitude 22.0 North, longitude 94.1 West. Isaias is 
moving toward the east-northeast near 8 mph (13 km/h). A continued 
east-northeastward motion is expected today, followed by a turn 
toward the northeast and north on Thursday and Friday. On the 
forecast track, Isaias is expected to pass to the north of the 
Yucatan Peninsula on Thursday and approach the U.S. northern Gulf 
Coast on Friday.
 
Maximum sustained winds have increased to near 40 mph (65 km/h) with
higher gusts. Rapid strengthening is forecast over the next day or
two, and Isaias is expected to become a hurricane by Thursday.
 
Tropical-storm-force winds extend outward up to 45 miles (75 km)
from the center.
 
The estimated minimum central pressure is 1004 mb (29.65 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.
 
RAINFALL: Isaias is expected to produce rainfall amounts of 2 to 4 
inches through Thursday across coastal portions of the Bay of 
Campeche with isolated higher amounts possible in the states of 
Campeche and western Yucatan.

From Friday through the weekend, Isaias is expected to produce 
rainfall amounts of 3 to 6 inches, with localized totals up to 10 
inches, across the northern 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.
 
WIND: Gusty winds are possible in portions of the Yucatan Peninsula
on Thursday.
 
SURF: Swells are expected to affect the western and northern
portions of the Yucatan Peninsula beginning on Thursday and spread
northward toward the Gulf Coast late this week. 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 complete advisory at 1000 AM CDT.
 
$$
Forecaster Papin
 

000
WTNT44 KNHC 070857
TCDAT4
 
Tropical Storm Isaias Discussion Number   3
NWS National Hurricane Center Miami FL       AL092026
400 AM CDT Wed Oct 07 2026
 
Satellite imagery depicts a bursting pattern with the tropical 
cyclone this morning, with cloud top temperatures below -85 C in the 
deep convection close to the estimated center. Earlier, an 0307 UTC 
ASCAT-C pass suggested the low-level circulation was still rather 
broad, with a peak wind retrieval of only 31 kt. However, the 
bursting convection already appears to be tightening up the 
circulation somewhat, with a nearby surface observation from a buoy 
north of the center recently reporting a sustained 10 m adjusted 
wind of 35 kt. This information is enough to upgrade the depression 
to Tropical Storm Isaias for this advisory. This initial intensity 
will be 35 kt, which also agrees with the 06 UTC Dvorak fix of 
T2.5/35 kt. Both Air Force Reserve and NOAA Hurricane Hunter 
reconnaissance missions are scheduled to sample the tropical storm 
later today. 
 
Isaias is estimated to be moving east-northeastward this morning at 
075/7 kt. This general motion should continue today as the storm's 
steering is influenced by a zonally oriented mid-level trough 
currently draped along the northern Gulf coast. Over time, this 
trough is expected to be reinforced by another short-wave that is 
moving across the Rocky Mountains, with the trough ultimately 
sharpening up northwest of Isaias over Texas. At the same time, a 
subtropical ridge centered south of Bermuda is expected to shift 
westward, helping to enhance the deep-layer southerly flow over the 
eastern Gulf. Thus, Isaias is expected to turn northeastward and 
then northward on Thursday and Friday, making its approach to the 
northern Gulf coast in 60-72 h. As mentioned in the previous 
discussion, there remains quite a bit of along and across-track 
spread in the track guidance, with the AI-model guidance remaining 
on the east side, and physics-based models on the west side of the 
guidance envelope. The NHC track forecast continues to favor more of 
the eastward solutions, but not quite as far east as the latest HFIP 
Corrected Consensus Approach (HCCA) or Google DeepMind ensemble mean 
(GDMI). This latest track is a eastward shift compared to the 
previous forecast, but given large amount of across- and along-track 
spread users should continue to monitor forecast updates given the 
below-average track confidence.

The short-term environment near Isaias is rather favorable, with 
very warm 30-31 C sea-surface temperatures, plenty of deep-layer 
moisture, with light to moderate shear diagnosed between 10-15 kt by 
SHIPS guidance. While it is difficult to get an exact gauge on the 
tropical storm's core structure since there have not been any 
recent microwave images, it is worth noting both the 00 UTC HAFS-A/B 
runs appeared to initialize with a broad structure similar to what 
was noted in the earlier ASCAT pass. Despite their initial broad 
structure, these hurricane-regional models show Isaias developing an 
inner-core rather quickly later today. There was a notable increase 
in the intensity aid guidance this forecast cycle, and the NHC 
intensity forecast is being raised accordingly, now showing Isaias 
reaching a peak intensity of 95 kt in 48 h while it is over the 
central Gulf. Vertical wind shear then increases quite dramatically 
in the final 24 hours before the cyclone reaches the northern Gulf 
coast, though it is looking more likely that Isaias will be a 
significant hurricane when it reaches the coast. Near landfall, 
Isaias will also be interacting with the short-wave trough, likely 
leading to an expanding wind field. Additional convective and 
motion asymmetries will likely cause rain and wind impacts to 
extend far from the center on the eastern side of the storm.
 
Key Messages:
 
1. There is an increasing risk of dangerous wind and storm surge 
impacts along portions of the northern Gulf Coast. Residents from 
Louisiana to the Florida Panhandle should closely monitor the latest 
forecast updates and ensure they have their hurricane plan in place. 
Hurricane and Storm Surge Watches will likely be required for a 
portion of the northern Gulf coast later today. 
 
2. Tropical Storm 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.
 
3. Yucatan Peninsula of Mexico: Tropical Storm Isaias is expected to
strengthen and could bring gusty winds and areas of heavy rain to
the western portion of the Yucatan Peninsula over the next day or 
two. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/0900Z 22.0N  94.1W   35 KT  40 MPH
 12H  07/1800Z 22.2N  92.9W   50 KT  60 MPH
 24H  08/0600Z 22.7N  91.4W   65 KT  75 MPH
 36H  08/1800Z 23.9N  89.7W   80 KT  90 MPH
 48H  09/0600Z 25.5N  88.5W   95 KT 110 MPH
 60H  09/1800Z 27.7N  87.7W   90 KT 105 MPH
 72H  10/0600Z 30.8N  87.7W   75 KT  85 MPH...INLAND
 96H  11/0600Z 38.2N  87.5W   25 KT  30 MPH...POST-TROP/INLAND
120H  12/0600Z...DISSIPATED
 
$$
Forecaster Papin