Pacific Hurricane and Tropical Cyclone Track Updates

Tropical Storm Rick Forecast Discussion



000
WTPZ42 KNHC 222101
TCDEP2

Tropical Storm Rick Discussion Number   2
NWS National Hurricane Center Miami FL       EP172021
400 PM CDT Fri Oct 22 2021

A curved band of deep convection has wrapped roughly halfway around 
and over the estimated center of the cyclone over the past several 
hours, and a central dense overcast may be trying to form. Outflow 
has been expanding in all directions, indicative of a low-shear 
environment. Although there were two recent ASCAT overpasses over 
the cyclone, the higher magnitude vectors were likely rain 
inflated. Thus, the initial intensity of the system is based on the 
latest Dvorak intensity estimates of 35 kt from both TAFB and the 
UW-CIMSS ADT, making Rick the seventeenth named storm of the 2021 
eastern Pacific basin hurricane season.

Rick has slowed its forward motion and is now moving 
west-northwestward at 6 kt. A ridge to the north of the storm is 
forecast to weaken tonight as a deep-layer trough digs southeastward 
toward the western United States. Rick is expected to turn 
northwestward tonight then north-northwestward by Saturday night 
towards this weakness. The model guidance is still having a 
difficult time agreeing upon how abrupt of a right turn that the 
cyclone will make this weekend, with the GFS consistently showing a 
northward motion by tonight, and much of the other guidance 
indicating the northwest then north-northwest motion over the next 
few days. The NHC track forecast was nudged a little to the right of 
the previous one due to an overall slight shift to the right in the 
guidance, and lies in between the NOAA corrected consensus HCCA, 
and FSU Superensemble solutions. It should be noted that the model 
spread between the right-outlier GFS and left-outlier ECMWF models 
is about 175 n mi at 48 h. Therefore, the track forecast remains of 
low confidence.

There is little change to the intensity forecast reasoning. The 
storm is expected to be within an ideal environment for 
strengthening over the next couple of days, with very little 
vertical wind shear, a moist airmass, and sea surface temperatures 
near 30 degrees C. Therefore, steady intensification is indicated by 
all of the model guidance through 48 h. There is some weakening 
indicated by the models just before the time the system would be 
nearing the coast of Mexico,  which could be due to some dry air 
entraining into the cyclone's circulation. The NHC intensity remains 
near the IVCN consensus solution through 72 h and below HCCA. Beyond 
landfall, the intensity forecast is near the Decay-SHIPS prediction. 
The NHC intensity forecast also calls for a 24-h period of rapid 
intensification, which seems reasonable given the environment, the 
model agreement, and the SHIPS Rapid Intensification guidance that 
now indicates a greater than 60 percent chance of a 45-kt increase 
in strength over the next 36 h, and 55 kt over the next 48 h.

Key Messages:

1. Rick is forecast to be a hurricane when it reaches the southwest 
coast of Mexico by Sunday night or Monday, and life-threatening 
storm surge and hurricane-force winds are possible within the 
Hurricane Watch area from Zihuatanejo 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 
southwestern coast of Mexico as early as Sunday from east of 
Zihuatanejo to Tecpan de Galeana, 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, Michoacan, and Colima starting Saturday 
Night, and could persist through Monday night.  This rainfall will 
likely produce flash flooding and mudslides.


FORECAST POSITIONS AND MAX WINDS

INIT  22/2100Z 13.1N 101.0W   35 KT  40 MPH
 12H  23/0600Z 13.7N 101.4W   45 KT  50 MPH
 24H  23/1800Z 14.6N 102.0W   60 KT  70 MPH
 36H  24/0600Z 15.3N 102.3W   75 KT  85 MPH
 48H  24/1800Z 16.1N 102.6W   80 KT  90 MPH
 60H  25/0600Z 17.1N 103.0W   75 KT  85 MPH
 72H  25/1800Z 18.3N 103.3W   65 KT  75 MPH...INLAND
 96H  26/1800Z 23.2N 103.9W   35 KT  40 MPH...POST-TROP/INLAND
120H  27/1800Z...DISSIPATED

$$
Forecaster Latto/Pasch



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