Pacific Hurricane Feed

Tropical Storm Kay Forecast Discussion

WTPZ42 KNHC 090854

Tropical Storm Kay Discussion Number  20
NWS National Hurricane Center Miami FL       EP122022
200 AM PDT Fri Sep 09 2022

After moving back offshore yesterday evening, Kay has been roughly
paralleling the northwestern coastline of the Baja California
peninsula. The satellite presentation is not all that impressive,
with the majority of the deep convective activity firing over the
warm waters of the Gulf of California and adjacent mountainous
terrain, well removed from Kay's center. An Air Force Reserve
Hurricane Hunter aircraft was able to reach the center earlier this
morning, and found that Kay's circulation is largely intact, with
peak 700-mb flight-level winds of 62 kt and a minimum central
pressure of 990 mb. While the standard wind reduction at that flight
level would still typically support 55 kt, the SFMR-derived winds
in that area were much lower, which better match a dropsonde also
launched in the area. South of the center, there were some
significant winds observed, with a sustained wind of 44 kt at Isla
Cedros at 0630 UTC. Based on a combination of all these data, the
initial intensity was reduced to 50 kt for this advisory.

Additional weakening over the next 24-36 hours is expected as Kay
will be traversing sub-23 C sea-surface temperatures and
approaching even cooler waters in the cold California Current. The
GFS, ECMWF, and HWRF models all indicate that Kay will cease to
produce organized deep convection near its center in about 36 hours,
marking its transition to a post-tropical remnant low off the coast
of Southern California. The low should spin down further and
dissipate sometime in the 4-5 day forecast. The latest NHC intensity
forecast is in good agreement with the intensity guidance suite.

From the two recon fixes, Kay continues to move off to the
north-northwest at 330/11 kt. A narrowing mid-level ridge draped
along the northeast side of the storm is expected to maintain this
motion with a gradual turn to the northwest and west-northwest today
into tonight. As Kay loses its remaining deep convection and becomes
more shallow, the weak low-level ridging in the Eastern Pacific
should result in the remnant low making a slow cyclonic turn away
from the western U.S. coastline. The latest track guidance has
shifted a bit more leftward this cycle, and the latest NHC track
forecast was also shifted in that direction, towards the track
consensus aids.

Although Kay's maximum sustained winds are lower, the tropical
cyclone 34-kt wind radii remain quite large on its eastern side, as
seen in recent scatterometer data showing these tropical-storm-force
winds extending up to the northern Gulf of California coast. Wind,
surf, and rainfall impacts continue to extend far from the center so
users should not focus on the exact forecast track of Kay.


1. Heavy rainfall could lead to flash flooding, including
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 later today in Southwest Arizona.

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 expected across portions of southern California and extreme
southwestern Arizona later today. For information on this wind
hazard, users should see High Wind Warnings and other products from
their local NWS Weather Forecast Office.


INIT  09/0900Z 29.4N 116.0W   50 KT  60 MPH
 12H  09/1800Z 30.5N 117.3W   40 KT  45 MPH
 24H  10/0600Z 31.3N 119.0W   35 KT  40 MPH
 36H  10/1800Z 31.5N 120.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  11/0600Z 31.3N 121.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  11/1800Z 30.6N 121.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  12/0600Z 29.9N 121.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  13/0600Z 28.6N 120.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  14/0600Z...DISSIPATED

Forecaster Papin

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