This winter has been dismal for quality surf in Florida. We started the winter with a bunch of wind chop, had a couple swells, and now we're barely seeing anything. We could blame the peaking La Niña', but last year was an even stronger La Niña and we had some great surf for at least the first half of the winter.
So what is it? and when the heck is it going to change? There is one phenomenon that trumps El Niño's and La Niña's….and that's the North Atlantic Oscillation, or NAO. I've talked about it before in my seasonal surf outlooks, and I've been trying to find a correlation between the NAO and the surf we get here in Florida. It's definitely not a cut-and-dry situation, but I do feel the NAO gives us clues to how the overall long term surf will be.
Here's how it works.
I won't get into all the very complicated science on what exactly the NAO is( you can read all about that here ), I will just simplify it for our purposes. The NAO is either positive, negative, or neutral.
When the NAO is negative, the jet stream comes out of Canada, makes a bee line right to the southeast, then straight out into the Atlantic. The jet stream is pretty much the track that low pressure storm systems take. (our potential groundswell makers).
This is when big lows will roll off the Carolinas and out toward Bermuda, passing right through our swell window. This also means cold arctic air has an interstate highway to ride down to the south, making us pull out the full suits.
When the NAO is positive, the jet stream is farther north, and rides up the northeast coast into the Canadian Maritimes. A strong sub-tropical ridge (High pressure) is parked out in the Atlantic, pretty much blocking, or deflecting all low pressure storms from going out to sea and creating a nice groundswell for us. That also means cold air stays up in Canada, we get more onshore winds, and stay warm.
Check out this graphic:
So back to our original question of what's the difference between last year and this year? Both years were La Niña's, but last year, most of the winter in a negative/neutral phase of the NAO. Which allowed some big cold fronts, chilly air, and great swells to arrive in South Florida!
It did go positive by the end of winter, which could be the reason why our surf season shut down late January.
This year, although still a La Nina, the NAO has been positive for just about the entire time. See the top graph below.
Notice the red squiggly lines at the end of the graph on the top graph. That's the forecast. The forecast shows the NAO dipping a little negative for the beginning of February, then shooting up positive for mid February, then trending downward again later. We should see another cold outbreak with some groundswell early in February, maybe a couple, then probably some onshore small stuff, then possibly ending February and beginning march with some solid swell.
Remember, this is NOT a cut-and-dry situation. There will be times of positive NAO where we will get a big cold outbreak and there will be times in a negative NAO where lows will not move off the coast.
But I'm finding out it's a good guess IN GENERAL of what we might be in for in the future.
WPTV HD / WPTV.com
West Palm Beach/