Skipper's Cockpit Weather Guide by Frank Singleton

Author:Frank Singleton
Language: eng
Format: epub
ISBN: 9781472989048
Publisher: Bloomsbury Publishing
Published: 2022-01-15T00:00:00+00:00

Regional and Limited Area Models

NWS centres run models using fine-scale topographic and meteorological data, including satellite imagery and weather radar data. Global models provide data around area boundaries. However, data collection, analysis, computation and data dissemination take a minimum of two or three hours. By the time forecasts are used by sailors, much small weather detail in the initial analysis will have disappeared. Weather features around 20 or 30 km size have lifetimes of a few hours. Consequently, detailed forecasts will be indicative rather than definitive. Extra value is likely to be in prediction of wind shadow and similar topographic effects, which may include sea breezes. Even then, results will depend on the large-scale prediction.

NWS publishing or providing detailed model data in chart or GRIB code include Iceland, Norway, Sweden, Denmark, Germany, France, Jersey (UK), Spain, Croatia. Names of some of these models are HIRLAM, HARMONIE, AROME, ALARO. There is a selection of NWS detailed models on the Meteociel site. The Turkish NWS Weatherwise is a useful regional product for the Mediterranean.

‘Unofficial’ LAMs start from global data interpolated to finer grids, usually with no detailed weather input. They should be able to model topography but are not likely to achieve the high accuracies claimed or implied. Most ‘unofficial’ LAMs use a version of the WRF. There are several sources of detailed forecasts in addition to the NWS mentioned above. Using XyGrib on a laptop, a good WRF source is openWRF on the openSkiron site, which is also a source of the DWD ICON-EU and COSMO. Using a tablet, this requires viewers from LuckGrib for IOS and SailGrib for Android. However, there is also a browser version of the openWRF page.

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