Hi,
Since the implementation of IFS Cycle 50r1 on 12 May 2026, we have noticed a significant increase in the number of genesis-category tropical cyclone tracks (storm IDs 70–99) received via our real-time dissemination under stream=oper, type=tf.
For example, the 20 May 2026 12Z control run produced 6 genesis tracks across 5 basins (70W, 71W, 72W, 70E, 70L, 70A), and the 21 May 00Z run produced 4 across 3 basins (70W, 71W, 70L, 70B). All messages show ensembleMemberNumber=51, ensembleForecastType=0.
Has there been a change to the TC tracking algorithm or its detection/filtering criteria as part of Cycle 50r1 that would explain an increase in the number of genesis tracks produced per run?
Our dissemination configuration for reference:
disseminate,
class = od,
stream = oper,
expver = 0001,
type = tf,
levtype = sfc,
time = 0000/1200,
step = 360
Thank you.
I’m not affiliated with EC, so please don’t take this as an official response.
From the 50r1 implementation page:
“Tropical cyclone track forecast will be extended to the step 360 for 00 UTC and 12 UTC runs.”
Tracks were only to 240 hours for the 00 and 12 UTC runs. More genesis track identifiers could be caused by the tracks covering a longer time period, and the data having tracks that form after +240 hours.
Hello,
Sorry for the long wait for this question to be answered!
The reason for the increased number of tropical cyclones under stream=oper, type=tf is the harmonisation between steams enfo and oper.
Until the Cycle 50r1 stream=oper only had named tropical cyclones, while stream=enfo contained both named and recorded tropical cyclones (that didn’t have the name).
Now bot streams have both named cyclones and those without the name, which resulted in the increased number of TCs in oper stream (Control forecast).
We will add this to the documentation in the IFS Cycle 50r1 Implementation page shortly.
Kind regards,
Milana