Jeppesen Meteorology Flashcards
AREA FORECASTS
AREA FORECASTS FOR OPERATIONS AT OR BELOW FL200
2.1 These domestic forecasts are issued in narrative form for aircraft operations at or below
FL200. They comprise a statement of the general synoptic situation and the meteorological conditions
expected to prevail in the designated area. A route forecast is issued for any part of a planned
flight for which a routine area is not prepared.
2.2 These forecasts are available from ATS automated briefing systems and briefing offices.
2.3 The domestic area forecast system provides for the routine issue of forecasts for designated
areas and the prompt issue of amendments to forecasts immediately that prescribed criteria is
satisfied.
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Preparation and Issue Times
a. No forecast is less than 9 hours or greater than 15 hours.
b. The area forecast covering daylight hours is available as soon as practicable in the morning.
c. Area forecasts are available a minimum of one hour before validity, except Western Australia,
where they are available two hours before validity.
Approved Abbreviations Used in Area Forecasts
a. Clouds: CU, TCU, SC, CB, ST, AS, AC, NS or combinations of these.
b. Weather: DZ, RA, SN, TS, SHGR, SHGS, FG, TSRA, TSGR, TSGS, SHRA, SHSN
c. Cloud Amounts: FEW, SCT, BKN, OVC and for CB, ISOL, OCNL, FRQ, EMBD.
d. Qualifiers: MOD, SEV.
e. Units: KT, KM, M, FT.
f. Time: Z.
g. Variations: TEMPO, INTER, FM and BECMG are only used for Critical Locations.
h. Directions: N, NE, E, SE, S, SW, W, NW.
i. General: AMD.
FORECASTS FOR OPERATIONS ABOVE A100
FORECASTS FOR OPERATIONS ABOVE A100
GENERAL
3.1.1 These forecasts are issued in chart form for aircraft operations above A100. They are
issued for the area and times covering the periods set out in Preparation and Issue Times, and
utilize symbols and abbreviations to depict significant meteorological conditions, and grid-point
winds and temperatures as detailed in Grid Point Forecasts.
3.1.2 They are available from the ATS Automated Briefing Systems AVFAX, DECTALK, ATS
briefing offices by telephone or facsimile, and meteorological offices.
3.1.3 Operators may be issued the following data and/or charts:
a. grid point forecast;
b. route sector wind and temperature;
c. significant weather charts; and
d. upper air charts.
DOCUMENTATION
3.2.1 The meteorological documentation for operations above FL200 will consist of the following,
as appropriate:
a. Forecasts;
2.3.1
2.3.2
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3.1
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b. Significant Weather Prognostic Charts;
1. Latitude Equator – 50° S, Longitude 100 – 180° E valid at 0000, 0600, 1200, 1800 UTC,
or
2. WAFS charts as applicable for areas outside of the above.
c. Wind and Temperature Charts:
1. Produced for the Australian region plus ICAO Areas E, F and K.
2. Valid at 0000, 0600, 1200, 1800 UTC, and updated six hourly.
d. Grid Point Forecasts (wind and temperature):
1. Latitude 10-50° S, Longitude 100-160° E for FL385, FL340, FL300, FL235, FL185 valid
at 0000, 0600, 1200, 1800 UTC;
2. WAFS charts as applicable for areas outside of the above.
NOTE: Charts are a mercator projection.
e. For domestic operations, Route Sector Winds and Temperatures together with standard
flight plan numbers for frequently used air routes.
SIGNIFICANT WEATHER CHARTS
3.3.1 The significant weather expected in the airspace from FL 250 to FL 630 (SIGWX High)
and A100 to FL250 (SIGWX Medium) are depicted on the relevant chart using approved symbols
and abbreviations. Significant features of the surface synoptic situation are also usually shown.
3.3.2 For domestic operations, the products of paragraph 3.2.1 b.(1) will be used; and for international
operations, that of paragraph 3.2.1 b.(2).
3.3.3 The availability of the Australian area SIGWX High are as follows:
Available (UTC) Valid (UTC)
0800 0000
1400 0600
2000 1200
0200 1800
Availability of SIGWX Medium is about one hour later.
3.3.4 Significant variations during three hours each side of the validity time are included on the
chart.
3.4 SIGNIFICANT WEATHER CHARTS — SYMBOLS
SIGNIFICANT WEATHER CHARTS — SYMBOLS
SIGNIFICANT WEATHER PROGNOSIS
NOTE 1: Significant variations during three hours each side of the validity time are included on
the chart.
NOTE 2: SIGWX High will be annotated ICAO AREA AUSTRALIA SIGWX FL250-630.
NOTE 3: For SIGWX Medium level (SWM) the chart will be annotated “Significant weather
(SIGWX) A100 – FL250”. Weather phenomena below A100 will not normally be shown.
