Eastern Pacific Basin Tropical Cyclones

Tropical Storm Kay Forecast Discussion


307 
WTPZ42 KNHC 091453
TCDEP2

Tropical Storm Kay Discussion Number  21
NWS National Hurricane Center Miami FL       EP122022
800 AM PDT Fri Sep 09 2022

Kay is gradually becoming less organized.  There is currently 
minimal convection near its center of circulation, although there is 
a complex of convective bands occurring about 75-150 n mi north of 
the center. Doppler radar data from Yuma and San Diego has shown 
winds as high as 60 kt aloft, although it is unclear how well these 
winds are mixing down to the surface.  Based on the radar and 
satellite intensity estimates, the initial intensity is reduced to 
45 kt, and this could be a bit generous.  An Air Force Reserve 
Hurricane Hunter aircraft is enroute to investigate Kay.

Kay should continue to weaken as it reaches sea surface 
temperatures of 20-21C by 24 h, and the dynamical model suggest it 
should stop producing convection near or just after that time.  The 
new intensity forecast shows the cyclone as a minimal tropical storm 
in 24 h, followed by decay to a remnant low as the convection 
dissipates and the winds drop below tropical-storm force.  The 
global models indicate that the remnant low should dissipate 
between 96-120 h, and the new intensity forecast follows this. 

The initial motion is now northwestward or 320/ 11 kt.  A mid-level 
ridge to the north of Kay is expected to cause the cyclone to 
gradually turn west-northwestward away from land in the next 12 h, 
followed by a westward turn between 12-24 h.  After that time, 
low-level ridging in the Eastern Pacific should steer the remnant 
low slowly southward and then southeastward before the system 
dissipates completely.  There was little change in the track 
forecast guidance since the last advisory, and the new forecast 
track is similar to the previous track.

Although Kay's intensity has decreased, the tropical cyclone 34-kt 
wind radii remain quite large on its eastern side. Wind, surf, and 
rainfall impacts continue to extend far from the center so users 
should not focus on the exact forecast track of Kay.


KEY MESSAGES:

1. As the center of Kay passes just offshore, heavy rainfall will 
likely result in flash flooding, including possible landslides, 
across the Baja California peninsula and portions of mainland 
northwestern Mexico through Saturday morning.  Flash, urban, and 
small stream flooding is likely across Southern California beginning 
today, especially in and near the peninsular ranges. Flash, urban, 
and small stream flooding is possible beginning today in Arizona 
and southern Nevada.

2. Tropical storm conditions are occurring over portions of the Baja
California peninsula, and these conditions extend all the way to the
northern Gulf of California coastline, where a Tropical Storm
Warning is in effect.

3. Strong winds not directly associated with Kay's core wind field
are occurring across portions of southern California and extreme
southwestern Arizona. For information on this wind hazard, users 
should see High Wind Warnings and other products from their local 
NWS Weather Forecast Office.


FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 30.3N 116.7W   45 KT  50 MPH
 12H  10/0000Z 31.1N 118.1W   40 KT  45 MPH
 24H  10/1200Z 31.4N 119.5W   35 KT  40 MPH
 36H  11/0000Z 31.4N 120.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  11/1200Z 31.0N 121.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  12/0000Z 30.3N 121.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  12/1200Z 29.6N 121.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  13/1200Z 28.5N 120.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  14/1200Z...DISSIPATED

$$
Forecaster Beven




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