Knowing your background I’ve got to ask you what the heck is a longitude of 279.1?
That’s what the people I’m following (http://rammb.cira.colostate.edu/products/tc_realtime/storm.asp?storm_identifier=AL112017) have for Irma now.
On the internet I can’t find any Earth coordinate system that uses such a number.
OK. Looking at it a little bit, I noticed the chart below it uses the normal longitude coordinates.
Then I noticed that the chart with the weird numbers is the FORECAST coordinates.
What I would say then is the the 2 (representing the 200) is simply put in there to distinguish what is being forecast from what has actually happened.
So the forecast positions of 279.1 is actually a forecast of the position of 79.1, but the 2 designates as being a forecast longitude instead of an actual one.
Try 179.1. Looks to be a typo. That would be somewhere in Fiji.