NOTE 4: Heights are indicated on SWH and SWM charts in flight level (FL), top over base. When
XXX is used, tops or bases are outside the layer of atmosphere to which the chart applies.
NOTE 5: Cumulonimbus, altocumulus and altostratus clouds are indicated by the abbreviations
CB, AC and AS respectively. CB is proceeded by ISOL (isolated, i.e. individual), OCNL (occasional,
i.e. well separated), FRQ (frequent, i.e. little or no separation) or EMBD (embedded in
layers of other clouds or concealed by haze). AC and AS amounts are indicated by the abbreviations
FEW, SCT, BKN or OVC. The upper figure following the abbreviations is the approximate
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flight level at the top of the cloud; the lower figure indicates the approximate flight level of the
base of the cloud; XXX will indicate that the base or top is outside the layer of atmosphere to
which the chart applies.
NOTE 6: The use of the abbreviation CB implies associated thunderstorms and the occurrence of
turbulence and icing.
NOTE 7: A similar convention is employed to indicate the height indications of phenomena such
as aircraft icing, turbulence, etc.
NOTE 8: When shown, centers of surface high or low pressure are represented by H or L respectively,
the position at the surface of the point of highest or lowest pressure is indicated by a “+”,
followed by the value of the MSL pressure in hectopascals. When used, an arrow indicates the
expected speed of movement (in knots). Movement of other significant features is shown in similar
fashion.
NOTE 9: Colors, if used, are to improve clarity of the presentation and have no other significance.
WIND AND TEMPERATURE CHARTS
3.6.1 Wind and temperature charts are provided for four regions:
a. Australian Region - Latitude 0 to 50S, Longitude 100E to 180E
b. ICAO Area E - Latitude 45N to 47S, Longitude 25E to180E
c. ICAO Area F - Latitude 42 30N to 47 30S, Longitude 100E to 110W
d. ICAO Area K - Latitude 0 to 90S, Longitude 0 to 180W
NOTE: Charts are a mercator projection except for ICAO Area K which is polar stereographic.
GRID POINT FORECASTS
3.7.1 Grid point wind and temperature forecast charts provide a display of wind and temperature
data derived from World Area Forecast System (WAFS) models. The data is presented in 5° latitude
and longitude squares overlaid on a geographic background. The values given represent the
wind and temperature at a specific flight level for the mid point of each square.
3.7.2 Grid point winds and temperatures are presented to aircrew on a geographic background
to facilitate interpretation on specific routes.
3.7.3 A block of Grid Point data contains the following information for each level:
a. dd: two numbers indicating the wind direction in degrees true to the nearest 10°;
b. fff: three numbers indicating the wind speed to the nearest 5KT;
c. tt: two numbers indicating the mean temperature in degrees Celsius (without the negative
sign).
Example: 2503563 dd fff tt
25 035 63
3.7.4 Grid point forecasts are issued two times daily according to the following schedule, with
data for three validity times at each issue.
Approximate Issue Time Validity Times
0800 1200, 1800, 0000
2000 0000, 0600, 1200
NOTE:
a. Validity periods for Grid Point Forecasts are +/-3 hours of the above validity times.
b. Issue time is approximate
3.7.5 Receipt of a forecast for a particular validity time will automatically amend and supersede
any prior issue for that time. Both issue and validity times appear with each forecast.
ROUTE SECTOR WINDS AND TEMPERATURES
3.8.1 Route Sector Winds and Temperatures (RSWT) forecast messages are provided for various
sectors of frequently used domestic air routes.
3.8.1.1 RSWT forecasts are prepared for six levels:
150 hPa – FL445
200 hPa – FL385
250 hPa – FL340
300 hPa – FL300
400 hPa – FL235
500 hPa – FL185
3.8.2 A block of RSWT data contains the following information for each level:
a. two numbers indicating the wind direction in degrees true to the nearest 10 degrees;
3.7.8
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b. three numbers indicating the wind speed to the nearest 5 knots;
c. two numbers indicating the mean temperature in degrees Celsius (without the negative sign).
3.8.3 Mean winds are usually given for the whole sector, but on some of the longer routes
RSWT information is subdivided into segments which are indicated in the title of the data box.
3.8.4 RSWT forecasts are issued twice daily with data for three validity times at each issue.
Approximate Issue Time Validity Times
0800 1200, 1800, 0000
2000 0000, 0600, 1200
NOTE:
a. Validity periods for RSWT are +/- 3 hours of the above validity times.
b. Issue time is approximate.
3.8.5 Receipt of a forecast for a particular validity automatically supersedes any prior issue for
that time. Both issue and validity times appear with each forecast, and amended information is
highlighted with a “+” symbol.
3.8.6 RSWT forecasts are available from AVFAX and from BoM and Airservices Australia web
sites.
Example of RSWT Messages
FORECAST ROUTE SECTOR WINDS AND TEMPERATURES. BUREAU OF METEOROLOGY
– BRISBANE 02:16 UTC 27/4/1998.
