Private Pilot | Lesson 14 - Aviation Weather Services
TABLE OF CONTENTS:
14.1 WEATHER BRIEFINGS
14.2 AVIATION ROUTINE WEATHER REPORT (METAR)
14.3 PILOT WEATHER REPORT (PIREP)
14.4 AREA FORECAST
14.5 TERMINAL AERODROME FORECAST (TAF)
14.6 WEATHER DEPICTION CHARTS
14.7 RADAR SUMMARY CHARTS AND RADAR WEATHER REPORTS
14.8 EN ROUTE FLIGHT ADVISORY SERVICE
14.9 WINDS AND TEMPERATURES ALOFT FORECASTS
14.10 SIGNIFICANT WEATHER PROGNOSTIC CHARTS
14.11 TRANSCRIBED WEATHER BROADCASTS
14.12 AIRMETS AND SIGMETS
14.1 Weather Briefings
Pilots can call any Flight Service station and request a preflight weather briefing by dialing 1-800-WX-BRIEF.
When requesting a telephone weather briefing, you should state:
- Your aircraft type and N-number (e.g., "Piper Archer 115JW)
- Whether you are flying VFR or IFR, and your intended route of flight ("VFR from San Diego to Burbank)
- Your proposed departure time and time en route ("departing at 1500 Zulu, time enroute one hour, ten minutes.")
A standard briefing should be obtained before every flight. A standard briefing provides all the necessary weather and NOTAM information needed to help ensure a safe flight.
- An outlook briefing is provided when it is 6 or more hours before your proposed departure time.
- An abbreviated briefing will be given when the user requests information to
- Supplement mass disseminated data,
- Update a previous briefing, and just needs specific information (e.g., only ceiling and visibility changes from the previous brief).
Ascent Quick Quiz - 14.1 Weather BriefingsQuestion 1: To get a complete weather briefing for the planned flight, the pilot should request
Question 2: Which type weather briefing should a pilot request, when departing within the hour, if no preliminary weather information has been received?
Question 3: Which type of weather briefing should a pilot request to supplement mass disseminated data?
Question 4: A weather briefing that is provided when the information requested is 6 or more hours in advance of the proposed departure time is
Question 5: What should pilots state initially when telephoning a weather briefing facility for preflight weather information?
Question 6: What should pilots state initially when telephoning a weather briefing facility for preflight weather information?
Question 7: When telephoning a weather briefing facility for preflight weather information, pilots should state
Question 8: When telephoning a weather briefing facility for preflight weather information, pilots should state
Question 9: To update a previous weather briefing, a pilot should request
Question 10: When requesting weather information for the following morning, a pilot should request
14.2 Aviation Routine Weather Report (METAR)
Aviation routine weather reports (METARs) are actual surface weather observations at the time indicated on the report. (METARs are NOT forecasts.)
There are two types of reports.
- METAR is a routine weather report.
- SPECI is a nonroutine weather report.
Following the type of report are the elements listed below:
- Type of report, METAR or SPECI.
- ICAO station identifier (Four-letter station ident).
US airports are identified by the three-letter domestic identifier prefixed with a "K." E.g., KLAX.
- Date and time of report. It is appended with a "Z" to denote Zulu or Coordinated Universal Time (UTC).
- Modifier (if required).
- Wind. Wind is reported in knots (KT) as a five-digit group .
If the wind is gusty, it is reported with a "G" after the speed, followed by the highest gust reported.
EXAMPLE: 17010G18KT means wind from 170° true at 10 knots, with gusts to 18 knots.
- Visibility. The prevailing visibility is reported in statute miles, denoted with "SM".
EXAMPLE: 1 1/2SM means visibility is one and a half statue miles.
- Runway Visual Range (RVR).
- Weather phenomena.
"RA" is used to indicate rain.
- Sky conditions.
The ceiling is the lowest broken or overcast layer, or vertical visibility into an obscuration.
Cloud bases are reported with three digits in hundreds of feet AGL.
EXAMPLE: OVC007 means overcast cloud layer at 700 ft. AGL.
- Temperature/dew point. They are reported in a two-digit form in whole degrees Celsius separated by a slash.
- Altimeter setting.
- Remarks (RMK).
EXAMPLE: RAB35 means rain began at 35 min. past the hour.
METAR KAUS 301651Z 12008KT 4SM -RA HZ BKN010 OVC023 21/17 A3005 RMK RAB25METAR is a routine weather observation.
