In article lgate.org,
Michael McNeil writes:
I'd have expected the pressure reports from the coastal stations would
have massive steps rather than a sinuous graph. This is the barometer
for Tiree to Main head from the 05:35 broadcast:

1006; 1002; 1001; 1011; 1015; 1015; 1016; 1016; 1017; 1016; 1012; 1013;
1008.

It runs with large leaps quite nicely up to the Channel Light Vessel
from Lerwick. Then one step down of 1 millimeter to Scilly. Similarly
from Lerwick to Ronalsway, dropping 1 millimeter to Valencia. From
Scilly to Valencia there is a drop of 4 millimeters.

Is this the signature of foggy weather?

Small pressure gradients imply light winds, which is one of the
requirements for fog. The others are humid air and clear skies, so that
the air close to the ground will cool sufficiently at night to reach
saturation point.

If you look at the pressure chart published in your daily newspaper,
then after allowing for the effect of the time difference you should be
able to match up the shipping forecast pressure readings with the
isobars shown on the chart.
--
John Hall "He crams with cans of poisoned meat
The subjects of the King,
And when they die by thousands G.K.Chesterton:
Why, he laughs like anything." from "Song Against Grocers"