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Old 26-01-2008, 23:11   #16
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Charlie, what were your seas like at 50 and 60 knts?
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Old 27-01-2008, 02:56   #17
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Weather really is a science of variables and as weathermen donít have the benefit of actually being where you, it is foolish for anyone to expect accurate forecasts at every spot. I am happy with generalizations from them.

As Kanani explains very well, learn to recognise and understand the weather patterns and use them to your advantage.
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Old 27-01-2008, 04:45   #18
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METEOROLOGICAL PHRASES TRANSLATED
Stolen from some meteorologist with a sense of humour

1. A baroclinic zone should result in rising motion due to density differences. This will result in atmospheric condensation and thus precipitation.
TRANSLATION: A front will bring us rain

2. 6-sided crystalline aggregates are being gravitationally forced to the surface.
TRANSLATION: It is snowing

3. The horizontal pressure gradient force is quite tight.
TRANSLATION: It is windy

4. Inflow and horizontal vorticity have been tilted into the mesocylone.
TRANSLATION: A tornado is forming

5. Condensation is occurring upon condensation nuclei as the parcel lifts, cools adiabatically and becomes saturated.
TRANSLATION: A cloud is forming

6. Sensible heat and a high vapor pressure of water molecules are producing extremely high theta-E values.
TRANSLATION: It is hot and humid

7. Latent heat release is producing bomb-o-genesis and an intensification of the thermal wind.
TRANSLATION: A Nor'easter is developing

8. Isentropic lifting is producing large scale synoptic uplift north of the warm front.
TRANSLATION: Clouds and precipitation are north of the warm front

9. CG 12 o'clock with towering Q.
TRANSLATION: Lightning struck in front of us from a developing thunderstorm cloud

10. The line echo wave pattern is being fed by warm air advection and moisture convergence.
TRANSLATION: A line of thunderstorms is developing

11. A veering wind in the vertical indicates warm air advection and synoptic uplift.
TRANSLATION: Warm air rises
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Old 27-01-2008, 04:53   #19
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My motto is "Trust, but Verify".

I've spent a lot of time reading about weather forecasting and studying the multitude of weather data sites. I've developed a healthy respect for how well they do, given the inexact nature of the science. I don't know as much as the weather forecasters, but I have learned how to evaluate what they say, and understand some of the inevitable uncertainties of forecasting.

It's a big mistake to simply accept the forecast as "gospel" and head out to sea. Having the ability to make some informed judgements on your own, based on researching the fundamental weather data, allows you to prepare for the unexpected.
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Old 01-02-2008, 11:49   #20
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Quote:
Originally Posted by Rez View Post
Charlie, what were your seas like at 50 and 60 knts?
Considering I was in the Puget Sound, they weren't as bad as the open ocean, not enough fetch. We saw wind waves up to 12', large enough to turn back the ferry. I can imagine those 12 footers combined with 15-20' swells would likely get your attention rather quickly.
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Old 01-02-2008, 12:51   #21
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Wave Heights

Quote:
Originally Posted by Rez View Post
Charlie, what were your seas like at 50 and 60 knts?
Rez,

According to Sheldon Bacon, in Adlard Cole's Heavy Weather Sailing, fully developed seas at 50 kts would reach 17 m (56'). At 60 kts they'd be 25 m (82'). "Fully developed" means unlimited fetch, with winds blowing at the given speed for a long enough time to develop the maximum wave height, probably about three days for those wind speeds.

Scary!

(Gord, don't worry, I'm not trying to take your job!!!)
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Old 01-02-2008, 13:08   #22
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My motto is "Trust, but Verify"...
... It's a big mistake to simply accept the forecast as "gospel" and head out to sea. Having the ability to make some informed judgements on your own, based on researching the fundamental weather data, allows you to prepare for the unexpected.
What HUD said, noting that Damon Runyan (Runyon) doesn’t often get proper credit for the opening quote, more usually attributed to Ronald Reagan (and less often to HUD); but Runyan also contributed another aphorism that could adapted to Weather Forecasts: "The race is not always to the swift, nor the battle to the strong, but that's the way to bet."
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Old 01-02-2008, 13:44   #23
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Rez,

According to Sheldon Bacon, in Adlard Cole's Heavy Weather Sailing, fully developed seas at 50 kts would reach 17 m (56'). At 60 kts they'd be 25 m (82'). "Fully developed" means unlimited fetch, with winds blowing at the given speed for a long enough time to develop the maximum wave height, probably about three days for those wind speeds.

