Tuesday, August 18, 2009

Something I Never Noticed Before About Hurricane Spotting

In the age of GPS, we always think that we know the position of things down to 10 feet or so. 10 yards on a bad day. But it seems the precision isn't quite what I thought it was. Hurricane BILL Forecast/Advisory (This is usually listed as the "Marine Forecast" on sites like Weather Underground)
HURRICANE CENTER LOCATED NEAR 15.0N 48.3W AT 18/0300Z
POSITION ACCURATE WITHIN 30 NM [my emphasis: Z-Deb]
30 nautical miles (34.5 statute miles) is a pretty long stretch, but then the ocean is a big place.

It isn't a big deal, because if you are actually in the vicinity of a tropical storm, there is never really any doubt where the eye is... generally speaking.

And you don't want to be 30 or 100 miles from the eye in any event. 12 foot seas are reported out 300 nautical miles from the center - that will ruin your day.

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