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Weather forecast glossary
Gale Warnings
GALE:
Winds of at least force 8 (34-40 knots) or gusts reaching 43-51
knots
- SEVERE
GALE: Winds of force 9 (41-47 knots) or gusts reaching 52-60
knots
- STORM:
Winds of force 10 (48-55 knots) or gusts reaching 61-68 knots
- VIOLENT
STORM: Winds of force 11 (56-63 knots) or gusts of 69 knots
or more
- HURRICANE
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.
IMMINENT:
Expected within 6 hours of time of issue. - SOON:
Expected within 6 to 12 hours of time of issue.
- LATER:
Expected
more than 12 hours from time of issue.
Visibility
FOG:Visibility
less than 1000m
- POOR:
Visibility between 1000m. and 2 n.miles
- MODERATE:
Visibility between 2 and 5 n.miles
- GOOD:
Visibility more than 5 n.miles.
Movement of Pressure Systems
SLOWLY: Moving
at less than 15 knots. - STEADILY: Moving
at 15 to 25 knots
- RATHER QUICKLY:
Moving at 25 to 35 knots
- RAPIDLY: Moving
at 35 to 45 knots
- VERY RAPIDLY:
Moving at more than 45 knots
Pressure tendency in station reports
STEADY:Change
less than 0.1hPa in the preceding 3 hours
- RISING
(OR FALLING) SLOWLY: Pressure change of 0.1 to 1.5 hPa in
the preceding 3 hours.
RISING (OR
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
3 hours.
- 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)
Wind
WIND DIRECTION:
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.
- VEERING:
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
NE.
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