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Hurricane Nora Discussion Number  13
NWS National Hurricane Center Miami FL       EP142021
400 PM CDT Sat Aug 28 2021
 
Nora developed a cloud-filled eye during the past few hours, with 
the center now grazing the coast and the eyewall moving across 
western Jalisco, Mexico.  An Air Force Reserve Hurricane Hunter 
aircraft has been investigating the hurricane, but unfortunately 
the storm is now too close to the mountainous coastline for the 
plane to safely locate the surface center or sample the 
likely-stronger wind field on the eastern side of the circulation.  
Based mainly on T4.5/77 kt Dvorak estimates from TAFB and SAB, the 
initial intensity is estimated to be 75 kt.

The center has been moving a little faster to the west of due 
north, or 350/12 kt.  The track models are in agreement that Nora 
should turn toward the north-northwest and northwest during the next 
few days, generally keeping the center of the hurricane over the 
waters of the Gulf of California.  However, due to the complex 
geography and mountainous topography of the region, the track 
forecast is challenging, and it's almost impossible to know if 
Nora's center will remain over water or graze the coastlines of 
Nayarit and Sinaloa over the next few days.  By days 4 and 5, Nora's 
center is forecast to move inland over Sonora after traversing a 
significant length of the Gulf of California.

Assuming a path that keeps Nora just offshore, low shear and very 
warm sea surface temperatures in the Gulf of California should be 
sufficient to at least maintain hurricane intensity for the next 3 
days.  However, any slight deviations of the track could cause Nora 
to weaken and fall below hurricane intensity sooner than is 
indicated in the official forecast.  Given the uncertainties, 
however, the government of Mexico has extended the hurricane 
warning farther north along the coasts of Nayarit and Sinaloa out 
of an abundance of caution.  Weakening will become more likely the 
farther north Nora gets up the Gulf of California, both due to 
possible land interaction and ingestion of drier air off the Mexican 
plateau.

 
Key Messages:
 
1. Nora is forecast to be a hurricane while it moves near or 
along the coasts of the Mexican states of Jalisco, Nayarit, and 
Sinaloa through Monday, and hurricane warnings are in effect for 
portions of that coastline.  Interests in these areas should closely 
monitor the progress of Nora and subsequent updates to the forecast.
 
2. Heavy rain associated with Nora is expected across the west coast 
of Mexico from the Mexican states of Guerrero, northward to southern 
Sonora, including Baja California Sur.  This rain will likely 
result in life-threatening flash flooding and mudslides across these 
regions.  Rainfall from Nora may spread into the southwestern U.S. 
and central Rockies during the middle to latter portion of next 
week.
 
3. Nora is forecast to continue moving northward over the Gulf of 
California Tuesday and Wednesday, bringing a risk of wind impacts to 
portions of the Mexican states of Baja California Sur, northern 
Sinaloa, and Sonora.  Given the above-average uncertainty in the 
forecast intensity, confidence is not high enough to determine the 
magnitude and location of these potential impacts.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/2100Z 19.7N 105.4W   75 KT  85 MPH...ON THE COAST
 12H  29/0600Z 21.5N 105.9W   75 KT  85 MPH
 24H  29/1800Z 22.9N 106.7W   75 KT  85 MPH
 36H  30/0600Z 23.5N 107.4W   75 KT  85 MPH
 48H  30/1800Z 24.2N 108.1W   75 KT  85 MPH
 60H  31/0600Z 24.8N 108.9W   70 KT  80 MPH
 72H  31/1800Z 25.6N 109.5W   70 KT  80 MPH
 96H  01/1800Z 27.6N 110.4W   55 KT  65 MPH...INLAND
120H  02/1800Z 29.4N 110.6W   30 KT  35 MPH...INLAND
 
$$
Forecaster Berg
 
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