Weather Information Flashcards
METAR
Meteorological Terminal Aviation Routine Report
- Surface Aviation weather observation
- Updated every hour
- Current conditions based on ATIS, AWOS and ASOS
- SPECI: special report to update current METAR for rapidly changing weather conditions
- Location, time, wind direction (magnetic), wind speed (knots), visibility (statute miles), cloud cover, cloud height, temp, dew point, altimeter, remarks
METAR KSTS 261451Z 30008KT 10SM SCT120 26/22 A3012
TAF
Terminal Aerodrome Forecast
- Forecast - Valid 24 hrs - Updated 4 times/day, within 5nm of airport
- Location, time issued, valid time, wind direction, wind speed, visibility, cloud cover, cloud height, potential severe weather
TAF KSTS 261121Z 261212 VRB03KT P6SM BKN200
BECMG 1314 22005KT FEW025
FA (Area Forecast)
- Forecast of VFR clouds and weather conditions
- Size of several states (~3000 sq miles)
- Broken up into 6 different regions -updated 3x a day
- 24 hr period ( 18 hr forecast, 6 hr categorical outlook)
- Cloud height, cloud cover, visibility, expected precipitation type and intensity
The area forecast together with the AIRMET Sierra bulletin are used to determine forecast en-route weather and to interpolate conditions at airports which do not have a terminal forecast (TAF) issued.
- Consists of:
- 12 hour forecast plus a 6 hr categorical outlook. All times are Coordinated Universal Time (UTC). All distances except visibility are in nautical miles. Visibility is in statute miles.
Synopsis section which is a brief summary of the location and movement of fronts, pressure system, and circulation patterns for an 18 hour period.
VFR clouds and weather section which is a 12 hour forecast, in broad terms, of clouds and weather significant to flight operations plus a 6 hour categorical outlook. This section is usually several paragraphs. AIRMET Sierra supplies information regarding Instrument Flight Rule (IFR) conditions. The breakdown may be by states, by well-known geographical areas, or in reference to
location and movement of a pressure system or front. A categorical outlook, identified by OTLK, is included for each area breakdown
PIREP
Pilot Weather Report
- UA: Routine PIREP
- UUA: Urgent PIREP
- Confirm conditions, ceiling, visibility, precipitation, icing, turbulence
ATIS
Automated Terminal Information Service
- Updated after receipt of weather observation
- Use Below 3000’ AGL
- Contains: Wind, Vis, Sky Condition, Temp/Dew, Altimeter, Remarks: Landing Runway and What Approach is in Use. (runways in use, runway/taxi way closures, ect.)
ASOS
Automated Surface Observation Service
- Continually updates
- Wind direction, speed, temp, dew point, pressure, cloud type, type of precipitation
AWOS
Automated Weather Observation Service
- Continually updated
- AWOS 1 - Wind, Vis and Altimeter
- AWOS 2 - 1 and Sky Condition and Temp/Dew
- AWOS 3 - 1 and 2 plus Density Alt.
ASOS
Automated Surface Observation System
- Better than AWOS
- Gives you everything
- Wind, Vis, Sky, Temp/Dew, Altimeter, cloud type, precipitation and Runway Information
Radar Summary Chart
- Based on precipitation (Echo return)
- Observed areas of precipitation, intensity, heights of tops of echoes, types of precipitation, sever weather watches
- Updated hourly
Lt. Green - Weak Precip, no turbulence
Yellow - moderate precip and moderate turb
Red - Heavy Precip & Severe Turbulence
Surface Analysis Chart
- METAR Reports shown over continental US
- Updated every 3 hours
- Shows Fronts, Pressure Systems and Isobars
- For planning flights, based on the fronts and winds/Temps
- Trough is an elongated low pressure
- Ridge is an elongated high pressure
The surface analysis chart is a computer-generated chart, with frontal analysis by
Forecasters, transmitted every 3 hours covering the contiguous 48 states and adjacent areas.
Weather Depiction Chart
- Shows where it’s IFR, MVFR and VFR
- METAR Reports shown over continental US
- Consists of fronts, high/low pressure, cloud cover, visibility (doesn’t show pressure millibars like Surface Analysis Chart)
- IFR/VFR/MVFR areas
- updated ever 3 hours
Weather Ceiling/Visibility Categories
VFR- ceiling >3000AGL, visibility >5 sm
MVFR- ceiling 1000-3000AGL, visibility 3-5 sm
IFR- ceiling 500-1000AGL, visibility 1-3 sm
LIFR - ceiling <500AGL, visibility <1 sm
Significant Weather Prognostic Charts (SIGWX)
A four-panel chart that includes 12– and 24–hour forecasts for significant weather and surface weather. The valid time for the chart is printed on the lower left corner.
The upper two panels show forecast significant weather, which may include non-convective turbulence, freezing levels, and IFR or MVFR weather.
