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Weather, by All Means  


Robert Connolly explains DRM weather ‘datacasting’ to ships, revisits the RTTY transmission mode and looks at synoptic weather forecasts,


Robert Connolly explains DRM weather ‘datacasting’ to ships, revisits the RTTY transmission mode and looks at synoptic weather forecasts, before diving into the fascinating history of the Shipping Forecast.  


There is one piece of important information all vessels at sea require, be they large cruise ships carrying three thousand or more passengers, a super-tanker, a trawler or even a small day boat – all of them need up-to-date and reliable, weather information.

The Safety of Life at Sea (SOLAS) regulations of the International Maritime Organisation (IMO) entered into force in 1980. According to these rules, weather information is delivered in different formats, including by means of broadcast radio.

In the British Isles, this includes, of course, BBC Radio Four’s Shipping Forecast on long wave (198kHz). Furthermore, there are many NAVTEX and HF Narrow Band Direct Printing (NBDP) transmissions containing weather updates. The relevant maritime meteorological data are also disseminated by means of Coastguard voice transmissions, in the shape of the Maritime Safety Information (MSI) broadcasts.

Moreover, seafarers can get MSI data delivered by satellite communications and even download weather information from the internet.

There are many other direct transmissions of weather data such as the Radio Facsimile (Fax, WEFAX) charts produced by Deutscher Wetterdienst (DWD, the German Weather Service).

These are still transmitted via HF radio, along with RTTY weather data reports also transmitted by DWD on HF frequencies (see later in this column).


DRM Datacasting to Ships

I recently discussed with our editor, Georg Wiessala, a relatively new source of weather data; the Digital Radio Mondiale (DRM) datacasting service provided by the company RFmondial.

The transmission capabilities of this form of digital point-to-multipoint broadcasting can provide data services to single ships as well as to larger naval units worldwide. With this technology, a variety of maritime applications can be delivered.

These include the provision of nautical data such as electronic charts, Gridded Binary (GRIB) weather data, Differential GPS information, NAVTEX/ NAVDAT and SAFTEY-Net MSI transmissions.

Other formats can provide some ‘infotainment’ such as audio broadcasting of live sports and/or ‘homeland-security’ broadcasts, intranet and WiFi.

The data files are processed, encrypted and then transmitted to the user, where they are decrypted by the receiver. DRM+ is also an option for the International Association of Marine Aids to Navigation Lighthouse Authorities (IALA) – in the context of the developing VHF Data Exchange System (VDES).


Revisiting RTTY

It has been quite a while since I have listened to RTTY and WEFAX transmissions. Therefore, I decided that it would be a worth my while to check whether these systems were still fully operational, given all the new technological developments in the delivery of weather information.

The current DWD WEFAX and RTTY transmission schedules from Offenbach (DDH) and Pinneberg (DDK), located about 20 km north-west of Hamburg, are available on the DWD website:

The RTTY frequencies currently used by DWD are 147.3, 4583, 7646, 10100.8, 11039 and 14467.3 kHz.

There are various software solutions for receiving the RTTY transmissions including SeaTTY and JVcomm32, both of which will also receive WEFAX transmissions.

A detailed list of weather reception software is available at this URL:

You can also try the Zorns-Lemma software for receiving weather data via RTTY and Radio FAX; this will also decode synoptic weather data into charts and automatically pull masses of weather data off the internet from NOAA servers and weather buoys around the world.


Synoptic Forecasts

When you do receive RTTY weather updates, you will notice that the actual weather reports for each station appear in a ‘synoptic’ format – as groups of figures (Fig. 1).

You will have to decode these, in order to understand the actual synoptic report. To this end, software tools are available for the use of mariners and hobbyists. These software decoders will receive synoptic weather information and produce a range of weather graphs, including synoptic charts, pressure charts, pressure tendency diagrams and wind and temperature charts.

In the 1990’s, when I was studying night-time MF propagation, I used a software suite called Skyview Synop. This program could receive and decode RTTY weather data and produce live weather charts of various types. To download a complete synoptic data set (needed to produce accurate charts), took up to three hours. During this time, my PC was hooked up to my receiver, with neither available for any other use.

In those days, synoptic data sets were updated every three hours; nowadays it is every six hours.

With the advent of a fast internet connection, I migrated from that system and started to use the Digital Atmosphere, software produced by US firm Weathergraphics.

