SailNet Community banner

1 - 15 of 15 Posts

·
Registered
Joined
·
1,446 Posts
Discussion Starter #1
How do you guess the weather?
Last night's forecast for today's weather was for really fine sailing conditions, especially in the afternoon. This morning's newspaper had a weather chart showing a frontal passage about noon time. So after running some errands I arrived at the marina at about 11:30, just in time to set dark clouds in the NE. So, I took a nap and watched what would unfold, which was rain, a 15 degree temperature drop a180 degree wind shift and blustery winds 22-29 kts. So, no sailing today. (Sorry James, I guess that makes me a picnic saler, a poser).
So, are there dependable weather forecasts for 24 hours out?
I use Wonderground and I-36, both of which are NOAA based, but both missed this one.
AARGH
John
 

·
Administrator
Joined
·
5,921 Posts

·
Registered
Joined
·
41 Posts
Every weather forecast is a guess, some much better than others. For each area some forecasts are better than others. I like accuweather for my long term and noaa for short term and compare the two.

This summer there was three weeks where the long term forecast were crap in my area, but this fall they were very accurate. Go figure.
 

·
TROUBLE
Joined
·
964 Posts
CC- I feel your pain, man. Sometimes the forecasters get it wrong, but I was expecting this one. It has been forecast for days. Not sure about your sources. Even AccuWeather had it right. Meanwhile, as we rock and roll in the slip, wearing sweats and socks, not enjoying the first major front of the season. Wishing we were on our way back to the Bahamas, rather than tied to a dock in Galveston.

Ralph
 

·
Registered
Joined
·
1,446 Posts
Discussion Starter #6
Well, in all honesty the online noaa based services were only off by about 12 hours. I guess the bottom fell out and the front accelerated, which is just the opposite of normal. I've been tied up with other activities and was looking forward to a nice sail after a week off.
Oh well.
How do you get and get smart about GRIB files?
John
 

·
Registered
Joined
·
6,686 Posts
I'm kinda like Donna - I look at the charts, look at the fronts out west and down south, figure which way they're headed, and do my own prediction. Most of the time, I'm a bit more accurate than NOAA, but keep in mind that it's nearly impossible to predict wind speeds. I had a good friend down in the Florida Keys who was a charter captain. Prior to becoming a charter fishing captain, he ran a commercial shrimp boat. When I questioned him about an upcoming NOAA weather forecast he looked me straight in the eyes and said "Boy, if I would have been shrimpin based on NOAA's weather predictions, I would have either starved to death or drowned." Old Bill was a pretty smart fella.

Gary :cool:
 

·
Master Mariner
Joined
·
9,007 Posts
If I was half as good at my job (a professional captain) as the weather people are at theirs, I'd have sunk every boat I've operated, twice, before I even got out of the slip!
There are some excellent book about weather; Alan Watts has a few good ones. With the information (NOT FORECASTS) available online and only a bit of understanding of how weather works, you can do your own forecasting and not be at the mercy of the weather people.
I do all my own forecasting (especially hurricane) and so far, it's worked out quite well for us.
 

·
Registered
Joined
·
5,067 Posts
If I was half as good at my job (a professional captain) as the weather people are at theirs, I'd have sunk every boat I've operated, twice, before I even got out of the slip!
There are some excellent book about weather; Alan Watts has a few good ones. With the information (NOT FORECASTS) available online and only a bit of understanding of how weather works, you can do your own forecasting and not be at the mercy of the weather people.
I do all my own forecasting (especially hurricane) and so far, it's worked out quite well for us.
Indeed NOAA 'forecasts' seem to be extremely conservative vs. 'the aversion of risk'; and, you'll miss a lot of good sailing because of this apparent protection of the populace from 'risk', especially when the weather is chaotic and changeably unstable.

The Dashew's: Mariners Weather Handbook is probably one the best for self-inflicted local forecasts based on available 'data'. Its expensive and highly 'technical' but with such information and acquired knowledge from such a 'textbook' one eventually finds it becomes second nature to adjust just about any 'forecast' for local personal needs. It covers not only surface weather but also the high altitude (500mb) weather that 'drives' the surface conditions.
Mariner's Weather Handbook: Steve Dashew, Linda Dashew: 9780965802826: Amazon.com: [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@51GCXEnibHL
 

·
TROUBLE
Joined
·
964 Posts
Well, in all honesty the online noaa based services were only off by about 12 hours. I guess the bottom fell out and the front accelerated, which is just the opposite of normal. I've been tied up with other activities and was looking forward to a nice sail after a week off.
Oh well.
How do you get and get smart about GRIB files?
John
You are right. Many times, the cold fronts either stall, and never make it. Or, at least slow down. Probably hard to predict this at times here on the Gulf.