KAUS is Austin, TX.
301651Z means the observation was taken on the 30th day at 1651 UTC (or Z).
12008KT means the wind is from 120° true at 8 kt.
4SM means the visibility is 4 statute miles.
-RA HZ means light rain and haze.
BKN010 OVC023 means ceiling 1,000 ft. broken, 2,300 ft. overcast.
21/17 means the temperature is 21°C and the dew point is 17°C.
A3005 means the altimeter setting is 30.05 in. of Hg.
RMK RAB25 means remarks, rain began at 25 min. past the hour., i.e., 1625 UTC.
Ascent Quick Quiz - 14.2 Aviation Routine Weather Report (METAR)Question 1: For aviation purposes, ceiling is defined as the height above the Earth's surface of the
Question 2: (Refer to figure 12.) What are the current conditions depicted for Chicago Midway Airport (KMDW)?
Question 3: (Refer to figure 12.) Which of the reporting stations have VFR weather?
Question 4: (Refer to figure 12.) The wind direction and velocity at KJFK is from
Question 5: (Refer to figure 12.) What are the wind conditions at Wink, Texas (KINK)?
Question 6: (Refer to figure 12.) The remarks section for KMDW has RAB35 listed. This entry means
14.3 Pilot Weather Report (PIREP)
Pilots often become their own best source of weather reporting by the Pilot Reports (PIREPs) that they file with Air Traffic Control.
PIREPs, like METARs, follow a specific format when they are transmitted, below.
- UUA/UA Type of report:
URGENT (UUA) - Any PIREP that contains any of the following weather phenomena: tornadoes, funnel clouds, or waterspouts; severe or extreme turbulence, including clear air turbulence (CAT); severe icing; hail; low-level wind shear (LLWS) (pilot reports air speed fluctuations of 10 knots or more within 2,000 feet of the surface); any other weather phenomena reported which are considered by the controller to be hazardous, or potentially hazardous, to flight operations.
ROUTINE (UA) - Any PIREP that contains weather phenomena not listed above, including low-level wind shear reports with air speed fluctuations of less than 10 knots.
- /OV Location: Use VHF NAVAID(s) or an airport using the three- or four-letter location identifier. Position can be over a site, at some location relative to a site, or along a route. Ex: /OV KABC; /OV KABC090025; /OV KABC045020-DEF; /OV KABC-KDEF
- /TM Time: Four digits in UTC. Ex: /TM 0915
- /FL Altitude/Flight level: Three digits for hundreds of feet with no space between FL and altitude. If not known, use UNKN. Ex: /FL095; /FL310; /FLUNKN
- /TP Aircraft type: Four digits maximum; if not known, use UNKN. Ex: /TP L329; /TP B737; /TP UNKN
- /SK Sky cover: Describes cloud amount, height of cloud bases, and height of cloud tops. If unknown, use UNKN. Ex: /SK SCT040-TOP080;
- /SK BKNUNKN-TOP075; /SK BKN-OVC050-TOPUNKN; /SK OVCUNKN-TOP085
- /WX Flight visibility and weather: Flight visibility (FV) reported first and use standard METAR weather symbols. Intensity (- for light, no qualifier for moderate, and + for heavy) shall be coded for all precipitation types except ice crystals and hail. Ex: /WX FV05SM - RA; /WX FV01 SN BR; /WX RA
- /TA Temperature (Celsius): If below zero, prefix with an "M." Temperature should also be reported if icing is reported. Ex: /TA 15; /TA M06
- /WV Wind: Direction from which the wind is blowing coded in tens of degrees using three digits. Directions of less than 100 degrees shall be preceded by a zero. The wind speed shall be entered as a two- or three-digit group immediately following the direction, coded in whole knots using the hundreds, tens, and units digits.
Ex: /WV 27045KT; /WV 280110KT
- /TB Turbulence: Use standard contractions for intensity and type (CAT or CHOP when appropriate). Include altitude only if different from FL.
Ex: /TB EXTRM; /TB OCNL LGT-MDT BLO 090; /TB MOD-SEV CHOP 080-110
- /IC Icing: Describe using standard intensity and type contractions. Include altitude only if different from FL. Ex: /IC LGT-MDT RIME; /IC SEV CLR 028-045
- /RM Remarks: Use free form to clarify the report putting hazardous elements first
Ex: /RM LLWS -15 KT SFC-030 DURGC RY 22 JFK
All heights (clouds, icing, other) are given as MSL.
