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Tropical Storm Olaf Discussion Number   5
NWS National Hurricane Center Miami FL       EP152021
300 PM MDT Wed Sep 08 2021

Olaf's appearance has remained steady today and the storm is 
characterized by a large curved band that encompasses much of the 
circulation. There is good outflow in all quadrants, indicative of a 
low-shear environment. An earlier ASCAT pass sampled peak winds of 
37 kt, and this data along with a blend of the latest Dvorak 
T-numbers from TAFB and SAB indicate that the initial intensity is 
around 40 kt.
 
The storm is forecast to remain over warm waters and in a moist 
environment for the next 36 hours. Therefore, additional 
strengthening is likely during that time period. In a couple of 
days, the cyclone is forecast to begin moving over cooler waters, 
and into a drier and a much more stable atmospheric environment. 
This should result in rapid weakening, and Olaf is expected to 
become a remnant low this weekend. The latest NHC intensity forecast 
is little changed from the previous one, and continues to be in good 
agreement with the IVCN intensity consensus aid. Although the NHC 
forecast does not explicitly show Olaf becoming a hurricane, this 
could still occur Thursday or Thursday night.
 
Olaf continues to move slowly northwestward, or 325/5 kt. A 
mid-level ridge building over northern Mexico should help maintain 
this heading 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 when 
the shallow cyclone is steered by the surrounding low-level flow. 
The overall model guidance shifted slightly to the east through 48 
hours, and thus the NHC track forecast was nudged in that direction 
for that time frame. Because of this track shift, probabilities of 
tropical storm and hurricane conditions have increased for southern 
portions of Baja California Sur. Therefore, the government of 
Mexico has issued a Hurricane Watch and a Tropical Storm Warning 
for portions of this area. After 48 h, the guidance has shifted a 
little to the south, and the NHC forecast was tweaked in that 
direction as well.
 
Key Messages:
 
1.  Olaf is forecast to strengthen to near hurricane intensity while 
it passes to the southwest of the southern portion of Baja 
California Sur Thursday and Friday. Tropical storm conditions are 
expected and hurricane conditions are possible across that area 
beginning late Thursday. Interests there should continue to monitor 
the progress of Olaf.
 
2.  Heavy rains associated with Tropical Storm Olaf are possible 
across portions of far southern Baja California Sur Thursday through 
Friday.  This will pose a threat of flash flooding and mudslides.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/2100Z 19.4N 107.7W   40 KT  45 MPH
 12H  09/0600Z 20.2N 108.3W   50 KT  60 MPH
 24H  09/1800Z 21.2N 109.4W   60 KT  70 MPH
 36H  10/0600Z 22.3N 110.9W   60 KT  70 MPH
 48H  10/1800Z 23.2N 112.5W   55 KT  65 MPH
 60H  11/0600Z 23.5N 114.2W   45 KT  50 MPH
 72H  11/1800Z 23.5N 115.5W   35 KT  40 MPH
 96H  12/1800Z 23.1N 118.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  13/1800Z 22.4N 120.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
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Forecaster Latto
 
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