There's nothing on Earth like a tropical system -- not even another tropical system. It's almost like they have a mind of their own. What other natural phenomenon spends weeks developing just to suddenly decay in a matter of hours? Or bears down on a single point of coast with all the focused ferocity of a charging elephant, only to break off within a few miles of impact to decimate some poor unsuspecting victim? And when you start comparing the Atlantic's version of a cyclone to that of the Eastern Pacific basin, the differences only intensify like a tropical wave coiling off the Cape Verde islands in August. That's why, for years, all but the most insane armchair forecasters gave up trying to figure these things out and simply waited for one lucky swell to arrive.

But Sean Collins isn't your average weather freak. He's been tracking storms for 36 of his 49 years. In the process Collins has faced both sides of the tropical phenomenon -- not only riding swells but riding out tropical storms out in the open sea. And the lessons learned in three decades of scientific study have garnered a unique insight into how these systems operate, which he willingly shares so the average surfer might at least slightly understand the most unpredictable storms on the planet.

How long have you been forecasting hurricanes?
I've been forecasting hurricanes since high school. We've been sailing down to Baja since the mid-60s and during the fall we were always keeping an eye out for hurricanes. My thing was always to catch the waves, but my dad always wanted to avoid them entirely [laughs]. Actually, in the 70's, before GPS and all this kind of stuff, we had to use sextants to navigate. We needed the exact time to tell the altitude, the azimuth of the sun, and all that, so these radio broadcasts from Colorado and Hawaii would go thousands of miles broadcasting the current time. And every hour they gave hurricane and tropical storm positions. So sometimes we'd drive to Baja with this little radio and our tracking charts. We got tons of waves -- it was insane. And I certainly learned a lot.

How did that experience transfer into what you know now?
It was invaluable knowledge. Nowadays, I think most forecasters just look at the models, which are wrong a lot of the time. But we still go through the process of figuring it out the old way, applying wind speeds and durations and distances and times of arrival and sizes all that stuff. And then we compare it. We're right about 90% of the time, which is more accurate than a model.

On the East Coast, hurricane season is all you ever hear about. But the Eastern Pacific appears to have more storms per season; it's a lot more active.
Oh, for sure. Hurricanes require several things. First, the water temps have to be 80 degrees or more to sustain the fuel needed for the hurricane to develop. Then you also need stable winds in the upper atmosphere -- kind of like an upper level high pressure -- so the storm can develop kind of a chimney effect. And once it does that then it's kind of refueling itself.

In the Atlantic, the water temperatures really don't warm up off of Africa to give you that stable air mass until the middle of summer toward October. Whereas in the Eastern Pacific off of Mexico and Central America around the Gulf of Tuanapec it's stable starting in June, so they get a lot more hurricanes starting earlier in the season. And then they just keep churning away. So the Eastern Pacific Basin gets more -- say 15 named per season compared to the East coast average of ten. But the East Coast season is actually a lot shorter since you don't get many named storms until August and September or even October.

On the other hand, you don't really hear a lot of swells hitting California. Is it because they're going away from the coast?
Yeah, well, hurricanes are really small storms. And part of the whole secret in generating swell is fetch and having a large area of ocean that the wind can blow over. So hurricanes are limited because they only a few hundred miles on one side of the hurricane for a fetch, whereas a typical winter storm -- like a big northern pacific low -- can have a fetch of thousands of miles. It just sends swell everywhere like a shotgun. Hurricanes send 90% of their swell in the direction of their movement, so there's just a tiny width of swell moving forward.

So as hurricanes move west off of Mexico, they send most of their swell toward Hawaii. But if it slows down -- say to below ten knots -- then that's slow enough to where the backside of the storm has time to generate some swell. And the slower it moves, the better. And the best thing is if it gets out into the window -- you know, where it's past Baja -- and it stops and even starts coming north toward us. And those are the best ones that we get. Especially if they have more size.

But generally a storm will move east to west before drifting northwesterly toward Hawaii because the subtropical jet stream takes it out in that direction. When you get late in the year, toward September and October, the subtropical jet stream starts going a little bit more toward the north. So often times, later in the year is when we start getting some of our bigger hurricane swells because the traffic is not going so much east to west, it's starting to move toward us.

