Understanding The Weather Forecasts That Preceded The Maui Wildfires - Honolulu Civil Beat

About the Author

Steven Businger

Steven Businger is a professor at the Atmospheric Sciences Department in SOEST, University of Hawaii Manoa.

The meteorological conditions that caused the ongoing tragedy were complex.

In all the coverage of the tragedy produced by West Maui wildfires, a story that has been a bit overlooked is the accuracy of the forecasts produced in advance of the storm by the National Weather Service Honolulu Forecast Office.

The weather that caused the ongoing tragedy on Maui was complex.

Essentially a high amplitude atmospheric wave forced by strong winds interacting with the mountains of northwest Maui produced powerful, dry downslope winds on the lee slopes of West Maui mountains.

NWS forecasters are familiar with this weather pattern, which meteorologists refer to as a “downslope windstorm.”

The downslope windstorm was well predicted by a NOAA high resolution model (Figure 1).

Figure 1: 28-hour forecast of winds (in knots) over Hawaii by NOAA’s High Resolution Rapid Refresh model for 4 p.m. on Aug. 8. Note forecast winds > 65 mph in the lee of the West Maui mountains and in the lee of the Kohala Mountains on the Big Island, where observations documented wind gusts exceeding 80 mph.

In this case the downslope windstorm produced 60-90 mph gusts that hit a very localized area; winds strong enough to shear off wooden power poles, tear roofs apart, and down power lines.

Already on Aug. 4, four days prior to the event, extended outlooks foresaw the potential of a high wind event with very low humidity.

Early on Aug. 6 an urgent Fire Weather Watch was issued.

On the afternoon of Aug. 7, the day before the event forecasters issued a High Wind Warning.

In the Area Forecast Discussion, the forecaster wrote, “The strongest winds are expected over mountain terrain and downslope into leeward areas.”

In addition, a Red Flag Warning was issued for leeward portions of all the Hawaiian Islands with wind gusts over 60 mph.

Figure 2: West to East Cross section produced by the Maunakea Weather Center custom high resolution weather model showing the 43-hr forecast wind field (shaded) and potential temperature (contours) valid at 7 AM HST on Aug. 8. One knot = 1.15 mph. In a dry atmosphere the flow tends to follow surfaces of constant potential temperature. (Graphic courtesy of Dr. Tiziana Cherubini of the Mauakea Weather Center/2023)

A Red Flag Warning indicates that critical fire weather conditions are either occurring now or will shortly.

Under Impacts associated with a Red Flag Warning, the NWS notes, “Any fires that develop will likely spread rapidly.”

The specificity and the timeliness of the NWS advisories and warnings is a major achievement that reflects the difficult training required of NWS forecasters (most in Hawaii have M.S. degrees in Atmospheric Sciences, aka meteorology) and the quality of the products (e.g., satellite and radar imagery) and the numerical forecast guidance available from NOAA in the Honolulu Forecast Office (see image NOAA wind forecast above).

As better satellites are launched and larger computers are employed, forecasts will continue to improve (e.g., Figure 2).

The outcome of ongoing investigations will help to determine how NWS forecasts, advisories, and warnings can best be used to prevent such tragedies in future.

Community Voices aims to encourage broad discussion on many topics of community interest. It’s kind of a cross between Letters to the Editor and op-eds. This is your space to talk about important issues or interesting people who are making a difference in our world. Column lengths should be no more than 800 words and we need a photo of the author and a bio. We welcome video commentary and other multimedia formats. Send to news@civilbeat.org. The opinions and information expressed in Community Voices are solely those of the authors and not Civil Beat.

Read this next:

Empathy Emerges Amidst The Ashes Of The Maui Wildfires

Local reporting when you need it most

Support timely, accurate, independent journalism.

Honolulu Civil Beat is a nonprofit organization, and your donation helps us produce local reporting that serves all of Hawaii.


About the Author

Steven Businger

Steven Businger is a professor at the Atmospheric Sciences Department in SOEST, University of Hawaii Manoa.

Latest Comments (0)

Hmmmm...bureaucrats and businesspeople not heeding the proclamations of scientists with advanced degrees. Where have we seen this before?

luckyd · 1 month ago

A wonderfully informative article and much praise goes to NWS and all the meteorologists who continue to provide this valuable and accurate information. Unfortunately, it points to the failures of the MEMS and other leaders who fail to take action in the days leading up to this red fire warning.

Scotty_Poppins · 1 month ago

Iʻm writing this at 945a on August 21. Thereʻs One Comment I can view. Hoping thereʻll soon be dozens more. Itʻs an excellent piece. Summary: Goinʻ Get BIG Wind. Prepare Now.But...People, Leaders, Subordinates...they arenʻt Paying Attention. Who in Maui County received the NWS Alerts? Anyone?

Patutoru · 1 month ago

Join the conversation


IDEAS is the place you'll find essays, analysis and opinion on every aspect of life and public affairs in Hawaii. We want to showcase smart ideas about the future of Hawaii, from the state's sharpest thinkers, to stretch our collective thinking about a problem or an issue. Email news@civilbeat.org to submit an idea.


You're officially signed up for our daily newsletter, the Morning Beat. A confirmation email will arrive shortly.

In the meantime, we have other newsletters that you might enjoy. Check the boxes for emails you'd like to receive.

  • What's this? Be the first to hear about important news stories with these occasional emails.
  • What's this? You'll hear from us whenever Civil Beat publishes a major project or investigation.
  • What's this? Get our latest environmental news on a monthly basis, including updates on Nathan Eagle's 'Hawaii 2040' series.
  • What's this? Get occasional emails highlighting essays, analysis and opinion from IDEAS, Civil Beat's commentary section.

Inbox overcrowded? Don't worry, you can unsubscribe
or update your preferences at any time.