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Old 30-07-2016, 15:05   #31
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Re: Faith in Weather Forecast?

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Originally Posted by Kenomac View Post
How many of you actually put much faith in weather forecasting? I've read many posts over the past years on this forum stating themes such as "I never go out if the forecast is for winds above 15 knots," "only fools get caught out in bad weather with forecasting as good as today's," etc. etc.

We use three different marine weather apps which generally, are very good. Pocket gribs, Weather4D Pro, and Buoyweather (we subscribe). But as you can see from the pocket grib photo and from the video, you don't always get what you think. Here we are in what was forecast to be calm seas less than 1 meter and winds of 2.2 knots sailing around the southern foot of Italy. What we had for this six hour period was a consistent 26-36 knots of actual wind, 20-30 knots apparent wind, and 2-3.5 meter swells which we were able to sail comfortably using only our staysail to maintain 6.5-8 knots of boat speed.

It was a 50 hour passage with various combinations of sail and wind speed, even including a round up under full sails just south of Messina, when the wind speed increased from 20 knots directly behind us up to 55 knots in just a few moments.

All in all, it was an average passage which didn't really include anything unexpected, since we now allow for weather variations. Mrs. Mac looks a little tense in the video, she really isn't, it's just the way she's sitting. She's actually quite used to sailing in these conditions. I welcome your thoughts on the matter. Do any of you actually count on and put any faith in the forecast? I've found it's always better to be prepared for the worst even when 2.2 knots is forecast. ;-)

Ken

In the Carib on long passages away from land i.e 3 night 4 day Guadeloupe to Bonaire or 4 night 4 day Curaçao to st Croix noaa was right on the called it as we experienced it maybe a knot or two on the gusts off. I trust God noaa and myself in that order.
Ernie on the Mary Jane USCG 100 ton.
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Old 30-07-2016, 15:17   #32
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Re: Faith in Weather Forecast?

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Originally Posted by Sulaire View Post
When cruising under the foot of italy, it pays to pay attention to the winds on the top side of the foot,any medium stregnth northerlys there get accelerated through the mountains into jets like this for this coming monday, again pw shows this up well.

Attachment 128748
Great image...nice big red blob where he was (realize not the same time frame).

We get gap winds like that here in Central America too. The major ones, like Tehuantepec, are pretty well predicted, but there are many minor ones which are totally unpredicted (another example of what the models won't show you). We got caught by a very localized gap wind while kayaking in Panama. It was about 40 knots straight out of a narrow bay where we were trying to land...no way in a kayak. Only about 100 yards to either side were similar bays...beautiful light wind conditions in both.

Maybe a not so well predicted gap wind that caught OP.
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Old 30-07-2016, 15:22   #33
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Re: Faith in Weather Forecast?

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Originally Posted by Kenomac View Post
When we got hit suddenly by 55 knot winds we were only less than one mile off shore. During the video where it was predicted to be 2.2 knots and we had 20-38 knots we were 40 miles from land in all directions.
Judging from the posted image of Italian gap winds, 40 miles out could have still have been a gap wind.
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Old 30-07-2016, 16:38   #34
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Re: Faith in Weather Forecast?

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Originally Posted by meirriba View Post
The gribs around Messina show ~20kn. What area you have referred to with ~2.2kn?

As to reliability you must take everyhing as probabilities. I keep on file a forecast received mid-Atlantic during ARC2003. It warned of a 'major tropical event, gusts over 80kn'.
The actual wind was 15-20kn.
You are being too hard on the NOAA forecasters. They were correct.

In December 2003 there was a named weather system called Peter, the first December named system in modern times.

