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Hurricane Norma Discussion Number  13
NWS National Hurricane Center Miami FL       EP172023
300 PM MDT Fri Oct 20 2023
 
After a brief period of weakening earlier today, data from the Air 
Force Hurricane Hunters this afternoon indicate that Norma has 
strengthened back to a major hurricane. The aircraft data showed 
maximum 700-mb flight-level winds of 124 kt, with peak SFMR winds of 
104 kt in the northeast quadrant. Based on these data, the initial 
intensity is raised to 105 kt. The eyewall is open to the southeast 
based on aircraft reports. The eye signature has become better 
defined over the past few hours in radar data from Los Cabos, 
Mexico, as new bursts of intense inner core convection have 
developed. The radar data show that the outer rainbands of Norma are 
beginning to spread over southern portions of Baja California Sur.

In the short term, the renewed inner core of Norma could allow the 
hurricane to resist some of the negative influences of southerly 
shear and drier air in the surrounding environment. The updated NHC 
forecast still shows some weakening but is higher than the previous 
one during the first 24-36 h of the forecast, based largely on the 
higher initial intensity. Land interaction with the Baja California 
peninsula, along with the previously described negative factors, 
should induce a more steady weakening trend through early next week 
while Norma approaches mainland Mexico.

Scatterometer data and aircraft fixes show that Norma has moved 
slightly left-of-track today, and its initial motion is 330/7 kt. 
The hurricane is expected to turn toward the north-northwest and 
north during the next day or so while it moves between a mid- to 
upper-level trough to its northwest and a mid-level ridge to its 
east. This will bring the center of Norma over the southern tip of 
Baja California Sur within the hurricane warning on Saturday. The 
track models have again trended westward this cycle, and the updated 
NHC forecast is nudged in that direction during the next 24-36 h. 
Then, the models generally agree that Norma will turn northeastward 
and approach the coast of Sinaloa in western Mexico, although there 
are still notable speed differences between the various track 
models. This portion of the NHC forecast is similar to the previous 
one, although a bit slower based on the latest consensus aids. Norma 
is forecast to move inland along the coast of Sinaloa on Monday and 
quickly dissipate thereafter over the terrain of western Mexico.
 
 
Key Messages:
 
1. Norma is expected to bring hurricane conditions and a dangerous 
storm surge to portions of the far southern Baja California 
peninsula within the hurricane warning area on Saturday. 
Preparations to protect life and property should be rushed to 
completion. 
 
2. Heavy rains from Norma will begin to impact the far southern 
portions of Baja California Sur today and continue through Sunday, 
with heavy rains reaching Sinaloa on Saturday. This rainfall will 
produce flash and urban flooding, along with possible mudslides in 
areas of higher terrain.
 
3. Norma is forecast to approach the west coast of Mexico as a
tropical storm on Sunday and Sunday night, and a Tropical Storm
Watch is in effect for a portion of that area.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/2100Z 20.1N 109.8W  105 KT 120 MPH
 12H  21/0600Z 21.2N 110.0W  100 KT 115 MPH
 24H  21/1800Z 22.6N 110.1W   85 KT 100 MPH
 36H  22/0600Z 23.4N 109.7W   70 KT  80 MPH
 48H  22/1800Z 23.9N 109.0W   60 KT  70 MPH
 60H  23/0600Z 24.2N 108.1W   50 KT  60 MPH
 72H  23/1800Z 24.6N 107.1W   35 KT  40 MPH...INLAND
 96H  24/1800Z...DISSIPATED
 
$$
Forecaster Reinhart
 
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