ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
 
Tropical Storm Rick Discussion Number   4
NWS National Hurricane Center Miami FL       EP172021
400 AM CDT Sat Oct 23 2021
 
The satellite presentation of Rick has continued to improve
overnight.  The center is embedded within a fairly symmetric and
expanding central dense overcast, and there is evidence of outer
banding features.  There has been no recent microwave imagery
to examine the inner core structure, but given the recent satellite
appearance and the earlier microwave data, it is likely that the
inner core has become better defined. Subjective Dvorak T-numbers
supported an intensity of 55 kt at 0600 UTC, and given the
continued improvement in organization, the advisory intensity has
been set at 60 kt. An Air Force Reserve reconnaissance aircraft is
scheduled to investigate Rick this afternoon and should provide a
better assessment of the storm's strength and structure.
 
Rick has been intensifying quickly since it developed yesterday
morning, and environmental conditions consisting of very low
vertical wind shear, warm sea surface temperatures, and a moist
low- to mid-level atmosphere are expected to continue to support
rapid strengthening during the next day or so. The SHIPS rapid
intensification index is showing a greater than 90 percent chance
of rapid strengthening over the next 24 hours, and also indicates a
better than 80 percent chance of a 45 kt increase in intensity over
the next 36 hours.  Based on this guidance the NHC intensity
forecast calls for rapid strengthening during the next 24 to 36
hours, and the official forecast shows Rick reaching major
hurricane status within 36 hours.  This is near the higher end of
the intensity guidance envelope, but is not as high as the HFIP 
corrected consensus aid.  Increasing shear after that time and the 
possibility of an eyewall replacement cycle could cause some 
fluctuations in intensity before Rick reaches the coast of Mexico. 
After landfall, rapid weakening is expected, and Rick is likely to 
dissipate over the mountainous terrain of Mexico in 72 to 96 hours.
 
Rick has turned north-northwestward or 330/5 kt.  A slow 
north-northwestward to northward track is expected around the
western side of a mid-level ridge centered of the Caribbean. 
Although the guidance agrees on that general steering flow, there 
are still significant difference regarding the location and timing 
of landfall in southern or southwestern Mexico. The GFS, Canadian, 
and HWRF are along the eastern edge of the track model envelope 
while the ECMWF, UKMET, and CTCI models are along the western side. 
The NHC track forecast has been adjusted slightly east of the 
previous advisory but remains close to the various consensus aids. 
It should be noted that the global model ensembles suggest a 
stronger cyclone is likely to track more eastward.  Therefore the 
official forecast has been nudged in that direction and it is 
possible future eastward adjustments could be required.
 
Based on the latest forecast, the government of Mexico has extended 
both the Hurricane and Tropical Storm Watches farther eastward. 
Hurricane and Tropical Storm Warnings will likely be required for 
portions of the watch areas later this morning. 

Key Messages:
 
1. Rick is expected to be at or near major hurricane strength when 
it reaches the coast of southern Mexico by Sunday night or Monday, 
and life-threatening storm surge and dangerous hurricane-force 
winds are possible within the Hurricane Watch area from Tecpan de 
Galeana to Punta San Telmo.  There is larger-than-normal 
uncertainty in the track forecast of Rick, and the arrival time of 
hazardous conditions within the watch area could change 
significantly with future forecasts. Residents in this area should 
follow any advice given by local officials and check updates
to the forecast.
 
2. Rick could bring tropical storm conditions to portions of the
southern and southwestern coasts of Mexico as early as Sunday from
east of Tecpan de Galeana to Acapulco, and by Monday morning
from west of Punta San Telmo to Manzanillo, where a Tropical Storm
Watch is in effect.
 
3. Heavy rains associated with Rick are expected to move into the
Mexican states of Guerrero and Michoacan starting tonight, and 
could persist through Monday night.  This rainfall will likely 
produce flash flooding and mudslides.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/0900Z 13.9N 101.4W   60 KT  70 MPH
 12H  23/1800Z 14.6N 101.8W   75 KT  85 MPH
 24H  24/0600Z 15.3N 102.1W   90 KT 105 MPH
 36H  24/1800Z 16.0N 102.3W  100 KT 115 MPH
 48H  25/0600Z 17.0N 102.7W  100 KT 115 MPH
 60H  25/1800Z 18.5N 103.1W   80 KT  90 MPH...INLAND
 72H  26/0600Z 20.5N 103.5W   30 KT  35 MPH...INLAND
 96H  27/0600Z 25.0N 104.0W   20 KT  25 MPH...POST-TROP/INLAND
120H  28/0600Z...DISSIPATED
 
$$
Forecaster Brown
 
NNNN