SIO: HEROLD - Post Tropical

[Nancy Smar]

91S INVEST 200301 0000 12.5S 57.0E SHEM 15 1010

[Nancy Smar]

DATE: 2020/03/12 AT 1200 UTC

PART 1:

WARNING SUMMARY:


Nil but warnings and advisories will be initiated at 12Z on the Area of Disturbed Weather 10-20192020 located to the North-West of Tromelin.

PART 2 :
TROPICAL WEATHER DISCUSSION:


There is globally little thunderstorm activity over the basin except off the northeastern coasts of Madagascar where the thunderstorms activity has strengthened over the last 24 hours within a low pressure area.

Area of Disturbed Weather to the North-West of Tromelin Island:
Location of the center at 09Z : 13.4S / 52.9E
Mean 10mn max wind : 20/25 kt within the northern semi-circle.
Estimated central pressure : 1002 hPa
Forward motion: Quasi-stat

Micro-wave imagery of last night and this morning along with classical satellite imagery suggest that a new center has formed north-west of the former center previously monitored near Tromelin. This new center has gathered most of the thunderstorms activity and clearly show signs of an ongoing cyclogenesis: the low level inflow is good equatorwards but still lacks to the south due to the presence of a surface / low levels trough. In the upper levels, the outflow is well established based on the cirrus motion. A moderate easterly constraint is present as the system lies just to the north of the upper levels ridge. The oceanic potential is sufficient with 29oC surface temperature but the depth of warm waters is rather limited according to mercator ocean analysis. In this context, most of the guidance deepens significantly this system within the next 48 hours with even a possibility for some rapid intensification (Arome solution). This system is expected to track generally southwards and then east-south-eastwards during the week-end (west-north-westerly mid-levels flow enhanced by a succession of Rossby waves breaking to the south and the persistence of a near equatorial ridge to the North).

Over the next 2 days, the risk of formation of a moderate tropical storm becomes high north-west of Tromelin.

[Yellow Evan]

This is now Harold, correct?

[aspen]

Now the equivalent of a Category 1 hurricane. Finally, the SWIO is showing signs of life again! This is incredibly tame compared to last season, where there were already half a dozen Cat 4 equivalent systems, and Idai was making landfall in Mozambique.

[cycloneye]

 https://twitter.com/zoom_earth/status/1239009487937306625

[cycloneye]

 https://twitter.com/jnmet/status/1239133956320235522