Eastern Pacific Basin Tropical Cyclones

Hurricane Rick Forecast Discussion


000
WTPZ42 KNHC 250248
TCDEP2

Hurricane Rick Discussion Number  11
NWS National Hurricane Center Miami FL       EP172021
1000 PM CDT Sun Oct 24 2021

Rick's convective organization and inner-core structure have both
continued to improve since the previous advisory. GMI and SSMI/S
passive microwave satellite data at 2245Z and 2310Z, respectively,
revealed that the hurricane had redeveloped a 20-nmi-wide low- and
mid-level closed eye that was surrounded by a solid ring of intense
convection. With better center placement now, satellite intensity
estimates using an embedded center technique indicate that Rick is
just below the T5.0/90-kt intensity classification threshold. Based
on these data, the intensity was increased to 80 kt at 0000 UTC and
has been held at that value at the advisory time due to no
appreciable change in Rick's appearance in infrared satellite
imagery.  An Air Force Reserve reconnaissance aircraft is currently
enroute to provide a better assessment of Rick's intensity and
compact wind field structure around 0600 UTC.

The aforementioned GMI and SSMI/S microwave satellite data, compared
to earlier microwave imagery, indicate that Rick's eye/center has
been moving due north over the past 9 hours, or 360/05 kt. The
hurricane is currently located to the right or east of the previous
forecast track and model guidance, and only the new GFS model run
is on the right side of the latest track guidance envelope. The new
NHC track forecast has been nudged a little to the right of the
previous track, but not quite as far east as the northward-moving
GFS model scenario since the bulk of the other track forecasts
still show Rick making a turn toward the north-northwest during the
next 6 hours. The subtropical ridge steering the hurricane is
forecast to remain in place for the next 36 hours, which should
result in Rick making landfall in about 12 h, with the cyclone
dissipating in 36-48 h over the mountainous interior of
south-central or central Mexico.

The deep-layer vertical shear across Rick is forecast to increase
to 15-18 kt in 12 h. However, the shear direction is going to be
from the south, which be along rather across Rick's forward motion,
thus lessening the otherwise adverse effects of the increasing
shear. As a result, some slight strengthening will be possible
until the hurricane makes landfall late Monday morning. The latest
NHC intensity forecast is slightly higher than the previous
advisory, but a 5-kt increase is easily within NHC's statistical
range of intensity forecast skill. After landfall occurs, Rick
should rapidly weaken due to the hurricane's relatively slow
forward motion over the very rugged terrain of south-central and
central Mexico. In fact, it wouldn't be surprising if the hurricane
dissipated sooner than indicated in the official intensity forecast.
However, very heavy rainfall causing dangerous flash flooding and
mudslides will still continue well after Rick dissipates as a
tropical cyclone owing to persistent, moist southerly onshore flow
being lifted by the mountainous topography.


Key Messages:

1. Rick is forecast to reach the coast of southern Mexico by late
Monday morning, bringing life-threatening storm surge and dangerous
hurricane-force winds within a portion of the Hurricane Warning area
from Tecpan de Galeana to Punta San Telmo.  Residents in this area
should follow any advice given by local officials.

2. Rick is expected to continue bringing tropical storm conditions
to portions of the southern coast of Mexico from east of Tecpan de 
Galeana to Acapulco, and by Monday morning from west of Punta San 
Telmo to Manzanillo, where a Tropical Storm Warning is in effect.

3. Heavy rains associated with Rick are expected to spread across
the Mexican states of Guerrero and Michoacan through tonight, and
could persist through Tuesday.  This rainfall will likely produce
dangerous flash flooding and mudslides.


FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 16.8N 101.6W   80 KT  90 MPH
 12H  25/1200Z 17.7N 101.9W   85 KT 100 MPH
 24H  26/0000Z 18.7N 102.3W   45 KT  50 MPH...INLAND
 36H  26/1200Z 19.6N 102.9W   20 KT  25 MPH...INLAND
 48H  27/0000Z...DISSIPATED

$$
Forecaster Stewart



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