Area Forecasts For Operations At or Below 10,000 Feet The Area Forecast system is designed primarily to meet the needs of pilots of general aviation. There is an emphasis on plain language and brevity in a simple, easy to read format. The system provides for the routine issue of forecasts for designated areas (see map below) and the prompt issue of amendments when prescribed criteria are satisfied. More detail of the area forecast boundaries with place locations is contained in Airservices Australia's Planning Chart Australia (PCA). There may be variations in commencement of validity between different regions, and between those times when daylight saving is or is not operating. However the following principles apply: the standard validity period is twelve hours but this may vary from state to state. an area forecast covering daylight hours will be available as soon as practicable in the morning. area forecasts are not prepared for those times when air traffic volume is so low as not to justify routine issues. In these cases a route forecast will service any individual flights. area forecasts will generally be available a minimum of one hour before commencement of validity. Message Structure Message Identifier The forecast is identified as AREA FORECAST unless the forecast is an amendment in which case it will be denoted AMEND AREA FORECAST. In the case of amended area forecasts, all individual sections that are amended will be annotated with AMD preceding the section heading. Validity Period The validity period is written DDHHMM TO DDHHMM, where DD is the day of the month and HHMM is the time in hours and minutes UTC. Area Number The relevant forecast area is specified by an area forecast district number. These are given in more detail on the current Airservices Australia's Planning Chart Australia. Note that Areas 24, 87 and 88 are only designated for the purpose of Area QNH. Any flights in these areas can be provided with a route forecast. Overview The overview will highlight any conditions which may inhibit safe operations for pilots flying under visual flight rules, and will make reference, where necessary, to any spatial and temporal variations. It will assist the pilot in making the following types of decisions: Are the meteorological conditions Visual Meteorological Conditions (VMC), marginal, Instrument Flight Rules (IFR) or too poor for flying? Is it better to plan for a coastal or inland track? If bad weather is encountered, what is the contingency plan? Return? Change altitude? Change heading? Land immediately? Subdivisions Area forecasts may be divided into spatial, temporal or weather-related subdivisions. Spation subdivisions are given using PCA (Planning Chart Australia) or lat/lon coordinates Winds and Temperatures Upper level winds are given for 2000 (or 3000 in elevated regions), 5000, 7000, 10 000, 14 000 and 18 500 feet. The expected mean wind direction is given in three figures to the nearest ten degrees True, followed by a solidus (/), followed by the mean wind speed in two figures to the nearest five knots, 290/40. CALM and VRB05 (wind direction variable at 5 knots) are used when appropriate. A REMARKS section may be included below the WIND section to provide further information on winds. Upper level temperatures are given for 10 000, 14 000 and 18 500 feet. These are given in whole degrees Celsius, following the forecast of the upper wind for the level concerned. e.g. 290/40 PS08, 300/50 ZERO, 360/10 MS10. The abbreviation PS is used for positive temperatures, and MS (minus) is used for negative temperatures. Cloud The inclusion of cloud is restricted to: any CB or TCU. any cloud with a base at or below 5000 feet above the highest terrain in the area covered by the forecast. any cloud layer of more than 4/8 (broken or overcast) amount with base at or below 20 000 feet above MSL. any cloud associated with any forecast precipitation, moderate or severe icing and moderate or severe turbulence. Cloud amount is given 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) ...except for cumulonimbus and towering cumulus, for which amount is described as: ISOL - Isolated OCNL - Occasional (well separated) FRQ - Frequent (little or no separation) EMBD - Embedded (in layers of other cloud) Cloud type is given using the following abbreviations: CU - Cumulus SC - Stratocumulus CB - Cumulonimbus TCU - Towering cumulus ST - Stratus AS - Altostratus AC - Altocumulus NS - Nimbostratus If subdivisions are used and one or more subdivisions have no cloud associated with it, the format used is NIL CLOUD. When CU and SC, or AC and AS, occur together at similar heights, they are combined, i.e. CU/SC or AC/AS. Cloud base and tops are given in feet above MSL (mean sea level). Weather Weather information relating to the layer below 21 000 feet above MSL is given following the word 'WEATHER'. If subdivisions are used and one or more subdivisions have no weather associated with it the format is, WEATHER A: NIL. Visibility Horizontal visibility is given in metres to the nearest 100 metres up to and including 5000 metres, and in whole kilometres above that value. Forecast visibilities of 50 metres or less are given as 'ZERO'. The forecast value is followed by the units used e.g. '8KM' or '1000M'. Significant variations of visibility are included. If the visibility is forecast to be above 10 kilometres throughout the area, the words 'UNRESTRICTED' or 'GOOD' are used. Vertical variations of horizontal visibility, which might prevent flight under VMC conditions, are significant. For example, information is supplied on the depth of layers affected by drizzle, haze and dust storms, and the levels of haze layers under inversions. Visibility variations with these phenomena is given. Freezing Level Freezing level is the height, in feet, above MSL of zero degrees Celsius. Reference is made to any variations in height greater than 1000 feet, and to the occurrence of more than one freezing level. Icing The icing section gives information on the expected occurrence of moderate or severe icing in cloud (including convective cloud), or precipitation, in the layer below 20 000 feet above MSL. The height above MSL of the bottom and top of the layer is given as, for example, MOD IN RA 5000/8000. When the layer of icing is expected to extend above 20 000 feet, descriptions such as MOD ABOVE 14000 are used. Turbulence This section provides information on moderate or severe turbulence including turbulence associated with convective cloud. The height above MSL of the bottom and top of any layer(s) is given as, for example, MOD IN CLOUD 12000/16000 When the turbulence is expected to extend to ground level, descriptions such as BELOW 8000 are used. When the turbulence is expected to be confined to clouds, descriptions such as MOD IN CLOUD BELOW 8000 are used. When the turbulence is expected to extend above 20 000 feet, descriptions such as SEV ABOVE 15000 are used. Critical Locations These are locations such as gaps in mountain ranges which are frequently used by general aviation aircraft. Currently, critical location forecasts are appended to Area Forecasts for Bowral and Mt Victoria (NSW) on AREA 21; Mt Victoria and Murrurundi (NSW) on AREA 20; and Kilmore Gap (Vic) on AREA 30. Critical location forecasts are written in a mixture of plain language and TAF format making reference as necessary to cloud, visibility and weather. CAVOK is used to indicate visibility greater than 10 KM, cloud ceiling above 5000 FT above ground level and nil significant weather. Remarks This section will include any relevant information not included elsewhere in the forecast. Abbreviations and Codes Used in Area Forecasts AC - Altocumulus AC/AS - Altocumulus and Altostratus with bases at the same level AS - Altostratus AMD - Amendment BKN - Broken CAVOK - Cloud and visibility and weather ok. CB - Cumulonimbus CU - Cumulus CU/SC - Cumulus and Stratocumulus with bases at the same level DZ - Drizzle EMBD - Embedded FEW - Few FG - Fog FM - From (only used in Critical Locations section) FRQ - Frequent GR - Hail GS - Small Hail INTER - Intermittent variations (only used in Critical section Locations) ISOL - Isolated MOD - Moderate NS - Nimbostratus OCNL - Occasional OVC - Overcast RA - Rain SC - Stratocumulus SCT - Scattered SEV - Severe SH - Shower SN - Snow ST - Stratus TCU - Towering Cumulus TEMPO - Temporary variations (only used in Critical Locations section) TS - Thunderstorm Z - Code for UTC (universal time) Example
