Subtropical storm in south Madagascar?

[DanieleItalyRm]

Subtropical storm in south Madagascar?
Look the Loop: http://www.sat24.com/af?ir=true

this storm formed on 18 Jul from a well organized system over 23°C sea surface:





yesterday 19 jul:



I think it acquired tropical caracteristics:

[DanieleItalyRm]

iN THIS MOMENT:

[HouTXmetro]

Intresting, how common are systems around that part?

[DanieleItalyRm]

for me it became into tropical cyclone for the tropical transition:

[Meso]

Living in South Africa I see these systems quite often. I haven't had the chance to look at the history of the system but I'm assuming it's moving from west to east, given the season.

Remember it's the dead of winter down here right now, and while that area is tropical, water temperatures are no doubt way below the summer temps, probably around 20-24'C.

In winter we get 'cut-off lows' which move from west to east, often developing off the east coast of South Africa, these are typically cold core systems, though occasionally they have an impressive circulation with associated convection. Though these west to east moving systems will never have a symmetrical shape. These storms can often occur around Cape Town as well, where I am located, though as they are brought NE for a while (before typically moving SE with the jet stream) they may develop some more convection over the center as they enter slightly warmer waters (waters around Cape Town are about 12-15'C in winter)...

Here is an image of a cut-off low situated off South Africa in 2001 -


These systems differ from the tropical activity that we get in the months of February through May in that those systems tend to develope east of Madagascar and then move west or south. These winter cut-off lows are often associated with cold fronts and thus come from the opposite direction and move from west to east.

To answer the question about how common they are, there are several each year. Some look more tropical than others.

[DanieleItalyRm]

for GFS have a warm core, this is a subtropical cyclone.

[Meso]

As expected it formed along the east coast of South Africa over the northern KZN coast near the Mozambique border. 23'C is very marginal temperatures for tropical development. I think it may have some sub-tropical storm characteristics, though many more of the cut-off lows in that area each year probably also do, but the met agencies here don't really discuss sub-tropical storms. Even if they have sub-tropical characteristics, as far as I am aware they are still just referred to as cut-off lows. And the nature of the storm is very different to the cyclone activity we get in summer.

[DanieleItalyRm]

For me in this case a tropical or subtropical system moved south east and GRADUALLY become in extratropical system. Instead, In cases like Vince or Grace, extratropical system become in tropical system:


18 jul:


20 jul:


This is a possible high resolution warm core in this cases:

[Meso]

You should take a look at the system on the KZN coast today! Another cut-off low with an eye. I need to find that cyclogenesis page with the warm/cold core information. The storm has brought much snow to the country.