Turbulence is reported as
- Light = LGT
- Moderate = MDT
- Severe = SVR
Icing is reported as
- Clear = CLR
- Rime = RIME
Wind direction and velocity are given as a five- or six-digit code (e.g., / WV 27045 means 270° at 45 kt.).
Air temperature is expressed in degrees Celsius (°C).
Cloud layers are reported with heights for bases, tops, and layer type if available. "No entry" means that information was not given.
SK 024 BKN 032/042 BKN-OVC
Decoded the PIREP above identifies a broken layer of clouds between 2,400 ft. MSL to 3,200 ft. MSL.
A second layer of clouds are broken to overcast starting at 4,200 ft. MSL.
Ascent Quick Quiz - 14.3 Pilot Weather Report (PIREP)Question 1: (Refer to figure 14.) If the terrain elevation is 1,295 feet MSL, what is the height above ground level of the base of the ceiling?
Question 2: (Refer to figure 14.) The base and tops of the overcast layer reported by a pilot are
Question 3: (Refer to figure 14.) The wind and temperature at 12,000 feet MSL as reported by a pilot are
Question 4: (Refer to figure 14.) The intensity of the turbulence reported at a specific altitude is
Question 5: (Refer to figure 14.) The intensity and type of icing reported by a pilot is
14.4 Area Forecast
Aviation Area Forecasts (FA) are the forecasts general weather conditions for an area consisting of several states. FAs are issued three times a day and consist of:
- A 12-hr. forecast, and
- A 6-hr. categorical outlook .
The FA can be used as an indicator for the general conditions at airports which have no terminal aerodrome forecasts (TAFs).
There are four sections in an FA:
- Communication and Product Header section
- Precautionary Statements section
- Synopsis section
- VFR Clouds/Weather section (VFR CLDS/WX); this is the "forecast" section
- Included in the VFR CLDS/WX section is the 6-hr. categorical outlook. The categorical outlook is not considered a "forecast".
An example of the standardized formatting of an FA is reproduced below. (This same FA formatting will be utilized during your pilot written exam.)
To get a complete weather picture, including icing, turbulence, and IFR conditions, you must thoroughly review the current Area Forecast (FA), as well as all current In-Flight Aviation Weather Advisories. In-Flight Aviation Weather Advisories will help to determine the freezing level and areas of probable icing aloft, as well as any areas of turbulence or general IFR conditions that you should avoid along your flight.
Ascent Quick Quiz - 14.4 Area ForecastQuestion 1: To best determine general forecast weather conditions over several states, the pilot should refer to
Question 2: To determine the freezing level and areas of probable icing aloft, the pilot should refer to the
Question 3: The section of the Area Forecast entitled "VFR CLDS/WX" contains a general description of
Question 4: From which primary source should information be obtained regarding expected weather at the estimated time of arrival if your destination has no Terminal Forecast?
Question 5: (Refer to figure 16.) The Chicago FA forecast section is valid until the twenty-fifth at
Question 6: (Refer to figure 16.) What sky condition and visibility are forecast for upper Michigan in the eastern portions after 2300Z?
Question 7: (Refer to figure 16.) What is the outlook for the southern half of Indiana after 0700Z?
Question 8: (Refer to figure 16.) What sky condition and type obstructions to vision are forecast for upper Michigan in the Western portions from 0200Z until 0500Z?
14.5 Terminal Aerodrome Forecast (TAF)
Terminal aerodrome forecasts (TAFs) are weather forecasts for selected airports with operating control towers around the country.
Cumulonimbus clouds (CB) are the only cloud type forecast in TAFs as these are storm clouds and could greatly effect flight planning to that airport.
Remember, a TAF is a FORECAST of expected weather conditions.
The elements of a TAF are listed below:
- Type of report
TAF is a routine forecast.
TAF AMD is an amended forecast.
