Weather Briefings - Private
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When 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.
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A standard briefing provides detailed weather information along one’s route of flight.
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An abbreviated briefing may be requested to supplement data obtained through a self-briefing,
update a previous briefing, or for specific information.
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An 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
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Aviation routine weather reports, or METARs, contain actual weather observations at the time
indicated on the report.
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There are two types of reports, routine and non-routine. A non-routine report is indentified by the
letters “SPECI” preceding “METAR”.
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Elements of the METAR include the following. The first is the type of report, in this case a
routine report as indicated by “METAR”.
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This is followed by the four-letter station identifier.
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The day of the month and the Coordinated Universal Time (UTC) when the observations were
made are indicated after the station identifier.
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Wind direction relative to true north and wind speed are indicated next. In this example wind is
from 320° at 5 knots.
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Visibility is given in statue miles.
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The type of weather phenomena follows visibility.
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Cloud cover is given as scatter, broken or overcast. Cloud height is given in hundreds of feet.
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Temperature 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.
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The altimeter setting follows temperature. In this case A2980 indicates the altimeter setting is
29.80 inches of mercury.
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Remarks 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
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Pilot weather reports, or PIREPs, are weather reports provided by pilots observing conditions
while flying. All heights are given in mean sea level.
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A routine report is indicated by the letters “UA”. An urgent report is indicated by “UUA”
preceding the report.
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The 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.
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The time of the observation is identified by “TM” and is given in Coordinated Universal Time.
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The altitude of the observation is identified by “FL”. The altitude is in hundreds of feet.
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Aircraft type is identified by “TP” followed by the type.
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Sky cover is identified by “SK” and includes cloud cover (scatter, broken, overcast) and height of
the cloud bases and tops.
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In 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.
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Flight visibility and weather may be included and is identified by “WX”. Flight visibility is
identified by “FV”.
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Temperature 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”.
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Wind direction and speed is identified by “WV”.
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Turbulence is identified by “TB”. Standard contractions for severity are used. Altitudes are
indicated if different than the FL altitude.
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Icing conditions is identified by “IC”. Standard contractions for intensity and type are used.
Altitude is given if different from FL altitude.
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Remarks, 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
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The aviation area forecast, “FA”, provides a 12-hour forecast and a 6-hour categorical outlook for
a specific region.
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The report contains four sections. The first section is the header, which provides valid times and
the region.
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The second section is a precautionary statement.
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The third section is a synopsis of the weather for the region.
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Finally, the forecast for specific regions is given in the forth section.
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An 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
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The terminal aerodrome forecast is a weather forecast for a specific airport.
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There are two types of aerodrome forecasts. A routine forecast is indicated by “TAF”. An
amended forecast is indicated by “TAF AMD”.
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The forecast includes the station identifier, date and time the forecast was prepared, the valid
period of the forecast, and forecasted meteorological conditions.
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The abbreviations “VC”, “VRB”, “WS” and “NSW” mean vicinity, variable, wind shear, and no
significant weather respectively.
Weather Depiction Chart – Private and Instrument
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The 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.
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The chart provides pilots a quick look at overall weather conditions.
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Reporting 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.
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Ceilings are indicated below the circle and visibility is indicated to the left of the circle. Visibility
is not indicated when greater than 6 SM.
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A bracket to the right of a station indicates the station is automated.
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Significant weather is indicated on the chart using the symbols shown.
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Areas of marginal VFR (ceilings1,000 to 3,000 ft and/or visibility 3 to 5 SM) are enclosed by
solid black contour lines.
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Areas where the ceiling is below 1,000 ft and/or visibility less than 3 SM are enclosed within
solid black contour lines and shaded.
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Frontal systems are also indicated on the chart.
RADAR Summary Chart – Private and Instrument
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Radar summary charts graphically depict a collection of radar reports showing type, intensity and
direction of movement of hazardous precipitation, thunderstorm cells and squall lines.
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The symbols shown are used on radar summary charts.
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Echo tops are the maximum height of the cloud indicated in hundreds of feet.
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Severe weather watch areas are outlined by a heavy dashed line
En Route Flight Advisory Service (EFAS) – Private
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En 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.
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EFAS provides information regarding weather and thunderstorm activity along a route of flight.
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It is designed to be a continuous exchange of information between pilots and weather briefers
regarding visibility, turbulence and icing.
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The advisory service is normally available from 0600 to 2200 local time.
Winds and Temperatures Aloft Forecast (FD) – Private and Instrument
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The Winds and Temperature Aloft Forecast provides wind direction, wind speed, and air
temperature for specific altitudes.
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The 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 of 270°.
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The two numbers following wind direction is the wind speed in knots. In this example, wind
speed is 15 knots.
