AUSTIN (KXAN) — “The approaching hurricane could raise ocean levels enough to flood your neighborhood with six feet of water,” the television meteorologist warns ahead of the major hurricane’s landfall.
The National Ocean and Atmospheric Administration (NOAA) and National Hurricane Center (NHC) use sophisticated weather and ocean models combined with topographical mapping to create storm surge inundation forecasts like this. And the engine at the center of it all just received a major upgrade.
Storm surge is the abnormal rise in ocean levels from a tropical cyclone as wind piles water up on the shoreline and lower atmospheric pressure eases its downward force on the sea. It is the No. 1 killer in landfalling hurricanes.
Surge levels are not only determined by the storm’s intensity, but also by a complicated cocktail of the storm’s forward speed, central pressure, size, angle of approach to the coast, shape of the coastline, and the width and slope of the ocean bottom.
Here are the upgrades the model just received to better predict storm surge flooding in the 2023 hurricane season:
- New forecasts for surge, tide and waves for Puerto Rico and the U.S. Virgin Islands
- The ability to run the model simultaneously for two storms in different areas
- Improved model calculations of friction over different types of land surfaces, which helps more accurately compute the extent of water inundation along the coast
NOAA’s Probabilistic Storm Surge (P-Surge) model uses official NHC wind forecasts for a storm approaching landfall as well as average track, size and intensity errors over the last five years. The model outputs 500 to 1,000 potential landfall scenarios. These inputs are then fed into NOAA’s Sea, Lake and Overland Surges from Hurricanes (SLOSH) model, which computes water levels and above-ground inundation due to storm surge and tide.
NHC forecasters then translate the outputs into “most-likely” and “worse-case” scenarios so local emergency managers and officials can plan evacuations and shelters accordingly.
The P-Surge model debuted in 2008 and is now on version 3.0. The 2023 Atlantic hurricane season begins June 1.