Aerodrome Forecasts and Observations Flashcards
Sources of MET Observations
Local Surface Observations
- Staffed stations
- Approved Observers
- Automatic electronic devices
- Oceanic buoys
Atmospheric observations
- Balloons
- Radiosondes
Airborne Reports
- By pilots (manual or automatic)
- ATC observations
OKTA Scale
NCD Nil Cloud
FEW 1-2 OKTAS
SCT 3-4 OKTAS
BKN 5-7 OKTAS
OVC 8 OKTAS
When is Embedded used to describe cloud?
When cloud is within another layer and is not readily recognised.
When is Obscured used to describe cloud?
When cloud is obscured by haze or smoke and cannot be readily seen.
What is Squall Line used to describe?
Thunderstorms along a line with little or no space between individual clouds.
SIGMET information concerns the occurrence, or expected occurrence, of one or more of the following:
- Thunderstorms
- Tropical cyclones
- Hail
- Severe turbulence
- Severe icing
- Severe mountain waves
- Widespread sandstorms or dust storms
- Volcanic ash cloud
SIGMETs for Thunderstorms are only issued when?
When the thunderstorms are:
- Obscured (OBSC) by haze or smoke and cannot be readily seen;
- Embedded (EMBD) within cloud layers and cannot be readily recognised;
- Frequent (FRQ) with little or no separation between adjacent storms and covering more than 75% of the area affected; or
- Squall line (SQL) thunderstorms, i.e. thunderstorms along a line with little or no space between individual clouds.
SIGMET format?
- WMO Bulletin Identifier
- WMO Indicator of originating office
- Date/Time
- YMMM or YBBB
- SIGMET standard identifier
- Daily Sequence Number
- Valid perior
- ICAO location indicator
- FIR Indicator
- Message description of phenomena
- STS meaning Status of SIGMET, followed by:
—– NEW meaning a New SIGMET,
—– REV meaning a Reviewed SIGMET, or
—– CNL meaning Cancellation of SIGMET.
Elements of AIRMET
AIRMET information concerns the occurrence or expected occurrence, in an area over which meteorological watch is being maintained, below level A100 of one or more of the following phenomena when the phenomena have not been included in a current Area Forecast:
- isolated and occasional thunderstorms
- Moderate icing
- Moderate mountain waves;
- Widespread areas of visibility < 8KM;
- Widespread areas of cloud coverage of BKN or OVC below 1,500FT AGL
CB or TCU clouds which are isolated, occasional or frequent.
What is a TAF?
- A forecast for an area 5nm from the Aerodrome Reference Point
- It is a statement of expected conditions for a specified time.
Elements of a TAF3?
Issued routinely every 3 hours at major airports
Adelaide, Brisbane, Cairns, Darwin, Gold Coast, Hobart, Melbourne and Sydney
Also provided at Military aerodromes as per ERSA. Any deviations from ERSA published TAF3 hours notified by NOTAM
Same format as TAF with “TAF3” in RMK section
Issued from the Aviation Forecast Office 30-60 minutes before the forecast validity period, with a target issue of 45 minutes
Replaces TTF (Trend Type Forecast)
Meaning of FROM (FM)?
- Indicates a rapid change from the preceding forecast of a lasting nature
- Can be an improvement or a deterioration
- The conditions following a FM period stay in force until another FM, BECMG, TILL or the end of the TAF/TAF3
- In a TAF the format is ddhhmm
- In a TAF3 the format is ddhh
Meaning of BECOMING (BECMG)
- Indicates a less rapid change from the preceding forecast of a lasting nature
- The change can be an improvement or deterioration
- Format is ddhh
- The conditions following a BECMG period stay in force until another FM or BECMG or the end of the TAF/TAF3
Meaning of PROBABILITY (PROB)
- Indicates a probability of a phenomena occurring
- PROB30 or PROB40 are the only ones used
- Less than 30% it is ignored
More than 40% it becomes a part of the forecast
Meaning of INTERMITTENT (INTER)
- Is used to indicate changes that will occur frequently for periods of less than 30 mins
- In a TAF the format is ddhh/ddhh
- In a TAF3 the format is ddhh/ddhh
