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Hurricane Olaf Discussion Number   9
NWS National Hurricane Center Miami FL       EP152021
300 PM MDT Thu Sep 09 2021
 
Olaf is quickly strengthening. An eye is now apparent in visible and 
satellite imagery. For most of the morning and early afternoon, a 
large and very symmetric eyewall was also apparent in radar data 
from Cabo San Lucas. Dvorak intensity estimates at 1800 UTC were 
4.5/77 kt from both TAFB and SAB at 1800 UTC, and estimates from the 
U-W CIMSS ADT have increased to 80 kt since then. The initial 
intensity has been set at 80 kt, in close agreement with all 
available estimates.
 
Olaf has moved consistently to the right of the forecast track for 
the past 12 hours, and the NHC track forecast has been shifted in 
that direction again. Olaf is now forecast to move very near or over 
southern Baja California Sur tonight. Regardless of the hurricane's 
exact track, it is very likely that a portions of southern Baja 
California Sur will get direct impacts from the eyewall of Olaf 
tonight. A large ridge centered over the southwestern U.S. is still 
expected to cause Olaf to make a slight turn toward the northwest 
tonight or early Friday. The hurricane should then make a westward 
turn by early Saturday as it weakens and the ridge extends westward. 
Despite the recent adjustments required to the NHC forecast, this 
forecast is still generally supported by all of the 
typically-reliable track guidance. By around 60 h, Olaf will likely 
have lost all of its deep convection and become a shallow 
post-tropical low, steered primarily southwestward by low-level 
flow.
 
The environment should support additional intensification during the 
next 12 h as Olaf approaches the Baja California peninsula, so any 
fluctuations in intensity will likely be driven by internal dynamics 
at this point. The appearance of Olaf's eyewall in radar imagery has 
degraded a little during the past couple of hours, but it is 
possible this is due to attenuation of the radar signal and not 
fully representative of the hurricane's structure. Regardless, Olaf 
should begin to weaken once it interacts with land or moves inland. 
By late Friday, the rate of weakening is forecast to increase due to 
a combination of continued land interactions and cool sea surface 
temperatures. Olaf should quickly weaken over the weekend as it 
continues to move over cold water, and it will likely become a 
post-tropical cyclone on Sunday. The NHC intensity forecast is above 
the consensus at 12 h to allow for additional short-term 
strengthening, but follows the consensus closely at 36 h and beyond.
 
Key Messages:
 
1.  Olaf is forecast to move very near or over the southern portion
of Baja California Sur tonight and Friday. Hurricane conditions
are expected to begin within the southern portion of the hurricane
warning area tonight and will spread northward through Friday.
 
2.  Heavy rains associated with Olaf are expected across portions of
southern Baja California Sur through Friday. This will pose a threat
of significant and life-threatening flash flooding and mudslides.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/2100Z 22.2N 108.9W   80 KT  90 MPH
 12H  10/0600Z 23.1N 110.0W   85 KT 100 MPH...INLAND
 24H  10/1800Z 24.2N 111.5W   70 KT  80 MPH...OVER WATER
 36H  11/0600Z 24.6N 112.9W   60 KT  70 MPH
 48H  11/1800Z 24.5N 114.1W   50 KT  60 MPH
 60H  12/0600Z 23.9N 115.3W   40 KT  45 MPH...POST-TROPICAL
 72H  12/1800Z 23.2N 116.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  13/1800Z 22.0N 119.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  14/1800Z 21.5N 122.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster D. Zelinsky
 
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