WGNO

National Hurricane Center to expand tropical outlooks to 7 days in 2023

National Hurricane Center, Miami, Florida. (Photo: NOAA)

NEW ORLEANS (WGNO) — The National Hurricane Center will expand their tropical weather outlooks from five days to seven days later this year.

From May 15 through November 30, the NHC issues a “Tropical Weather Outlook” four times each day to discuss significant areas of disturbed weather across the Atlantic.

In past hurricane seasons, the agency would provide separate 2-day and 5-day probabilities of tropical cyclone formation for these disturbances.

The NHC said in a February announcement, “While the 2-day formation probabilities will remain unchanged, the 5-day formation probabilities will be extended to cover 7 days.”

Reliability diagram for Atlantic probabilistic tropical cyclonegensis 2-, 5-, and experimental 7-day forecasts from 2019 to 2021. (Image: NOAA)

The NHC began experimenting with extending their outlooks out to 7 days in 2019.

When comparing the verification of tropical cyclone formation to the 2-day, 5-day, and experimental 7-day forecasts in the Atlantic basin for the 2019 to 2021 period, the results were similar.

The NHC said in a 2022 report, “It can be seen that a slight low bias exists at most ranges, but in general the forecasts are fairly calibrated for all lead times.”

Tropical Weather Outlooks will be issued regularly beginning May 15. The 2023 Atlantic Hurricane Season begins June 1.