W2A Standard Briefingprovides Detailed Weather Information Along One S Route of Flight
Weather Briefings - Private
W1When speaking with a weather briefer over the telephone, one should initially identify oneself as a pilot, state the intended route and destination, VFR or IFR flight, type of aircraft and proposed departure time and time en route.
W2A standard briefingprovides detailed weather information along one’s route of flight.
W3An abbreviated briefing may be requested to supplement data obtained through a self-briefing, update a previous briefing, or for specific information.
W3AAn outlook briefing should be requested when the call to the briefer is 6 or more hours in advance of the proposed departure time.
Aviation Routine Weather Report (METAR)– Private and Instrument
METAR KMDW 121856Z 32005KT 11/2SM RA OVC007 17/16 A2980 RMK RAB35
W4Aviation routine weather reports, or METARs, contain actual weather observations at the time indicated on the report.
W5There are two types of reports, routine and non-routine. A non-routine report is indentified by the letters “SPECI” preceding “METAR”.
W6Elements of the METARinclude the following. The first is the type of report,in this case a routine report as indicated by “METAR”.
W7This is followed by the four-letter station identifier.
W8The day of the month and the Coordinated Universal Time (UTC) when the observations were made are indicated after the station identifier.
W9Wind direction relative to true north and wind speed are indicated next. In this example wind is from 320° at 5 knots.
W10Visibility is given in statue miles.
W11The type of weather phenomena follows visibility.
W12Cloud cover is given as scatter, broken or overcast. Cloud height is given in hundreds of feet.
W13Temperature and dew point are in degrees Celsius. When the difference between temperature and dew point is within five degrees and is decreasing, fog is likely.
W14The altimeter setting follows temperature. In this case A2980 indicates the altimeter setting is 29.80 inches of mercury.
W15Remarks may be added at the end of the METAR. In this example, RAB35 means rain began 35 minutes past the hour.
Pilot Weather Reports (PIREPs)– Private and Instrument
UA/OV KOKC-KTUL/TM 1800/FL120/TP BE90/SK BKN018-TOP055/0VC072-TOP089/CLR ABV/TA M7/WV 08021/TB LGT 055-072/IC LGT-MOD RIME 072-089
W16Pilot weather reports, or PIREPs, are weather reports provided by pilots observing conditions while flying.All heights are given in mean sea level.
W17A routine report is indicated by the letters “UA”. An urgent report is indicated by “UUA” preceding the report.
W18The location of the report is indicated by “OV”. The location can be over a NAVAID, a position relative to a NAVAID, or along a route. In this example, it is along a route.
W19The time of the observation is identified by “TM” and is given in Coordinated Universal Time.
W20The altitude of the observation is identified by “FL”. The altitude is in hundreds of feet.
W21Aircraft type is identified by “TP” followed by the type.
W22Sky cover is identified by “SK” and includes cloud cover (scatter, broken, overcast) and height of the cloud bases and tops.
W23In this example the clouds are broken at 1,800 ft with clouds tops at 5,500 ft,and overcast at 7,200 with tops at 8,900 ft, clear above.
W24Flight visibility and weather may be included and is identified by “WX”. Flight visibility is identified by “FV”.
W25Temperature is identified by “TA” and is given in degrees Celsius. If the temperature is below zero, the letter “M” will prefix the temperature to indicate “minus”.
W26Wind direction and speed is identified by “WV”.
W27Turbulence is identified by “TB”. Standard contractions for severity are used. Altitudes are indicated if different than the FL altitude.
W28Icing conditions is identified by “IC”. Standard contractions for intensity and type are used. Altitude is given if different from FL altitude.
W29Remarks, identified by “RM”, may be included in free form to clarify the report. Hazardous elements are listed first.
Aviation Area Forecast (FA) – Private and Instrument
W30The aviation area forecast, “FA”, provides a 12-hour forecast and a 6-hour categorical outlook for a specific region.
W31The report contains four sections. The first section is the header, which provides valid times and the region.
W32The second section is a precautionary statement.
W33The third section is a synopsis of the weather for the region.
W34Finally, the forecast for specific regions is given in the forth section.
W35An area forecast must be supplemented by In-Flight Aviation Weather Advisories (AIRMETs) in order to gain a complete weather picture including freezing level, icing, turbulence and IFR conditions.
Terminal Aerodrome Forecast (TAF) – Private and Instrument
W36The terminal aerodrome forecast is a weather forecast for a specific airport.
