WRF

Expedition WRF weather simulations

Expedition WRF is best thought of as a system to add small scale thermal and land effects to the GFS forecast.

It is aimed at sailing locations where high resolution model data isn't available (eg Cape Town and NZ) or is is harder to obtain (eg Australia).

Various areas are also available on demand for regattas, such as the Americas Cup, Sail GP, the Olympics and Mediterranean sailing venues.

Data

MSLP, rain, 10m wind and gusts, 20m wind, 2m temperature, CAPE & total cloud cover. Others available on request.

The Expedition interface allows only the wind or basic parameters to be downloaded.

Updated every 6 hours (4x daily), except for NZ where the model is updated every 3 hours for the duration of AC36. Update times can be checked in Expedition before downloading.

Resolution

1/12° (0.083°, < 5nm), 1 hour increments to 72 hours

1/36° (0.028°, < 2nm), 30 minute increments to 36 hours

1/108° (0.009°, 1/2nm), 30 minute increments to 24 hours

Implementation

Expedition WRF uses GFS and other surface datasets for initialisation and boundary conditions. The 1/36° domains are similar in horizontal and vertical resolution to the HRRR.

Minimum of 45 levels. WRF can be run with 35 or fewer levels, but more is always better.

Nesting inside GFS has two main benefits:

Merging WRF and GFS data is seamless. Flowx shows this very nicely.

Timeliness and skill level of the forecast is improved. We don't have NOAA's resources to run WRF or MPAS on a global domain, at least to the same level as the GFS.

Notes

WRF can over-estimate 10m winds, especially in stable conditions or where there is a lot of wind shear. From experience this implementation does very well in sea breeze and thermal scenarios.

For example, Expedition WRF was exceptionally good for sea breeze situations during the 2021 Americas Cup, but the NIWA UM model tended to be better for gradient flows where the southwest wind dominated. Similarly, it does very well in the Mediteranean, but tended to over-estimate wind speed during the Tokyo Olympics.

What it isn't

It isn't a replacement for the national mesoscale models such as Access, Arôme, HIRLAM and HRRR.

It also doesn't replace the global models for larger scale areas.

Custom events

Temporary WRF areas, may not be in current Expedition distribution.

Olympics

Japan 1/12°
Enoshima 1/36°
Enoshima 1/108°

Estonia ORC worlds

Tallinn 1/12°
Tallinn 1/36°
Tallinn 1/108°