How do most forecast wave conditions?

[Rockinar]

How do most forecast wave conditions? NOAA website or depend on something like Windy?

[Beneteau2011]

I use the ECMWF model in PredictWind

(Coastal sailing, not more than 50 nm offshore)

[Captain Bill]

Look at all the available and believe it will be worse than the worst one. Last June I was going from Charlotte Harbor to the Dry Tortugas. Five forecasts said 3-4 with winds 15 gusting 18. One said 5-6, winds 18 gusting 23, all from the east. The crap weather started when we were half way there and started out of the NW and had gone NE within an hour. Then the wind went E to ESE 23 gusting 30. Seas went up to 9-10 in short order and about a 5 second period. We got our but kicked that night. Another time going from Miami to Bimini it was forecast at 15 to 20 and 3-4 with 4-5 in the gulf stream. My wind instrument said 20 apparent from the SW but I was doing over 10 knots so around 30 true and seas were 8ft or so. Another time 4 forecasts for 3-4 and 12 to 15 and one outlier said 6 ft. Got half way across and the seas were 12 ft and these seas were not in squalls or thunderstorms, just straight line winds. My rule is be prepared for the possibility of it being twice as bad as the worst forecast. If it's better, be glad, but at least you were prepared if its not.



Weathermen lie!

[StuM]

I compare the different models in Windy and then take then all with a large pinch of salt.


It's worth considering thatthe Australian BOM for instance includes a disclaimer on their forecasts:
"Please be aware
Wind and wave forecasts are averages. Wind gusts can be 40 per cent stronger than the forecast, and stronger still in squalls and thunderstorms. Maximum waves can be twice the forecast height."

[jimbunyard]

Hmmm...waves = fetch x wind speed...

[CaptTom]

I've noticed that the NOAA coastal forecasts often (but not always!) predict a "worst case" scenario, and that the waves and wind are significantly less. But of course I'd confirm that with Windy and other sources.

I also use the formula @jimbunyard posted, but add in time, too. You can often go a long way before things build to that worst case, as long as you have options to duck into.

[cr180]

As others have said, wave forecasts tend to underestimate actual wave conditions. Our experience has been that the forecast models do not have the technical ability to account for swell (ocean waves due to far away wind fetch), local wind chop, and the most impact, wind against current. So we look for 2’ or less and are always are greeted with more!

[flightlead404]

Originally Posted by CaptTom

I've noticed that the NOAA coastal forecasts often (but not always!) predict a "worst case" scenario, and that the waves and wind are significantly less. But of course I'd confirm that with Windy and other sources.

I also use the formula @jimbunyard posted, but add in time, too. You can often go a long way before things build to that worst case, as long as you have options to duck into.

US pilots know that between October and April the NOAA says "VFR flight not recommended due to icing" and between April and November the NOAA says "VFR flight not recommended due to thunderstorms".

I'm a total newbie but have both Predictwind and Windy and have already found them to be woefully wrong sometimes.

So, I'm adding a 25% fudge factor and plan multiple bailouts.

[dfelsent]

Know that the NOAA (US) wave forecasts are for the average of the highest 1/3. They specifically say that one should expect to see an occasional wave of double the forecast wave height.

https://www.weather.gov/key/marine_sigwave

So if the forecast is 2-4 you might see 8. Once in a great while.

I do not know what other MET agencies use for standards.

I use this model: http://www.stormsurf.com/mdls/menu_wam.html

It is also available from other sources including fnmoc.

BUT please remember that the tidal currents will dramatically affect local heights.
As in benign to life threatening.
As will local geography.

[phorvati]

They can not forecast the seastate that you can rely on. Local guides and pilots are better at telling you when sea state gets bad for specific area. On the other hand your experience is your best forecast. It gets complicated, gulfstream, tidal flows, shoaling, wind, its all unique per specific area, wind direction and strength. I guess the only time weather model prediction is reliable is when there are no currents, shoals and other land factors in your forecast.

[sailjumanji]

Windy if in cell range. OCENS SpotCast subscription on our InReach if outside of cell range.