So basically the reason the East Coast gets good waves from hurricanes is because the storms automatically head in their direction.
Yeah. The East Coast is actually a much better receptor of those swells because you've got the hurricanes moving toward you all the time. And you can basically tell what part of the coast will get swell by the direction it's heading. Plus they can be further away because they're moving toward you, so you have a little longer swell period. On the East Coast, storms can be a couple thousand miles away and you will still get swells. On the West Coast, the majority are always moving away, so most of the time we don't get swells from them until they slow down or start turning north a little more, so we can get within that swell range. So hurricanes on the west coast really need to be within 1500 miles to really generate any kind of swell.

So is Hawaii the main beneficiary of the Eastern Pacific hurricanes?
No. Hawaii can be, but they don't really key on hurricanes too much, because they usually hit the windward side of the island where it's all windy. And most of the time Hurricanes go across, by the time they reach Hawaii they've been sucked up to the north and east of the islands and the best stay to the south. Plus, the storms really have to get within 1000 miles of Hawaii and most don't last that long. The one thing about hurricane swells is they decay quite a bit because you're limited with the size of the storm and the fetch, so you end up having a shorter swell period. Most hurricane swells are 12 to 13 seconds. And when the periods are that low, they're more acceptable to getting knocked down by opposing seas and swells.

Then what has to happen for places in California to get swell?
Once a storm gets around the corner of Baja then you're pretty much in the window. Then the storm ideally would slow down and start moving toward the north or northwest, whihc is more toward the coast. And at that point the bigger, the wider, and the higher the wind speeds, all the better.

So basically the reason the East Coast gets good waves from hurricanes is because the storms automatically head in their direction.
Yeah. The East Coast is actually a much better receptor of those swells because you've got the hurricanes moving toward you all the time. And you can basically tell what part of the coast will get swell by the direction it's heading. Plus they can be further away because they're moving toward you, so you have a little longer swell period. On the East Coast, storms can be a couple thousand miles away and you will still get swells. On the West Coast, the majority are always moving away, so most of the time we don't get swells from them until they slow down or start turning north a little more, so we can get within that swell range. So hurricanes on the west coast really need to be within 1500 miles to really generate any kind of swell.

But the swell usually starts up out of the south-southeast and pretty much bypasses San Diego County almost entirely. It gets up into Orange County and even up into Northern LA County and Ventura. And then as the storm moves further out toward the west -- and the swell direction changes more from southeast to south and then to south-southwest --then other parts of the coastline like San Diego and southern Orange County start picking up the swell.

And of course on the East Coast a tropical depression develops of Africa in the Cape Verdes and heads west, then it either ends up dipping under Florida and into the Gulf of Mexico or running up the coast with the Gulf Stream.
Right. And that's really steered by the Upper Level wind patterns. But once it starts approaching the Caribbean and the windward islands it should be in the East Coast's swell window, and it's going to kick off the swell in the same direction it's moving. And, again that's tied into the movement of the storm. So the faster it moves, the more focused or narrower the swell is going to be. On the opposite scale, if the storm is completely stalled it will send an even amount of swell everywhere, 360 degrees.

And what about the Gulf of Mexico?
Generally, those will start earlier in the year than East Coast storms because the water's so much warmer -- like June, July, August, and sometimes September. Some are tropical waves off of Mainland Mexico that develop in the Gulf and go north -- those are the ones that occur earlier in the year. And then the others develop in the Atlantic, go below Florida and get into the Gulf where it's even warmer and they intensify.

Again, the majority of the swell will go in the direction it's heading, so whatever in it's path will get the best waves. A lot of times, the ones that form of off Mex go north into Texas or across in the Florida. The ones from the Atlantic, it depends on upper level winds, but they tend to travel to east to west. Those are good for Texas -- before they hit -- and they'll also send the Florida Panhandle some swell right as they cross under Florida. And if it just sits in the middle, the whole Gulf will have waves because the coastline is so small.

So if somebody's at home trying to digest all this info and use it to their advantage, what do you suggest?
Well the Internet is a wonderful resource and we've got a pretty cool weather tracking here on Surfline -- you can always use that. And then there's a lot of other tracking charts from universities and the national hurricane center. Hurricanes are pretty tricky, there's a lot of variables. But just compare our forecasts with what your forecasts are and try to work it out. It's a fun way to learn.