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When 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.
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The wind group is followed by the temperature in degrees Celsius. At and below 24,000 ft, a
minus or plus sign is used.
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Above 24,000 ft, the sign is omitted and the temperature is assumed to be below zero.
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If 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.
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For 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).
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If the wind is forecasted to be 199 knots or greater, 99 will appear in the wind group for wind
speed.
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For example, a forecast that reads 669959 means the wind is from 160° at 199 knots or more,
temperature is -59° Celsius.
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Winds aloft forecasts are not provided for altitudes that are within 1,500 feet of the station
elevation.
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In addition, temperature forecasts are not provided at the 3,000-foot level or a level within 2,500
feet of the station elevation.
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For intermediate altitudes, use interpolation for determining winds aloft and temperature as
shown in the example.
Significant Weather Prognostic Chart – Private and Instrument
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The 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.
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The 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.
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The lower two panels forecast surface conditions for 12 and 24 hours from the time of issuance.
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The 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.
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The top panels will also enclose regions with a solid line that are IFR where ceilings are less than
1,000 ft and/or visibility is less than 3 SM.
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Freezing levels are indicated on the top panels by a dashed line with the corresponding freezing
level.
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A peaked hat indicates moderate turbulence. The corresponding altitude with an underline means
from the surface to 18,000 feet.
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The bottom two charts show the location of highs and lows and regions of significant weather.
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Outlined regions that are not shaded indicate precipitation covering half or less of the area.
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Outlined regions that are shaded indicate precipitation covering more than half the area.
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Standard meteorological symbols are used to indicate precipitation type and intensity.
Transcribed Weather Broadcasts – Private
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Transcribed Weather Broadcasts, or TWEBS, are continuous broadcasts of recorded
meteorological and other pertinent information over certain VOR and NDB facilities.
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The broadcasts are tailored for specific routes of flight.
AIRMETS and SIGMETS – Private
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AIRMETs and SIGMETs are issued to alert pilots of hazardous flying conditions.
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AIRMETs 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.
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SIGMENTs report conditions that are hazardous to all aircraft.
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A 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
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The 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.
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The chart is used for advance planning and provides information regarding the possibility of
future severe weather.
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Areas 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.
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Areas where severe thunderstorm activity is expected are labeled with a risk category of slight,
moderate or high.
High-Level Significant Weather Prognostic Chart – Instrument
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The High-Level Significant Weather Prognostic Chart for the United States covers airspace from
above 24,000 ft to 60,000 ft.
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Tropopause heights are indicated in hundreds of feet (MSL) or flight levels and are placed in
either a rectangular box or a five-sided polygon.
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When inside a rectangular box, the tropopause has a very flat slope in that area.
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When inside a five-sided polygon, it indicates a high or low height for the tropopause.
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Wind speed, direction and altitude are indicated on the chart.
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Each pennant equals 50 knots and each barb equals 10 knots.
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For example, a wind arrow with two pennants and two barbs indicates a wind speed of 120 knots.
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Regions of moderate or greater turbulence are enclosed by bold, dashed lines. Altitudes and
intensity of the turbulence is also included.
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The appearance of three Xs indicates the base of the turbulence is below 24,000 ft.
W100 Regions that contain expected cumulonimbus development are enclosed by scalloped lines.
W101 The region is labeled to indicate the storms are isolated, occasional, or frequent.
W102 Embedded thunderstorms with 1/8 coverage are considered isolated.
W103 Embedded thunderstorms with 1/8 to 4/8 coverage are considered occasional.
W104 Thunderstorms with 5/8 to 8/8 coverage are considered frequent.
Observed Winds Aloft Chart – Instrument
W105 The Observed Winds Aloft Chart contains arrows with pennants and barbs.
W106 Each pennant represents 50 knots and each barb represents 10 knots. A half barb is 5 knots.
W107 The number at one end of the barb indicates direction. First determine the quadrant from which
the wind is blowing and fill in the rest.
W108 For example, wind from the southeast annotated with a “4” indicates the wind is from 140°.
W109 Temperature is also indicated near the arrow.
Miscellaneous Charts and Forecasts – Instrument
W110 AIRMETs, SIGMETs and PIREPs provide the most accurate information regarding current and
forecasted icing conditions.
W111 Severe weather watch bulletins are not scheduled. They are issued as required.
W112 The convective outlook provides information on possible thunderstorm activity during the
following 24-hour period.
W113 The 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.
W114 Constant Pressure Charts provide information regarding winds and temperature aloft.
W115 The Transcribed Weather Broadcast provides specific information concerning expected sky
cover, cloud tops, visibility, weather, and obstructions to vision.