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Getting the Best Ten-Minute Forecast

January 17, 2017

Whether you're waking up for your watch on an ocean crossing, heading out for a major regatta, or ready to hit the water after a long day at the office, every sailor needs to know the forecast. However, when it comes down to it, who really knows? With an abundance of websites and cell phone apps, it can be overwhelming and difficult to find accurate forecasts. But in just ten minutes, you can create a reliable forecast that will help you prepare for your day on the water; here's how.

Beautiful and helpful - Aside from being one of the prettiest forecasts, the Windytv app and website are also very detailed and easy to use for a quick look at wind and weather conditions at your exact location.

Weather can be unpredictable, and even for the most seasoned sailor, trying to predict the weather can be difficult! No one wants to get stuck on the water in gale-force winds or with no wind at all, so having a reliable forecast is important. This step-by-step guide, including information on the best weather apps available, will help you hit the water informed and monitor the conditions all day long.

Veteran sailing coach Ed Adams said, “A professional forecast takes about an hour to put together, as there’s high value in looking at all the possibilities. You can, however, get eighty percent of the way to a good forecast in about ten minutes.”  Whether you’re conducting the team’s daily weather brief or you simply want to increase awareness on the course, use this four-step program to create a more accurate weather forecast (and if you want to attempt a more professional forecast, give step five a try!).

The Ten-minute Weather Forecast

1. Use the National Weather Service (NWS) for the basics.
Will it be sunny, cloudy, warm, or cold? Also check the NWS marine forecast for any warnings.

Website: www.weather.gov

BONUS: If you have extra time, the NWS has technical discussions for the major weather office, which publishes how experts came up with the forecast on any given day. Defintiely worth a read.

2. Take a look at the wind field.
Don't forget to zoom in and out to see the observations.

Website: www.sailflow.com (subscription required to see all anemometers)

3. See what kind of weather is heading your way.
Fronts? Squall lines? How fast is it moving?

Websites: www.wpc.ncep.noaa.gov and www.weather.cod.edu/satrad/ 

4. Look at the models. 

  • Low resolution global models: good for long-range forecasts (GFS, CMC, ECMWF) 
  • Regional models: predict weather for today and tomorrow (NAM, HIRLAM)
  • Rapid update models: shows the next few hours – especially helpful as inclement weather approaches! (HRRR, RAP)
  • High resolution models: best for your specific location (public and proprietary versions of the WRF)

Websites: www.spotwx.comwww.sailflow.com, and www.predictwind.com 

5. Consider downloading GRIB files.
If the race or adventure is a big one, it’s worth the time to download GRIB files, especially the high-resolution models, and study them with a GRIB viewer. These can show local effects and how a wind shift might fill across the racecourse. Subscriptions are usually required.

Wesites: www.predictwind.com or www.squid-sailing.com/en/ 

BONUS STEP: Look at upper-air observations and forecasts. These can tell you what wind might mix down from aloft (on unstable days), or whether the wind will be more geographically-channeled (on stable days).

WHICH APP’S BEST FOR YOU?

Which cell phone weather apps are most popular amongst sailors? In a 50-sailor poll, the average number of regularly-used apps was four. Generally, the best apps pull forecasts from the National Weather Service (NWS). All of the following are reliable, so choose the ones that best suit your style of racing or cruising.

Sailflow (free) specifically designed for sailors, it gives professional meteorological forecasts. A $9.99/month subscription provides additional observations.

Windytv (free) perhaps the best-looking app, this one could easily be used as a screensaver! It gives specific local wind readings with the option to layer on other predictions as well. There's also a great, interactive website: www.windytv.com.

PredictWind (free) weather forecasts in high resolution maps.

Windfinder (free) wind forecasts (10 day) and observations, also wave and tide information.

Radarscope (free or $9.99/year). “The paid version is completely worth it,” said one anonymous sailor/ meteorologist, who’s also an employee of Commanders weather. 

