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:

Roma per Tutti 2026


Sailonline are honoured and delighted to have been asked to partner an online first Roma per Tutti yacht race with organizing yacht club, Circolo Nautico Riva di Traiano . In real life, this will be the 33rd edition of this 540nm offshore race from Rome’s Riva di Traiano to the Aeolian Islands and back. Online, the race will not only be our first partnership with CN Riva di Traiano, but also the second race of our Magical Mediterranean series. A number of Mini 6.50s have been entered for the 33rd edition of the Roma per Tutti; so our own vintage Mini is also our virtual yacht of choice for this one.
Race #2019
INFOby brainaid.de
Mini 6.50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SUPBUD - SYC
Race starts: Apr 11th 10:00 Registration Open!
▶ Flash
GO TO RACE

Rommel by Balloon 2026 - Through the Sahara


Generalfeldmarschall Johannes Erwin Eugen Rommel may have been that chivalrous, gallant tank commander of legend, led astray by the Prussian military traditions of loyalty and chain of command, but one thing he wasn’t, was mad. So, let’s do it anyway – not stick to the coast and the battle for logistical superiority – but depart the oases of Siwa south west into the desert for Agadez and its uranium. And let’s go by balloon, it’s only 2500km (1250nm)!
Race #1973
INFOby brainaid.de
SOL Balloon PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: BOL - SYC
Race starts: Apr 07th 13:00 Registration Open!
▶ Flash
GO TO RACE

Falklands to Tasmania 2026

Welcome to yet another all-new route. This next race is part of our Ocean Championship as well as the ROW series. Falklands to Tasmania, is like last year's island to island. It’s one of the longer ones 6400nm, more than half way around the world (and the Antarctica). It starts the 2026 OCQ2, and will be sailed in our Steinlager 2, contrary to prior notice.
Race #2021
INFO by brainaid.de
Steinlager 2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - ROW - OCCH - SYC
Race starts: Apr 06th 11:00 Registration Open!
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member KaSToR
  2. Sailonline Yacht Club Member WRmirekd
  3. Sailonline Yacht Club Member rafa
  4. Sailonline Yacht Club Member rumskib
  5. Sailonline Yacht Club Member CriticalHippo
  6. Sailonline Yacht Club Member CollegeFund
  7. Sailonline Yacht Club Member Panpyc
  8. Sailonline Yacht Club Member Sax747
  9. Sailonline Yacht Club Member sassy63
  10. Sailonline Yacht Club Member vida

View full list

Series

Mobile Client

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

The mobile client