W37There are two types of aerodrome forecasts. A routine forecast is indicated by “TAF”. An amended forecast is indicated by “TAF AMD”.
W38The forecast includes the station identifier, date and time the forecast was prepared, the valid period of the forecast, and forecasted meteorological conditions.
W39The abbreviations “VC”, “VRB”, “WS” and “NSW” mean vicinity, variable, wind shear, and no significant weather respectively.
Weather Depiction Chart – Private and Instrument
W40The weather depiction chart is a graphical representation of sky conditions throughout the United States based on METAR reports at the time stated on the chart.
W41The chart provides pilots a quick look at overall weather conditions.
W42Reporting stations are indicated by a circle. An empty circle indicates the sky is clear. A 1/4 filled circle indicates scattered clouds. A 3/4 filled circle indicates broken. An “X” in the circle indicates the sky is obscured.
W43Ceilings are indicated below the circle and visibility is indicated to the left of the circle. Visibility is not indicated when greater than 6 SM.
W44A bracket to the right of a station indicates the station is automated.
W45Significant weather is indicated on the chart using the symbols shown.
W46Areas of marginal VFR (ceilings1,000 to 3,000 ft and/or visibility 3 to 5 SM) are enclosed by solid black contour lines.
W47Areas where the ceiling is below 1,000 ft and/or visibility less than 3 SM are enclosed within solid black contour lines and shaded.
W48Frontal systems are also indicated on the chart.
RADAR Summary Chart – Private and Instrument
W49Radar summary charts graphically depict a collection of radar reports showing type, intensity and direction of movement of hazardous precipitation, thunderstorm cells and squall lines.
W50The symbols shown are used on radar summary charts.
W51Echo tops are the maximum height of the cloud indicated in hundreds of feet.
W52Severe weather watch areas are outlined by a heavy dashed line
En Route Flight Advisory Service (EFAS) – Private
W53En Route Flight Advisory Service, or EFAS, provides weather advisories for flights below 18,000 ft. Called Flight Watch, it is available on the frequency 122.0 MHz.
W54EFAS provides information regarding weather and thunderstorm activity along a route of flight.
W55It is designed to be a continuous exchange of information between pilots and weather briefers regarding visibility, turbulence and icing.
W56The advisory service is normally available from 0600 to 2200 local time.
Winds and Temperatures Aloft Forecast (FD) – Private and Instrument
W57The Winds and Temperature Aloft Forecast provides wind direction, wind speed, and air temperature for specific altitudes.
W58The first two numbers represent wind direction (relative to true north) after a zero is added at the end. In this case, 27 results in a direction of270°.
W59The two numbers following wind direction is the wind speed in knots. In this example, wind speed is 15 knots.
W60When the wind speed is less than 5 knots, the code 9900 is used in the wind group. This indicates the winds are light and variable.
W61The wind group is followed by the temperature in degrees Celsius. At and below 24,000 ft, a minus or plus sign is used.
W62Above 24,000 ft, the sign is omitted and the temperature is assumed to be below zero.
W63If the wind speed is forecasted to be between 100 and 199 knots, the report adds 50 to the wind direction and subtracts 100 from the wind speed.
W64For example, at 30,000 ft the forecast reads 751041. Wind direction is therefore 75 – 50, or 250°. Wind speed is 10 + 100, or 110 knots. And the temperature is -41°C (the minus is assumed above 24,000 ft).
W65If the wind is forecasted to be 199 knots or greater, 99 will appear in the wind group for wind speed.
W66For example, a forecast that reads 669959 means the wind is from 160° at 199 knots or more, temperature is -59° Celsius.
W67Winds aloft forecasts are not provided for altitudes that are within 1,500 feet of the station elevation.
W68In addition, temperature forecasts are not provided at the 3,000-foot level or a level within 2,500 feet of the station elevation.
W69 For intermediate altitudes, use interpolation for determining winds aloft and temperature as shown in the example.
Significant Weather Prognostic Chart – Private and Instrument
W70The Significant Weather Prognostic Chart includes four chart panels and are used to determine areas to avoid, such as freezing levels and less than VFR, during a flight.
W71The upper two panels forecast significant weather from the surface up to 24,000 ft for 12 and 24 hours (left and right panels respectively) from the time of issuance.
W72The lower two panels forecast surface conditions for 12 and 24 hours from the time of issuance.
W73The top panels will enclose regions with a solid scallop line that are marginal VFR where ceilings are 1,000 to 3,000 ft and/or visibility is 3 to 5 SM.
