Tropical Storm Patty Forecast Discussion

000
WTNT42 KNHC 040236
TCDAT2

Tropical Storm Patty Discussion Number   8
NWS National Hurricane Center Miami FL       AL172024
300 AM GMT Mon Nov 04 2024

Patty has continued producing deep convection since the time of the 
previous advisory, although the convective structure has recently 
degraded slightly on the latest infrared images.  The infrared 
satellite images and an 03/2138 UTC ASCAT pass depict a more compact 
cyclone with a confined radius of maximum winds than earlier in the 
system's life. Patty is also no longer co-located with the 
upper-level low that was earlier responsible for its hybrid 
characteristics. Based on these observations, Patty has made the 
transition into a tropical storm. The earlier ASCAT pass showed 
tropical storm force winds as high as 39 kt in the southern 
semicircle.  The initial intensity is therefore held at 40 kt.

The initial motion of the tropical storm is estimated to be 
eastward, or 085/17 kt.  Patty is expected to turn 
east-northeastward over the next day, and only a slight northward 
adjustment was made to the previous forecast, closer to the latest 
track consensus guidance.

All guidance insists Patty will weaken significantly during the next 
day or two as the cyclone encounters progressively colder 
sea-surface temperatures, stronger vertical wind shear and drier 
air.  Although the timing of when Patty is forecast to lose its 
convection and become post-tropical has been pushed back slightly, 
confidence is fairly high that the system will be falling apart and 
weakening in a day or two.  The various global models agree that 
Patty should open up into a trough and dissipate by hour 48, around 
the time that the circulation reaches the west coast of the Iberian 
Peninsula.  Due to orographic lifting, some rainfall impacts appear 
possible for portions of Portugal and Spain from Patty's remnants.

Key messages:

1. Between late Monday and Tuesday, heavy rainfall across portions 
of Portugal and western Spain is possible from Patty or its 
remnants.


FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 37.7N  20.0W   40 KT  45 MPH
 12H  04/1200Z 38.4N  16.7W   40 KT  45 MPH
 24H  05/0000Z 39.8N  12.8W   35 KT  40 MPH...POST-TROPICAL
 36H  05/1200Z 41.0N  10.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  06/0000Z...DISSIPATED

$$
Forecaster Hagen