CI Norwood
Ref: FTGU Pages 158-172, AIM MET Section
Meteorology 3

1.
What are the four air masses that affect Canada?
2.
What is a Front?
3.
What does a thunderstorm need in order to form?

 Weather services and maps
 How to read:
 Surface/Upper level/Prog charts
 METARs/TAFs
 GFAs/FDs
 Need to know this as interpretation of weather is crucial to aircraft safety.

 NavCanada FSS system
 Provides weather information to help pilots before and during flight
 Service puts pilots in contact with specialists who help pilots make educated decisions and calculations based on factors relating to weather conditions

 Fully interpretive weather briefing service available from the Flight Information Centers (FIC)
 Access through toll free number
 Equipped with complete set of weather products, including satellite and radar imagery
 Specialists trained to interpret the weather data for the needs of users in aviation industry, as well as offer advice on particular weather situations
 Documents for long distance flight available on request

 Staffed by flight information specialists
 Situated at various aerodromes across Canada
 Services offered:
 Enroute Flight Information Service (FISE)
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Flight Planning Service
Surface weather observation service
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Aviation Weather Information Service (AWIS)
Aviation Weather Briefing Service (AWBS)
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VFR Alerting Service
NOTAM service
 PIREPs

 Continuous recording of certain local weather information intended for aviation is issued by some
FSS and is available by telephone
 Include:
 Issuing station name and introduction, Instructions
 SIGMETs, AIRMETs, METAR and SPECI
 TAF and FDs
 Freezing level, icing and turbulence
 PIREPs
 Times of sun-rise and sun-set

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Short term alerts to aircraft in flight concerning potentially hazardous weather conditions
Issued for the following phenomenon:
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Active thunderstorm cells
Squall lines
Severe hail
Severe turbulence
Severe icing
Significant mountain wave effects
Hurricanes
Far-reaching sand or dust storms
Volcanic ash
Low-level wind shear

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Continuous broadcast of recorded non-control information at busier airports
Essential information:
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Weather information
Active runways
Available IFR approach
NOTAMs, etc.
Pilots listen to ATIS prior to contacting control unit
Reduce controller’s workload and relieve frequency congestion
Updated every hour or when necessary
Comes with a letter designator to ensure most current version is in use

 Shows SIGWX for a specific flight range:
 Icing, turbulence and convective activity
 Flight between FL250-FL630 (380-75 hPa)
 Valid at 0000, 0600, 1200, 1800 UTC
 Issued by the National Weather Service of the United
States government; the equivalent of the Canadian
Weather Service

 Shows SIGWX for a specific flight range:
 Icing, turbulence and convective activity
 Flight between FL100 – FL240 (700-400 hPa)
 Valid at 0000, 0600, 1200, 1800 UTC
 Issued by the Canadian meteorological centre of
Environment Canada
 Based on information collected from all the aviation weather forecast centers of the country

 Graphical depiction of:
 MSL pressure patterns
 Surface location of fronts
 Surface precipitation and obscurations to vision
 Pressure patterns can be considered accurate up to
3,000 feet
 Observed every six hours, issued 2 to 3 hours after observation

 Computer generated graphical depiction of reported atmospheric conditions at the pressure level, which include:
 Wind speed and direction
 Temperature
 Moisture content
 Frontal surface locations
 Measured twice a day, at 0000Z and 1200Z
 Issued for 850 mb (5,000’), 700 mb (10,000’), 500 mb
(18,000’) and 250 mb (34,000’)

 Height: Contours represent the height of the pressure level in decameters, spaced 60 m apart on except on
250 mb charts where it’s spaced 120 m
 Temperature: Analysed on 850 and 700 mb, drawn as dashed lines at 5 degree intervals. Can be read in the top corner of station plots at higher altitudes
 Wind speed and direction: Can be determined by direction and spacing of contours, or by isotachs on the 250 mb chart, given in 30 kt intervals

 Provides the forecast of temperature and winds for a given flight level
 Three distinct geographic regions:
 EAST, NORTH and WEST
 Essentially the same as the FDs except only one flight level can be seen due to graphically depicted form
 Computer generated
 Wind direction in relation to True North
 Valid at 00, 06, 12, 18 UTC
 National Weather Service (US government)

 Graphical forecast of weather at the surface
 For the purposes of aviation, Canada does not issue surface prognostic charts, American ones can be used
 Issued for latest surface analysis, 12-, 24-, 36- and 48hour forecast times
 Shows pressure systems and patterns, front positions, precipitation and ground obscurations

 Aviation Routine Weather Report
 Observation of the actual weather from the ground
 Issued on the hour and valid only for the time taken
 A SPECI is a special weather report that when a significant change in the weather has occurred
 Each METAR and SPECI is composed of several standard groups
 METAR CYKZ 202000Z 33009KT 15SM FEW020
BKN091 M01/M06 A2993 RMK SC2AC3 SLP144=

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Report type:
Location type:
Date/Time:
METAR or SPECI
CYYZ (Toronto)
231700Z -> 23 rd day at 1700 Zulu
Report modifier: AUTO or CCA, CCB
Wind:
Visibility:
00000KT -> Calm
35009KT -> 350°T @ 9 kts
VRB03KT -> Variable @ 3 kts
30015G25KT -> 300°T @ 15 gusting 25 kts
30015G25KT 260V340 -> 300°T @ 15 gusting
25 kts, wind is varying from 260 true to 340 true
5/8 SM, 1 ½ SM, P6SM, 15 SM
RVR: R33/4000FT/U -> Rwy 33, 4000’ increasing
R24L/1000V1200FT/D -> ?

