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Tropical Storm Olaf Discussion Number  13
NWS National Hurricane Center Miami FL       EP152021
300 PM MDT Fri Sep 10 2021
 
The low-level center of Olaf is completely exposed in visible 
satellite imagery this afternoon. The system has been devoid of 
organized convection since around 1200 UTC, and Olaf is at risk of 
losing its status as a tropical cyclone overnight if it is unable to 
generate new convection within the next 12 h. Despite its lack of 
convection, a weather station at Puerto Cortes measured sustained 
tropical-storm-force winds several hours ago as the center of Olaf 
passed very near the observation site, and it has more recently 
reported several tropical-storm-force gusts. The initial intensity 
is lowered to 40 kt for this advisory based on the aforementioned 
surface observations and T2.5/35 kt Dvorak classifications from TAFB 
and SAB.
 
Olaf has rapidly weakened today, and this weakening trend is 
expected to continue during the next couple of days. The cyclone 
will be moving over sub-26 deg C sea-surface temperatures and into a 
drier, more stable environment that should largely suppress new 
convective development. Model simulated satellite imagery from the 
GFS and ECMWF indicate that Olaf will struggle to produce any new 
convection by tomorrow, and the intensity guidance consensus favors 
continued weakening as the vortex spins down. The official NHC 
intensity forecast shows Olaf becoming a 25-kt remnant low by 24 h. 
The remnant low is forecast to linger around for several days after, 
but remain weak as it moves over the open waters of the eastern 
Pacific.
 
The tropical storm has begun moving more westward away from Baja
California Sur, and its initial motion is estimated to be
west-northwest (295 degrees) at 9 kt. A mid-level ridge building to
the north of Olaf should steer the cyclone westward tonight into
Saturday. By late Saturday, the shallow cyclone will begin moving
southwestward as it is steered around a low-level ridge to its
northwest. The official NHC track forecast lies near the middle of
the guidance envelope, closest to the multi-model consensus aids.
 
 
Key Messages:
 
1.  Olaf is moving away from the Baja California peninsula, and
lingering tropical storm conditions along portions of the
southwestern coast of Baja California Sur are forecast to diminish
this evening.
 
2.  Heavy rains associated with Olaf are expected across portions of
southern Baja California Sur through tonight. This rainfall may
trigger life-threatening flash flooding and mudslides.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/2100Z 24.6N 112.7W   40 KT  45 MPH
 12H  11/0600Z 24.8N 113.6W   35 KT  40 MPH
 24H  11/1800Z 24.7N 114.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  12/0600Z 24.2N 115.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  12/1800Z 23.3N 117.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  13/0600Z 22.3N 118.3W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  13/1800Z 21.4N 119.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  14/1800Z 20.8N 121.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  15/1800Z 20.5N 123.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Reinhart
 
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