SATL: Subtropical Depression BAPO - South of Brazil

[wyq614]

This has been given a name by Brazil, but JTWC ignores it, and it has not gained disturbance status...

[RL3AO]

[jaguarjace]

Brazil's Navy Hydrography Center have now produced a list of names. Arani was the first name that had been used by the Center.

http://www.mar.mil.br/dhn/dhn/downloads/normam/normam_19.pdf - Page 18

[Dean_175]

From Navy Hydrography Center Bulletin (1200 UTC February 6)

WARNING NR 098/2015

SPECIAL WARNING

ISSUED AT 1530 - FRI - 06/FEV/2015

SUBTROPICAL STORM “BAPO” WITH CENTRAL PRESSURE 996 AT 30S043W, MOVING AT 10/15 TO SOUTH/SOUTHWEST WITH WIND 7/8 WITH GUSTS 9/10 AFFECTING AREA ALFA EAST OF 050W, AREA BRAVO SOUTH OF 28S AND EAST OF 043W AND SOUTH OCEANIC AREA WEST OF 035W. ESTIMATED POSITION AT 071200 – 34S044W. IT IS NOT EXPECTED THE CENTER OF THE CYCLONE REACHES COASTAL REGION.

VALID UNTIL 080000.

[jaguarjace]

[Dean_175]

The 1200UTC Feb 6 GFS run seems to show some possible minimal strengthening of the system until early Saturday morning (EST). Storm shown to weaken by Saturday night (EST)-early Sunday morning-with development of frontal characteristics and loss of subtropical characteristics occurring later on Sunday. GFS shows the system to move slowly to the west-southwest (by about 5-10 longitude) until Saturday afternoon or night- at which it begins to recurve and move to the SE-without landfall.




Disclaimer: This is not an official forecast and is not endorsed by any official meteorological organization.

[cycloneye]

Does it look more frontal?

[Dean_175]

Does it look more frontal?

Maybe a little bit still right now- but certainly not as frontal as the system appeared last night in which there was very little convection directly around the center and it was hard to even locate the center with satellite imagery. Right now the system appears much more organized on satellite imagery- with convection obviously spiraling around the center and the system looking much more like a typical subtropical cyclone.

To me - while the cloud band looks a bit frontal- it is looking much more subtropical with convection starting to spiral around the center -which is appearing more "detached" from the cloud band. In addition- the isobars don't look particularly frontal and look "tight" -like a subtropical system would.

EDIT-That said: looking at GFS cyclone phase space , cloud pattern, and ascat wind data- I wouldn't say that this is a truly non-frontal system. I even doubt that all meteorological agencies would consider this a subtropical storm. I am not sure how to post an image- however, the wind data shows sharp front -like horizontal wind variations - rather than the smooth broad spiral in a typical tropical cyclone.

GFS cyclone phase space shows that this system is still slightly "asymmetric".

[Dean_175]

I am predicting that this storm will remain around the same intensity through tonight- and will not further organize much. It should drift slowly West-SW (over sea surface temperatures of only 23 celsius), before recurving around 7am EST (1200 UTC) and moving southeastward. After tonight-early morning (EST) - convection around the center should weaken and by late tomorrow afternoon should have lost most subtropical characteristics and no longer be considered subtropical.

DISCLAIMER: The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[jaguarjace]

[Dean_175]

Current satellite imagery (I don't have any way of posting a pic) shows almost no convection around the center and a significant loss of organization. I would consider this system to no longer be subtropical.

[jaguarjace]

[jaguarjace]

Link: https://youtu.be/ujyOlH2Dmvk
Credit: NOAA GOES / NESDIS