Present Weather Flashcards
What is Present Weather?
Weather occurring at the time of observation on or over the aerodrome. Weather may be reported as ‘in the vicinity’ (VC) if it occurs within 8km of the aerodrome but not on the aerodrome itself.
What is the reporting order of weather phenomena?
Precipitation -> Obscuration -> Other
How many characters can the present weather group contain?
A maximum of 9 characters.
How many groups may be inserted to report the present weather?
Up to 3 groups can be inserted to report simultaneously occurring independent phenomena.
How are simultaneous but different forms of precipitation reported?
They should be reported as one single group in order of dominance (e.g RADZ).
Name the descriptor codes
- MI - Shallow (Marshmallow)
- BC - Patches (Batches)
- PR - Partial
- DR - Low Drifting
- BL - Blowing
- SH - Showers
- TS - Thunderstorm
- FZ - Freezing
Name the precipitation codes
- DZ - Drizzle
- RA - Rain
- SN - Snow
- SG - Snow Grains
- PL - Ice Pellets
- GR - Hail (Grail)
- GS - Small Hail/Snow Pellet (Grail Small)
Name the obscuration codes
- BR - Mist (Brist)
- FG - Fog
- FU - Smoke (Fumer)
- VA - Volcanic Ash
- DU - Dust
- SA - Sand
- HZ - Haze
Name the Other codes.
- PO - Dust/Sand Whirls or Dust Devil (O is a whirl)
- SQ - Squalls
- FC - Funnel cloud or water spout
- DS - Dust Storm
- SS - Sandstorm
What is BL?
Blowing. A descriptor used to indicate dust, sand or snow that has been raised by the wind to a height of 2m or more.
What is DZ?
Drizzle. Uniform precipitation of very fine drops of water that have a diameter of less than 0.5mm. Generally the heavier the drizzle, the lower the cloud base and the worse the visibility.
What is DU?
Dust. A widespread suspension of small particles of dust raised from the ground. As this is in obscuration, it is only reported when the vis is 5000m or less. Rarely reported in the UK.
What is PO?
Dust/Sand Whirls or Dust Devil. A near vertical and rapidly rotating column of air, forming a dust/sand whirl. Dust Devils are usually only a few metres in diameter and extend no higher than 200-300ft. Rarely reported in the UK.
What is FG?
Fog. A suspension of very small water droplets (or ice crystals) in air, when the visibility is less than 1000m in all directions and the relative humidity is 100%. The temperature and dewpoint are usually the same or very similar.
What is FZ?
Freezing. A descriptor used when it is necessary to indicate the water droplets in fog, drizzle or rain are in a supercooled state.
What is FC?
Funnel Cloud (Tornado). Rotating column of air, often a violent whirlwind, indicated by the presence of an inverted cone-shaped cloud. A funnel cloud that touches the surface is described as ‘well-developed’ and the ‘+’ descriptor is used. Rarely reported in the UK.
What is GR?
Hail (Grail). Balls of ice with a diameter 5mm or more, falling from deep cumuliform cloud that contains vigorous updrafts.
What is GS?
Small Hail (Grail Small). Balls of ice with a diameter 5mm or less, falling from deep cumuliform cloud that contains vigorous updrafts.
What is HZ?
Haze. A widespread amount of small dry particles in the air. As it is an obscuration it shall be reported when the visibility is 5000m or less and and the relative humidity is less than 95%. The difference between the temperature and dewpoint is usually more than 1 degree.
What is PL?
Ice Pellets. Frozen raindrops, falling from deep stratiform cloud usually having a diameter of 5mm or less. Ice Pellets may occur before or after Freezing Rain and indicate that supercooled precipitation may be present at higher levels.
What is DR?
Low Drifting. A descriptor used to indicate dust, sand or snow that has been raised by the wind to a height of less than 2m.
What is BR?
Mist (Brist). A suspension of water particles in the air reported when the visibility is between 1000m and 5000m and the relative humidity is 95% or more. The difference between the temperature and dewpoint is usually 1 degree or less.
What is PR?
Partial. A descriptor used only with Fog to indicate that Fog, 2m or more deep covers a substantial part of the aerodrome, while the rest is clear.
What is BC?
Patches (Batches). A descriptor used only with Fog to indicate that Fog, 2m or more deep is present at the aerodrome but in irregularly distributed patches.