Subtropical Storm Patty Forecast Discussion

978 
WTNT42 KNHC 030232
TCDAT2

Subtropical Storm Patty Discussion Number   4
NWS National Hurricane Center Miami FL       AL172024
300 AM GMT Sun Nov 03 2024

The convective structure of Patty has changed some over the past 
several hours as the center passes just south of the central 
Azores. While the cloud tops have cooled, the convection is now 
mainly to the northeast of the center, and the overall cloud pattern 
is elongated south-to-north.  The system remains embedded in a 
deep-layer cold air mass, with surface temperatures in the Azores 
currently below 20C.  Satellite intensity estimates have decreased 
a little due to the decreased convective symmetry, and this is the 
basis for lowering the initial intensity to 50 kt.

Patty is expected to weaken over the next few days as the parent 
upper-level low decays to an open trough, leaving the storm in 
stronger shear.  While this happens, it should also move into a 
drier and more stable airmass.  This combination is expected to 
cause the convection to dissipate by 36 h, with the storm becoming 
a post-tropical low at that time.  The latest global model guidance 
suggests that the remnant low is likely to decay to a trough by 72 
h, so the new intensity forecast now calls for dissipation by then.

The initial motion is now 095/17 kt.  The mid-latitude westerly 
flow is expected to steer the cyclone eastward for 12-24 h, 
followed by an east-northeastward motion. The models remain in 
fairly good agreement, and the forecast track is again near the 
middle of the guidance envelope.

Key Messages:

1. Tropical storm conditions are expected in the Azores through the 
weekend, where Tropical Storm Warnings are in effect.

2. Locally heavy rains are possible across the Azores through the 
weekend.


FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 37.9N  27.8W   50 KT  60 MPH
 12H  03/1200Z 37.6N  24.7W   45 KT  50 MPH
 24H  04/0000Z 37.6N  20.8W   45 KT  50 MPH
 36H  04/1200Z 38.5N  16.6W   40 KT  45 MPH...POST-TROPICAL
 48H  05/0000Z 40.1N  12.7W   35 KT  40 MPH...POST-TROPICAL
 60H  05/1200Z 41.6N   9.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  06/0000Z...DISSIPATED

$$
Forecaster Beven