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This practical weather guide is limited in what it contains. To supplement this, Nav Canada has created a guide to help with practical weather reading. This includes all weather services such as decoding AIRMETs, SIGMETs and more.
This guide is available by clicking here. (Opens link in new window)
METAR
‐ Meteorological code
‐ Reports actual weather conditions at a station as observed by automatic weather observation system or by a certified weather observer
‐ Issued every hour
‐ Will be issued and designated SPECI (special report) regardless of time if:
o Ceiling or visibility significantly increase or decrease
o Tornado, Waterspout, or Funnel Cloud appears or disappears
o Thunderstorm begins/becomes severe/heavy or ends
Precipitations Abbreviations
‐ Intensity
( – ) = Light ( ) = Moderate* ( + ) = Heavy
*Moderate intensity has no sign/designator
‐ Descriptor
SH = Showers MI = Shallow BC = Patches DR = Drifting
FZ = Freezing BL = Blowing TC = Thunderstorms PR = Covers part of aerodrome
‐ Precipitation
RA = Rain IC = Ice Crystals SN = Snow SG = Snow Grains
DZ = Drizzle GS = Snow Pellets GR = Hail UP = Unknown Precipitation**
PE = Ice Pellets
‐ Obscuring Phenomena
HZ = Haze DU = Dust FU = Smoke FG = Fog (Vis < 5/8 SM)
SA = Sand BR = Mist (Vis > 5/8 SM)
‐ Other
SQ = Squall VA = Volcanic Ash DS = Dust storm FC = Funnel Cloud
SS = Sandstorm PO = Dust/Sand Whirls +FC = Tornado / Waterspout
Terminal Area Forecast
‐ Meteorological code for forecast weather conditions within 5NM of aerodrome
‐ Next issue time stated at the end of each TAF
‐ If forecast is amended: TAF AMD
‐ Issues approx. 30 minutes before forecast period
‐ Aerodrome (Terminal) Advisory
Same as a TAF but after time group insert advisory:
1) OFFSITE: If observer is not within 1.6NM of runway complex
2) OBS INCOMPET: Observation based on incomplete data
3) NO SPLS: Aerodrome does not have ongoing weather watch to produce specials
FD
‐ Meteorological code for forecast wind direction and velocity and temperature at a given height above ground level
‐ Temperature not forecast for 3,000ft
‐ Temperature assumed negative above 24,000ft
‐ If station elevation is above 1,500ft, winds at 3,000ft not forecast
‐ Wind < 5kts coded as 9900 (light and variable)
‐ Wind 100‐199kts:
o Subtract 50 to direction to determine where wind is coming from
o Add 100 to speed of wind
o Ex. Winds 130 @ 120 knots coded 6320
‐ Wind 200kts or more coded as 199kts
Graphical Area Forecast
‐ Series of temporarily adjusted weather charts
‐ Each depicting most probable meteorological conditions expected to occur below 24,00ft over a given area at a specified time
‐ Issued 4 times daily approx 30 min before beginning of forecast period
o Usually 2330, 0530, 1130 and 1730
‐ Valid usually 0000z, 0600z, 1200z, 1800z
‐ Consists of 6 Charts:
o Near term forecast for clouds and weather
o A 6 hour forecast for clouds and weather
o A 12 hour forecast for clouds and weather which includes an IFR outlook for additional 12 hour period
o Near term forecast for icing/turb./freezing level
o 6 hour forecast for icing/turb./freezing level
o 12 hour forecast for icing/turb./freezing level
‐ Areas: Nunavut, Yukon & NWT, Pacific, Prairie, Ont & Quebec, Atlantic
SIGMET
‐ Significant Meteorological Report
‐ Issued for significant weather which was not forecasted in GFA
‐ Criteria for issue:
Active Thunderstorm in Area Hurricanes
Lines of Thunderstorms Widespread sand or dust storms
Heavy Hail Volcanic Ash
Severe turbulence or icing Low level wind shear
Marked mountain waves
AIRMET
‐ Issued if weather conditions occur that were not forecast in the AWWS GFA
– Criteria for issue: IFR Conditions, Freezing Precipitation (not requiring SIGMET), Moderate icing, moderate turbulence, thunderstorms, surface mean wind over a large area increasing to 20 kts or more, gusting 30 knots or more when not forecast, Difference between forecast and observed wind is > 60 degrees.
All of this information on pilot training and flight training in Canada is also available at www.flighttrainers.ca.