ISSUE 26173 VALID 270300 – 270900
FL – ISA YBBN/25S/YBMA
445 – 56 2703065 2502565
385 – 56 2603054 2503054
340 – 52 2603547 2503045
300 – 45 2703536 2602535
235 – 32 2803019 2801518
185 – 21 2702007 2701006
NOTE 1: Blanks indicate no data available.
NOTE 2: Some sectors are split into more than one RSWT segment; e.g., YBBN/25S/YBMA.
Route Sector Numbers
1. YMML – YSSY
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3.8.8
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2. YMML – YMHB
3. YMML – YPAD
4. YMML – CANDY
5. CANDY – CRICK
6. YCDU – YCAG
7. YCAG – YPPH
8. CRICK – YPPH
9. YMML – YMMI – LGS
10. YPAD – YPWR – YBAS
11. YPPH – ERE – YPPD
12. YPPD – CIN – TROUT – YPDN
13. YPDN – GRY – YBTL
14. YBBN – YBMK – YBCS
15. YSSY – YBBN
16. YBBN – 25S – YBMA
17. YBMA – YPDN
18. YBAS – ASB – YPDN
19. YPAD – LGS
20. YMMI – YCDU
21. YSSY – APOMA
22. APOMA – 138E – YBAS
23. YBBN – YROM – NONET – YBAS
24. YBAS – YBMA
25. YBMA – YBTL
26. YSDU – VENEL – YPAD
27. YSSY – YMCO – YMHB
28. YMML – YMDG – YBBN
29. LGS – YBAS
30. YBCS – YBMA
31. [Reserved]
32. YPPH – YCAR – YPLM
AERODROME FORECASTS
4.1 Aerodrome forecasts (TAF) are a statement of meteorological conditions expected for a
specified period in the airspace within a radius of five (5) nautical miles of the aerodrome reference
point.
Aerodrome Forecasts
4.2 The TAF service provided is in accordance with the airfield category, the category of airfield
being determined by the type and the amount of traffic as shown in the following table:
TREND FORECAST (TTF)
5.1 TTFs are prepared for the following locations: Adelaide, Amberley, Brisbane, Cairns, Canberra,
Darwin, East Sale, Melbourne, Nowra, Oakey, Pearce, Perth, Port Hedland, Rockhampton,
Sydney, Townsville and Williamtown.
NOTE: The provision of TTF at some aerodromes is limited to routine flights only. METAR/SPECI
is normally available outside these hours.
5.2 TTF is defined as an aerodrome weather report (METAR/SPECI) to which a statement of
trend is appended. The TTF relates to weather conditions expected to affect the aerodrome of
origin for the validity period of the forecast. The validity period is normally three hours, commencing
at the time of observation. However, where the TTF service is not a 24 hour service, the validity
period will be less than three hours during the last three hours of service. The end time of this
shortened validity period will be indicated in the remarks section, eg. USE TAF FOR ARRIVAL
AFTER 0800Z.
5.3 The TTF supersedes the TAF for its validity period and is the current forecast for pilots of
aircraft whose arrival time falls within the validity period.
5.3.1 For aerodromes where the TTF service is not a 24 hour service, the TAF will become the
valid forecast from the time indicated in the remarks section of the TTF, eg. USE TAF FOR
ARRIVAL AFTER 0800Z.
NOTE: For pilots whose arrival time falls outside the three-hour period, the TAF is the current
forecast.
5.4 Where applicable, TTF replaces TAF and present weather in VOLMET broadcasts.
PROVISIONAL FORECASTS
6.1 Forecasts may be prefixed “PROV” (to denote provisional) when considered likely to be deficient
in accuracy because origination was by a forecasting office issuing information for a location
or area not under its authority.
NOTE: The Director of Meteorology may, however, authorize the issue of provisional TAF in additional
circumstances.
6.2 Provisional aerodrome forecasts will be confirmed or amended as soon as possible.
SIGNIFICANT FORECAST ABBREVIATIONS AND TERMS
– SKC = SKY CLEAR
– FEW = 1 to 2 OKTAS
– SCT = 3 to 4 OKTAS
– BKN = 5 to 7 OKTAS
– OVC = 8 OKTAS
– NSC and CAVOK = NIL SIGNIFICANT CLOUD
7.2 The only cloud types that are included in aeronautical code format are towering cumulus
(TCU) and cumulonimbus (CB). Forecasts in narrative form, such as low level area forecasts, will
continue to include cloud types other than TCU and CB when appropriate.
7.3 In the case of CB cloud, the amount will be indicated in “non-aerodrome” type forecasts as
follows:
– ISOL – ISOLATED: for individual CBs
– OCNL – OCCASIONAL: for well-separated CBs
– FRQ – FREQUENT: for CBs with little or no separation
7.4 GOOD is used in the visibility section of low level area forecasts to indicate a visibility
greater than 10km over the entire area. When weather elements are forecast to reduce the visibility
below 10km, GOOD is replaced by those elements and their associated visibilities. Note that the visibility remains greater than 10km in parts of the area unaffected by those elements.
