Atlantic Basin Tropical Cyclones

Potential Tropical Cyclone Fifteen Forecast Discussion


053 
WTNT45 KNHC 302058
TCDAT5

Potential Tropical Cyclone Fifteen Discussion Number   1
NWS National Hurricane Center Miami FL       AL152022
500 PM EDT Sun Oct 30 2022

This morning we were fortunate to have concurrent NOAA and Air Force 
Reserve Hurricane Hunter missions, which provided a wealth of 
flight-level, Tail Doppler Radar, and dropsonde data over the system 
in the central Caribbean Sea. The data indicated that a 
well-defined, while somewhat broad, circulation had formed with a 
minimum pressure of 1005 mb. A combination of SFMR winds and surface 
dropsonde data also suggested that the system had 35-kt winds in its 
northern semicircle. With that said, the satellite presentation of 
the system currently lacks sufficient convective organization to be 
considered a tropical cyclone. However, given the well-defined 
center and tropical-storm-force winds, there is significant risk for 
tropical storm conditions in the near future in portions of Jamaica 
and Grand Cayman Island. With the expectation that this system will 
likely become a tropical storm soon, advisories have been initiated 
on Potential Tropical Cyclone Fifteen. 

The estimated motion of the disturbance is off to the west-northwest 
at 290/9 kt. This general motion is forecast to continue for the 
next day or so, as an expansive mid-level ridge is currently 
centered north of the system and expected to move westward with 
the cyclone. Toward the end of the forecast period, the ridge may 
nose further westward as a deep-layer trough becomes established 
well to the the northeast, which could result in a south of due 
west motion when the system approaches the coast of 
Belize.  Landfall is expected between the 72- and 96-hour forecast 
points. The initial NHC track forecast is roughly a blend of the 
latest GFS and ECMWF guidance, which is also quite close to  
the HCCA and TCVA consensus aids. 

Based on the current structure, it may take a bit longer for the 
convection to become sufficently organized to allow the formation of 
a tropical cyclone, but this is forecast to occur at some point 
tonight, likely during the typical diurnal maximum. After deep 
convection become better established, environmental conditions 
appear to be conducive for further intensification, especially in 
the 24-48 hour period when the vertical wind shear is expected to be 
lowest (5-15 kt) as the system traverses 29-30 C sea-surface 
temperatures. Mid-level relative humidity is quite low (55-60 
percent), but given the relatively low shear, this may act to keep 
the system's structure small with a constricted radius of maximum 
winds. The initial intensity forecast after 24 hours closely follows 
the latest HCCA and ICON intensity guidance, making the system a 
Category 1 hurricane in 60-72 hours. The system should weaken 
quickly over land and is forecast to dissipate before day 5. 

Based on the latest forecast, the government of Jamaica has issued 
a Tropical Storm Watch for Jamaica, and the government in the 
Cayman Islands has issued a Tropical Storm Watch for Grand Cayman 
Island. 


Key Messages:

1. Tropical storm conditions are possible within the Tropical Storm 
Watch areas beginning Monday for Jamaica and on Tuesday for Grand 
Cayman Island. 

2. Interests along the coast of Central America, especially near 
Belize, should monitor the progress of this system. Additional 
watches and warnings will likely be required early this week. 


FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 15.7N  73.6W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  31/0600Z 16.0N  74.9W   35 KT  40 MPH...TROPICAL CYCLONE
 24H  31/1800Z 16.3N  76.6W   40 KT  45 MPH
 36H  01/0600Z 16.7N  78.8W   50 KT  60 MPH
 48H  01/1800Z 17.2N  81.3W   60 KT  70 MPH
 60H  02/0600Z 17.5N  83.6W   65 KT  75 MPH
 72H  02/1800Z 17.4N  85.7W   70 KT  80 MPH
 96H  03/1800Z 16.4N  89.5W   35 KT  40 MPH...INLAND
120H  04/1800Z...DISSIPATED

$$
Forecaster Papin/Cangialosi




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