Scary!

(Gord, don't worry, I'm not trying to take your job!!!)

With respect to Mr. Bacon, seas above 30 ft in the North Atlantic are quite rare, requiring a rather large storm system to build them. While it may be technically possible to build an 82' sea with only 60 kts of wind, the only place you will ever find seas that large (in the North Atlantic) is in a hurricane or the rare nor'easter with over 100kt winds. Even then, you would only get a few 82' waves, mostly from constructive interference from smaller waves. I'd be interested to hear how a sustained 50 kt wind stacks up the Southern Ocean.

Brett
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Old 01-02-2008, 13:59   #24
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As far as I can throw her or him.

Better than nothing however. I like SouthBoundII for offshore info. Herb bases his forecasting on local sailor's reports as well as weather data and his long experience.
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Old 01-02-2008, 14:10   #25
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I always laugh when people get angry at the weatherman. Or they put absolute faith in what the forecast says. Weather-charts, computer-modelling and observation aside; forecasting basically has three parts:
1) statistical analysis - eg. 120 years of empirical observation at this station tells us that on Feb 1 there is an "x" percent chance that it will snow/rain/be sunny, that the average temp is "x" and the percentage chance it will be higher/lower is "y", etc., etc.;
2) short-term trend analysis - over last few days - temperature rising/falling, pressure rising/falling, getting sunny/cloudy, etc., etc.; and
3) upstream observation - eg. prevailing winds in Canada are westerly; weather moves from West to East across the country; the conditions in North Bay today are the conditions in Ottawa tomorrow.

There are literally hundreds of variables that could throw a wrench into the forecast. As others have said - learn about the weather and watch for the signs that the forecast didn't foresee.
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Old 01-02-2008, 14:21   #26
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With respect to Mr. Bacon, seas above 30 ft in the North Atlantic are quite rare ...
Brett
The North Atlantic seems to be experiencing localized 30 Ft (9m) waves right now, and is expected tp see more of the same (moving Eastward).

NOAA Wave Watch:
NOAA WAVEWATCH III wave models (table)

Wave Model - North Atlantic Sea Height
Wave Model - North Atlantic Sea Height (STORMSURF)
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Old 01-02-2008, 16:11   #27
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This may be of interest. It is the transcript of a radio documentry on the prediction of rogue waves. Produced on the ABC (australian public radio station) by the science program catalyst. In light of the fateful 1998 Sydney to Hobart yacht race where very large breaking waves (estimations of up to 80 feet, making it impossible for one rescue helicopters auto hover to function) I think it fair to say that you wouldnt want to be to far south in a bad blow !!
Catalyst: Rogue Waves - ABC TV Science
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Old 10-02-2008, 13:20   #28
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I trust the weather forecast implicitely, that is when I can get it as this true story shows!

VHF Channel 16: “This is Cape Town, Port Elizabeth and Durban Radio. There will be no Weather Forecast at 7.15 this evening due to staff unavailability”.
Stunned silence from the airwaves for a moment, followed by a call from some vessel to ask what that was all about.
VHF Channel 16: ” I am the only person on duty and I don’t have time to read a Weather Forecast with all my other work”.
Click. Silence for the rest of the night. That’s Africa for you!
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Old 10-02-2008, 15:30   #29
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Pretty tough to trust what I can't see. Even with no formal training interpreting satellite images, it makes me feel better if I can see them myself. . . .
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Old 10-02-2008, 17:14   #30
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In 1992 around christmas I headed offshore with weather forecast of sunny and 10-15s. Ended up running into no name storm with hurricane force winds. When I called coast guard to report position as we had the mast in the water twice from knockdowns from breaking waves. we were told that there were 12 reports of maydays with sunken boats and people in the water. We were in 23' sloop. we navigated down the main ship channel with loran and compass as there was literally zero visability and made it behind egmont key. One thing that stood out in memory, the marine am fm radio came on by itself, went full blast playing some song that went DO YOU WANT TO DIE, DO YOU WANT TO DIE. and didnt turn off till power wires were pulled off.
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