Facebook

Login

Support Sailonline

If you haven't already - join the SAILONLINE YACHT CLUB!

Please also consider making a donation - all amounts are greatly appreciated!

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

Page: Previous 1 2

Posted by
ita10267


Users avatar

Posts
88
Registered at
2008-12-29 10:33:09
2015-02-10 21:30:23 - Re: The Weather Research & Forecasting Model (WRF)
so, you are referring to the grid discretization.
In SOL this changes from race to race. Usually we start from 0.5x0.5 deg GRIB file from NOAA which is then interpolated to the grid of our interest. In Leg4, for the first time, we are running the ocean on a 1x1 deg grid. The "pointy" edges are caused by the interpolation algorithm (bilinear), which is the same we use to get wind in between grid points.
The WRF model we are using in the BOS-NEW race is evaluated on a much denser grid. This is not an interpolation process but a complete physical evaluation. The 0.5degx0.5deg GRIBS from NOAA are taken as boundary and starting conditions then the calculations are done on a powerful computer. The result is a 0.05X0.05 deg GRIB.
Posted by
A2


Users avatar

Posts
347
Registered at
2009-10-26 00:39:42
2015-02-10 22:28:06 - Re: The Weather Research & Forecasting Model (WRF)
Thank you for the additional information. Your terms are more precise, I am glad you understood my explanation.
None so blind
Posted by
ita10267


Users avatar

Posts
88
Registered at
2008-12-29 10:33:09
2015-02-11 14:37:14 - Re: The Weather Research & Forecasting Model (WRF)
A small video on high resolution weather

http://youtu.be/n5ThrmvMJxA
Posted by
ita10267


Users avatar

Posts
88
Registered at
2008-12-29 10:33:09
2015-02-13 11:14:02 - Re: The Weather Research & Forecasting Model (WRF)
forecast for sunday morning
Attachments
Posted by
JB


Users avatar

Posts
305
Registered at
2013-03-07 08:54:34
2015-02-16 11:03:51 - Re: The Weather Research & Forecasting Model (WRF)
Viva Andrea.

Great expectations for this race with the new “WRF” weather forecast system and corresponding GRIB files. The first and only routing I’ve made was Friday morning with qTVlm (file“weather_225_wrfems_20150213_1030.grb”).

A small thought. The GRIB files for the SWR Leg 4 are around 1,3 Mb size, for the Boston test aprox. 2 Mb. If we linearly extrapolate the file size in function of the corresponding race field’s dimensions we get a big size GRIB file.

Some pre-race facts.
- Calculations for routing are “heavier” as expected - the GRIB as much more and also better info;
- It’s easier to obtain a geometrical stable tacking path within the qTVlm minimum 5 minutes step calculations (I could have used the 10 minute time step for getting the same results);
- The qTVlm routing optimization process was quicker - the “raw path” is already very good.

The race “test”.
I only used the Zappe Android app (again) for running this one.
With the initial WF it went smoothly and the first South tack was accomplished normally.
After the second WF I couldn’t load the app as it started crashing caused by memory issues. The result was an impossibility to make the second South tack (at the time I was running aprox. at #11). I tried several tweaks on the phone, as closing all the open apps, inputting minimum setting on the SOL apps, etc., but it didn’t work, so I’ve stayed for hours without the possibility for maneuvering the boat.
At the same time I was running psail on the SWR and on Huelva TR without any issues.

The future trend is more power on the “mobile” and less pc/laptop-ish.
Hence this “test” made using the Android app - well, the message is delivered.
I totally support and expect the trend will also be more and better GRIB’s, like the ones from WRF.
Andrea we go in the right direction. Thank you.
Sail Fair.
Attachments
Posted by
ita10267


Users avatar

Posts
88
Registered at
2008-12-29 10:33:09
2015-02-17 07:01:29 - Re: The Weather Research & Forecasting Model (WRF)
JB,
at present time we have to allow for some WX data outside the race course (the purple line). This to allow predictor to work properly in the client. In this race we have used 0.5deg from each side. In the end we had more than 30% of datapoints "useless" for the race. In an optimal condition (no points outside race area), wxfile should have been around 4MB, which travels compressed now, so perfectly usable for the "desktop" client.
Regarding mobile, probably it has some problems (depending on hardware) regarding memory and cache. Probably Zappe can look into that.
Finally, the WRF is defined every hour, so dataset is 3X for the same resolution compared to GFS. As outlaw commented, we should push for even higher time resolution (1 frame every 15min). In this case probably we'll have denser frames for the first 6hrs and sparser afterwards.
Ciao
a.
Posted by
kroppyer


