Wind Prediction

[UFO]

I have been using Windy.com and the BOM for sailing up the West coast of Australia.


So far both have been less than stellar with predictions even on the morning of departure being very far from the real world.


I have had predicted 12Kt SW be 8Kt NE, 15Kt E be no wind at all for the whole day and a 13Kt SE which was predicted for around 20 hours be several hours of no wind and then a 25Kt E.


What apps and tools are you guys using when trying to plan passages?



Currently I am trying to keep to day sails or max 36 hours when required, but even for these short hops I am finding it incredibly hard to plan as the wind is rarely what is predicted.

[Karanga]

Predictwind
PredictWind
PredictWind
Worth the paid subscription.
Various presentations of the info, and I prefer the Tables.

It is interesting to compare forecasts from Windy and PredictWind. While you can change the model in Windy between ECMWF (or whatever the letters are) and GFS, and now some other obscure model, these are each just one model within the PredictWind suite of models.
Amazing to see how accurate it often is, including wind strength by the hour.
Tim

[Paul L]

Windy does not predict the weather. It is a very good app to display model predictions. It displays models, GFS and ECMWF, among others. These are the main, worldwide GRIB models from the US and from Europe. PredictWind uses these same models too and displays them with different colour shades.

Next time you use Windy, select the menu and scroll down to the Forecast Model section. You can select different models to display and you can see how old each model is and when the next update is expected,

[HankOnthewater]

First I use local knowledge, and if I am in a new area, ask the locals.

I use Windy mostly, mainly because of its ease of use, and if want to get it right, then I use predict wind as well (am subscribed to that), and I check all the models. If they mostly agree, then the forecast should not be too far off. At times there is wild variation between the models, then maybe follow the worst case scenario to be safe.
I use rarely Australia's BOM Meteye, as their windspeed is often 20-40% out (where I live). Anyway Meteye is for coastal use only.
For passage making I use BOM 4 day isobar charts
Colour Forecast map for next 4 days
and at times the the interactive chart as well
Interactive Weather and Wave Forecast Maps

When going to sea, just before leaving, I download the latest gribfile and use it with OpenCPN. Note those will be useless after the first 3-4 days.

Lastly at sea, I listen to Australia HF broadcasts via Wiluna or Charleville twice a day, here is some info on that.
Schedules and Frequencies for HF Marine Radio Voice Services

Still at sea, I have a pactor modem connected to my HF radio, but can't get that going with my current computer. Must spend another day or so figuring that one out. It is on the "to do list".

Of course satellite phones and data connections change this HF attitude, and phones are far easier to use.....

On longer trips, my son texts me on my satellite phone any urgent information, including serious weather coming my way. He knows where I am either via Marinetraffic, and I text him once a day my position.

On edit: I see that Paul above made some comments. If you pay a dollar a month or so, to become a premium windy customer, the forecasts are updated hourly instead of 8 hourly I think.

[UFO]

Originally Posted by Paul L

Windy does not predict the weather. It is a very good app to display model predictions. It displays models, GFS and ECMWF, among others. These are the main, worldwide GRIB models from the US and from Europe. PredictWind uses these same models too and displays them with different colour shades.

Next time you use Windy, select the menu and scroll down to the Forecast Model section. You can select different models to display and you can see how old each model is and when the next update is expected,

Yes I have tried the various models, all are particularly crap for this part of the world including the Aussie BOM

[Paul L]

Originally Posted by UFO

Yes I have tried the various models, all are particularly crap for this part of the world including the Aussie BOM

If you think they are all crap, then no point in using them.

By comparing models for consistency, lowering your expectations to how accurate you expect models to be and studying the local weather, the GFS and Euro models are extremely useful to passagemakers.

[HankOnthewater]

UFO, for WA I find the ECMWF model the most accurate, both on Predictwind and Windy. However, I always take all information with a grain of salt, or to say it in another way, with a healthy amount of scepticism. That is why I check the isobar chart of BOM. Those charts are rarely wrong. From that chart one can deduce wind direction and to some degree windspeed. And if the forecast model of one of the other providers is in contradiction with the isobars, then something is wrong.

Apart from boating, I also dabble in weather predictions for my other work, mostly relating to cloud and rain, and again I have not been been far wrong, both in 7 day forecasts, 48 hour forecasts and 12-18 hour ones. Hehehe, they still keep asking me.
Unlike boating, if I were to get it wrong, then there no lives at stake, just lots of $$$$$$

[Paul L]

Originally Posted by HankOnthewater

Paul, for WA I find the ECMWF model the most accurate, both on Predictwind and Windy. However, I always take all information with a grain of salt, or to say it in another way, with a healthy amount of scepticism. That is why I check the isobar chart of BOM. Those charts are rarely wrong. From that chart one can deduce wind direction and to some degree windspeed. And if the forecast model of one of the other providers is in contradiction with the isobars, then something is wrong.

Apart from boating, I also dabble in weather predictions for my other work, mostly relating to cloud and rain, and again I have not been been far wrong, both in 7 day forecasts, 48 hour forecasts and 12-18 hour ones. Hehehe, they still keep asking me.
Unlike boating, if I were to get it wrong, then there no lives at stake, just lots of $$$$$$

Yes, different areas seem to be better served by different models. Offshore in the tropics I find GFS just fine.

As far as the isobar chart, the models also provide pressure that can be displayed as isobars (turn pressure on in Windy for example). The zero hour model is essentially the current (at the time of the model run) pressures. The same as a current isobar chart. The future predictive isobar charts are drawn using the models' predictions along with the forecasters adjustments, if there is one.

[HankOnthewater]

@Paul L, yes I always do use the isobar overlay on windy, and at times they differ with the official (for Australia) BOM site, particularly when more than a few days out

[deblen]

You might try this:
https://www.windfinder.com/#9/-31.9848/116.4221

[Calif.Ted]

I look at Windy and the NOAA (government) marine forecasts but I've actually found Surfline to be most accurate at the coastal locations they report. They have cameras at places that are good for checking real time conditions also.

[LoudMusic]

The first person that reliably and accurate predicts the weather will rule the world.

[ilenart]

Hi Tim,

in May I did a Fremantle - Pt Denison - Abrolhos and return trip over three weeks. Was mainly using PredictWind, but was also listening into the HF broadcasts, plus BOM when in range. Found the Predictwind Departure Planning tool very useful. Was able to utilise effectively so that I avoided just about all headwinds for the whole trip. Was particularly useful when a low went accross us when we were at Pelsaert Island and enabled us to avoid the bad weather, then get a nice tailwind back to Jurien Bay. Was able to pick the best 6 hourly departure. On the forecast models I used the consensus, rather than any particular one for planning the routes.

When I could get it I was also using the Australia MSLP Analysis & Forecast charts from the BOM lite website. Very handy for predicting overall wind direction. Note that if you are out of range to get BOM lite you can download a larger Predict Wind GRIB file and work out the high and low movements by the pressure lines. Can take awhile to download, however I had the unlimited Iridium Go data plan, so was not an issue.

Note that for the trip I had +10 knots most of the time, with a couple of +40 knot periods when the lows were going past. I less than 10 knots none of the forecasts will be very accurate.

Ilenart

[ben373]

Enjoying this thread and playing with Windy did not understand how powerful it is.