Hurricane Idalia at Landfall: August 30, 2023, at 7:30am EDT

Author: William Putman

Hurricane Idalia made landfall along the northern gulf coast of Florida on the 30th of August 2023. Radar reflectivity from observations (left) and as simulated by the Goddard Earth Observing System (GEOS) atmospheric model visualizes the internal structure of Idalia. The GEOS modeling and assimilation system produces daily forecasts capturing the landfall of Idalia within miles of the actual landfall of the storm days in advance. The GEOS Forward Processing (GEOS-FP) model and data-assimilation system (right) presently executes with 12km horizontal resolution and 72 vertical levels. A new experimental version of the GEOS model (GEOS-Exp, middle) is executing on a global stretched grid producing forecasts at 4km horizontal resolution of the continental united states with increased vertical resolution to 137 levels and new atmospheric physics and non-hydrostatic dynamics. Improvements in the representation of Idalia’s structure are clearly seen as GEOS-Exp radar simulations show improved central pressure values (941 hPa Observed, 940 hPa GEOS-Exp and 963 hPa GEOS-FP), near surface wind speeds (115 knots Observed, 116 knots GEOS-Exp and 73 knots GEOS-FP), the presence of a very compact eye including the northwest asymmetric eye wall, and the banding convection spiraling from the southeast quadrant of the storm into the main circulation.

slide graphic from hurricane idalia
Figure 1: A Hurricane Idalia at Landfall: August 30, 2023, at 7:30am EDT

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