- ICAO station identifier
- Date and time the forecast is actually prepared
- Valid period of the forecast
- Forecast meteorological conditions. This is the body of the forecast and includes the following:
- Sky condition
KBRO 300545Z 300606 VRB04KT 3SM SCT040 OVC150 TEMPO 2124 SHRA
FM0200 10010KT P6SM OVC020 BECMG0306 NSW BKN020=TAF is a routine forecast.KBRO is Brownsville, TX.300545Z means the forecast was prepared on the 30th day at 0545 UTC.300606 means the forecast is valid from the 30th day at 0600 UTC until 0600 UTC the following day.VRB04KT 3SM SCT040 OVC150 TEMPO 2124 SHRA means the forecast from 0600 until 0200 UTC is wind variable in direction at 4 kt., visibility 3 SM, scattered cloud layer at 4,000 ft., ceiling 15,000 ft. overcast, with occasional rain showers between 2100 and 2400 UTC.FM0200 10010KT P6SM OVC020 BECMG0306 NSW BKN020= means the forecast from 0200 until 0300 is wind 100° true at 10 kt., visibility greater than 6 SM, ceiling 2,000 ft. overcast then becoming no significant weather, ceiling 2,000 ft. broken between 0300 to 0600 UTC.
Ascent Quick Quiz - 14.5 Terminal Aerodrome Forecast (TAF)Question 1: (Refer to figure 15.) In the TAF for KMEM, what does "SHRA" stand for?
Question 2: (Refer to figure 15.) During the time period from 0600Z to 0800Z, what visibility is forecast for KOKC?
Question 3: (Refer to figure 15.) In the TAF from KOKC, the clear sky becomes
Question 4: (Refer to figure 15.) What is the valid period for the TAF for KMEM?
Question 5: (Refer to figure 15.) Between 1000Z and 1200Z the visibility at KMEM is forecast to be?
Question 6: (Refer to figure 15.) What is the forecast wind for KMEM from 1600Z until the end of the forecast?
Question 7: (Refer to figure 15.) In the TAF from KOKC, the "FM (FROM) Group" is forecast for the hours from 1600Z to 2200Z with the wind from
Question 8: (Refer to figure 15.) The only cloud type forecast in TAF reports is
14.6 Weather Depiction Charts
A weather depiction chart is the outline that you would get, if you collected all the METARs in the United States and used the information contained within them to create a structured graphic representation of the sky conditions based on METAR reports. The weather depiction chart is able to convey, with a relatively quick glance, a general overall picture of where the reported weather conditions are below, or marginal, or above VFR minimums. The weather depiction chart also displays recent positions of frontal systems and indicates the type of front by symbols.
Example Weather Depiction Chart
The reporting stations that provide the weather information are marked with a small circle.
The sky conditions at the station are conveyed by the degree that the circle is filled in
- If the sky at the station is clear, the circle is open.
- If the sky has scattered clouds, the circle is 1/4 solid,
- If there is a broken ceiling, the circle is 3/4 solid.
- If the sky at the station is overcast, the circle is solid.
- If the sky is obscured, then there is an "X" in the circle.
Visibility is indicated next to the circle in Statute Miles (SM).
- 3 means 3 SM visibility.
- If the visibility is greater than 6 SM, it is not reported.
The cloud heights are expressed in hundreds of feet above ground level. So, 110 means 11,000 ft. AGL.
Areas with ceilings below 1,000 ft. and/or visibility of less than 3 SM, (areas that have weather which is below VFR minimums) are shaded in and enclosed with solid black contour lines.
Areas of marginal VFR with ceilings of 1,000 to 3,000 ft. and/or visibility at 3 to 5 SM are bracketed by solid black contour lines but are unshaded.
Ceilings greater than 3,000 ft. and visibility greater than 5 SM are not indicated by contour lines on weather depiction chart. So, the clear areas on the chart are the areas of "clear" VFR weather.
Significant weather is indicated by the following symbols:
Ascent Quick Quiz - 14.6 Weather Depiction ChartsQuestion 1: (Refer to figure 18.) Of what value is the Weather Depiction Chart to the pilot?
Question 2: (Refer to figure 18.) The IFR weather in northern Texas is due to
Question 3: (Refer to figure 18.) What weather phenomenon is causing IFR conditions in central Oklahoma?
Question 4: (Refer to figure 18.) What is the status of the front that extends from Nebraska through the upper peninsula of Michigan?
Question 5: (Refer to figure 18.) According to the Weather Depiction Chart, the weather for a flight from southern Michigan to north Indiana is ceilings
Question 6: (Refer to figure 18.) The marginal weather in central Kentucky is due to low
14.7 Radar Summary Charts and Radar Weather Reports
Radar Summary Charts graphically display a collection of radar reports concerning the type, intensity, and movement of precipitation like lines and cells of thunderstorms, squall lines, and other areas of hazardous precipitation. Lines and cells of hazardous thunderstorms can be easily seen on a radar summary chart.
