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Are you sure we won’t get swell from Henriette? It’s a cat 1 and growing…

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Adam Wright
by
(Tuesday) 8.6.13

Uburoi Asked: Are you sure we won’t get swell from Henriette? It’s a cat 1 and growing…

Adam Wright – Solspot Forecaster:

Yeah she is strengthening…but unfortunately she just isn’t in the right spot to send us waves. If she had done this before passing the 120W longitude line it would have helped, but now she is so far west that the only way for us to get any rideable swell would be for her to either:

1. Completely stop moving west, spin in place and grow in both intensity as well as overall diameter.

2. Come recurving back to the NE, essentially swinging the swell making side of her our direction, and track directly toward Socal for a day or two.

Both of which are highly unlikely at best.

The problem is that even though the core winds are a little stronger, she isn’t all that large, hurricane force winds only extend about 20 nautical miles from the core, and Tropical Storm strength winds (35-knots) only go out to about 80-nautical miles. This means she only has an effective fetch that is maybe 100-nm long and about 80-nm wide, which may sound like a lot, but the strongest part of the fetch is aimed WNW-NW, (away from us) at this point.

Think of Henriette having a swell flashlight, where it points that is where most of the swell will travel. On small or extremely fast moving storms that flashlight is very dim to start, so once the storm has passed a point where it no longer moving toward your position, we would see very little “swell-light”, if any at all.

The only time we see swells from a storm that is moving perpendicular to our location is when they have much different characteristics. A much larger storm, one that may not have great wind speeds, but has the wind fields extending out to 200- or 250-nm from the core, could do it, particularly if it had some extra support from winds coming off the ITCZ, and the storm is moving on a fairly slow track.

Another case would just be if the storm is a complete bad-ass…basically it would be like the Chuck Norris of storms… and it is chewing through the EPAC with CAT-4/5 winds and throwing out huge seas. A storm like that would still send most of the energy along its movement path, but the overall intensity would allow for a smaller “percentage” of energy to move out perpendicular to the storm’s path. Even if it was only able to push, let’s say 25% of the swell our way, but the main swell is 20-feet along the storm’s path, we would still have 5-feet of tropical energy heading our way, which is plenty big for most people.

Anyway…the short-version is that even at CAT-1, she is too small and too far away to produce a swell that wouldn’t decay completely away before it could arrive in Socal.

If you are interested in hurricanes and how we get waves from them…check out the post I put together…

http://solspot.com/content/featured/adam-wright/how-we-get-waves-from-hurricanes

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