How Strong Was Typhoon Kajiki?

Here we go again: We just had another tropical cyclone (typhoon, in this case) that was right on the borderline between Category 3 and Category 4 intensity. And because of data and measurement problems, we may never know how strong Typhoon Kajiki actually was.

After forming near the Northern Mariana Islands last Friday, Kajiki rapidly intensified the next day. But how strong did the storm become before weakening again? Well, according to the Navy's Joint Typhoon Warning Center (JTWC), maximum sustained wind speeds were 110 knots -- or 125 miles per hour. That's just a few knots of wind short of Category 4 strength (114-135 knots).

How did JTWC determine Kajiki's intensity, though? The same way it always does: Looking at a satellite image and using a cloud pattern recognition scheme known as the Dvorak technique. There was no reconnaissance plane in Kajiki -- such flights were discontinued in the Northwest Pacific region over a decade ago. So all we have are inferences from satellite images.

However, a different satellite based technique -- the Advanced Dvorak Technique, pioneered at the University of Wisconsin-Madison -- makes Kajiki much stronger, comfortably in the Category 4 range. So who should we trust?

Well, there's no right answer. There are problems with both techniques. All we can say is this: If Kajiki had occurred in the Atlantic region, we would have probably had a much more comprehensive analysis of its strength supplemented by aircraft data. And I suspect we may well have had another Category 4 storm on the year.

Needless to say, this complicates your Storm Pundit's little project to count the total number of these storms that have occurred globally in 2007 (See The Daily Green's interactive map). There are now three storms -- Kajiki, Cyclone George, and Cyclone Jaya -- that I would put on the borderline between Category 3 and 4. And we'll never know for sure how to classify them.

We human beings like firm answers, quantifiable certainties -- but nature could really care less about that desire.