Meteorological Forecasts at ESO Sites

Welcome to this site. It provides informations regarding the meteorological conditions above ESO observatories. An Introductory Presentation is available for new-comers, as well as an update of the performances after one year of operation. Hints for the terminology are available in the Weather Glossary.

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Cloudiness and Water Vapour from Satellite Images

Your Sky NOW and NEXT : The forecasts of water vapour and cirrus clouds for the next 36 hours above La Silla and Paranal with the most recent IR image in the water vapour channel.

Your Sky RECENTLY : a 4x4km resolution thermal IR image of the South Pacific region with a zoom on ESO sites (updated every 3h with about 45mn lag).

Credits: the forecasts are produced 4 times per day using a model developped by A. Erasmus under contract with ESO. The model is based on a combination of GOES satellite images provided by SSEC, University of Wisconsin-Madison, global meteorological forecasts provided by ECMWF (see below) and local meteorological data from the ESO Astronomical Site Monitors.

Synoptic Meteorology, Jet Stream and Ground Conditions

The meteorological images are refreshed every 12 hours, as soon as the provider (ECMWF) sends the forecasts. The 00UT and the 12UT forecasts provide short term predictions, up to T+36H, with a step of 6 hour. The 12UT forecasts also include general tendencies up to T+192 hour (8 days) with a step of 12 hour. Usually, the short terms forecasts are refreshed at 03 UT and 08 UT, and the long term are refreshed at 03 UT.

The first pages provide general tendencies for the south Pacific and the Chilean coast. The next pages are reconstructed radio-profiles above the sites of interest for ESO (La Silla, Paranal - VLT, and Chajnantor - ALMA).

General tendencies for the Chilean coast (short term, long term)

Reconstructed radio profiles above Paranal (70W24',24S37')(short term, long term)

Reconstructed radio profiles above La Silla (70W42',29S16')(short term, long term)

Reconstructed radio profiles above Chajnantor (67W45',23S01')(short term, long term)

The forecast of ground level conditions at Paranal, at La Silla, data query via Java interface

Note: The profiles are constructed from a bilinear interpolation: the four nearest points of the grid are isolated and the profile computed with respect to the distance between the site and the four points.

Credits: the forecasts are produced by ECMWF (European Center for Medium Range Forecast). Two type of grid are used: the first, with a step of 3 degrees, on [65W to 110W]x[10S to 43S], and the second use a step of .5 degree on [67W to 71.5W]x[22S to 26.5S] and on [67W to 71.5W]x[27S to 31.5S].
The files are then processed using Grads scripts developped at ESO by P. Labit along the lines defined by CRS4 to produce those images. For more details, see Meteorological Forecast Products, User and Maintenance Manual ref:TRE-ESO-17443-1678.

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Last modified: Thu Jul 16 11:43:01 MET DST