The benefit of using the Weathergraphics tool is that, at the click of a mouse, I can download a complete synoptic set within seconds. The software can output whatever type of charts I require, after just another couple of mouse clicks. This allows me to not only free up my receiver for other monitoring but also to use the computer for other tasks.


Voluntary Vessels and Weather Ships

The majority of weather reports transmitted by DWD come from aa wide range of land-based observation stations. Many of them are at airports and identified by their ICAO code.

In a received DWD RTTY signal, land station reports are preceded by the letters ‘aaxx’, followed by a date & time group. However, you will also notice other reports that commence with ‘bbxx’. The latter combination of letters indicates that the report has come from a sea station, a ship or off-shore oil rig.

The World Meteorological Organisation (WMO) has registered a significant number of commercial ships providing such regular, voluntary, weather observation reports.

In this way, the vessels in question distribute valuable weather data across our seas and oceans on a permanent basis. This, in turn, helps to produce more accurate weather charts and forecasts globally.

In the mid-1900s, before the days of satellites, various countries had dedicated ‘weather ships’, located in the oceans. These vessels collected weather information, in the same way as did land observation stations.

With the use of selected commercial vessels providing voluntary observations to the WMO, a much more detailed picture of weather patterns became available and the weather-ships were de-commissioned.

DWD transmits reports from ships in the Atlantic, North Sea, North Polar Sea and the Mediterranean.


Hamburg, Northwood && Co.

The current radio weather fax (WEFAX) frequencies used by DWD are 3855, 7880 and 13882.5 kHz. Transmission is in F1C mode (white + 425Hz, black - 425 Hz).

Initially, when using radio fax reception software, you may need to make some minor corrections to the software, in order to remove the ‘slant’ that comes with your first received images. Details on how to do this are contained in the software help files.

More often than not, the program in question has a facility to do this quickly and without having to experiment, so you get an optimal setting.

Once set, this should not require changing again, provided you do not uninstall the software or change your computer hardware.

In addition to the DWD WEFAX services, weather charts are also transmitted from Fleet Weather Northwood in the UK, using the callsign GYA.

The main frequencies are 4610, and 8040kHz, with 2618.5kHz also used between 2000 and 0600 UTC. The frequency 11086.5kHz is active between 0600 and 2200 UTC, with a transmitter power of 10kW.

When I checked these frequencies here a few days before preparing this column, I noticed that signal strength was very weak compared to what it used to be when I last checked a couple of years ago. In fact, the signal strength was so weak I struggled to receive charts although I heard the typical Fax transmission sound.

There are other stations active in Russia, North America, the Asia Pacific and several other world regions. The latest version of the Worldwide Marine Radio Facsimile Broadcast Schedules is dated September 2017 and can be downloaded from this website:

Another useful resource for RTTY and Radio Fax frequencies and broadcast times is William Hepburn’s website:

Please remember that sources such as these are only as accurate as the information provided and that changes can, and do, occur.

In today’s technological age, using RTTY and WXFAX for the dissemination of weather information is fairly ‘old school’. Who knows just how long these transmissions will continue to exist? Many mariners are becoming dependent on electronic navigation aids and satellite communications.

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However, while this renders the internet more accessible as a source of steady weather information, you need to be aware that electronic data are always subject to potential hacking.

Therefore, RTTY and WXFAX are a good continuity resource, should an electronic ‘meltdown’ occur.


Old and New School

I am sure that we have all, at some point, heard the sea area forecasts broadcasts transmitted by BBC Radio 4 on 198 kHz four times per day, for the various sea areas it covers.

Dividing sea areas into blocks with individual names is not just confined to the extended waters around the British Isles, many other countries operate a similar system. It is helpful to mariners who can then pay special attention to the forecast for the particular sea area they are currently in (or are about to enter) while at sea.

The trusted BBC Shipping Forecast is a national institution. It provides weather information for 31 sea areas around the UK, with broadcasts at 00.48 and 5.20am, 12.01pm and 5.54pm. The first and last broadcasts of the day also include reports from additional weather stations and Inshore Waters Forecasts.

The regions are always listed in the same order, starting north with Viking, located between Scotland and Norway, and then proceeding in a roughly clockwise direction: Viking, North Utsire, South Utsire, Forties, Cromarty, Forth, Tyne, Dogger, Fisher, German Bight, Humber, Thames, Dover, Wight, Portland, Plymouth, Biscay, Trafalgar, Fitzroy, Sole, Lundy, Fastnet, Irish Sea, Shannon, Rockall, Malin, Hebrides, Bailey, Fair Isle, Faeroes and Southeast Iceland.