TEMPO and INTER
7.5 TEMPO and INTER indicate significant variations, from the previously given mean conditions,
of a temporary or intermittent nature, expected during the period given in the TAF format
ddhh/ddhh, e.g. 0108/0114 (from 08 until 14 UTC on the 1st), or the TTF format hhmm/hhmm,
e.g. 0630/0900 (from 0630 until 0900 hours UTC).
a. TEMPO is used to indicate change in prevailing conditions expected to last for periods of
between 30 and 60 minutes in each instance;
b. INTER is used to indicate changes expected to occur frequently for periods of less than 30
minutes duration, the conditions fluctuating almost constantly, between the times specified in
the forecast.
FM (from) and BECMG (becoming)
The change groups FM (from) and BECMG (becoming) are used to specify significant
changes (both deteriorations and improvements) from the preceding information that are more
lasting in nature. FM is used when rapid changes are expected at the specified time, and is given
in the TAF format FMddhhmm, e.g. FM301000 (from 1000 UTC on the 30th), or the TTF format
FMhhmm, e.g. FM1815 (from 1815 UTC). BECMG is given only in TAF and is used when the
changes are expected to develop at a regular or irregular rate during the specified time period,
and is given in the format BECMG ddhh/ddhh, e.g. BECMG 3010/3011 (between 10 and 11 UTC
on the 30th) . In both cases, the new conditions will continue until the end of the validity period of
the TAF/TTF, or until replaced by another FM or BECMG
PROB%
PROB% is used to indicate an expected 30 or 40% probability of occurrence, e.g. PROB30.
CLOUD HEIGHT DATUM
8.1 In aerodrome and trend forecasts, cloud heights are given above aerodrome elevations. In
other forecasts, heights are expressed:
a. as a flight level; or
b. with reference to mean sea level.
WIND SHEAR WARNING SERVICE
GENERAL
10.1.1 Aircraft reports of wind shear encountered during climb and descent are the primary
means of detecting wind shear. The meteorological forecasting office provides advice, when possible,
on the likely duration of the event and forecast low level winds.
10.1.2 Where wind shear has been observed and reported, or when from a consideration of the
meteorological situation it is assessed as a risk, then a WIND SHEAR WARNING is issued. Wind
Shear Warnings for an event will specify a validity period, and sequence numbers will be
assigned to each warning associated with an event. A Wind Shear Warning will be cancelled
when wind shear is no longer expected. This service is provided at Adelaide, Brisbane, Cairns,
Darwin, Melbourne, Perth, Sydney, and some defense locations.
10.1.2 When wind shear is forecast or reported by pilots at an intensity greater than “light,” this
information, together with a forecast low level wind, will be included on the ATIS at any of the
above aerodromes.
WIND SHEAR — PILOT REPORTING
WIND SHEAR — PILOT REPORTING
10.2.1 Wind shear encountered by aircraft must be reported by pilots to ATS.
10.2.1.1 Due to cockpit workload, reports may be initially reported as WIND SHEAR and a full
report provided when workload allows.
10.2.1.2 The full report must include:
a. an assessment of the intensity as follows:
1. light – shear causing minor excursions from flight path and/or airspeed;
2. moderate – shear causing significant effect on control of the aircraft;
3. strong – shear causing difficulty in keeping the aircraft to desired flight path and/or airspeed;
or
4. severe – shear causing hazardous effects to aircraft controllability.
b. a factual plain language report regarding airspeed/ground speed changes (gain or loss) or
undershoot/overshoot effects; and
c. the altitude or altitude band at which the adverse effect was experienced; and
d. where practicable, other relevant information such as significant changes in wind direction
and/or speed may be included.
10.2.2 At non-towered aerodromes, the report should also be broadcast to all aircraft on the
CTAF and should include the name of the aerodrome.
10.2.3 The responsibility to continue an approach to land, or to take-off, following notification of
low level wind shear, rests with the pilot-in-command.
AERODROME WEATHER AND FORECAST DECODE
IDENTIFIER
11.1.1 METAR is used to identify routine observations (hourly or half hourly) when conditions
are at or above specified levels. SPECI is used to identify special observations; ie, observations
when conditions are below specified criteria, or when there have been significant changes since
the previous report. SPECI is also used to identify observations reported 10 minutes following an
improvement to above SPECI conditions;
11.1.2 TTF METAR or TTF SPECI is used to identify METAR or SPECI to which a trend forecast
is appended (see also para 5.2). The use of this identifier is restricted to those locations
which issue Trend Forecasts;
11.1.3 TAF, TAF AMD, TAF COR, TAF… CNL, TAF … NIL and PROV TAF are used to identify
Aerodrome Forecast, Amended Aerodrome Forecast, Corrected Aerodrome Forecast, Cancelled
Aerodrome Forecast, Nil Aerodrome Forecast and Provisional Aerodrome Forecast respectively.
