Official Discussion issued by the National Hurricane Center

Idalia (AL102023) DATA RELEASED: 8/28/2023 10:00:00 PM UTC

Copy of official data

Tropical Storm Idalia Discussion Number  10
NWS National Hurricane Center Miami FL       AL102023
1000 PM CDT Mon Aug 28 2023

Idalia is producing intense bursts of convection near the center,  
with an overall comma-shaped cloud pattern along with a dry slot 
over the western part of the circulation.  Upper-level outflow is 
restricted over the northwestern quadrant.  Radar images from 
the Meteorological Service of Cuba show a partial eyewall forming.  
Flight-level and dropwindsonde data from NOAA and Air Force aircraft 
indicate that Idalia is very near hurricane strength.  The maximum 
winds are set again to 60 kt for this advisory.

The system has moved a bit slower than earlier today with an 
initial motion estimate of just slightly east of due north at 
around 7 kt.  Idalia should be steered northward along the western 
side of a mid-level ridge and then turn north-northeastward due to 
a trough to its northwest.  This track will take the center across 
the northeastern Gulf coast on Wednesday morning, and over 
northern Florida and southeastern Georgia thereafter.  In 2 to 3 
days, a mid-tropospheric trough moving off the eastern U.S. coast 
will likely cause the tropical cyclone to turn northeastward to 
eastward off the coast of the Carolinas.  The official track 
forecast for this advisory is essentially the same as the previous 
one.  This is near the middle of the track guidance, which are 
fairly tightly clustered, with the GFS on the left side and the 
ECMWF on the right side.

Although Idalia is currently experiencing some moderate 
northwesterly vertical wind shear, the dynamical guidance indicates 
that the shear will lessen while the system is over the eastern 
Gulf of Mexico.  This, along with a conducive thermodynamic 
atmospheric environment and high oceanic heat content, should cause 
Idalia to strengthen rapidly in the 12- to 36-hour time frame.  The 
official intensity forecast, like the previous one, shows the system 
becoming a major hurricane before landfall along the Florida Gulf 
coast.  This is in general agreement with the regional hurricane 
hurricane models, HAFS and HWRF, but above much of the other
intensity guidance.

Idalia is forecast to move into an area that is highly susceptible 
to storm surge, and regardless of the cyclone's specific landfall 
intensity, there is increasing confidence that a significant storm 
surge event will occur.


1. There is a danger of life-threatening storm surge inundation
along portions of the Florida Gulf Coast where a Storm Surge Warning
is in effect, including Tampa Bay and the Big Bend region of
Florida. Inundation of 8 to 12 feet above ground level is expected
somewhere between Chassahowitzka and Aucilla River.  Residents in
these areas should follow any advice given by local officials.

2. Hurricane conditions are expected within portions of the
Hurricane Warning area along the Florida Gulf Coast, with the
potential for destructive winds where the core of Idalia moves
onshore. Strong winds will also spread inland across portions of
northern Florida near the track of the center of Idalia.

3. Heavy rainfall from Tropical Storm Idalia is expected across 
portions of western Cuba and may produce areas of flash and urban 
flooding as well as landslides.  Areas of flash and urban flooding, 
some of which may be locally significant, are expected across 
portions of the west coast of Florida, the Florida Panhandle, and 
southern Georgia Tuesday into Wednesday, spreading into portions of 
the eastern Carolinas Wednesday into Thursday.


INIT  29/0300Z 22.0N  85.0W   60 KT  70 MPH
12H  29/1200Z 23.7N  85.0W   75 KT  85 MPH
24H  30/0000Z 26.2N  84.6W   90 KT 105 MPH
36H  30/1200Z 29.0N  83.7W  105 KT 120 MPH
48H  31/0000Z 31.5N  81.6W   50 KT  60 MPH...INLAND
60H  31/1200Z 33.2N  78.8W   50 KT  60 MPH...OVER WATER
72H  01/0000Z 34.0N  76.0W   50 KT  60 MPH
96H  02/0000Z 33.5N  72.0W   45 KT  50 MPH
120H  03/0000Z 33.0N  70.0W   45 KT  50 MPH

Forecaster Pasch