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Hurricane Genevieve Discussion Number  14
NWS National Hurricane Center Miami FL       EP122020
300 PM MDT Wed Aug 19 2020
 
Genevieve's satellite presentation has continued to degrade this 
afternoon with the eye becoming less distinct in visible imagery and 
a warming of the cloud tops in the surrounding ring of convection.  
Objective and subjective Dvorak T-numbers have continued to fall, 
and the reduction in wind speed has been confirmed by recent data 
from an Air Force Reserve reconnaissance aircraft that has provided 
a couple of center fixes during its mission this afternoon.  
Somewhat surprisingly, the plane only reported peak flight-level 
winds of 82 kt and SFMR winds of 69 kt. The latest minimum pressure 
reported by the aircraft was 974 mb.  Since the aircraft only flew a 
single alpha pattern, it is possible that the strongest winds were 
not captured.  Therefore the initial intensity has been 
conservatively adjusted to 80 kt.  

The hurricane will be moving over  gradually decreasing sea 
surface temperatures over the next day or so, but only gradual 
weakening expected during this time.  Once Genevieve begins to move 
away from the Baja California peninsula, it will be moving over 
much cooler waters, and a slightly faster rate of weakening is 
expected, with the system degenerating into a remnant low by 96 
hours.  The new NHC intensity forecast is in best agreement with the 
SHIPS statistical guidance for the first day or two, and then 
trends closer the intensity consensus aids thereafter. 

Genevieve is moving north-northwestward or 330/7 kt. Mid-level 
ridging to the north of the system is expected to cause the 
hurricane to turn northwestward tonight, and a northwestward motion 
should then continue over the next several days.  On this track, the 
center of Genevieve will pass near or just southwest of the 
southern portion of the Baja California peninsula overnight and on 
Thursday. The recent eastward shift in the guidance did not continue 
in the 1200 UTC models, so little overall change was required from 
the previous NHC track foreast.  The updated forecast is near the 
middle of the guidance envelope not far form the multi-model 
consensus aids.
  
 
Key Messages:
 
1. The center of Genevieve is forecast to pass near or just west of 
the Baja California peninsula tonight and Thursday.  Tropical storm 
conditions are expected to spread across southern Baja California 
Sur through Thursday.  Hurricane conditions are expected within the 
Hurricane Warning area beginning tonight and continuing into 
Thursday.
 
2. Heavy rainfall from Genevieve may lead to life-threatening flash 
flooding and mudslides across portions of far southern Baja 
California Sur through Thursday.
 
3. Large swells generated by Genevieve will affecting portions of 
the west-central coast Mexico and the coast of the southern Baja 
California peninsula through Friday. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/2100Z 21.4N 110.1W   80 KT  90 MPH
 12H  20/0600Z 22.2N 110.6W   80 KT  90 MPH
 24H  20/1800Z 23.1N 111.7W   75 KT  85 MPH
 36H  21/0600Z 23.9N 113.0W   70 KT  80 MPH
 48H  21/1800Z 24.8N 114.5W   60 KT  70 MPH
 60H  22/0600Z 26.0N 116.3W   50 KT  60 MPH
 72H  22/1800Z 27.1N 118.2W   40 KT  45 MPH
 96H  23/1800Z 29.1N 121.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  24/1800Z 30.5N 122.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Brown
 
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