AERODROME WEATHER AND FORECAST DECODE
LOCATION
ORIGINATION TIME
VALIDITY PERIOD
AUTO
LOCATION
11.2.1 The location is indicated by the ICAO location indicator, the place name or the approved
abbreviation.
ORIGINATION TIME
11.3.1 The origination time of a TAF and METAR/SPECI is given in UTC using a six figure
group followed by the abbreviation Z.
VALIDITY PERIOD
11.4.1 The validity period of a TAF is given in UTC in the format ddhh/ddhh, where ddhh is the
day of month and hour, e.g. 0100/0206 is a validity period from 00 UTC on the 1st until 0600 UTC
on the 2nd.
AUTO
11.5.1 This group will be included when the METAR/SPECI contains only automated observations,
which may include visibility, present weather, and cloud.
11.5.2 When the Automatic Weather Station (AWS) includes sensors for horizontal visibility,
present weather and cloud, the AUTO report will include the parameters from these sensors in the
“body of the message” (where previously only manually observed visibility, present weather and
cloud data were included).
NOTE: Pilots should exercise caution when interpreting automated visibility, present weather and
cloud information as data from these instruments may not be equivalent to human observations.
WIND
11.6.1 Wind direction is rounded to the nearest 10 degrees and is given in three (3) figures relating
to True North.
11.6.2 Wind speeds are given in two (2) figures.
11.6.3 When the wind is calm, the group is encoded as 00000KT.
11.6.4 A variable wind direction is given as VRB and is used when the reporting or forecasting
of a mean wind direction is not possible, such as in the following conditions:
a. Light winds (3 kt or less)
b. When forecasting a single direction is not possible; eg, with a tropical cyclone, or with the
passage of a thunderstorm, in which case the forecast wind might be, for example,
VRB60KT.
11.6.5 Maximum wind speed is given only when it is 10 kt or more greater than the mean wind
speed. It is indicated by the letter G which is followed by the maximum wind speed; eg, 280°,
mean speed 20 kt, maximum speed 35 kt, is given as 28020G35KT.
VISIBILITY
11.7.1 In TAF, the prevailing visibility (the greatest visibility coveringmore than half the aerodrome)
is always given.
11.7.2 In METAR/SPECI, if the visibility is not the same in different directions and:
a. the minimum visibility is the prevailing visibility, or
b. if the visibility is fluctuating rapidly, then the minimum visibility is the only information provided.
11.7.3 When the minimum visibility is not the prevailing visibility and the minimum visibility is
less than 5000M, both the prevailing visibility and the minimum visibility will be given. In this case
the prevailing visibility is reported first followed by the minimum visibility including an indicator to
show the general direction of the minimum visibility in relation to the observing point (the meteorological
station), e.g. the visibility groups 9000 0600N indicate a prevailing visibility of 9000M and a
minimum visibility of 600M to the north.
11.7.4 A visibility of 10KM or more is given by 9999.
AUTOMATIC VISIBILITY INFORMATION
11.8.1 A report from an AWS with a visibility sensor will include data from this sensor in the
body of the report if the report is fully automated (in which case the abbreviation AUTO is also
included in the message).
NOTE: Pilots should exercise caution when interpreting automated visibility information as it may
not be equivalent to a human observation. The information is reported as a ten minute average;
and, as it is sourced from a single instrument sampling only a very small parcel of the atmosphere,
it may not be representative of the entire airport.
11.8.2 AWS may issue special reports (SPECI) for visibility using data from visibility sensors
(where previously only manual observations of visibility could initiate a visibility SPECI).
RUNWAY VISUAL RANGE (RVR)
11.9.1 RVR may be reported in SPECI messages from aerodromes with RVR instrumentation.
11.9.2 RVR will be reported in the format RDD/VVVVi or RDD/VVVVVVVVVi where:
a. R and V are fixed
b. DD gives the runway indicator, e.g. 36
c. VVVV gives the RVR value
d. i gives any distinct upward or downward tendency of the RVR over the averaging period,
where i can be either U (upward), D (downward) or N (nil), e.g. R36/0900U
11.9.3 When RDD/VVVVi is reported, VVVV is the average RVR. The averaging period is normally
the preceding 10 minutes.
11.9.4 RDD/VVVVVVVVVi is reported when the RVR has varied significantly during the averaging
period. VVVVVVVVV gives the one-minute mean minimum RVR followed by V followed by the
one-minute mean maximum RVR during the averaging period, e.g. R16/0500V1100.
11.9.5 Parallel runways will be distinguished by appending to DD the letter L, C or R indicating
the left, center or right runway, respectively, e.g. R32L/0900.
