Eastern Pacific Basin Tropical Cyclones

Tropical Storm Kay Forecast Discussion


000
WTPZ42 KNHC 050857
TCDEP2

Tropical Storm Kay Discussion Number   4
NWS National Hurricane Center Miami FL       EP122022
400 AM CDT Mon Sep 05 2022

Deep convection has increased in a band around the southern and 
eastern portions of the circulation overnight.  A couple of ASCAT 
passes from around 0345-0445 UTC revealed peak winds of 38-41 kt, 
and a much larger wind field over the northeastern quadrant than 
previous estimated.  The ASCAT data, a TAFB Dvorak classification 
of T3.0 and UW/CIMSS SATCON all supported a 45 kt intensity around 
0600 UTC.  Since the convective organization has continued to 
increase over the past few hours, the initial intensity for this 
advisory has been set at 50 kt. 

Although Kay is currently within an area of light to moderate 
northeasterly shear, it will be moving over SSTs of 28-29 degrees 
Celsius during the next couple of days which should allow steady 
strengthening.  Most of the dynamical model guidance also predicts 
significant deepening of Kay during that time, giving more 
confidence to the forecast.  The updated NHC intensity forecast 
shows a slightly faster rate of strengthening in the short 
term and now calls for Kay to become a hurricane within 24 hour.  
The new forecast also calls for a slightly higher peak intensity 
than before.  After 60 h, cooler SSTs along the storm's track 
are likely to induce gradual weakening, but Kay is forecast to 
remain a large hurricane when it passes near the southern and 
central portions of the Baja California peninsula.  The latest NHC 
intensity prediction again lies between the IVCN and HCCA aids. 

Kay appears to have wobbled back left since the previous advisory, 
but the longer term motion is 290/13 kt.  Kay should remain on a 
west-northwestward heading through tonight, but by Tuesday a 
northwestward motion around the western periphery of a mid-level 
ridge over Mexico is expected to begin.   A turn to the 
north-northwest is forecast by midweek and the guidance is in good 
agreement that Kay will move in the direction of the southwest and 
west-central coast of the Baja peninsula.  Although there has been 
some increase in model spread this cycle with the UKMET keeping the 
system farther offshore, the typically reliable GFS and ECMWF are 
near the eastern side of the guidance envelope and are in good 
agreement on Kay moving very close to or over a portion of the west 
coast of the Baja peninsula.  The NHC track forecast is near a 
blend of those models and is very similar to the previous track.  
Users are reminded not to focus on the exact details of the
long-range forecast as wind and rainfall impacts are likely to 
extend far from the center of the hurricane. 

Tropical Storm or Hurricane Watches will likely be required later 
today for portions of the Baja California peninsula, and interests
there should closely monitor the latest forecast updates.


KEY MESSAGES:

1. Although the center of Kay is expected to stay offshore of  
southwest mainland Mexico, heavy rainfall could lead to flash 
flooding, including landslides, across portions of the Mexican 
Riviera and western Mexico through Wednesday night.

2. Kay is forecast to strengthen into a hurricane while it moves
northward toward the Baja California peninsula later this week.
While the details of the long-range track and intensity forecasts
are uncertain, there is increasing risk of wind and rainfall 
impacts in the Baja California peninsula during the middle and 
latter parts of the week. Interests there should closely monitor 
updates to the forecast as tropical storm or hurricane watches 
will likely be required for a portion of that area later today.


FORECAST POSITIONS AND MAX WINDS

INIT  05/0900Z 15.7N 105.3W   50 KT  60 MPH
 12H  05/1800Z 16.0N 106.8W   60 KT  70 MPH
 24H  06/0600Z 17.0N 108.5W   70 KT  80 MPH
 36H  06/1800Z 18.1N 110.2W   80 KT  90 MPH
 48H  07/0600Z 19.6N 111.7W   90 KT 105 MPH
 60H  07/1800Z 21.4N 112.7W   90 KT 105 MPH
 72H  08/0600Z 23.3N 113.4W   85 KT 100 MPH
 96H  09/0600Z 27.5N 115.1W   65 KT  75 MPH
120H  10/0600Z 29.9N 118.3W   45 KT  50 MPH

$$
Forecaster Brown



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