Query on retrospective IBTrACS updates

[Stratis Markou]

Hello,

I am aware that in addition to the regular updates of IBTrACS to add cyclones to it, I believe data from past seasons are also retrospectively updated. I have some questions about these retrospective updates:

- By what point in the current year are previous years' data expected to be finalised? For example, at what point in 2026 will most of the data for 2025 be final? Even a rough description of the schedule from previous years would be very helpful.

- Are different fields finalised sooner or later than others, or are there fields that are more or less than others to change retrospectively? For example, latitude/longitude versus maximum sustained speeds versus quadrants versus storm classification stage (e.g. USA_STATUS): are the fields typically updated all at the same time or do they have different latencies?

Thank you in advance for your help!

Kind regards,
Stratis Markou

PS: thank you for all your work maintaining IBTrACS, it's an amazing resource for the community!

[Jennifer Gahtan - NOAA Federal]

Hi Stratis,

As of v04r01, we input agency best track (BT) data from agencies as it is available. All fields from an individual agency will get updated at the same time.

BT data from the NHC (NA and EP basins) was finalized in March and usually is in this timeframe, though note sometimes Central Pacific storms get updated later. 

For the rest of the Northern Hemisphere, the last available BT data will likely be from JTWC. Based on recent years, I would not expect JTWC data to be available and input until the fall (maybe September). JMA and CMA were input this spring and I expect other NH agencies to be finalized over the summer.

For the Southern Hemisphere, JTWC is usually also the longest and I would expect the 2025 season (Fall 24/Spring 25) to be available late Fall 2026. We already have all other SH agency data for 24/25 input.

Also note, in agency BT updates, sometimes older storms also get reanalysed.

For more details on added best track data for v04r01 see the IBTrACS change log, which is also linked from the website.

Thanks,

-Jennifer

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Jennifer Gahtan, Ph.D.

Physical Scientist
CSSD
NOAA's National Centers for Environmental Information (NCEI)
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