11.9.6 When the RVR is greater than the maximum value which can be assessed by the system
in use, the group VVVV will be preceded by the indicator P, and VVVV will give the highest value
which can be assessed, e.g. R32L/P1900.
11.9.7 When the RVR value is assessed to be greater than 2000 meters, the group VVVV will
be reported as P2000, e.g. R32L/P2000.
11.9.8 When the RVR is less than the minimum value which can be assessed by the system in
use, the group VVVV will be preceded by the indicator M, and VVVV will give the lowest value
which can be assessed, e.g. R32L/M0100.
11.9.9 When the RVR value is assessed to be less than 50 meters, the group VVVV will be
reported as M0050, e.g. R32L/M0050.
PRESENT WEATHER
11.10.1 Present Weather is reported using the codes listed at Section 12.
11.10.2 Appropriate intensity indicators and letter abbreviations will be combined in groups of
two (2) to nine (9) characters to indicate present weather at, or in the vicinity of, the aerodrome. If
more than one form of precipitation is observed, the appropriate letter abbreviations shall be combined
in a single group with the first reported being the dominant type of precipitation. In such a
group, the intensity shall refer to the total precipitation.
11.10.3 Up to three (3) groups may be used to report present weather.
11.10.4 The intensity of precipitation, blowing dust, sand or snow, dust storm and sand storm
will be indicated by the prefix (-) for light (+) for heavy, and no prefix for moderate.
11.10.5 The qualifier VC will be used to report certain significant weather phenomena in the
vicinity (between approximately 8 and 16 KM of the aerodrome reference point) of the aerodrome.
AUTOMATIC PRESENT WEATHER INFORMATION
11.11.1 A report from an AWS with a present weather sensor will include data from this sensor
in the “body of the report” if the report is fully automated, in which case the abbreviation AUTO is
also included in the message. Pilots should exercise caution when interpreting automated present
weather information, as it may not be equivalent to a human observation.
CLOUD
11.12.1 Cloud height is reported in hundreds of feet using three figures; eg, 700 ft is reported as
007.
11.12.2 Cloud amount is reported using the following abbreviations:
FEW = few 1 to 2 OKTAS
SCT = scattered 3 to 4 OKTAS
BKN = broken 5 to 7 OKTAS
OVC = overcast 8 OKTAS
11.12.3 Nil cloud is reported as SKC (sky clear). Cloud information is not included in a forecast if
the sky is clear.
11.12.4 Cloud information is reported from the lowest to the highest layer or mass in accordance
with the following:
a. The lowest layer or mass, regardless of amount.
b. The next layer or mass, covering more than 2 OKTAS.
c. The next higher layer or mass, covering more than 4 OKTAS.
d. Cumulonimbus and/or towering cumulus clouds, whenever observed and not reported in a.,
b., or c. above
.
11.12.5 Type of cloud is identified only for cumulonimbus and towering cumulus observed at or
near the aerodrome. These will be given as CB and TCU respectively. When an individual layer or
mass of cloud is composed of cumulonimbus and towering cumulus with a common cloud base,
the type of cloud is reported as cumulonimbus only, and the amount shall be reported as the sum
of the CB and TCU amounts.
11.12.6 Whenever cumulonimbus cloud is forecast, the degree of associated thunderstorm
activity or probability of occurrence is included.
11.12.7 A clear sky will be indicated in a report by SKC.
11.12.8 When the sky is obscured, the cloud group is omitted and vertical visibility may be given
in the format VVhhh, where hhh is the vertical visibility in hundreds of feet. When information on
vertical visibility is not available, hhh may be given as ///, indicating that the sky is obscured but
information on the vertical visibility is not available.
CAVOK
11.13.1 CAVOK is included in the report (from staffed stations only) or forecast when the following
conditions are observed, or forecast to occur, simultaneously:
a. visibility of 10 kilometers or more;
b. Nil significant cloud, i.e. no cloud below 5,000 ft or below the highest 25NM minimum sector
altitude, whichever is greater, and no cumulonimbus or towering cumulus at any height; and
c. Nil significant weather, i.e. none of the weathers listed at paragraph 12.
When the term CAVOK is given, the elements visibility, weather and cloud will not be given.
11.13.2 In METAR/SPECI, whenever a total of BKN or more low or middle-level cloud is at or
above 5000FT, and CAVOK has been reported, the cloud amount and base will be given after the
RMK indicator.
AU
AUTOMATIC WEATHER STATIONS WITH CLOUD INFORMATION
11.14.1 A report from an AWS with a cloud sensor will include data from this sensor in the body
of the report if the report is fully automated (in which case the abbreviation AUTO is also included
in the message). The data will be in the same form as manual reports except that:
a. NCD will be reported if no cloud is detected, and
b. there will be no indication of cumulonimbus or towering cumulus.
