ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
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
NNNN