Tropical Cyclone Discussion

265
WTPZ42 KNHC 280854
TCDEP2
 
Hurricane Polo Discussion Number  31
NWS National Hurricane Center Miami FL       EP172026
200 AM MST Mon Sep 28 2026
 
Polo has remained fairly steady over the past 6 hours in terms of 
its overall convective structure.  The ragged eye and inner core 
have perhaps only become slightly less impressive.  The TAFB current 
intensity number is 5.5/102 kt and recent UW-CIMSS objective 
estimates are in the 90-100 kt range.  The initial intensity is 
nudged downward to 100 kt.
 
The major hurricane is now moving north-northeastward at 9 kt on the
western side of a mid-level ridge that is situated over northern
Mexico.  Polo is forecast to turn northeastward by this afternoon 
as a trough amplifies over California, taking the core of the 
hurricane over the Baja California Peninsula late this afternoon or 
evening.  Polo is then expected to briefly pass over the Gulf of 
California before making a second landfall in northwestern mainland 
Mexico late tonight or early Tuesday morning.  The latest NHC 
forecast is on top of the previous forecast, but slightly slower, 
and lies close to the HFIP Corrected Consensus Approach (HCCA) 
guidance.

The SHIPS and UW-CIMSS analyses are currently diagnosing less than 
10 kt of vertical wind shear over Polo.  The shear is expected to 
increase to about 15 to 18 kt by the time Polo makes landfall in 
Baja California Sur, but thermodynamic conditions aren't expected to 
change much.  Most of the guidance indicates slight weakening over 
the next 12 to 18 hours.  The most likely scenario for the intensity 
at landfall in Baja California is around 95 kt, but there is also a 
chance that Polo could maintain its current intensity until it makes 
landfall.  Land interaction with the peninsula and an increase in 
wind shear should cause some weakening, but Polo is still expected 
to be a hurricane when it reaches mainland Mexico. After the second 
landfall, rapid weakening is forecast over the rugged terrain of 
Mexico.  The official intensity forecast is only slightly lower 
than the previous one up until the first landfall, and then is 
similar to the previous forecast.  The NHC intensity forecast is in 
good agreement with the majority of the guidance.
 
Although Polo is expected to dissipate before it reaches the 
southern U.S., distant moisture associated with it and the 
Post-Tropical Cyclone Odalys will be transported into the 
southwestern United States during the next few days, and may 
indirectly contribute to a heavy rainfall and flash flood threat in 
the region. See products issued by the Weather Prediction Center for 
more information.
 
 
Key Messages:
 
1. Polo is forecast to make landfall on the west coast of the Baja
California Peninsula near major hurricane strength late today, 
within the Hurricane Warning area. Conditions are expected to begin 
to deteriorate there this morning, making further preparations
difficult. Hurricane and tropical storm conditions are expected to
spread across Baja California through today through tonight, and 
into mainland Mexico late tonight into early Tuesday. A storm 
surge is likely, especially in areas of onshore winds.
 
2. Heavy rainfall associated with Polo will impact Baja California 
Sur along with southern and central portions of Sonora today into 
Tuesday. This rainfall may produce life-threatening flooding and 
mudslides, especially in areas of steep terrain. Moisture from Polo 
will support heavy rainfall and flooding potential across the 
Southwest U.S. into the Southern High Plains late today into 
Tuesday.
 
3. Dangerous surf and rip currents are likely along portions of
the northwest coast of Mexico and Baja California for the next
couple of days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/0900Z 23.6N 113.8W  100 KT 115 MPH
 12H  28/1800Z 24.8N 113.2W   95 KT 110 MPH
 24H  29/0600Z 26.7N 111.6W   75 KT  85 MPH...EAST COAST OF BAJA
 36H  29/1800Z 29.5N 109.4W   40 KT  45 MPH...INLAND
 48H  30/0600Z...DISSIPATED