Why do I know this, I was there, heard the advisory from Herb, noted that the prevailing NE trades had ceased blowing from NE 4-5, at my location, to zilch ["a major tropical event"] and we sat flat calm mid ocean for some 24 hours.
So much was this an unexpected event that the chatter on the radio net was "where's the gas station" !!
Something mega stops the prevailing weather system. The forecast was correct to predict something major, but it predicted too broad an area potentially affected. It turned out to be no more than a strong gale in a much smaller area than forecast.
We continued on when the prevailing weather re-established to Force 4-5. I did meet a yacht mid-ocean a day later who had lain a-hull for several hours in a claimed 50 knot wind.

So the forecast was accurate.
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Old 30-07-2016, 17:17   #35
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Re: Faith in Weather Forecast?

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Originally Posted by belizesailor View Post
Judging from the posted image of Italian gap winds, 40 miles out could have still have been a gap wind.
I don't see any gap winds on the pocket grib screen shot from two weeks ago, the terrain in the area is quite flat, no mountains or valleys. Sulaire's image is from today.

A better guess, is that the approaching Mistral was arriving 4-6 hours ahead of schedule. The higher winds hit us in Brindisi only four hours after arrival. I thought we had at least a 10-14 hour head start and didn't expect them quite so soon after arrival.

The forecast was four to six hours early.
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Old 30-07-2016, 22:57   #36
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Re: Faith in Weather Forecast?

keep an eye on the barometer/if you have been through unfavourable conditions remember the bar pressure and be aware of what happens wen the glass is low
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Old 30-07-2016, 23:07   #37
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Re: Faith in Weather Forecast?

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Originally Posted by Kenomac View Post
How many of you actually put much faith in weather forecasting?
Have you considered upgrading to a high resolution ensemble forecast?


I made an attempt at explaining what an ensemble forecast is, that they are available for some few regions, and reported on the subscription prices in an earlier thread.


See: Internet-Independent Weather
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Old 30-07-2016, 23:25   #38
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Re: Faith in Weather Forecast?

Quote:
Originally Posted by Kenomac View Post
How many of you actually put much faith in weather forecasting? I've read many posts over the past years on this forum stating themes such as "I never go out if the forecast is for winds above 15 knots," "only fools get caught out in bad weather with forecasting as good as today's," etc. etc.

We use three different marine weather apps which generally, are very good. Pocket gribs, Weather4D Pro, and Buoyweather (we subscribe). But as you can see from the pocket grib photo and from the video, you don't always get what you think. Here we are in what was forecast to be calm seas less than 1 meter and winds of 2.2 knots sailing around the southern foot of Italy. What we had for this six hour period was a consistent 26-36 knots of actual wind, 20-30 knots apparent wind, and 2-3.5 meter swells which we were able to sail comfortably using only our staysail to maintain 6.5-8 knots of boat speed.

It was a 50 hour passage with various combinations of sail and wind speed, even including a round up under full sails just south of Messina, when the wind speed increased from 20 knots directly behind us up to 55 knots in just a few moments.

All in all, it was an average passage which didn't really include anything unexpected, since we now allow for weather variations. Mrs. Mac looks a little tense in the video, she really isn't, it's just the way she's sitting. She's actually quite used to sailing in these conditions. I welcome your thoughts on the matter. Do any of you actually count on and put any faith in the forecast? I've found it's always better to be prepared for the worst even when 2.2 knots is forecast. ;-)

Ken

Ken, you are sailing in the wrong direction. Running with it

https://tmblr.co/ZA2gzx29n-us- Can't direct link to my video It was shot earlier in the week whilst it was still pleasant

I've just about given up on looking for forecasts. Here in the Aegean, so many forecast sites get it wrong because their weather models don't seem to realise that there are many islands speeding up or slowing down the wind and sending it in all crazy directions.

Yesterday I tried to escape my anchorage on the promise of a F5 and then F6 where I will either beat into it or motorsail for 5nm until I can bare away. I left expecting F6 & F7 so I put 3 reefs in the main to be conservative. Ended up only rolling out the genoa for a short time as it was blowing F8 and when I got to the section I was expecting more wind it was up to a F9. Decided against motoring into it and sailed 13nm back to the anchorage.
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Old 31-07-2016, 00:44   #39
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Re: Faith in Weather Forecast?

