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Board » Technical Discussion » The Weather Research & Forecasting Model (WRF)

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We are proudly introducing the WRF Model as a new source of weather forecast data (GRIBs). WRF is recognized throughout the scientific community as the most accurate and reliable weather forecast model. An extensive (and technical) description of WRF can be found at:

http://www2.mmm.ucar.edu/wrf/users/model.html

The scope of this post, without entering into too much technical details, is to inform the SOL community about the features that this model can introduce and how we can benefit from it.

In SOL we historically use the GFS weather model. According to its definition the GFS model is basically one “of the predominant synoptic scale medium-range models” in general use. Therefore it is good (within its accuracy which is around 30km with the resolution we are currently using) if wind is dictated by pressure/temperature fields. This means that, in shorter races, we rely on a small number of grid points and, in between them, we use interpolation. The result is a smooth wind field that is hardly able to follow coastlines. Of course we miss all the finer features that come within this scale, like funnelling, day/night breeze, swirls etc.

We therefore decided to propose a trial of the WRF model, which is a local weather forecast that takes into account a number of small scale (accuracy in the 10m range can be reached) factors neglected in the GFS model. This is not an exhaustive list but a few of these factors are:

- Landmass elevation profile
- Urbanization
- green fraction
- soil composition (as sand heats differently from clay, concrete etc etc)
- ground heating
- sea heating

So, many new local effects can be visible by SOL users. Of course, for those who are not aware about basic meteorology, there will be no difference in sailing with the old GFS model compared to the new one other than a more “realistic” feeling and less smoothed appearance of the wind field. The experienced sailor, on the other hand, will recognize the patterns he is usually able to see IRL. So, overall, we believe that the realism of SOL can be improved and increased by the new wx source.

We have decided to test drive the new model on a classic run between Boston and Newport. For this purpose a 0.05deg spaced grid will be used. This is 10X more accurate than the most accurate GFS grid we have ever used. As a drawback, given the additional computational time and with the purpose of keeping update times consistent with the GFS model, a shorter maximum time window of only 2.5 days is available for the weather forecast as seen when moving the slider at the bottom of the client.

Please take your time to explore the new wind data and post your feedback here in this thread.
brilliant! like!!
Clipping along
Viva Andrea.

Absolutely fabulous!
Sail Fair.
Smart stuff. Nice. Thanks Andrea
I like to talk a lot... sometimes I even make sense, mostly not...
And here's a quick pic to show you what the difference(s) are and.. how to set them - this pic shows how to chance the arrows, but with this new model the contour-settings will also be worth playing with:




--- Last Edited by RainbowChaser at 2015-02-09 18:44:13 ---
Attachments
Typically with Our normal resolution Wx grids are organized by every half degree of Lon/Lat & High Def by every quarter degree.

With this new model, which sounds even better, will the Wx Grid quadrants be even smaller as well ?
None so blind
The Boston-Newport HI-RES test uses 0.05 degree grid. We of course need finer resolution for showing the detail.
Well if we can resolve the new model so that our translation displays quadrant boundaries per every 1/8th degree then that would be most welcome.

Also:

My understanding is that the NOAA Wx is extrapolated from a 3 hour time frame. So what is the time resolution of the new model prior to our adaptation ?

--- Last Edited by A2 at 2015-02-09 23:12:24 ---
None so blind
We have also higher time resolution with WRF. GRIB frames are spaced 1hr instead of 3hrs. This can help with faster gradients.

@A2: I don't really get your point regarding quadrants. Can you explain?

--- Last Edited by ita10267 at 2015-02-10 07:41:17 ---
I really do appreciate this opportunity to have these types of discussions.

First let me explain that I have little if any real sailing experience and lack the usual vocabulary that would seem natural to those that do. Also I do not employ any routing software to analyze in greater detail weather data as a whole. Let me be clear and state here & now that I have no complaint for those that incorporate such methods as that was the original purpose for the inception of this virtual sailing venue.

So over the time I have spent here using just the information available in the browser client and the process of careful observation along with my attempt to visualize how to plan my navigational strategy I have identified rectangular areas that I call "quadrants" bounded by, most often, half degrees of lon/lat depending on the Wx resolution. These boundaries are where the isotachs have their pointy edges and if you follow either a 270-90 horizontal or 360-180 vertical line that the wind speed will exhibit its maximal or minimal transitions.

--- Last Edited by A2 at 2015-02-10 14:40:31 ---
None so blind

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