October 03, 2021

An Unmanned Saildrone Takes Weather Observations in the Center of a Hurricane

I have to admit that I was thrilled with the news.  

On Thursday, September 30, an autonomous (unmanned) sailboat, called a Saildrone, made it into the center of Hurricane Sam, a category four tropical cyclone, measuring extraordinary winds and seas.  

And it even sent back live video.

Saildrone 1045 Made It Into Hurricane Sam

The hurricane Saildrone project, a joint effort of NOAA and an innovative private firm (Saildrone, Inc), has the goal of collecting valuable surface observations within tropical cyclones.  Observations of the upper layers of the ocean and near-surface atmosphere are particularly valuable because they provide information regarding the critical transfer of energy and moisture from the warm tropical ocean into the lower atmosphere.

One of the missing pieces in understanding and forecasting tropical storms.

There is really only one way to get this information: by having observing assets at the ocean-atmosphere interface.   And no manned vehicle would dare enter such a severe environment.

On Thursday, Hurricane Sam was an impressive category 4 storm with the strongest sustained winds estimated at 125 knots (144 mph), with gusts to 150 knots (173 mph).  The central pressure was estimated to be 938 hPa.

Hurricane Sam on Thursday morning.   You can clearly see the eye.

The Saildrone (Hull 1045) appears to have entered the eyewall of Hurricane Sam, observing significant wave heights if up to 50 ft!  Take a look at a video clip of what it was like in the storm:

Wow.  Just amazing.

Richard Jenkins, the CEO of Saildrone, shared these observations from the boat that day.  Significant wave heights go to 14 meters (46 feet), with peak gusts reaching 114 knots (131 mph).

As described in several blogs during the past two years, I have been heavily involved with Saildrone, working with them to test the robustness and data quality of the platform.

Two years ago, we had a line of early generation Saildrones, with larger sails (see below).  Such a large sail turned out to be a real vulnerability with steep waves and strong winds.   

Last year, I served as the meteorologist for a test of new hurricane-ready Saildrones with shorter, stockier sails that are far less liable to sheared off or be damaged (check out the first picture above to compare).  Ironically, the historic Saildrone that entered hurricane SAM had a technical problem last year off the Northwest coast and struggled to reach the Washington Coast where it was retrieved.

As Richard Jenkins told me a few days ago.....you have to be ready for some losses and problems in the development of such a complex platform.

NOAA's Pacific Marine Environmental Lab (PMEL) has been an active partner with Saildrone and is leading this year's hurricane-PMEL experiment with five of the hurricane Saildrones in the Atlantic.  A really good national investment.

The hope is that a network of Saildrones will lay in wait across the Gulf of Mexico and tropical Atlantic each hurricane season, providing critical information within the dangerous environment in and near the eyewall of tropical storms.


The Second Edition of My Northwest Weather Book is Now Available!

My new book is greatly improved and expanded over the first edition, with new chapters on the meteorology of Northwest wildfires and the weather of British Columbia.  A completely revamped chapter on the effects of global warming on our region.  And it has been brought up to date with recent weather events and the imagery is improved greatly.

Where can you get it?

Local bookstores, such as the University of Washington bookstore.  The UW Bookstore has just received several dozen copies.

Or secure a copy from the publisher:  UW Press.

Or Third Place Books in Lake Forest Park or Seattle.

And yes, there are online sellers like Amazon and Barnes and Noble.


  1. Cliff, I prefer to buy my books from vendors that pay the authors a fair price. So certainly not from the online giants. Do you have a preference as to which of the other vendors we purchase from?

    1. thanks for asking....I really value brick and mortar bookstores....and, of course, UW Press, which bankrolled the book.

    2. I second that! I hate to see the demise of physical stores of all types! One of the casualties, very ironically because they dealt in electronics, was Radio Shack, which fell victim to online (i.e., electronic) commerce. I actually like to browse stores filled with interesting things (but I hate grocery shopping because it has to be done so often and it is always the same).

  2. The drone footage is amazing, weather channel has it on non stop,...your book is also amazing, but Cliff, the weather forecast ????????????????????

  3. Glad to see the U of W has some part in the development of Saildrone. Technology has come a long way since I graduated in Oceanography there in 1972. Keep up the good work Cliff.

  4. Almost makes me seasick just watching it.

  5. Hoping if there is a NW Weather conference this spring there will be a model of this for us to admire.

  6. Cliff, I am curious about the wind variables the Drone recorded.
    How are they compensating for the sail and surf speeds over the water, compared to the wind speed readings? Lots of angular velocities going on there.
    This is a very interesting project. thanks for posting. I bet Kristina Katsoros would be interested in this.

  7. Oh noes, there goes the AGW narrative once again:


    Must've made the Seattle Times folks grind their teeth into dust when they posted this. But not to worry, their scientific illiteracy will once again swing into action once they figure out a way to blame this on humanity, once again.

  8. How can we get one of these in a big storm off of our coast? That would be fun.

  9. Cliff, once again you present useful, honest info about weather / climate insights.

    You are my "go-to" guy about what happens weather-wise in this part of this complex, unpredictable planet.

    Whenever I hear the phrase "settled science", I know I'm hearing from a very ignorant source.

  10. Great post, Cliff. Love the sail drone. Science is the answer.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

Lightning Returns to the Pacific Northwest

 Lots of thunderstorms, some approaching severe levels, have hit eastern Oregon and Washington during the past day.....and there are severe ...