Tropical Storm Polo

000
WTPZ42 KNHC 211453
TCDEP2
 
Tropical Storm Polo Discussion Number   4
NWS National Hurricane Center Miami FL       EP172026
900 AM CST Mon Sep 21 2026
 
Polo is in the midst of a significant rapid intensification
episode.  Satellite images indicate a developing central dense
overcast with very deep convection in the core.  Additionally,
microwave images indicate that a small eye has formed beneath the
overcast with hints of a banded eyewall.  The initial intensity
is set to 55 kt, consistent with the latest TAFB classification,
and a NOAA Hurricane Hunter aircraft is enroute to provide a better
look at the intensity.
 
Conditions look ideal for explosive intensification during the next
day or two, with Polo's small inner core over very warm and
untapped waters above 30.5C, within light shear and plentiful
mid-level moisture.  Every model responds to these conditions by
showing rapid intensification, and the SHIPS rapid intensification
index is showing percentages as high as I have ever seen them.
The new forecast is raised from the previous one and is very
aggressive, but still below the latest HCCA corrected-consensus
aid, which verbatim would be at least a 99th percentile event for
intensification.  Polo is expected to be a small but very dangerous
hurricane by tomorrow and beyond.
 
The storm is drifting eastward, and still caught in weak steering
currents.  A mid-level ridge is expected to develop over Mexico by
late Tuesday, causing Polo to move towards the west-northwest or
northwest by Wednesday into late week.  This could bring the core
of the storm near or south of the coast of southwestern Mexico on
Thursday, and then south of the Baja California Peninsula on
Saturday.  There is a large north-south spread in the guidance,
which has both short and long-range implications.  Generally, the
guidance has nudged southward again, and the NHC forecast is
adjusted in that direction.  Given the spread in the track 
guidance, this is a low-confidence forecast.
 
 
Key Messages:
 
1. Heavy rainfall associated with Polo will impact coastal portions
of southwest Mexico through Thursday. This rainfall may produce
life-threatening flooding and mudslides, especially in areas of
steep terrain.
 
2. Polo is forecast to strengthen to a major hurricane while it
moves closer to the coast of southwestern Mexico during the next few
days. Although the core of the hurricane is forecast to stay
offshore, it is too soon to determine the exact location or
magnitude of impacts. Residents in southwestern Mexico should
closely monitor its progress and updates to the forecast. A Tropical
Storm Watch is in effect for portions of southwestern Mexico.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 15.4N 103.4W   55 KT  65 MPH
 12H  22/0000Z 15.2N 102.8W   85 KT 100 MPH
 24H  22/1200Z 15.1N 102.3W  105 KT 120 MPH
 36H  23/0000Z 15.4N 102.3W  125 KT 145 MPH
 48H  23/1200Z 16.0N 102.8W  135 KT 155 MPH
 60H  24/0000Z 16.8N 103.6W  140 KT 160 MPH
 72H  24/1200Z 17.6N 104.8W  140 KT 160 MPH
 96H  25/1200Z 18.6N 107.8W  130 KT 150 MPH
120H  26/1200Z 20.3N 110.4W  120 KT 140 MPH
 
$$
Forecaster Blake