Subtropical Storm Patty Forecast Discussion

000
WTNT42 KNHC 021436
TCDAT2

Subtropical Storm Patty Discussion Number   2
NWS National Hurricane Center Miami FL       AL172024
300 PM GMT Sat Nov 02 2024

Patty has strengthened over the past several hours. Satellite images 
continue to show the system maintaining a tight core with a ring of 
cold cloud tops surrounding the center. On a larger scale, however, 
the storm has a considerable amount of cool and dry air wrapping 
around the core and it is co-located with an upper-level low. These 
mixed tropical and extratropical characteristics are supportive of 
maintaining Patty's subtropical status. ASCAT data from a few hours 
ago showed peak winds near 50 kt in the southwestern quadrant, and 
given potential undersampling due to the instrument's resolution, 
the initial wind speed is increased to 55 kt. The wind radii have 
also been adjusted based on the ASCAT data.

Patty is likely near its peak intensity as it currently lies in a 
region of instability beneath its parent upper-level low and in 
relatively low vertical wind shear. However, the models show the 
upper-level feature weakening, resulting in more stable conditions 
and increasing westerly vertical wind shear. These environmental 
factors should cause steady weakening and lead to post-tropical 
transition by Sunday night. The low is expected to dissipate in 3 to 
4 days. The NHC intensity forecast is above the previous in the 
short term due to the higher initial intensity.

The subtropical storm is accelerating southeastward, and the latest 
initial motion estimate is 130/11 kt. A faster eastward motion is 
expected to begin soon, taking the storm near or just south of the 
Azores tonight and Sunday. An east-northeastward motion is expected 
after that toward western Europe. The models are in fairly good 
agreement, and this forecast lies near the middle of the guidance 
envelope. 

Key Messages:

1. Tropical storm conditions are expected in the Azores tonight and 
Sunday.

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


FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 39.0N  32.4W   55 KT  65 MPH
 12H  03/0000Z 38.2N  29.5W   50 KT  60 MPH
 24H  03/1200Z 37.8N  25.7W   45 KT  50 MPH
 36H  04/0000Z 37.8N  21.6W   40 KT  45 MPH...POST-TROPICAL
 48H  04/1200Z 38.7N  17.3W   35 KT  40 MPH...POST-TROPICAL
 60H  05/0000Z 40.0N  13.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  05/1200Z 41.6N  10.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  06/1200Z...DISSIPATED

$$
Forecaster Cangialosi