Subtropical Storm Teresa Forecast Discussion Number 1
ActuCyclone
24 septembre 2021
000 WTNT44 KNHC 242056 TCDAT4 Subtropical Storm Teresa Discussion Number 1 NWS National Hurricane Center Miami FL AL192021 500 PM AST Fri Sep 24 2021 The disturbance just north of Bermuda interacting with a mid- to upper-level low has developed a prominent band of deep convection within its eastern semicircle as well as a well-defined surface center. Additionally, the system is not displaying any significant baroclinicity (i.e., frontal boundaries), so it is not an extratropical cyclone. All of which indicates that the system has evolved into a subtropical cyclone. ASCAT-C scatterometer data from 1440Z suggested peak winds were around 40 kt, which is the basis for calling the system Subtropical Storm Teresa. The system is moving toward the northwest at 12 kt is it rounds the northern part of the mid- to upper-level low. By Saturday, Teresa should turn northward and then northeastward, as it begins to be caught up in the mid-latitude westerlies. The forecast is based upon the TVCN track consensus technique. Teresa will not be long-lived. A developing extratropical system forming off of New England should absorb Teresa between 36 and 48 hours. Until then, the subtropical storm has a small window to intensify slightly while traversing lukewarm water and encountering moderate vertical shear. If deep convection develops near the system's center, then Teresa could evolve into a tropical storm. However, it is more likely that Teresa will remain a subtropical storm until dissipation in around two days. It is worth noting that Teresa will likely be the 9th so-called "shortie" of the 2021 hurricane season -- systems that are short- lived and relatively weak. FORECAST POSITIONS AND MAX WINDS INIT 24/2100Z 34.5N 64.5W 40 KT 45 MPH 12H 25/0600Z 35.4N 65.5W 45 KT 50 MPH 24H 25/1800Z 36.3N 65.5W 45 KT 50 MPH 36H 26/0600Z 37.2N 64.4W 40 KT 45 MPH 48H 26/1800Z...DISSIPATED $$ Forecaster Landsea