Looking back at Colorado’s Marshall Fire

Smoke rises from the Marshall Fire on December 30, 2021. Credit: NOAA

The wind-driven Marshall Fire erupted into the most costly wildfire in Colorado history on December 30, 2021, evolving in one hour from a grass fire into a suburban firestorm that destroyed 1,084 homes and seven commercial properties as it swept into the Boulder suburbs of Louisville and Superior.

In a recent analysis, NOAA scientists and meteorologists in Boulder closely examined the forecasting challenges posed by the “mountain wave” windstorm, an event that regularly occurs along the base of the Rocky Mountains, as well as the operational challenges during the firestorm that followed. Their findings appeared recently in Weather and Forecasting, a journal published by the American Meteorological Society.

During the two days before the fire, numerical weather models began to suggest high winds for December 30. But starting at 5 p.m. on December 29, one short-term model began to generate remarkably consistent run-to-run forecasts for the location and onset of the windstorm, which gave NOAA/National Weather Service (NWS) meteorologists confidence to issue a high-wind warning across the urban areas of Boulder County, said lead author Stan Benjamin, a CIRES scientist working at NOAA’s Global Systems Laboratory.