Tropical Depression Ten Forecast Discussion Number 3

By | August 27, 2023
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Tropical Depression Ten Discussion Number   3
NWS National Hurricane Center Miami FL       AL102023
400 AM CDT Sun Aug 27 2023

The small circulation of Tropical Depression Ten continues to be 
well-defined in Cancun radar, with the center moving across Cozumel 
during the past few hours.  Data from a Weatherflow sensor on the 
island indicated that the pressure dropped to about 1001 mb, with 
sustained winds of about 30 kt.  A small burst of convection has 
formed just south of the center recently, with scattered banding 
features in the eastern semicircle.  Most of the satellite 
estimates are just shy of tropical storm strength, so the initial 
winds speed will stay 30 kt.  Both Air Force Reserve and NOAA 
Hurricane Hunter aircraft will be in the system later this morning 
to get a better look at the structure and winds.  

The depression has turned southward tonight, moving at about 4 kt, 
apparently rotating around the western periphery of its larger 
parent circulation to the east.  Little net motion is expected for 
about a day as steering currents remain weak.  After that time, a 
developing trough over the Gulf of Mexico and stronger ridging over 
the western Atlantic is expected to lift the system toward the north 
and north-northeast over the eastern Gulf of Mexico. This track 
takes the system toward Florida, and then near the southeastern 
coast of the U.S.  The overnight model guidance is a bit farther 
west and slower than the last cycle, probably due to the depression 
being further south than anticipated.  Thus, the NHC forecast is 
nudged westward, and lies on the east side of the guidance envelope. 
These are small changes overall, and the track should be considered 
lower confidence until it starts moving in a more consistent manner. 
The NOAA G-IV aircraft should be in the area this afternoon to 
help smooth out the model differences along with special upper-air 
soundings scheduled across many areas of the southeastern United 
States.

The very warm and deep waters of the northwestern Caribbean Sea and 
Gulf of Mexico should support at least gradual strengthening during 
the next few days, tempered by moderate shear from a flat upper- 
level trough.  However, this trough is forecast to amplify over the 
western Gulf of Mexico around Tuesday, which causes the shear to 
decrease near the cyclone in that time frame.  There's a notable 
risk of rapid intensification while the system moves across the 
record warm eastern and northeastern Gulf of Mexico, which is 
highlighted by the recent HAFS and HWRF guidance.  The new NHC 
forecast is raised from the previous one, near or above the model 
consensus, and could be too low.  I'm reluctant to make any big 
changes to the forecast until we get more in-situ data, but the 
upward overnight model trend certainly bears watching.  Users are 
reminded to continue monitoring forecasts for any changes to the 
system's expected intensity as it approaches Florida.  


KEY MESSAGES:

1. Heavy rainfall from Tropical Depression Ten is expected across
the eastern Yucatan Peninsula and western Cuba. The heavy rainfall
may produce areas of flash and urban flooding, as well as
landslides, across western Cuba.  The depression is forecast to
become a tropical storm later today, and tropical storm conditions 
are expected over portions of the Yucatan Peninsula and extreme
western Cuba where a Tropical Storm Warning is in effect.  Tropical
storm conditions are possible on the Isle of Youth, where a Tropical
Storm Watch is in effect.

2. The depression is forecast to strengthen during the next few days 
and could become a hurricane over the eastern Gulf of Mexico, 
bringing a potential of dangerous storm surge, heavy rainfall, and 
strong winds to portions of the west coast of Florida and the 
Florida Panhandle by the middle of this week.  Heavy rainfall is 
also likely to spread into portions of the Southeast U.S. by mid to 
late week.  Although it is too soon to specify the exact location 
and magnitude of these impacts, residents in these areas should 
monitor updates to the forecast of this system and ensure that they 
have their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0900Z 20.1N  86.8W   30 KT  35 MPH
 12H  27/1800Z 20.1N  86.5W   40 KT  45 MPH
 24H  28/0600Z 20.6N  86.3W   45 KT  50 MPH
 36H  28/1800Z 21.7N  86.3W   50 KT  60 MPH
 48H  29/0600Z 23.3N  86.2W   60 KT  70 MPH
 60H  29/1800Z 25.7N  85.7W   75 KT  85 MPH
 72H  30/0600Z 28.5N  84.7W   80 KT  90 MPH
 96H  31/0600Z 33.0N  81.2W   45 KT  50 MPH...INLAND
120H  01/0600Z 35.0N  75.5W   35 KT  40 MPH...OVER WATER

$$
Forecaster Blake

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