Severe Weather Watch areas are enclosed by heavy, dashed lines.
Example Radar Summary Chart
The following symbols are used on radar summary charts.
A Radar Weather Report is a textual report of radar observations.
They list information on the type, intensity, and cell movement of precipitation.
Ascent Quick Quiz - 14.7 Radar Summary Charts and Radar Weather ReportsQuestion 1: (Refer to figure 19, area B.) What is the top for precipitation of the radar return?
Question 2: What does the heavy dashed line that forms a large rectangular box on a radar summary chart refer to?
Question 3: (Refer to figure 19, area B.) What type of weather is occurring in the radar return?
Question 4: (Refer to figure 19, area D.) What is the direction and speed of movement of the cell?
Question 5: (Refer to figure 19, Area E.) The top of the precipitation of the cell is
Question 6: What information is provided by the Radar Summary Chart that is not shown on other weather charts?
Question 7: Radar weather reports are of special interest to pilots because they indicate
14.8 En Route Flight Advisory Service
En Route Flight Advisory Service (EFAS) provides in-flight weather advisories to pilots on 122.0 MHz below FL 180.
Generally, service is available from 6 a.m. to 10 p.m. local time.
EFAS provides information regarding actual weather and thunderstorm activity along your proposed route. EFAS acts continual exchange of information on winds, turbulence, visibility, icing, etc., between pilots and weather briefers.
Ascent Quick Quiz - 14.8 En Route Flight Advisory ServiceQuestion 1: How should contact be established with an En Route Flight Advisory Service (EFAS) station, and what service would be expected?
Question 2: What service should a pilot normally expect from an En Route Flight Advisory Service (EFAS) station?
Question 3: Below FL180, en route weather advisories should be obtained from an FSS on
14.9 Winds and Temperatures Aloft Forecasts
Winds and Temperatures Aloft Forecast provides a forecast of wind speeds and temperatures specific altitudes for certain locations across the US.
These forecasts are compromised of a series of digit groupings conveying wind direction with reference to true north and the wind speed in knots.
Example Winds and Temps Aloft Chart
A four-digit number is used when temperatures are not forecast.
- The first two digits indicate the wind direction after a zero is added.
- The next two digits indicate the wind speed.
- No temperatures are forecast for the 3,000-ft. altitude, or for altitudes that are within 2,500 ft. AGL of the reporting station.
A six-digit number includes the forecast temperature aloft.
- The last two digits indicate the temperature in degrees Celsius.
- A plus(+) or minus(-) symbol is indicated before the temperature, except at altitudes above 24,000 ft. MSL (where it is always below freezing - brrrr!).
When the wind speed is less than 5 kt., the forecast is coded 9900, which means that the wind is light and variable.
When the wind speed is over 100 kt., 50 gets added to the direction component and 100 is subtracted from the speed.
So, to decode this sequence, you simply have to reverse the process: subtract 50 from the direction component, and add 100 to the speed.
STL 34000 | 730649 decodes to:
St. Louis winds at 34000 ft. are (73-50) = 230°, and (100+06) = 106 kts., at -49°C (always negative above 24,000 ft.).
Ascent Quick Quiz - 14.9 Winds and Temperatures Aloft ForecastsQuestion 1: When the term "light and variable" is used in reference to a Winds Aloft Forecast, the coded group and windspeed is
Question 2: What values are used for Winds Aloft Forecasts?
Question 3: (Refer to figure 17) What wind is forecast for STL at 12,000 feet?
Question 4: (Refer to figure 17) Determine the wind and temperature aloft forecast for DEN at 9,000 feet.
Question 5: (Refer to figure 17) What wind is forecast for STL at 12,000 feet?
Question 6: (Refer to figure 17) Determine the wind and temperature aloft forecast for MKC at 6,000 ft.
Question 7: (Refer to figure 17) What wind is forecast for STL at 9,000 feet?
14.10 Significant Weather Prognostic Charts
Significant Weather Prognostic Charts, also called "Sig Prog Charts", are useful to determine areas to avoid due to freezing levels and/or turbulence. Significant Weather Prognostic charts contain four charts (or panels) per complete graphic.