The lower two panels show the forecast surface weather and depicts the forecast locations and characteristics of pressure systems, fronts, and precipitation.
- Used to review flight conditions for flight planning/briefing
- Low level is Surface to FL240
- Mid level is FL100 to FL450
- High level FL250 to FL630
- 12 & 24 hr forecasts for areas of VFR, MVF, IFR, turbulence, freezing levels
- Updated every 6 hours (4x daily)
AIRMET (Airmen’s Meteorological Information) (WA)
Focus on weather that may adversely affect aircraft safety in still flyable weather
-Forecast for hazardous weather for light aircraft
-Issued every 6 hours
Sierra: IFR and mountain obscuration
Tango: moderate turbulence, strong surface winds (over 30kts), low level wind shear
Zulu: icing and freezing levels
SIGMET (Significant Meteorological Information) (WS)
- Non-convective hazardous forecasts for all aircraft
- Conditions: Moderate to Severe
- Issued as required valid for 4 hours
- Cover area of 3,000 miles
- severe icing not associated with T-Storms
- severe turbulence or CAT not associated with T-Storms
- sandstorms/dust storms that lower vis. <3sm
- volcanic ash
- Types November through Yankee
Convective SIGMET (WST)
- Issued as required
- Valid for 2 hours
-Moderate to severe thunderstorms covering 40% of
the area - Surface Winds > 50 kts
- Thunderstorm lines at least 60 miles long
- Embedded thunderstorms -Tornadoes
- Hail over 3/4’’
- Severe Icing Conditions
G AIRMET
Graphical AIRMET
Radar Summary
- Observed areas of precipitation, intensity, heights of tops of echoes, types of precipitation, sever weather watches
- Updated hourly
Winds and Temperatures Aloft
- Forecast based on upper air observations from a weather balloon
- Determine winds for flight planning
- Location, altitude, wind direction (true north)/(temp c)
- updated 4 times a day
- 9900 Light and variable less than 5 kts -0000KT calm
- no winds given 1500 AGL, use METAR
- no temps given if stations is within 2500 AGL
- Temp inversions, best cruise altitude
Flight Service Station (FSS)
-primary source for preflight weather information
1-800-WXBRIEF
HIWAS
Hazardous Inflight Weather Advisory Service
-AIRMETs, SIGMETs, Convective SIGMETs, Urgent PIREPS
Weather Briefings
- Standard: most complete briefing
- Abbreviated: shortened version of standard, used to update previous briefing
- Outlook: forecast information 6 or more hours away
Composition of the Atmosphere
78% Nitrogen
21% Oxygen
1% Trace gases (argon, CO2, etc)
0-5% water vapor, this amount of water vapor is responsible for major changes in weather
Layers of the Atmosphere (Lowest to Highest)
-Troposphere (Tropopause-boundary layer that traps moisture and associated weather in the troposphere) -Stratosphere -Mesosphere -Thermosphere
Atmosphere Circulation
- Atmosphere is always in motion trying to find its equilibrium
- Major factor in atmospheric circulation is the uneven heating of Earth’s surface
Standard Atmospheric Properties
Sea Level Pressure and Temperature
-29.92”Hg (1,013.25millibars) and 15°C
Pressure change with altitude
1” Hg per 1000 ft
Characteristics associated with Low Pressure System
Air circulation is inward, upward, and counterclockwise.
-Area or rising air, which is conductive to cloudiness, precipitation, and bad weather
Characteristics associated with High Pressure System
Air circulation is outward, downward, and clockwise
-Area of descending air which tends to favor dissipating clouds and good weather
Unstable Air
Warm moist air
Stable Air
Cool dry air that resists vertical movement
Standard Lapse Rate
2°C per 1,000’
Isobar
line on a weather chart which connects areas of equal or constant barometric pressure.
Ridge
- Elongated area of high pressure
- High pressure ridge is depicted as yellow zig zag lines on a surface analysis chart
Trough
- Elongated Area of low pressure
- Low pressure trough is depicted as an orange dashed line on a surface analysis chart
Temperature Inversion
- When the temperature of the air rises with altitude
- smooth stable air, but usually poorer visibility if realative humidity is high
Relative Humidity
Actual amount of moisture in the air compared to the total amount of moisture the air could hold at the temp.
Dew Point
Temperature at which the air becomes saturated and the air condenses into fog, dew, frost, clouds, rain, or snow.
Dew point is the temperature to which a sample of air must be cooled to attain a state of saturation.
Sublimation
Solid to Gas. The water absorbs heat from surroundings
Deposition
Gas to Solid. (Snowflakes). Water releases heat to surroundings
Evaporation
Liquid to Gas. The water absorbs heat from surroundings.
Condensation
Gas to Liquid. The water releases heat to surroundings.
Radiation Fog
Occurs on cool calm nights when surface cools and brings cooling temperatures to dew point