Pacific Hurricane and Tropical Cyclone Track Updates

Tropical Storm Rick Forecast Discussion



928 
WTPZ42 KNHC 230248
TCDEP2

Tropical Storm Rick Discussion Number   3
NWS National Hurricane Center Miami FL       EP172021
1000 PM CDT Fri Oct 22 2021

Satellite imagery indicates that Rick is strengthening.
Conventional satellite imagery shows that a central dense overcast
has formed, and recently received SSM/IS data indicates that a small
convective ring or developing eyewall is present under the overcast.
Various subjective and objective satellite intensity estimates are
in the 40-45 kt range, and given the structure seen in the microwave
imagery the initial intensity has been increased to 45 kt.  The
cyclone currently has excellent upper-level outflow, with apparent
multiple outflow channels to the north and the south.

The initial motion is now 295/5 kt.  A low- to mid-level ridge to 
the north of Rick is weakening as a deep-layer trough moves into the 
western United States, which will leave Rick on the west side of a 
low-latitude ridge.  This evolution should allow the storm to turn 
more northward during the next 24-36 h.  However, there continues to 
be significant track spread between the right-side GFS, which has an 
almost immediate northward motion, and the left-side ECMWF/UKMET, 
which forecast a much later northward turn.  The new track forecast 
splits the difference between these extremes and follows the 
consensus models near the center of the guidance envelope.  This 
results in a forecast landfall in Mexico in just over 60 h. However, 
because of the spread, there is low confidence in the exact time of 
landfall, and landfall would occur earlier if Rick follows the GFS 
track.

For the next 36 h, Rick is expected to be in an area of light 
vertical shear, strong upper-level divergence, and warm sea surface 
temperatures.  This, combined with the structure seen in microwave 
imagery, suggests rapid strengthening is likely, and the SHIPS Rapid 
Intensification indices support this.  One possible issue is that 
tongues of dry air may try to entrain into the core, which could 
slow the development rate.  After 36 h, increasing shear and a drier 
air mass should stop intensification, with the intensity guidance 
suggesting some weakening before the system makes landfall in 
Mexico.  Rapid weakening should occur over the mountains of Mexico 
after landfall.  The new intensity forecast has higher intensities 
over the previous forecast and now calls for Rick to reach a peak 
intensity of 90 kt, which could be conservative.  The new forecast 
is along the upper edge of the intensity guidance until landfall, 
and it is in best agreement with the HCCA corrected consensus model.


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  23/0300Z 13.4N 101.3W   45 KT  50 MPH
 12H  23/1200Z 14.0N 101.7W   55 KT  65 MPH
 24H  24/0000Z 14.8N 102.1W   70 KT  80 MPH
 36H  24/1200Z 15.5N 102.4W   85 KT 100 MPH
 48H  25/0000Z 16.4N 102.8W   90 KT 105 MPH
 60H  25/1200Z 17.7N 103.2W   80 KT  90 MPH
 72H  26/0000Z 19.4N 103.5W   60 KT  70 MPH...INLAND
 96H  27/0000Z 24.0N 104.0W   20 KT  25 MPH...POST-TROP/INLAND
120H  28/0000Z...DISSIPATED

$$
Forecaster Beven




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