An Envelope of Possibilities for Atlantic Basin Tropical Cyclone Seasons

Levi G. Silvers, Mu‐Ting Chien, Philip J. Klotzbach, Michael M. Bell, Mona Hemmati, Juhyun Lee, Carl J. Schreck

Preprint · 10 October 2026 · Colorado State University (incl. CIRA)

In one sentence. Uses the ACE2 emulator ensembles to estimate the range of possible Atlantic hurricane counts for 2005, 2013 and 2024, finding 2024 underperformed in 90% of members.

Abstract

Estimating the range of possible tropical cyclone (TC) activity for a given season is not possible from observations. The envelope of possible activity must be derived from an ensemble of simulations for that season. This manuscript estimates the range of possible Atlantic TC activity during the 2005, 2013 and 2024 seasons using the ACE2 deep-learning model. Comparing the observed TCs with the ensemble mean number reveals that the 2005 season overperformed relative to the expected TC number, while both 2013 and 2024 underperformed. In particular, 90\% of the 2024 ensembles had more than the 18 named TCs observed during the 2024. When El Niño--Southern Oscillation is relatively weak, mean TC activity seems to be set by tropical Atlantic SST. While the Madden Julian Oscillation (MJO) does modulate TC activity, the range of TC variability among ensembles for a given year is not driven by MJO timing.

Labels

Labels and summary are generated by Claude and reviewed weekly. Wrong? Edit this entry.