W74The top panels will also enclose regionswith a solid line that are IFR where ceilings are less than 1,000 ft and/or visibility is less than 3 SM.
W75Freezing levels are indicated on the top panels by a dashed line with the corresponding freezing level.
W76A peaked hat indicates moderate turbulence. The corresponding altitude with an underline means from the surface to 18,000 feet.
W77The bottom two charts show the location of highs and lows and regions of significant weather.
W78Outlined regions that are not shaded indicate precipitation covering half or less of the area.
W79Outlined regions that are shaded indicate precipitation covering more than half the area.
W80Standard meteorological symbols are used to indicate precipitation type and intensity.
Transcribed Weather Broadcasts – Private
W81Transcribed Weather Broadcasts, or TWEBS, are continuous broadcasts of recorded meteorological and other pertinent information over certain VOR and NDB facilities.
W82The broadcasts are tailored for specific routes of flight.
AIRMETS and SIGMETS – Private
W83AIRMETs and SIGMETs are issued to alert pilots of hazardous flying conditions.
W84AIRMETs report conditions that are hazardous to light aircraft. AIRMETs are issued every 6 hours with unscheduled amendments as required and are valid for 6 hours.
W85SIGMENTs report conditions that are hazardous to all aircraft.
W86A convective SIGMENT is issued for when severe weather, such as tornadoes or lines of thunderstorm, are a hazard to all aircraft.
Severe Weather Outlook Chart – Instrument
W87The Severe Weather Outlook Chart provides a 48- hour thunderstorm outlook. The left panel covers the first 24 hours and the right panel covers the second 24 hours.
W88The chart is used for advance planning and provides information regarding the possibility of future severe weather.
W89Areas with probable thunderstorm activity are indicated by a line with an arrowhead. The affected area is to the right of the arrow when oriented in the direction of the arrow.
W90Areas where severe thunderstorm activity is expected are labeled with a risk category of slight, moderate or high.
High-Level Significant Weather Prognostic Chart – Instrument
W91The High-Level Significant Weather Prognostic Chart for the United States covers airspace from above 24,000 ft to 60,000 ft.
W92Tropopause heights are indicated in hundreds of feet (MSL) or flight levels and are placed in either a rectangular box or a five-sided polygon.
W93When inside a rectangular box, the tropopause has a very flat slope in that area.
W94When inside a five-sided polygon,it indicates a high or low height for the tropopause.
W95Wind speed, direction and altitude are indicated on the chart.
W96Each pennant equals 50 knots and each barb equals 10 knots.
W97For example, a wind arrow with two pennants and two barbs indicates a wind speed of 120 knots.
W98Regions of moderate or greater turbulence are enclosed by bold, dashed lines. Altitudes and intensity of the turbulence is also included.
W99The appearance of three Xs indicates the base of the turbulence is below 24,000 ft.
W100Regions that contain expected cumulonimbus development are enclosed by scalloped lines.
W101The region is labeled to indicate the storms are isolated, occasional, or frequent.
W102Embedded thunderstorms with 1/8 coverage are considered isolated.
W103Embedded thunderstormswith 1/8 to 4/8 coverage are considered occasional.
W104Thunderstorms with 5/8 to 8/8 coverage are considered frequent.
Observed Winds Aloft Chart – Instrument
W105The Observed Winds Aloft Chart contains arrows with pennants and barbs.
W106Each pennant represents 50 knots and each barb represents 10 knots. A half barb is 5 knots.
W107The number at one end of the barb indicates direction. First determine the quadrant from which the wind is blowing and fill in the rest.
W108For example, wind from the southeast annotated with a “4” indicates the wind is from 140°.
W109Temperature is also indicated near the arrow.
Miscellaneous Charts and Forecasts – Instrument
W110AIRMETs, SIGMETs and PIREPs provide the most accurate information regarding current and forecasted icing conditions.
W111Severe weather watch bulletins are not scheduled. They are issued as required.
W112The convective outlook provides information on possible thunderstorm activity during the following 24-hour period.
W113The surface analysis chart shows actual frontal positions, pressure patterns, temperature, dew point, wind, weather, and obstructions to vision at the valid time of the chart.
W114Constant Pressure Charts provide information regarding winds and temperature aloft.
W115The Transcribed Weather Broadcast provides specific information concerning expected sky cover, cloud tops, visibility, weather, and obstructions to vision.