Wunderground (free) a large number of weather stations give this app incredible local forecasts.

WindAlert (Free) “Wind alert is nice because it displays the tide and wind next to each other,” said a Sarasota-based sailing coach.

Now you have a better idea of how to create your own weather forecast, so download your favorite weather apps and start sailing!

The Discussion

Paul Renny

January 19, 2017

I always enjoy seeing new apps and resources when it comes to marine meteorology. One common theme however, is the increasing popularity of GRIBS. This can be a bit of a sucker hole as GRIBS are simply computer models comprised of SCAT data and have had no human input from a qualified meteorologist. When a meteorologist builds his or her forecast model, they use GRIB data as a tool along with observations, upper atmosphere data and many other sources to build an overall model. However, due to their graphic nature, it makes it very easy for someone with a GRIB viewer to think they are getting an actual wind forecast when in fact, they are only seeing one small part of the overall puzzle. Anyone who uses GRIBS really needs to understand, that for this reason, they should not be solely relied upon. I have seen instances where GRIB data has shown fair winds when actually, after the meteorologist completed the model, there was a hurricane in the exact same location. I caution anyone who plans to sail offshore with only GRIB data as utilized in commercial apps such as PredictWind. It is a great tool but should not be the primary source. My go to resource is the Ocean Prediction Center. http://www.opc.ncep.noaa.gov They even provide all the data and maps in a compressed version obtained via SAT phone using their FTP service for use offshore. Much cheaper than a full on SSB and modem. Even having studied Meteorology in University and having an understanding of how to build a forecast, depending on the passage, I still employ the services of a professional Meteorologist for offshore routing. The cost is negligible for the added benefit and it beats any app out there.

gerald Bibot

September 11, 2017

Dear Paul, Absolutely agree on your post when stating: " I caution anyone who plans to sail offshore with only GRIB data as utilized in commercial apps such as PredictWind. It is a great tool but should not be the primary source. " We cover some races in the Europe such as the Vendée Globe and the Volvo. We also support and coach teams and training structures in smaller events such as the Figaro solo. And what ever the format or the length of the race, it always comes down to the capacity of analysis of the navigator or skipper . The grib download and feed in a routing algorithm should always be the last step of a route preparation. Getting synoptic charts (Bracknell, NOAA, DWZ,..), satellite images to asses a time zero observation, is a prerequisite to really understand a weather evolution pattern. What we also encourage with our users is to overlap for a given area different independent models and see where these models do converge or diverge, and try to understand where, when... and eventually why ? For long range forecasts, there is absolutely no substance in making a assessment based on global deterministic forecasts (GFS, ECMWF, ...) Only ensemble models do have a certain rationality. Lots of apps like predictwind etc... do advertise on their ability to provide long term forecasts, say up to 15 days... they start to charge for this, while short terms forecasts, remain freely accessible. Beyond 3 to 4 days, deciding upon just one forecast scenario, is just as good as rolling the dices. Really. What's important based long term probabilistic forecasts, is to extract patterns of evolution. It's not always obvious, but it is the only objective rational thing to do. I recommend this excellent article from Will Oxley: http://www.squid-sailing.com/en/content/74-ensemble-forecasting-by-will-oxley For Coastal navigation, to get local effects, (breezes, venturi's, etc.) there are a lot of national weather services which do provide excellent regional GRIBS, covering 0-48 hours mostly. They come in very high resolution and benefit from a broad scientific continuous upgrade. Such support SME's are struggling to follow. So our advice for coastal navigation is definitely to trust entities which have the capacity (CPU, academic and human ressources) to specialize in smaller regional area's. Look for instance the excellent models of Meteo France (Arome HD) in their national waters, or HRR from NOAA in the USA. No-one ever did better. So no need to re-event the wheel there. Enjoy your sailing! Gérald Squid Sailing / Volvo Ocean Race Official supplier