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Tropical Storm Olaf Discussion Number   4
NWS National Hurricane Center Miami FL       EP152021
900 AM MDT Wed Sep 08 2021
 
The depression has strengthened into Tropical Storm Olaf this 
morning. A well-defined curved band now wraps over 50 percent around 
the center of the cyclone, with cloud tops to -80 degrees C. The 
initial intensity has been raised to 35 kt for this advisory based 
on the latest TAFB Dvorak intensity estimate and the UW-CIMSS ADT. 

Olaf is forecast to remain over warm waters and in a moist 
environment for the next 36 hours or so. The only inhibiting factor 
to strengthening in the short term could be a slight increase in 
vertical wind shear beginning tonight. In a couple of days, the 
cyclone is forecast to begin moving over cooler waters and into a 
drier, much more stable atmospheric environment that favors rapid 
weakening. These unfavorable conditions should cause Olaf to 
degenerate into a remnant low this weekend. The latest NHC intensity 
forecast was decreased only slightly from the previous one, and is 
in good agreement with the IVCN intensity consensus. Although the 
NHC forecast no longer explicitly shows Olaf becoming a hurricane, 
this could still occur Thursday or Thursday night. 

The storm is now moving northwestward at 6 kt, to the southwest of a 
mid-level ridge building over northern Mexico. This northwestward 
motion should continue for a couple of days with a gradual increase 
in forward speed. By Friday night, Olaf is expected to turn 
west-northwestward as it weakens, and by Saturday a westward motion 
is forecast as the cyclone becomes shallow and steered by the 
surrounding low-level flow. The latest NHC track forecast is little 
changed from the previous one, and lies near the various multi-model 
consensus tracks. It should be noted that the model solutions that 
depict a stronger cyclone favor a track slightly more to the north 
than the NHC forecast, closer to the southern Baja peninsula, while 
the weaker model solutions lie to the south of the NHC forecast 
track.

Key Messages:
 
1.  Olaf is forecast to strengthen to near hurricane intensity 
while it passes to the southwest of southern portions of Baja 
California Sur Thursday and Friday, and tropical storm conditions 
are possible in these areas. Interests there should continue to 
monitor the progress of Olaf.
 
2.  Heavy rains associated with Olaf are possible across southern 
portions of Baja California Sur Thursday through Friday. This will 
pose a threat of flash flooding and mudslides.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/1500Z 18.9N 107.5W   35 KT  40 MPH
 12H  09/0000Z 19.6N 108.0W   45 KT  50 MPH
 24H  09/1200Z 20.6N 109.0W   55 KT  65 MPH
 36H  10/0000Z 21.7N 110.5W   60 KT  70 MPH
 48H  10/1200Z 22.9N 112.2W   55 KT  65 MPH
 60H  11/0000Z 23.5N 113.9W   45 KT  50 MPH
 72H  11/1200Z 23.8N 115.4W   35 KT  40 MPH
 96H  12/1200Z 23.7N 118.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  13/1200Z 23.0N 120.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
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Forecaster Latto
 
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