The forecast for each area lists the following:

Wind Direction and Strength.

Precipitation, if applicable.

Visibility (‘good’ is more than five nautical miles, ‘poor’ is less than 2nm and ‘fog’ is less than 1,000m).

One other interesting fact is that the BBC Shipping Forecast never exceeds 370 words.


A Question of Names

How did the UK sea areas mentioned in the Shipping Forecast get their names? My thanks to reader Bob Houlston G4PVB who kindly pointed me in the right direction for a suitable explanation of those, sometimes strange, sea area names we take for granted.

Many of the areas are named after sandbanks: Viking, Forties, Dogger, Fisher, Sole and Bailey.

The areas Cromarty, Forth, Tyne, Humber, Thames and Shannon are all named after estuaries.

The areas Wight, Lundy, Fair Isle, Faeroes, Portland, Hebrides, South-East Iceland and Utsire are named after islands.

Rockall and Fastnet are derived from islets.

Dover and Plymouth are named after towns.

Sea area Malin is named after Malin Head, the most northern point of Ireland.

German Bight is an indentation on the Northern European shoreline.

Biscay is, of course, named after the Bay of Biscay.

Trafalgar takes its name from Cape Trafalgar.

This southernmost sea region (Trafalgar) is only mentioned routinely in the last forecast of the day, unless there is a gale warning specifically for that area. Prior to 1956, German Bight was called Heligoland and renamed to reflect the more general usage amongst the nations concerned.

Also, in 1956, and following international consultation, Dogger was revised with the north-eastern portion to be named Fisher and Forties; the northern half became Viking.

The renaming of Iceland as Southeast Iceland was undertaken for the sake of greater clarity.

In 1984, shipping areas in the North Sea were coordinated with those of neighbouring countries, introducing North Utsire and South Utsire and reducing Viking in size. One unusual sea area name is FitzRoy, after Robert FitzRoy (1805 to 1865) the captain of HMS Beagle, Britain’s first professional weatherman and the founder of the UK Met Office.

Previously this area was named Finisterre (literally, ‘the end of the world’). It gained the name FitzRoy in 2002 to avoid confusion with the smaller sea area of the same name used in the marine forecasts of the French and Spanish Meteorological Offices.

There is an interesting video regarding the BBC Shipping Forecast, available at this URL:

Last but not least, the vessels in this month’s photo (Fig. 2) are the tugs, Mourne Shore and Mourne Valley. They assist large vessels into the Carlingford Lough ports of Greenore and Warrenpoint.


Editor’s Choice: More on the Shipping Forecast


Selection from RadioUser

Connolly, R. (2010) ‘WEFAX and RTTY on HF Maritime Radio’ (RadioUser, December 2010: 34)

Richards, M. (2011) ‘HF FAX Slant Correction (RadioUser, January 2011: 18)

-- ‘Maritime Weather Broadcasts’ (RadioUser, May 2012: 34)

-- ‘Common Problems with Receiving HF-FAX’ (RadioUser, February 2011: 16)

Wiessala, G. (2012) ‘My Weather Day’ (RadioUser, May 2012: 52)



Atkinson, A. and Clayton, M. (2011) Lundy, Rockall, Dogger, Fair Isle: A Celebration of the Islands Around Britain (Ebury)

Compton, N. (2016) The Shipping Forecast: A Miscellany (BBC Books)

Connelly, C. (2005) Attention All Shipping: A Journey Round the Shipping Forecast (Abacus)

Gribbin, J. (2016) FitzRoy: The Remarkable Story of Darwin's Captain and the Invention of the Weather Forecast (CreateSpace)

Harris, M. (2000) Understanding Weatherfax (2nd ed.) (London: Adlard Coles Nautical)

Houghton, D. (2008) Weather Forecasts (Royal Yachting Association)

Jefferson, P. (2011) And Now the Shipping Forecast (UIT)

Moore, P. (2016) The Weather Experiment: The Pioneers Who Sought to see the Future (Vintage)

Thompson, H. (2006) This Thing of Darkness (A novel on Robert FitzRoy) (Tinder)

Thomson, W. (2016) The Book of Tides (Quercus)



BBC Weather Shipping Forecast:

History of the Shipping Forecast:

Met Office Shipping Forecast:

Northwood Fleet Weather Centre (History):

The Shipping Forecast: A Map of Britain’s Splendid Isolation:

The Tragic Life of Charles Darwin’s Captain (BBC History):


This article was featured in the July 2018 issue of Radio User