7

I don't think I've ever noticed M before.

H and S are Hurricane and Tropical Storm.

alt text

5

M must be new this year - I hadn't noticed it before either. From the Forecast Positions legend on the map, it looks like M denotes winds predicted to exceed 110mph at a forecast position. Since 111mph is the lower bound of Category 3 on the Saffir-Simpson Hurricane Scale, my guess is that M stands for "Major Hurricane".

2

I believe that it is a 'Major Hurricane'. Major hurricanes are defined as being of Category 3 or greater. The wind speeds in the definition of a Category 3 hurricane on this page http://www.nhc.noaa.gov/aboutgloss.shtml matches the wind speed classes in the legend on the map.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.