Example Significant Weather Prog Chart
- The two upper panels forecast significant weather from the surface up to 24,000 ft: one for 12 hr. and the other for 24 hr. from the time of issuance.
- The two lower panels forecast surface conditions: one for 12 hr. and the other for 24 hr. from time of issuance.
The top panels show
- Ceilings less than 1,000 ft. and/or visibility less than 3 SM (IFR) by a solid line around the area;
- Ceilings 1,000 to 3,000 ft. and/or visibility 3 to 5 SM (MVFR) by a scalloped line around the area;
- Moderate or greater turbulence by a broken line around the area;
- A peaked hat * indicates moderate turbulence.
- Altitudes are indicated on the chart; e.g., 180 means from the surface to 18,000 ft.
- Freezing levels, given by a dashed line corresponding to the height of the freezing level.
The bottom panels show the location of
- Highs, lows, fronts
- Other areas of significant weather
- Areas of precipitation
- Unshaded outlined areas indicate precipitation covering half or less of the area.
- Shaded outlined areas indicate precipitation covering more than half of the area.
- Precipitation type and intensity is reported with standard symbols.
Some examples include:
- Thunder storms embedded in a larger area of continuous moderate rain
- Thunder storms embedded in a larger area of intermittent moderate rain
- Continuous light to moderate snow
- Intermittent light to moderate snow
Precipitation symbols may be connected to the area of precipitation by an arrow if there is not sufficient room on the chart to directly locate the symbols.
Ascent Quick Quiz - 14.10 Significant Weather Prognostic ChartsQuestion 1: (Refer to figure 20.) What weather is forecast for the Florida area just ahead of the stationary front during the first 12 hours?
Question 2: (Refer to figure 20.) Interpret the weather symbol depicted in Utah on the 12-hour Significant Weather Prognostic Chart.
Question 3: (Refer to figure 20.) At what altitude is the freezing level over the middle of Florida on the 12-hour Significant Weather Prognostic Chart?
Question 4: (Refer to figure 20.) How are Significant Weather Prognostic Charts best used by a pilot?
Question 5: (Refer to figure 20.) The enclosed shaded area associated with the low pressure system over northern Utah is forecast to have
14.11 Transcribed Weather Broadcasts
TWEBs are continuous recordings of meteorological and aeronautical information, based on specific routes of flight, and broadcast on certain NDB and VOR frequencies.
Ascent Quick Quiz - 14.11 Transcribed Weather BroadcastsQuestion 1: To obtain a continuous transcribed weather briefing, including winds aloft and route forecasts for a cross-country flight, a pilot should monitor a
Question 2: Transcribed Weather Broadcasts (TWEB's) may be monitored by tuning the appropriate radio receiver to certain
Question 3: Individual forecasts for specific routes of flight can be obtained from which weather source?
14.12 AIRMETs and SIGMETs
SIGMETs and AIRMETs are issued to notify pilots en route of the possibility of encountering hazardous flying conditions.
SIGMET advisories include weather phenomena which are potentially hazardous to all aircraft.
- Lines of thunderstorms
- Embedded thunderstorms
- Thunderstorm areas greater than or equal to thunderstorm intensity level 4 with an area coverage of 40% or more
- Hail greater than or equal to 3/4 in. diameter
- Severe or extreme turbulence or clear air turbulence (CAT) not associated with thunderstorms
- Severe icing not associated with thunderstorms
- Duststorms, sandstorms, or volcanic ash lowering visibility to less than 3 SM
- Volcanic eruption
AIRMET advisories generally only apply to lighter, smaller aircraft (single-engine general aviation airplanes).
AIRMETs notify pilots of:
- Moderate icing
- Moderate turbulence
- Visibility less than 3 SM or ceilings less than 1,000 ft.
- Sustained winds of 30 kt. or more at the surface
- Extensive mountain obscurement
Ascent Quick Quiz - 14.12 AIRMETs and SIGMETsQuestion 1: SIGMETs are issued as a warning of weather conditions hazardous to which aircraft?
Question 2: AIRMETs are advisories of significant weather phenomena but of lower intensities than SIGMETs and are intended for dissemination to
Question 3: Which in-flight advisory would contain information on severe icing not associated with thunderstorms?
Question 4: What information is contained in a CONVECTIVE SIGMET?
Question 5: What is indicated when a current CONVECTIVE SIGMET forecasts thunderstorms?