Thursday, December 3, 2009

Storm and Swell Alert – North Pacific is looking to get Nasty

So I have been looking at the forecast charts and the swell models for the last few days (well lets not kid anyone…my near OCD has me looking at the charts all the time…and once I find a way I will probably have it fed directly into my brain). So like I said, I have been looking at the charts and there, right at the end of the forecast run, was this ugly mutant of a storm.

Usually I don’t put a ton of faith in the weather models when we move waaaaaaay out into the forecast run, they have a tendency to overcall things, and the timing is rarely ever correct…but in this case this storm definitely caught my eye.

Now, a couple of days later, the storm is still there on the charts and the swell models are still calling for it to crank out a LOT of swell…particularly for Hawaii (and the really, really unlucky people that live in the Aleutian Islands.) There is also a pretty large hunk of WNW swell that is supposed to head over to California, hitting NorCal pretty hard and throwing some large surf into Socal as well.

I am still a little “iffy” on the storm’s intensity and timing since it is not forecast to develop for another 4-5 days, which, for me, is still in the marginal area of the forecast run. Personally I would like to have the storm get a couple of days closer to developing before we start ringing alarm bells.

OK, that being said, lets look at what we can expect if this storm lives up to the current forecast.


The storm itself is part of what is called a “complex low-pressure”, which basically means that it is a series of fronts and low-pressure centers that are all mixing together in one big mess. Usually with these complex lows you have an “anchor” low-pressure that sits up in the higher-latitudes and a series of intense storms that push through the mid-upper latitudes like they are riding some crazy merry-go-round.

In this case the anchor low is currently developing, and will likely move into place over the upcoming weekend…and even though it is the leading element of the bigger system it will be sending out waves as well (that will arrive a few days earlier than the larger system).

The most intense part of this complex low is when everything sort of collapses into one big low-pressure…which happens in about 4-5 days.

The current GFS pressure model is calling for the low pressure to drop to something close to 952mb, (which if this was a tropical storm/hurricane it would be something close to a category 3 system…which is why the Holy Crap is on that chart). As a frontal storm it means that winds will be close to 50-60+ knots near the core of the low. With those sort of winds, and all the pre-existing sea-state that gets kicked up by the preceding fronts, we can expect the storm to produce something that looks like this…and yes those are 40-foot+ seas.

Needless to say that even if the top 10-15-feet of that is just storm fluff there will still be a pretty significant swell forming from this storm.


Surfwise…Hawaii is forecast to receive the largest chunk of energy…likely something in the range of 18-20 feet of deepwater energy at 17-20 seconds, which can translate to 30-40-foot faces as it hits some of the Hawaiian reefs. The swell is pretty NW’erly in swell angle, which is good for spots like Jaws (Peahi). It looks like this swell will come up fast late on Dec 6th with the peak of the swell hitting overnight into Dec 7th. One thing that could suck is the winds…the trailing part of the storm’s front could show around the same time setting up W-NW winds which doesn’t do the north shores of any islands and good.

Northern and Central California will see a smaller but still impressive amount of energy that will hit North of Point Conception…something like 15-16 feet of deepwater swell at 18-20 seconds. This will show some energy late on Dec 8th but will likely peak throughout the day on 9th…the angle will be pretty WNW’erly (275-295) which means that it will hit a lot more spots with more energy than the NW swells usually do.

Southern California is forecast to see this swell showing some long-period energy, particularly at the more northerly counties of Santa Barbara and Ventura, by the afternoon on the 9th. The peak of the swell will hit throughout the day on the 10th. The WNW angle works better for Socal as well (280-300), so there will be less shadowing. At this point the swell looks good for easy head high to overhead surf at the average spots, and the top spots going several feet overhead. The best San Diego spots could see more consistent double-overhead+ sets.

Unfortunately weather looks like it will be an issue for all of California as well…a smaller cold front is forecast to bring onshore wind and rain about the same time as the swell peaks…hopefully this part of the forecast won’t be correct.

So that is all I have for now…keep in mind that this is pure forecast at this point…I will definitely keep you guys posted as the storm actually develops. Cross your fingers that it lives up to the forecast hype.

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