Death Of A Good Friend To Voyaging Sailors

Over the last few years, we noticed that US weather forecasters have been forecasting higher winds, even hurricane force, in specific and well defined areas of mid-latitude low pressure systems with increased frequency and accuracy than before, but we did not know how they were doing it. Now we do.

Unfortunately, the tool that the forecasters were using to pull off this important increase in forecast accuracy and granularity—unexpected hurricane force winds in a small area of a big mid-tropical low have, I suspect, caused more yacht casualties at sea than hurricanes—is no longer available to them with the demise of the QuickScat satellite, pictured above.

Also, I’m guessing that the death of the QuickScat antenna will have at least some negative effect on the accuracy of GRIB files, particularly in remote areas.

These days, a lot of ocean voyagers are relying exclusively on GRIBs, which are generated automatically by computer with no human input or sanity checking, for their weather planning. The loss of QuickScat is just one more reason why we think that’s a really bad practice. GRIBs certainly have an important place in our weather analysis, but we always use them in conjunction with weather maps and text forecasts so as to benefit from the human insight of a trained meteorologist.

{ 2 comments… add one }

  • Jon January 31, 2013, 1:18 am

    Hi John,

    Fortunately, all is not lost. Two other satellites currently provide similar information to what QuikSCAT provided. Of course, how long those satellites will last and whether they will be replaced is anyone’s guess. Some might find the data they collect fun to look at: http://manati.star.nesdis.noaa.gov/datasets/ASCATData.php

    For those who choose to play around with that link, please keep in mind that it is not an operational webpage, and the data should not be considered ground truth. As you might imagine, the task of determining wind speed and direction from a satellite 500 miles above the ocean has significant challenges.

    Another note: The data you see on the linked page may be up to 22-hours older that the time stated at the top of each image, which reflects the time that data was downloaded, not the time it was collected. It’s easy to get confused and think you’re looking at winds from a couple hours ago when in fact they’re nearly a day old.

    Bottom line, as with GRIBs, these satellite wind fields are generated automatically, and are no replacement for a trained forecaster. They are NOT ground truth. In fact, this very moment I’m looking at a wind field with vectors that are 180 degrees out from reality, due to the ambiguity associated with scatterometer-derived wind fields. Be suspicious!

    Regards,
    Jon

    Reply
    • John January 31, 2013, 9:45 am

      Hi Jon,

      That’s the insidious thing about GRIBS and like data, isn’t it? They look so darn solid and convincing that we all need constant reminders that they should always be read with a healthy dose of scepticism and common sense. Great information, thank you.

      Reply

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