Winds of at least force 8 (34-40 knots) or gusts reaching 43-51
GALE: Winds of force 9 (41-47 knots) or gusts reaching 52-60
Winds of force 10 (48-55 knots) or gusts reaching 61-68 knots
STORM: Winds of force 11 (56-63 knots) or gusts of 69 knots
FORCE: Winds of force 12 (64 knots or more).
Note the term is Hurricane Force: the term hurricane on its own
is only used to imply a true tropical cyclone.
Expected within 6 hours of time of issue.
Expected within 6 to 12 hours of time of issue.
more than 12 hours from time of issue.
less than 1000m
Visibility between 1000m. and 2 n.miles
Visibility between 2 and 5 n.miles
Visibility more than 5 n.miles.
Movement of Pressure Systems
at less than 15 knots.
at 15 to 25 knots
Moving at 25 to 35 knots
at 35 to 45 knots
Moving at more than 45 knots
Pressure tendency in station reports
less than 0.1hPa in the preceding 3 hours
(OR FALLING) SLOWLY: Pressure change of 0.1 to 1.5 hPa in
the preceding 3 hours.
FALLING) SLOWLY: Pressure change of 1.6 to 3.5 hPa in the preceding
3 hours. RISING (OR FALLING) QUICKLY: Pressure change of
3.6 to 6.0 hPa in the preceding 3 hours. RISING (OR FALLING)
VERY RAPIDLY: Pressure change of more than 6.0 hPa in the preceding
NOW RISING (OR FALLING): Pressure has
been falling (rising) or steady in the preceding 3 hours, but
at the time of observation was definitely rising (or falling)
(1hPa = 1mb)
Indicates the direction from which the wind is blowing.
WIND BECOMING CYCLONIC: Indicates that
there will be considerable change in wind direction across the
path of a depression within the forecast area.
The changing of the wind in the direction of motion of the hands
of a clock, e.g. SW to W. BACKING: The opposite direction to veering, e.g. SE to