Tuesday May 23rd, 2017

Weather Research and Forecasting (WRF) Model Outputs

Summary of project

This site is intended for forecasters in the Caribbean region. Outputs from the mesoscale numerical prediction model, Advance Research Weather Research and Forecasting Model (ARW), hereafter referred to as WRF, will be uploaded to this site twice a day during the Atlantic hurricane season and once otherwise. The WRF runs are initialized by data from the Global Forecast System (GFS) model for 0000Z and 1200Z during the hurricane season and 0000Z otherwise. WRF outputs for the run using the latest initialized data and 24hrs previous to that hour will be available.

Summary of WRF

There are three (3) versions of the Weather Research and Forecasting model. The one used for these simulations is the ARW. The ARW is a portable state-of-the-art atmospheric simulation system which has been developed by that is portable and efficient on available parallel computing platforms. This version of WRF is suitable for use in a broad range of applications across scales ranging from meters to thousands of kilometers.

Explanation of domains and resolution

Normally, WRF is run for two domains, however, when there are weather systems of interest, a third domain will be introduced to cover the location of the system. The largest domain, domain 1, extends from 30W to 95W and 0 to 35N, whilst domain 2 extends from 50W to 90W and 5N to 30N.Currently domain 1 is run at a 54km resolution, i.e. the area is split into 54km*54km squares, where as domain 2 is at a 18km resolution and if there is a domain 3; the high resolution box, it will be run at a 6km resolution.

Explanation of outputs

The outputs produced are categorized in 4 major sections: surface, vertical levels, cross sections and tephigrams.

Surface

An overlay of mean sea-level pressure, horizontal winds and 3 hr precipitation is provided for each domain within the model. Please note that "bleeding" occurs at the edges of the domains and this is especially the case for precipitation, thus one should use ones' discretion when considering results close to the edges of the domain.

Vertical levels

Pressure Level

Variables

850mb

Relative humidity, geopotential height and horizontal winds

700mb

Relative vorticity, geopotential height and horizontal winds

500mb

Relative vorticity, geopotential height and horizontal winds

300mb

Geopotential height, divergence and horizontal wind

200mb

Streamlines

A plot of cloud top temperature will also be provided in this section. Please note that "bleeding" occurs at the edges of the domains especially for the case of clouds, thus one should use ones' discretion when considering results close to the edges of the domain.

Cross sections

Latitudinal cross sections are provided for 8N, 13N, 18N and 23N. These cross sections extend the width of domain 1 [i.e. from ~20W(the rightmost longitude on the image) to ~90W (the left most longitude on the image)]. Each cross section provides an overlay of relative vorticity, horizontal winds, equivalent potential temperature and vertical velocity.

Storm potential

This section contains a plot of the simulated radar reflectivity for domain 1. Tephigram plots are provided for selected stations. The tephigram plots are supplied every 12 hrs.