Tempestade Tropical Sebastien (#Atlântico AL20)

luismeteo3

Furacão
Registo
14 Dez 2015
Mensagens
17,112
Local
Fatima (320m)
National Hurricane Center Miami
Tropical Cyclone Advisory #16 - 5:00 AM AST November 23 2019
TROPICAL CYCLONE SEBASTIEN (AL202019)
==========================================
West Southwest of Azores islands

At 9:00 AM UTC, Tropical Cyclone Sabastien (997 hPa) located at 27.8N 50.6W or 1335 nm west southwest of the Azores has sustained winds of 55 knots with gusts of 65 knots. The cyclone is reported as moving east northeast at 15 knots.

Gale/Storm Force Winds
=================
100 nm from the center

Forecast and Intensity
===================
12 HRS 29.4N 48.2W - 50 knots (Tropical Cyclone)
24 HRS 31.6N 44.2W - 40 knots (Tropical Cyclone)
48 HRS 37.0N 31.6W - 35 knots (Tropical Cyclone) southwest of the Azores (Vila do Porto)

The cloud pattern of Sebastien has changed significantly overnight. Deep convection has decreased substantially during the past several hours and the remaining thunderstorms are organized around a mid-level eye feature seen in satellite images. Model vertical cross sections indicate that Sebastien is extremely titled with the low-level center, although I can't see it, likely well displaced to the southwest of the mid-level eye. The initial intensity is held at 55 kt based on the ASCAT data that came in a little after 0000Z, but it looks like Sebastien is on a weakening trend.

Strong southwesterly vertically wind shear of about 40 knots is responsible for the titled structure of the cyclone. Since the shear is not expected to let up and because Sebastien is headed for steadily cooler waters, it seems reasonable to assume that weakening is likely. Although the models agree that Sebastien should slowly lose its strength, it remains unclear if Sebastien will transition to a post-tropical cyclone before it opens up into a trough during the next few days. The NHC forecast continues to show dissipation by day 3, but it is certainty possible that it dissipates before then.
 


luismeteo3

Furacão
Registo
14 Dez 2015
Mensagens
17,112
Local
Fatima (320m)
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