Chair Report

It is acknowledged that military requirements for fog and low cloud are
more demanding than for commercial planes, but there was not sufficient
information to quantify this.
2) ROAD SECTOR
This sector involves various kinds of users (drivers, road authorities, rescue teams, big
haulage companies etc).
(i) In general, customers in this sector are interested in low visibilities in the
range from 0 to 200 meters. Most critical when visibility is less than 50
meters.
(ii) Customers are interested when visibility decreases very rapidly along
the road.
(iii) In mountainous areas there is a need for low cloud forecasting.
(iv) Fog forecasts are required on the road. Rather general forecasts are not
so important.
(v) Customers also require that such forecasts reach them directly (e.g. by
broadcasting them over the radio or by road signs).
(vi) There are two requirements regarding the leading time
- The first one refers to nowcasting i.e. of the order of few
hours or even less (increasing requirement on the nowcasting
scale).
- The second refers to one day in advance.
(vii) The provision of the forecast time for fog dissipation is recommended.
(viii) There is a requirement for freezing fog forecasts (not necessarily
linked to low visibility).
3) MARINE SECTOR
There is not enough information to consolidate recommendations. However, the working
group has noted the existence of publication WMO Handbook for Offshore forecasting
WMO/TD N850.
Some general recommendations are:
(i) Ships at sea require forecasting of low visibilities in the range of 0 to 1
km.
(ii) Port Authorities require more detailed information on fog conditions and
forecasts but they do not specify exactly what they mean.
4) PUBLIC SECTOR
There is a general need for forecasts for fog and low cloud up to one day in advance.