For gribs, I use Ugrib - Software Informer. Ugrib 0.2.4.0 is a free application that allows access to global weather data.

It was a pain to download, but works very well once installed. Passage Weather is nothing more than gribs, but does give waves, Visibility and precipitation, sea temp, surface pressures, and Gulf Stream. Sailing Weather - Marine Weather Forecasts for Sailors and Adventurers - PassageWeather

Also have had pretty good luck with Wind, waves & weather forecast Galveston East Buoy - Windfinder

I have my private pilot's license, but haven't flown in years. I did learn, and remember much of the basics about weather. Hey, if we were all experts about weather, there would be no such thing as weather routers like Chris Parker.

Ralph
 

·
Freedom isn't free
Joined
·
3,057 Posts
Just my take, from a much less technical guy when it comes to weather... and of course I am inland too, so weather patterns are less dramatic for us... but after about 2 years of writing down forecasts 5 days, 3 days, 24 hours before, and 12 hours before, then day of sailing... my observations are:

Temperatures are usually accurate, within about 10% 3 days out
example, 3 days out, they predict highs will be 65... we get there and it's 59

Precipitation potential is usually accurate with a 50/50 chance 24 hours out
example.... day before they say we're going to get rain from 7am to 7pm.. it rains for about half the morning, and clears up around noon..

Winds forecasts 12 hours out, can be about 50/50
example: Noon Friday, they predict winds will be 8-12 gusting to 17... Saturday, winds are 4-6, dying off.

Winds the day of sailing... are accurate to about 20-25% of actual wind speed.
Example: Saturday morning winds predicted to be 5-7... actual is 4-6.

This using NOAA point forecasts.

5 days out (and the 5 day forecasts) are good for predicting which strong fronts will crawl across our nation, they aren't real good for predicting when they'll actually hit (or at what strength).
Example: Monday shows Friday's forecast, with a trough dipping across most of the country pulling arctic air in.... Friday there is a frontal passage... but it's weakened, but overcast, and brings in some winds.

Years ago when I lived to snowboard I learned just how bad weather forecasting really is. Sailing has just reaffirmed that discovery.
 

·
TROUBLE
Joined
·
964 Posts
Well, in all honesty the online noaa based services were only off by about 12 hours.
Keep that in mind if you are doing a passage. To be clear, I'm a coastal cruiser, that occasionally does some overnight passages (150-200 miles). Let's say that you were crossing from Carrabelle to Clearwater Beach, or Rodriguez Key to Bimini, Bahamas, and this storm hit you 12 hours early. That's why, when I plan a passage, I don't go unless I have a good window for the following day as well....just in case. I study weather for 2-3 or more hours, days before a crossing. But hey, I'm a picnic sailor too apparently. Use everything you can find (your favorite forecasts), and don't go if some are good, but others are bad and don't agree. I'm not going with a 50/50 chance of having conditions I like.

Ralph
 

·
██▓▓▒▒░&
Joined
·
13,645 Posts
John, how well you can guess depends on where you are and what tools you can access. In the MetroNY area, if the winds are from the west you can look at Chicago's wx and that's what you will have tomorrow. OTOH if there's a front stalled (occluded front) coming up from the south or a three-way mix somewhere within 500 miles...all bets are off, no one knows what will win out.

If you're in one general area, you can usually observe and remember patterns like that. If you're cruising and in new places, it is harder to know how the cards usually fall. Or when you see a satellite image of something like Superstorm Sandy, a thousand miles wide...you can betcha it won't be a good day, no matter where or how that goes.

you just need to observe, practice, read up a little, and you can do it as well as the Know-A-Nothing Man.
 

·
Registered
Joined
·
2,705 Posts
I have used this website for a while now:

www.earth.nullschool.net

It provides for 5 days out as a prediction and their predictions (for me) are pretty good.

By clicking in the spot that you are querying, the detail of wind speed is provided - I think it is a good indicator of what to expect.
 
  • Like
Reactions: Classic30
1 - 15 of 15 Posts
Top