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Tropical Storm Zeta Discussion Number   5
NWS National Hurricane Center Miami FL       AL282020
500 PM EDT Sun Oct 25 2020

Although the overall cloud pattern of Zeta is still not very well 
organized, with a lack of distinct banding features, it continues to 
generate very intense deep convection mainly over the southeastern 
portion of the circulation.  Moreover, in spite of its ragged 
appearance, the storm has strengthened today.  Reports from a NOAA 
Hurricane Hunter aircraft investigating the system this afternoon 
indicate that, based on adjusted flight-level and SFMR-observed 
surface winds, the intensity has increased to near 45 kt and the 
central pressure has fallen to 999 mb.  Since the storm will be 
moving over the high oceanic heat content of the northwestern 
Caribbean Sea and in a moist environment with low vertical shear 
through Monday, strengthening is forecast and Zeta will likely 
become a hurricane before it nears the Yucatan Peninsula in a day or 
so.  After Zeta moves into the Gulf of Mexico, southwesterly shear 
is likely to increase and oceanic heat content below the cyclone 
will diminish, especially when the system approaches the northern 
Gulf coast on Wednesday.  Therefore, no strengthening is forecast in 
2-3 days and Zeta could be weakening by the time it reaches the 
northern Gulf coast.  However, the intensity forecast is still 
subject to significant uncertainty.

The center has been meandering this afternoon, and apparently has 
reformed nearer to the deep convection over the southeastern 
quadrant.  Since this is not considered representative of 
larger-scale motion, the system is still considered to be 
quasi-stationary at this time.  However, the track guidance is in 
agreement that Zeta will move northwestward over the next 1-2 days, 
passing near or over the Yucatan Peninsula.  Thereafter, the cyclone 
is likely to turn north-northwestward to northward while it moves on 
the western side of a mid-tropospheric anticyclone near Florida.  A 
turn toward the north-northeast is expected when Zeta nears the 
northern Gulf coast, due to an approaching shortwave trough.  The 
track guidance has more than the usual amount of spread at the 
72-hour time frame, with the ECMWF and the GFS predictions being 
about 300 miles apart near the northern Gulf coast.  The official 
forecast track lies between these 2 solutions, and is similar to the 
previous NHC track.  However, given the inherent uncertainties, one 
should not focus on the exact forecast track.

Based on the new intensity forecast, the government of Mexico has 
issued a Hurricane Warning for a portion of the Yucatan peninsula.

KEY MESSAGES:
 
1. Hurricane conditions and storm surge are expected in portions of 
the northern Yucatan Peninsula of Mexico Monday night and early 
Tuesday. Tropical storm conditions could occur over extreme western 
Cuba on Monday.
 
2. Through Wednesday, heavy rainfall is expected from Zeta across 
portions of central and western Cuba, the Cayman Islands, Jamaica, 
the northeast Yucatan peninsula of Mexico, southern Florida and the 
Keys. This rainfall may lead to flash flooding in urban areas.

3. Zeta is forecast to be at or just below hurricane strength when 
it approaches the northern Gulf Coast on Wednesday, and there is an 
increasing risk of storm surge, rainfall, and wind impacts from 
Louisiana to the Florida Panhandle. Residents in these areas should 
monitor the progress of Zeta and updates to the forecast.

FORECAST POSITIONS AND MAX WINDS
 
INIT  25/2100Z 17.7N  83.4W   45 KT  50 MPH
 12H  26/0600Z 18.7N  84.3W   55 KT  65 MPH
 24H  26/1800Z 19.7N  85.7W   65 KT  75 MPH
 36H  27/0600Z 21.1N  87.6W   65 KT  75 MPH...INLAND
 48H  27/1800Z 23.2N  89.6W   65 KT  75 MPH
 60H  28/0600Z 25.7N  90.8W   65 KT  75 MPH
 72H  28/1800Z 29.4N  90.3W   60 KT  70 MPH...INLAND
 96H  29/1800Z 37.0N  83.0W   25 KT  30 MPH...INLAND
120H  30/1800Z...DISSIPATED
 
$$
Forecaster Pasch
 
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