Intensity or Proximity
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 Precipitation intensity refers to all forms at the time combined
- ->Light (-RA = Light rain)
Moderate (no qualifier)
+ Heavy (+SN = Heavy snow)
VC = In the vicinity (within
5SM)
Descriptor
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MI = Shallow
BC = Patches
PR = Partial
DR = Drifting
BL = Blowing
SH = Showers
TS = Thunderstorms
FZ = Freezing

Precipitation
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DZ = Drizzle
RA = Rain
SN = Snow
SG = Snow grains
IC = Ice crystals (Vis ≤ 6
SM)
PL = Ice pellets
GR = Hail
GS = Snow pellets
UP = Unknown precipitation
Obscuration
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BR = Mist (Vis ≥ 5/8 SM)
FG = Fog (Vis < 5/8 SM)
FU = Smoke (Vis ≤ 6 SM)
DU = Dust (Vis ≤ 6 SM)
SA = Sand (Vis ≤ 6 SM)
HZ = Haze (Vis ≤ 6 SM)
VA = Volcanic ash (Any vis)

Other
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PO = Dust/sand whirls
(dust devils)
SQ = Squalls
+FC = Tornado or waterspout
FC = Funnel cloud
SS
DS
= Sandstorm
= Duststorm

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SKC
FEW
SCT
- “sky clear” - no cloud present
- “few” - >0 to 2/8 oktas
- “scattered” - 3/8 to 4/8 oktas
BKN
OVC
- “broken” - 5/8 to <8/8 oktas
- “overcast” - 8/8 oktas
CLR - “clear” - clear below 10,000’ as interpreted by an autostation
Significant convective cloud (CB or TCU) are identified with the sky condition group
SCT025TCU – Scattered TCUs at 2500’
A ceiling is said to exist at the lowest BKN or OVC layer
All cloud heights are in AGL

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Temperature/Dewpoint:
Altimeter setting:
Recent weather:
Wind shear:
10/05 – Temp: 10°C,
Dewpoint: 05°C
05/M01 – Temp:
05°C, Dewpoint: -1°C
A2992 – 29.92” Hg
A3031 – 30.31” Hg
Significant weather
Low level windshear within 1600’
AGL along t/o or landing path or a specific runway “WS R33L”

 Include:
 Cloud layer type and opacity in oktas (SF5)
 General weather remarks
 Sea level pressure: SLP134 = 1013.4 hPa
 SPECI CYEL 201958Z 36010KT 1SM -SHSN OVC008
RMK SF8 WNDS ESTD=
 METAR CYEL 201900Z 36010KT 15SM -SHSN
BKN030 BKN080 M05/M10 A3003 RMK
SC6AC2 WNDS ESTD SLP190=

 Description of the most probable weather conditions with the most probable time of occurrence
 Gives weather within 5 NM of the centre of the runways complex
 Uses the same weather coding as the METAR, although forecast times are included
 Altitudes in AGL
 Degrees are given in True

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Report type: TAF or TAF AMD
Location: CYYZ
Issue Date/Time: 281139Z: 28 th day @
1139 Zulu
Period of validity: 2812/2918 – Valid from
1200 Zulu on the 28 th to
1800 Zulu on the 29 th
TAF CYYU 201948Z 2020/2108 30012KT 3SM -SN OVC012
TEMPO 2020/2022 P6SM SCT015 BKN030
FM202200 30010KT P6SM SCT015 BKN030 TEMPO
2022/2108 4SM –SHSN BKN015 RMK NXT FCST BY
210200Z=

 Uses the same format as the METAR
 VC or ‘vicinity’ in a TAF means 5 – 10 NM
 A maximum of 3 significant weather groups are allowed per forecast period
 If one significant weather groups is forecast to change, all other that will exist will be indicated
 CB layers will be identified with cloud groups (i.e.
SCT040CB)

 In all change groups, multiple elements are considered single entities
 “SCT030 BKN050 OVC080...change indicator...BKN050” would mean that after the change indicator, there would only be a broken layer at 5000’
 FM – Permanent change (rapid) – All forecast conditions are superseded by this.
FM280945 30015KT P6SM BKN030

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BECMG – Permanent change (gradual) – When the conditions evolve over a period of time (one to two hours)
BECMG 2808/2809 OVC030
Any weather element not indicated as part of the BECMG group remains the same
TEMPO – Transitory change group – Temporary fluctuations in some or all weather elements during a specified period
TEMPO are only used if the condition is expected to last less then an hour, if more, than a time period would be given (i.e.
TEMPO 2812/2815 1SM RA BR)
PROB – Probability group – Probability of alternative weather values occurring (that are considered hazards to aviation) ->
PROB30 2817/2821 +TSRA