NOTE: Pilots should exercise caution when interpreting automated cloud information as it may not
be equivalent to a human observation. The information is reported as a thirty minute average
(with double weighting given to the last ten minutes); and, as it is sourced from a single ceilometer
sampling only the sky directly overhead, it may not be representative of the skyline.
11.14.2 AWS may issue special reports (SPECI) for cloud using data from cloud sensors (where
previously only manual observations of cloud could initiate a cloud SPECI).
SIGNIFICANT VARIATION
11.15.1 Aerodrome forecasts will include significant changes or variations (indicated by FM,
BECMG, INTER and TEMPO) to the previously given conditions when the relevant criteria are
met. These relate to improvements as well as deteriorations.
11.15.2 The variation groups TEMPO and INTER are used to indicate significant variations of a
temporary or intermittent nature. The change groups FM and BECMG are used to specify
changes that are more lasting in nature. The indicators are the beginning of a self-contained forecast.
11.15.3 When reduced visibility due to fog, mist, dust, smoke or sand is forecast, but the probability
is assessed at between 30% and 40%, the terms PROB30 or PROB40 are used. The term
may also be added before a TEMPO or INTER statement to express probability assessments of
thunderstorms. If greater than, or equal to, 50% probability is forecast, reference is made to the
phenomena in the forecast itself and not by the addition of the statements PROB30 or PROB40.
11.15.4 The terms NSW (NIL significant weather), SKC and NSC may be included following a
FM or BECMG to indicate significant improvements expected.
11.15.5 If a TAF or TTF includes a forecast of turbulence, its commencement will be indicated
by the abbreviation FM, and its cessation within the forecast coverage will be indicated by the
abbreviation TILL. Start and finish times are given in the format ddhhmm (day of month, hour,
minute). Turbulence associated with cumulonimbus (CB) and towering cumulus (TCU) clouds is
not included in forecast.
TEMPERATURE
11.16.1 Aerodrome weather reports contain both temperature and dew point.
11.16.2 Up to four forecast values of air temperature are given, for the times HH, HH+3 hours,
HH+6 hours and HH+9 hours, where HH is the time of commencement of the TAF validity period.
Users should use linear interpolation to determine the forecast value between these points. The
temperature forecasts are prefixed by the letter “T”.
11.16.3 Negative values are indicated by the letter M before the numeral.
QNH
11.17.1 QNH is given in whole hectopascals using four (4) figures.
11.17.2 Observed intermediate values are rounded down. QNH is always given, prefixed by the
letter Q; eg, Q0997.
11.17.3 Up to four forecast values of QNH are given, for the times HH, HH+3 hours, HH+6
hours and HH+9 hours, where HH is the time of commencement of the TAF validity period. Users
should use linear interpolation to determine the forecast value between these points. The QNH
forecasts are prefixed by the letter “Q”.
SUPPLEMENTARY INFORMATION
In METAR/SPECI, supplementary information is used to report the following:
a. recent weather (RE) of operational significance, and
b. wind shear (WS) information on a take-off or landing runway.
REMARKS SECTION
11.19.1 Rainfall. The remarks section of the report will include rainfall recorded by an automatic
rain gauge. The information is in the form RF##.#/###.# where the first three (3) digits after the
indicator RF will report the rainfall recorded in the 10 minutes prior to the observation time, and
the next four (4) digits report the total rainfall recorded since 0900 local time. Both amounts are
expressed in millimeters to the nearest 0.2mm.
NOTE: In situations of fine droplet precipitation, such as very light drizzle or fine mist situations,
there may not be sufficient precipitation recorded to indicate any rainfall in the last 10 minutes.
Therefore, pilots should regard automated reports of rainfall as guidance material.
11.19.2 Plain Language. Any other significant weather conditions (eg, an approaching front or
visible bushfires) are appended as plain language.
ELEMENTS NOT AVAILABLE
11.20.1 A report from a full automated AWS that does not include information from sensors for
visibility, weather, and cloud will report ////, // or ////// respectively in lieu of these parameters.
WEATHER CODE AND TRANSLATION
CODE TRANSLATION
Weather Descriptors
BC Patches (or Patches of)
BL Blowing
DR Drifting
FZ Freezing
MI Shallow
SH Showers (or Showers of)
TS Thunderstorms (or Thunderstorms with)
PR Aerodrome partially covered (used only to describe fg)
Phenomena
BR Mist
DU Dust
DS Dust storm
DZ Drizzle
FC Funnel Clouds
FG Fog
FU Smoke
GR Hail
GS Small Hail Pellets
HZ Haze
IC
Ice Crystals (very small ice crystals in suspension, also known as Diamond
Dust)
PL Ice Pellets
PO Dust Devils
RA Rain
SA Sand
SG Snow Grains
SN Snow
SQ Squalls
SS Sand storm
UP Unknown Precipitation Type (from weather sensor)
VA Volcanic Ash
NOTE 1: Intensity is indicated with precipitation, duststorms and sandstorms. In these cases, the
weather code is prefixed by the qualifier - for light and + for heavy. Moderate intensity is indicated
by the absence of a prefix.
