Advisories

000
WTNT44 KNHC 072049
TCDAT4
 
Tropical Storm Isaias Discussion Number   5
NWS National Hurricane Center Miami FL       AL092026
400 PM CDT Wed Oct 07 2026
 
Satellite and aircraft data show that Isaias continues to 
strengthen.  GOES-19 imagery indicates that a central dense overcast 
has formed, and the system has become more symmetric than this 
morning.  The peak NOAA Hurricane Hunter aircraft 700-mb winds 
were 61 kt, with the pressure dropping to 994 mb.  The initial 
intensity is set to 55 kt as a reflection of this data.
 
Isaias is basically on track, moving east-northeast at 7 kt. There 
is no change to the synoptic reasoning as a deepening trough along 
the northwestern Gulf Coast and a strengthening Atlantic subtropical 
ridge should cause the system to move faster to the northeast 
tomorrow and northward on Friday.  As long as the cyclone remains 
intact, it makes physical sense that the system will move on the 
faster and eastward side of the guidance due to the stronger shear 
Isaias should encounter near landfall.  Thus, the new forecast is 
adjusted slightly to the east, closer to the AI-based and 
corrected-consensus models.
 
NOAA radar data (P3-TDR) show that the system is experiencing some 
southwesterly shear, with tilt analyses displaying the mid-level 
circulation displaced 5-10 n mi to the northeast of the low-level 
center.  This structure seems sufficient for further intensification 
given a continuation of similar low or moderate shear and very warm 
SSTs in a very humid environment.  Models are fairly consistent 
about the shear increasing on Friday, but almost all guidance still 
shows a category 1 or 2 hurricane at landfall.  While the regional 
hurricane models have generally come down on the peak intensity this 
cycle, it is unknown whether this is the start of a real trend, and 
we would prefer to see more than one guidance cycle before making 
any adjustments.  The new forecast is close to the previous one, 
near the high side of the model suite.
 
Key Messages:
 
1. Isaias is expected to strengthen and be a strong hurricane when 
it approaches the northern Gulf Coast on Friday. There is an 
increasing risk of life-threatening storm surge along portions of 
the northern Gulf Coast, and a Storm Surge Watch is in effect from 
The Mouth of the Mississippi River to Yankeetown, Florida. Residents 
in the watch area should follow advice given by local officials and 
evacuate if told to do so.

2. The risk of damaging hurricane-force winds is increasing over 
portions of the Florida Panhandle, southern Alabama, and southern 
Mississippi.  A Hurricane Watch has been issued from Bay St. Louis, 
Mississippi, to Indian Pass, 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 Thursday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/2100Z 22.7N  92.9W   55 KT  65 MPH
 12H  08/0600Z 23.1N  91.8W   70 KT  80 MPH
 24H  08/1800Z 24.1N  90.1W   80 KT  90 MPH
 36H  09/0600Z 25.8N  88.7W   90 KT 105 MPH
 48H  09/1800Z 28.1N  87.6W   95 KT 110 MPH
 60H  10/0600Z 31.0N  87.3W   60 KT  70 MPH...INLAND
 72H  10/1800Z 34.0N  87.5W   30 KT  35 MPH...POST-TROP/INLAND
 96H  11/1800Z 37.5N  84.5W   15 KT  15 MPH...POST-TROP/INLAND
120H  12/1800Z...DISSIPATED
 
$$
Forecaster Blake