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Cape Cod: "And on the seventh day ..."
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justall



Joined: 30 Jul 2007
Posts: 431

PostPosted: Fri Aug 05, 2016 8:57 pm    Post subject: Cape Cod: "And on the seventh day ..." Reply with quote

" ... the wind bloweth". Amen.

Had been waiting a week for today. Nice day. May there be more.
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jpeter



Joined: 18 Oct 2009
Posts: 337

PostPosted: Sat Aug 06, 2016 12:41 pm    Post subject: Reply with quote

Kalmus was good for anyone who made it into the lot. Soccer tournament. 10 spaces of so for windsurf folks. Lot full. Solid 26 28 avg all am . Good session. Waves yesterday to top it all off. Jp
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paulf.



Joined: 21 Mar 1996
Posts: 427

PostPosted: Sun Aug 07, 2016 10:28 am    Post subject: Reply with quote

West Dennis was as predicted in the afternoon. Morning gusts to 30+ had lots of rerigging. Wonder what brought that unpredicted surge?
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boardsurfr



Joined: 23 Aug 2001
Posts: 1245

PostPosted: Sun Aug 07, 2016 2:22 pm    Post subject: Reply with quote

For Kalmus, it is quite common to get an extra 5-15 mph wind in WSW (compared to the highest numbers in the computer models). That happened yesterday. West Dennis was similar, but the period of 30 mph winds was shorter in West Dennis (about 11 am to 1 pm) than in Kalmus (8 am to 2 pm). The meter reading show an increase by 5-10 mph when the wind directions goes more westerly (7:45 am, 4:30 pm, 7:20 pm), and a big drop when it turns from WSW to SW (2 pm, 3 pm, 5 pm). Again, this is pretty typical.

In WSW, we have a nice "corkscrew" sea breeze going. One big difference between SW and WSW is how large the land area where the air rises to fuel the sea breeze is: from Kalmus, that's about 10 miles in a SW, and 20 miles in WSW (10 & 14 miles for West Dennis). Considering that the land area that fuels a sea breeze can be 50 miles deep, that alone may be enough to explain that WSW comes in stronger.

Another issue at play may be that more southerly synoptic winds may simply "blow the top off" a regular sea breeze. Sea breezes require a circular pattern: hot air rises over land, and is replaced by cold air from the sea. For a straight sea breeze, the air that cools down as it rises has to travel in the opposite direction of the surface wind to then return down to the surface and complete the cycle. Typical explanations of "pure" sea breezes even have a prevailing wind that is opposite of the sea breeze direction (e.g. north wind in a southerly sea breeze).

In contrast, a wind direction that is side-onshore, and almost side shore, allows for the circulation to happen - in a corkscrew-like manner. That's a general rule - corkscrew sea breezes are the strongest. For Kalmus, that WSW. In WSW on a nice sunny day, we can simply add the strength of a typical sea breeze (10-15 mph) to the strength of the prevailing wind.



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inlandsea



Joined: 29 Sep 1996
Posts: 174

PostPosted: Sun Aug 07, 2016 3:06 pm    Post subject: Reply with quote

Its blowing NOW! Im too tired
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paulf.



Joined: 21 Mar 1996
Posts: 427

PostPosted: Sun Aug 07, 2016 6:50 pm    Post subject: Reply with quote

Wouldn't seem to me that well over forecast values at 8am has anything to do with thermal sea breezes.
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boardsurfr



Joined: 23 Aug 2001
Posts: 1245

PostPosted: Sun Aug 07, 2016 8:43 pm    Post subject: Reply with quote

paulf. wrote:
Wouldn't seem to me that well over forecast values at 8am has anything to do with thermal sea breezes.

It's a bit early for sea breezes, but a temperature gradient was in place already. The water temperature at the Nantucket sound buoy at 8 am was 73 F, the temperature at the Hyannis Airport sensor rose from 74 F at 7 am to 77 F at 8 am. West Dennis averages jumped above 25 mph at 10:28 am, when the temperature there reached 79 F.
There's probably some topographic component to the strong WSW winds at Kalmus, too - maybe some channelling with Lewis Bay and Great Island. It's pretty common to see WSW wind being strongest in Kalmus. Today was no exception, with 23-26 averages from 5 to 6:30, compared to 18-21 from 5:45 to 7 in WD. The timing looks more like sea breeze timing. I don't care much what causes it - it was fun!
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jpeter



Joined: 18 Oct 2009
Posts: 337

PostPosted: Mon Aug 08, 2016 6:25 am    Post subject: Reply with quote

Pt Gammon, only a mile away typically gets 5mph less wind than at the sensor, So I agree with the topographical component comment. As the wind shifts from sw to wsw, Pt Gammon seems to improve. JP
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boardsurfr



Joined: 23 Aug 2001
Posts: 1245

PostPosted: Tue Aug 09, 2016 11:41 am    Post subject: Reply with quote

Considering that West Dennis shows the same strong winds in ESE that Kalmus has in WSW, I'd say that all the evidence points towards a black hole in West Yarmouth. A very specific kind of black hole that attracts wind (and maybe tourists, although it definitely does spit those back out again).

I marked the approximate location on the picture below. Maybe we can get some Pokemon seekers to search for it. No, scrap that, they'd have to remove their eyes from the little screens.



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justall



Joined: 30 Jul 2007
Posts: 431

PostPosted: Tue Aug 09, 2016 12:57 pm    Post subject: Reply with quote

boardsurfr wrote:
Considering that West Dennis shows the same strong winds in ESE that Kalmus has in WSW, I'd say that all the evidence points towards a black hole in West Yarmouth.


Hah! Case solved ... a previously undiscovered wind sink. Who knew.

Looks like we'll get some puffs later this week. Nice!
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