NOTE 2: METAR/SPECI may provide an indication of weather in the vicinity (within approximately
8 and 16 KM of the aerodrome reference point). The proximity qualifier VC will be used only in
combination with the abbreviations TS, DS, SS, FG, FC, SH, PO, BLDU, BLSA and BLSN
METEOROLOGICAL REPORTS
AERODROME WEATHER REPORTS
Aerodrome Weather Reports are reports of observations of meteorological conditions at an aerodrome.
The reports are generated by electronic recording devices called automatic weather stations
(AWS) and may have manual input by approved observers. Manual input of visibility,
weather and cloud is for an area within a radius of approximately 5 NM of the aerodrome reference
point.
1.1.1 Owing to the variability of meteorological elements in space and time, to limitations of
observing techniques and to limitations caused by the definitions of some of the elements, the
specific value of any of the elements given in a report shall be understood by the recipient to be
the best approximation to the actual conditions at the time of observation
1.1.2 Routine Reports (METAR) are issued at fixed times, hourly or half hourly, and are made
available at pre-flight briefing or on request to aircraft in flight.
1.1.3 Special Reports (SPECI) are aerodrome weather reports issued whenever weather conditions
fluctuate about or are below specified criteria.
1.1.3.1 At staffed stations, SPECI reports are issued when either of the following conditions are
present:
a. when there is BKN or OVC cloud covering the celestial dome below an aerodrome’s highest
alternate minimum cloud base or 1500 ft, whichever is higher;
b. when the visibility is below an aerodrome’s highest alternate minimum visibility or 5000m,
whichever is greater.
At non-staffed stations with cloud and visibility sensors, SPECI for cloud and visibility based on
output from these sensors may also be issued.
1.1.3.2 SPECI will also be issued under the following conditions:
a. Wind —
1. when mean direction changes by 30 degrees or more, the mean speed before or after
the change being 20 kt or more; or
2. when the mean speed changes by 10 kt or more, the mean speed before or after the
change being 30 kt or more; or
3. when gusts vary by 10 kt or more from a mean speed of 15 kt or more; or
4. when a gust exceeds the last reported gust by 10 kt or more.
b. Other conditions —
1. when any of the following begins, ends or changes in intensity — thunderstorm, hailstorm,
mixed snow and rain, freezing precipitation, drifting snow, duststorm, sandstorm,
squall, fog;
2. when wind shear at the aerodrome is observed or reported by pilots;
13. at the incidence of any other phenomena likely to be significant to the operation of an
aircraft;
4. when the QNH altimeter setting changes by 2 hPa or more;
5. when the temperature changes by 5 degrees C or more.
1.1.4 Take-off and Landing Reports are provided at aerodromes where a control tower is
established. This service may also be provided by a CA/GRS or UNICOM.
1.1.4.1 Take-off and landing reports are included on ATIS, where available, or passed to aircraft
reporting taxiing or inbound.
1.1.4.2 Take-off and landing reports contain, as available:
a. wind velocity, with direction in degrees magnetic;
b. altimeter setting;
c. air temperature (if appropriate to the type of aircraft);
d. low cloud, if significant;
e. visibility, if significant, in meters up to and including 5000m, above this value in kilometers. A
visibility greater than 10km is given as “VISIBILITY GREATER THAN 10km”;
f. additional items; i.e., extent of cloud below the main ceiling, disposition and intensity of rain,
reported turbulence area, etc.;
g. CAVOK — when the following conditions are observed to occur simultaneously:
1. visibility of 10km or more;
2. Nil significant cloud, i.e. no cloud below 5000 ft or below the highest 25NM minimum
sector altitude, whichever is greater, and no cumulonimbus or towering cumulus at any
height; and
3. Nil significant weather, i.e. none of the weathers listed at Weather Code and Translation.
When the term CAVOK is used, the elements d., e. and f. will not be advised.
1.1.4.3 The meteorological information provided by Air Traffic Controllers may be obtained by
observation of the whole horizon or only the area that will contain the probable flight path of an
aircraft.
1.1.4.4 Reports based on AWS data will be limited to wind direction and velocity, QNH and temperature,
except when a qualified observer at the aerodrome provides visually observed information.
APPROVED OBSERVERS
1.2.1 “Approved observers” are officers of the Bureau of Meteorology, Air Traffic Controllers and
other persons on the ground approved for the purpose by the BoM and/or CASA.
1.2.2 For the purpose of observing visibility for take-off and landing at an aerodrome, the pilotin-
command shall be deemed an approved observer for that flight.
OBSERVING POINT
1.3.1 The location of the observing point for aerodrome weather reports is such that the meteorological
conditions observed within visual range, or interpreted from instruments at that point,
are representative of conditions at the aerodrome.
