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

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.
Thank you for the additional information. Your terms are more precise, I am glad you understood my explanation.
None so blind
A small video on high resolution weather

http://youtu.be/n5ThrmvMJxA
forecast for sunday morning
Attachments
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.
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.
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)
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:

Pantaenius Shetland Race 2022 - Leg 2
As always, we don't spend much time in Lerwick, Shetland and after some brief but excellent celebrations we are rapidly heading back to Bergen, Norway, for the second leg of the Pantaenius Shetland Race 2022. The North Sea always provides with some exciting racing and we are sure that this race will be no different!
Race #1581
INFO from brainaid.de
First 40.7 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
RANKING: SYC - SHE
RACE CLOSE: Thursday,
June 30 at 2300 UTC.
Race starts: Jun 26th 09:00 Registration Open!

▶ Flash
GO TO RACE

Isla St George Sprint 2022
The Bass Islands, in western Lake Erie, are a mere couple of miles west of the southernmost boundary of Canada. In this 21nm PYOC sprint, we will set off from East Harbor in our RC 44s and leave North Bass Island (historically Isle St. George) to port before quickly returning to East Harbor.
Race #1584
INFOby brainaid.de
RC 44 PARTICULARS
NAM_AWIP WX Updates:
0245 / 0845 / 1445 / 2045
Ranking: SPRQ2 - SPRCH - SUPSOL - SYC
RACE CLOSE: Wednesday,
29 June at 2300 UTC
Race starts: Jun 25th 18:00 Registration Open!

▶ Flash
GO TO RACE

Newport Bermuda Race 2022


The 635-mile biennial Newport Bermuda Race is one of the oldest regularly scheduled ocean races, and with the Fastnet Race and the Sydney to Hobart Race, it is one of the three great classic races of the yachting world. Founded in 1906, this the 52nd running of the Bermuda Race can also be participated in online.
Entries are invited for one of the four divisions:
Double-Handed Division:
Jeanneau Sun Fast 3300
St. David's Lighthouse Division:
First 44.7 Asymmetric
Gibbs Hill Lighthouse Division:
Reichel Pugh 64
Finisterre Division:
Delphia 47
Details for each yacht are available in the ‘Particulars’ links below and be sure to register your online choice on the Bermuda Race Online link – there are some fine prizes to be won.
As in real life, you can only sail one boat in one division, so choose your virtual yacht carefully, and because of the unusual (for SOL) 4-division nature of the event, please note results will not count towards ANY Sailonline Rankings.
Race #1568
INFOby brainaid.de
Sun Fast 3300 PARTICULARS
First 44.7 A PARTICULARS
RP 64 PARTICULARS
Delphia 47 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: None
Sponsors:

RACE CLOSE: Saturday,
July 2 at 2300 UTC.
Race starts: Jun 17th 17:00 Registration Closed
▶ Flash
GO TO RACE

Geraldton to Cape Town 2022
A race in the Southern Indian Ocean is always entertaining, especially in a Riptide 50. Traditionally the course would be West to East, to take advantage of the prevailing winds, but this time the SRC is challenging us to an E-W course, from Geraldton in Western Australia to Cape Town in South Africa. A brief 4800nm!
PRIZE: SMPF
Race #1575
INFO by brainaid.de
Riptide 50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
OCQ2 - OCCH - SUPSOL - SYC
Race starts: Jun 12th 05:00 Registration Closed

▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member rafa
  3. Sailonline Yacht Club Member Pit8008
  4. Sailonline Yacht Club Member FreyjaUSA
  5. Sailonline Yacht Club Member GREATSKUA
  6. Sailonline Yacht Club Member Sax747
  7. Sailonline Yacht Club Member Vida_Maldita
  8. Sailonline Yacht Club Member Satori
  9. Sailonline Yacht Club Member sassy63
  10. Sailonline Yacht Club Member HappyHour

View full list

Series

Mobile Client

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

The mobile client