Users avatar

Posts
347
Registered at
2010-02-05 15:25:55
2015-02-19 11:29:52 - Re: The Weather Research & Forecasting Model (WRF)
Hi ita,

It seems the WRF changes a lot more with each Wx update compared to the GFS. Is that just because the changes are a lot more noticeable with the Higher resolution, or also because it's a lot harder to forecast accurately on this scale? (I guess they both play a big role)
Posted by
ita10267


Users avatar

Posts
88
Registered at
2008-12-29 10:33:09
2015-02-19 16:46:03 - Re: The Weather Research & Forecasting Model (WRF)
In synoptic conditions, i.e. wind given by large pressure systems, forecast are simpler and more reliable (see the Bos-New race with the heavy storm). In fluky conditions, with basically no pressure gradient, wind is given by "local"effect such as cloud coverage etc. So yes, on mesoscale, weather is less "consistent".

As a comparison, GFS is "averaged" over a much bigger gridsize, so all the small scale variation are zeroed and you ave a more stable but less interesting windfield. On the other hand NAM model, on a 0.1deg scale, has the same behaviour.

Page: Previous 1 2

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

The British Isles Circumnavigation 2026


The British Isles Circumnavigation is here! Inviting skippers to take on an epic 1,720nm clockwise voyage around Britain and Ireland! Starting and finishing in Cowes, the course passes some of the most iconic landmarks in offshore sailing, including Fastnet Rock, Tearaght Lighthouse, Black Rock, St. Kilda and Muckle Flugga before the long run home. Racing in our fast and versatile TP52, this Super-Buddy Championship race will reward smart routing, changing weather strategy and sustained concentration over every mile. Good luck!
Race #2052
INFO by brainaid.de
TP-52 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
Race starts: Aug 09th 10:00 Registration Open!
▶ Flash
GO TO RACE

SSANZ Triple Series 2026 - Race 2

Welcome back to race two of the SSANZ Triple Series—it's time for the Lewmar 100! Our dynamic fleet of Young 88s returns for another exhilarating 65 nautical mile battle across the stunning waters off Auckland, New Zealand. Once again, our skilled Sailonline racers will test their strategic minds and endurance. With intense competition, shifting conditions, and plenty of tactical decision-making, this race promises high-energy sailing and edge-of-your-seat excitement from start to finish!
Race #2047
INFO by brainaid.de
Young 88 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SSANZ - SUPBUD - SYC
RACE CLOSE: Friday,
August 14 at 2300 UTC.
Race starts: Aug 08th 21:15 Registration Closed
▶ Flash
GO TO RACE

Lake Vättern PYOC 2026


Back in 2013, longstanding SOLer Musigny and his friend xthyra invited us for a three race tour of beautiful Lake Vättern in the heart of southern Sweden. After many years, we return there for a quick sprint from a start in front of the village of Brandstorp, either way around Visingso island in the middle of the lake, but PORT HAND ROUND a buoy off the Granna piers on the eastern shore and back, once again avoiding Visingso as best you can. At least 20nm in trusty Scandinavian 11m One Designs; good luck!
Race #2046
INFO by brainaid.de
11m OD PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SPQ3 - SPCH - SYC
RACE CLOSE: Wednesday,
August 12 at 2300 UTC.
Race starts: Aug 08th 21:00 Registration Closed
▶ Flash
GO TO RACE

Easter Island to Tristan da Cunha 2026

Welcome to the second leg of our RNW series, rounding Cape Horn. This middle-most leg Round the New World, from Easter Island to Tristan da Cunha, is also part of our Ocean Championship, and as such the second race of OCQ3 2026. This race, like the previous race in the RNW series, will be sailed in our revised 'version 2' Imoca 60 Foil. Race #2050
INFO by brainaid.de
Imoca 60 Foil v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ3 - RNW - OCCH - SYC
Race starts: Aug 03rd 11:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member KaSToR
  2. Sailonline Yacht Club Member CriticalHippo
  3. Sailonline Yacht Club Member WRmirekd
  4. Sailonline Yacht Club Member Panpyc
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member cdhinman
  7. Sailonline Yacht Club Member rthinman
  8. Sailonline Yacht Club Member ms0689
  9. Sailonline Yacht Club Member BRENTGRAY
  10. Sailonline Yacht Club Member Sax747

View full list

Series

Mobile Client

SYC members have the benefit of access to our mobile/lightweight web client!

The mobile client