Proposed Changes to NWS Houston/Galveston Forecast Zones for 2021

Proposed Forecast Zone Changes

During the 2020 Atlantic basin hurricane season, it became apparent that the use of the Port Bolivar warning breakpoint could potentially cause confusion about the extent of tropical watches and warnings in the Houston/Galveston County Warning Area (CWA). This breakpoint lies in the middle of Texas forecast zone 438, Galveston Island and Bolivar Peninsula. Port Bolivar, or the Galveston Bay Entrance, divides Galveston Island on the west from Bolivar Peninsula on the right.

When Port Bolivar is used as the end of tropical watches and warnings, only one of Galveston Island and Bolivar Peninsula are intended to be included in the alerted area. However, NWS tropical watches and warnings are disseminated by WFO Houston/Galveston for entire zones, not a specific point on the coast. A watch or warning set to break at Port Bolivar functionally includes the other half of the zone in the alert provided to partners and the public, contrary to the desired result.

This image shows the old configuration of the zones in our forecast area:

To create greater consistency between alerts issued by NWS Houston/Galveston and the National Hurricane Center, we propose splitting forecast zone 438 at the Galveston Bay Entrance/Port Bolivar, so that Galveston Island and the Bolivar Peninsula are separate forecast zones. This allows the greatest flexibility in describing the threat from tropical cyclones to the Galveston Bay area. This change is expected to take place March 30, 2021 at noon, CST.

If this change is approved and takes place, you may see forecasts that used to refer to "Galveston Island and Bolivar Peninsula" as one unit will keep them separate in the future. The new zones will have this name change:

"Galveston Island and Bolivar Peninsula" becomes "Galveston Island" and "Bolivar Peninsula".

This image shows the proposed structure of our forecast zones along the coast. Galveston Island will retain the designator TXZ438, while Bolivar Peninsula will be given the designation for a new forecast zone, TXZ439:

It is important to note that these zones will also include nearby small islands and land masses separated by the Intracoastal Waterway. For example, Pelican Island, Tiki Island, and the Deer Islands will be part of the Galveston Island zone. Goat Island will be part of the Bolivar Peninsula zone.