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NHC and CPHC Extend Tropical and Graphical Weather Outlooks

Storm Preppers - NHC and CPHC Extend Tropical and Graphical Weather Outlooks

There are new changes to the release of tropical and graphical weather outlooks. The National Hurricane Center and the Central Pacific Hurricane Centre have expanded their 5-day Tropical Weather Outlook (TWO) and Graphical Tropical Weather Outlook (GTWO) to 7 days. These are routine analyses that are helpful in identifying areas of disturbed weather and assess their probabilities of development.

These enhancements which were implemented during the WMO’s annual hurricane committee meeting in 2022, will be beneficial to residents and first responders. All stakeholders will have more time to prepare for expected tropical storms and hurricanes. The changes to the TWO and the GWTO went into effect on 15 May 2023.


About the Tropical Weather Outlook (TWO)

The Tropical Weather Outlook (TWO) is an alert about significant areas of disturbed weather and their potential for development over the next five days. The outlook includes a probability forecast of the formation of a tropical cyclone during the first 48 hours and the entire 5 day forecast period. Probabilities of formation for each area of disturbed weather are provided to the nearest 10% and expressed in terms of one of the following categories:

0 – 30%: Low probability of development
40 – 60%: Medium probability of development
70 – 100%: High probability of development

Current TWOs are on the National Hurricane Centre’s home page.

About the Graphical Tropical Weather Outlook (GTWO)

The Graphical Tropical Weather Outlook (GTWO) is a visual of significant areas of disturbed weather and their potential for development over the next 48 hours. It shows the location of tropical cyclones and other disturbances on a clickable interactive graphic. Each disturbance on the outlook has an “X”, a number, and carries text discussions below the graphic. For ease of identification, disturbances are distinguished by a coloured “X”:

Yellow X (0 – 30%): Low probability of development
Orange X (40 – 60%): Medium probability of development
Red X (70 – 100%): High probability of development

Current GTWOs are released shortly after TWOs, and are also posted on the National Hurricane Centre’s home page.

Source: National Hurricane Center: Extension of the Tropical Weather Outlook and Graphical Tropical Weather Outlook 


Further Reading

For more information about changes to the tropical and graphical weather outlooks, please visit the following links:

WUFT-TV: National Hurricane Center issues first 7-Day tropical weather outlook Monday
WFSA 12: A change to the tropical outlooks issued during hurricane season
New York Post: New names, major changes announced for the 2023 hurricane season
News 4 Jax: New Hurricane Season comes with extended forecast from the National Hurricane Center

Image: Brian McGowan via Unsplash

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