Yes thread has some good examples of how people get into problems when they don't fully understand the tech they use. A grib image IS NOT a weather forecast.
A weather forecast is when a meteorologist with knowledge of the forecast area prepares a prediction of the weather for a specific time period, place and level of detail. Up to 48hr they should be very accurate.
Relying on many Grib images for a coastal passage is about as much use as looking at the N pacific chart to plan a trip across San Francisco Bay.
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Old 31-07-2016, 00:47   #40
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Re: Faith in Weather Forecast?

PS If you want good forecast the worlds navies prepare excellent ones for most areas and broadcast them for free via SSB WFax every 6h.
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Old 31-07-2016, 01:16   #41
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Re: Faith in Weather Forecast?

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Yes thread has some good examples of how people get into problems when they don't fully understand the tech they use. A grib image IS NOT a weather forecast.
A weather forecast is when a meteorologist with knowledge of the forecast area prepares a prediction of the weather for a specific time period, place and level of detail. Up to 48hr they should be very accurate.
Relying on many Grib images for a coastal passage is about as much use as looking at the N pacific chart to plan a trip across San Francisco Bay.
Move to New England and see how accurate the meteorologists are.

Or better yet, come on over here to Italy or Croatia and try to understand a forecast by a meteorologist in Serbian or Italian if it's not your native language. Even if the forecast is done in English, it can be just as difficult to understand. Most of the time we need to use the best tools available to us at the time, and most of the time things work out just fine. If I'd waited for a proper professional weather window done by a meteorologist to sail from Naples to Brindisi, I'd most likely still be waiting in Naples to depart. Instead.... three weeks later, I'm enjoying Montenegro.

BTW: We never got into problems as you suggested, it was smooth sailing all the way because we've come to expect the unexpected. The round up was no big deal and conditions shown in the video are what our boat likes to see.

I think people should actually head out in conditions which gradually push their abilities, so that they don't get knocked on their arses the first time the wind blows more than expected. They'll never get the experience if they sit around waiting for the professional meteorologists to announce the perfect day. IMHO

And NO, the 48 hour forecast here in the Med is not always accurate, just ask anyone who lives here or has a boat here.
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Old 31-07-2016, 01:20   #42
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Re: Faith in Weather Forecast?

In my 40 years plus of working very hard I never had the luxury of being able to make bad calls on a daily basis and keep my job!
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Old 31-07-2016, 01:26   #43
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Re: Faith in Weather Forecast?

I think that many place their 'faith' in wx forecasts ( ie predictions ) the same way they place their faith in electronics.

I have met so many that think gribs are the duck's guts and 100% infallible .... oops there we go again with the faith thing...

Inshore - stuff happens. I remember some years ago quoting the weather for the Channel... skipper reminding me that we were in the Solent...

Earlier this year... about 20 miles NE of East Cape , NZ, ... about 40 knots plus out of the west for 3 hours or so... nothing before or after in the gribs or any of the NZ forecasts....

Local knowledge is king... but **** still happens ....

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Old 31-07-2016, 01:51   #44
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Re: Faith in Weather Forecast?

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In my 40 years plus of working very hard I never had the luxury of being able to make bad calls on a daily basis and keep my job!
Agreed. As a Registered Nurse, people come to expect perfection during the performance of my job which isn't obtainable. I'd certainly loose my job if I made a big mistake.

But those meteorologists have it made.... They make bad calls all the time, are able to keep thier jobs, and even have faithfull followers who believe in them.

Kinda like being a politician.
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Old 31-07-2016, 02:09   #45
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Re: Faith in Weather Forecast?

Your first post appears to show a grib.... the raw data the weathermen ( sorry but cant spel mertroiwatsitogist ) work with...

That is a grib... not a weather forecast.... rely on that and you will come unstuck.... esp inshore
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