 TAF CYTS 201948Z 2020/2108 33012KT 11/2SM -SHSN
OVC015 TEMPO 2020/2022 P6SM NSW OVC020
FM202200 33012KT 6SM -SN FEW015 OVC040 TEMPO
2022/2102 2SM –SN OVC015
FM210200 31010KT P6SM SCT020 BKN030 TEMPO
2102/2108 4SM -SHSN
BKN020
RMK NXT FCST BY 210200Z=
 TAF CYTL 201948Z 2020/2108 33015KT P6SM SCT015
OVC025 TEMPO 2020/2108 2SM -SHSN BKN015 OVC030
BECMG 2102/2104 31012KT
RMK FCST BASED ON AUTO OBS. NXT FCST BY
210200Z=

 Series of weather charts that are adjusted for pre-flight planning in Canada
 Gives the most probable weather conditions under
24,000 feet (400 mb)

 Issued four times daily (2330, 0530, 1130 and 1730 UTC)
 Valid at 0000, 0600, 1200 and 1800 UTC
 Each GFA has six charts covering 3 time periods (neartime, 6-hour and 12-hour forecasts)
 Two charts issued at a time for three consecutive time periods
 Two types of GFA: Clouds and Weather/Icing, turbulence and Freezing level

 Canada is divided into 7 regions:
 Arctic, Yukon-NWT, Pacific, Prairie, Ontario-Quebec and Atlantic
 There is an additional forecast region that is created on demand in the arctic

 Wind speeds are given in knots (KTS)
 Direction is in degrees true
 Cloud heights in hundreds of feet
 Distances in nautical miles (NM)
 Visibility in statute miles (SM)
 All times are in UTC
 Pressure in millibars (mb)
 All heights are given in feet Above Sea Level (ASL)

Comments Box

 Consists of:
 Chart name
 Issuing station’s identifier
 Region
 Type of chart
 Issue date
 Validity

 Includes symbols that may be used in the chart
 Symbols are consistent with those used in
Significant Weather
Prognosis Charts
 Includes a scale in nautical miles for calculations

 Includes information that the forecaster believes is important
 Also used to prevent clutter in the weather section
 Always includes the standard phrases in the bottom box
 The IFR outlook is located here in the 12 hour forecast

 Graphic representation of the clouds and weather conditions or the icing, turbulence and freezing level forecast for a given time

 What are the validity periods of a GFA?
 Near-time, 6-hour, 12-hour and 12 hour IFR outlook
 What are the units of measurement?
 Wind speeds are given in knots (KTS)
Cloud heights in hundreds of feet
Visibility in statute miles (SM)
All times are in UTC
Pressure in millibars (mb)
All heights are given in feet Above Sea Level (ASL)

 If the speed of any system is greater than 5 knots, an arrow will give direction and speed of the system
 The centre of this depression is moving eastward at 15kts with an associated cold front moving south-east at 10kts

 A scalloped border shows the region where cloud is predicted
 In areas of unorganised clouds, no scalloped border is given
 Cloud bases and tops are given in feet ASL along with coverage and type

3 SM FU
Unrelated to precipitation
 Obstructions to visibility are given only when it is predicted to be less than
6 SM
 The type of obstruction is given after in standard abbreviation
 Solid lines indicated continuous precipitation
 Dotted area indicate showery precipitation

 Isobars are shown in 4 millibar intervals (i.e.
1000, 1004, 1008)
 Surface wind conditions in excess of 20 KTS are indicated on GFA
 Wind gusts have a “G” included with the wind barb

 Depicted when moderate or severe icing/turbulence is predicted
 Information included is type, severity and height that it will be encountered

 Indicated by dashed contour lines
 Height given above sea level given in 2500 foot intervals starting at the surface (SFC)

 Automatically amended by AIRMET and SIGMET bulletins
 GFAs will be reissued in case a significant error that will cause misinterpretation of the
GFA
 Indicated by CCA, CCB, just like in a METAR

Give an estimate of winds and temperatures to be found at determined altitudes

 Time of issue and period of validity are indicated on the report
 Data collected by 32 stations in Canada, 2 times a day at 0000Z and 1200Z
 Winds are in degrees True, altitudes in ASL
 No temperatures for 3000ft

 Up-to-date info must be obtained and analyzed prior to each flight in order to properly prepare for all significant weather which might affect the flight
 Required to choose a cruising altitude, calculate ground speed, drift, flight time and fuel consumption
 Basic information to obtain and review for VFR:
 METARs and TAF: departure, destination and enroute
 FD: for expected cruising altitudes
 GFA: overview of weather affecting the region
 NOTAMs: all significant info/changes for pilots

 Topics covered today:
 Weather services and maps
 How to read:
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Surface/Upper level/Prog charts
METARs/TAFs
GFAs/FDs
 Need to know this as interpretation of weather is crucial to aircraft safety.
 Next class will be Navigation