Aviation Weather Flashcards
METAR
METeorological Aerodrome Reports:
- surface weather observation published every hour
- SPECI - non-scheduled METARs published when there is a significant change
TAF
Terminal Aerodrome Forecast:
- Weather forecast for 5 SM radius area around the station
- issued 4 times a day every 6 hours
- covers 24 to 30 hour forecast periods
What is a Surface Analysis Chart? How often is it issued?
- issued every 3 hours, (6 hours for hawaii & tropical regions)
- shows pressure systems
- isobars
- fronts
- troughs & ridges
What are Radar summary charts? How often are they issued?
Issued every hour at H+35. Available 16 or 24 hrs a day
· Echo type
· Precipitation Intensity and intensity trend
· Echo configuration and coverage
· Echo heights
· Echo movement
· Severe weather watch areas
What are Wind & temp aloft forecasts and how often are they issued?
- wind forecasts at altitudes and flight levels
- issued 4 times daily
What is a Convective Outlook (AC)?
- delineates areas forecast to have thunderstorms (convective activity)
-available graphical or textual
- provides a 3 day forecast of convective activity
- Issued:
day 1: 5 times a day
day 2: twice
day 3: once
4 Types of weather briefings (SAOI)
1) Standard - full brief, includes everything
2) Abbreviated - updates previous weather info.
3) Outlook - for departure 6 hours away. includes forecasts for time of flight
4) Inflight- provided by FSS
What is an AIRMET and what are the Types of AIRMETs
AIRMET = weather of lower intensity than of SIGMETs but poses hazardous weather to ALL aircrafts VALID for 6 HOURS
Types:
1) Zulu
2) Tango
3) Sierra
AIRMET (Zulu)
- moderate icing and freezing levels
AIRMET (Tango)
- moderate turbulence winds of 30 kts or greater and low level wind shear
AIRMET (Sierra)
- IFR conditions and or extensive mountain obscurations
What is an SIGMET and when they are issued
SIGMET = non-convective weather hazardous to ALL aircrafts VALID for 4 HOURS
Issued when:
- severe icing NOT associated w/ thunderstorms
- severe or extreme CAT not associated w/ thunderstorms
- Dust storms, sandstorms, lowering surface vis. below 3 sm
Convective SIGMET
- Inflight advisory of convective weather, significant to the safety of ALL aircrafts
- VALID 2 HOURS & updated if there is any signifcant changes or H+55
- Severe thundestorms w/ surface winds 50 kts or greater
- Hail 3/4” or greater in diameter
- Embedded thunderstorms
- Tornadoes
- Line of thunderstorms 60 miles or greater
ASOS
Automated Surface Observation System
updated hourly
AWOS
Automated Weather Observation System
updated every minute
ATIS
Automated Terminal Information System
continuous broadcast of local airport wx updated hourly usually 55 minutes passed the hour
What are the 3 ingredients for a thunderstorm?
1) Visible moisture
2) Unstable temperature lapse rate
3) Uplifting force
What are the 3 stages in a thunderstorm life cycle?
1) Cumulus - lifting action of air begins, strong updrafts prohibit moisture from falling. Approx. 15 minutes after cumulus stage, mature stage starts.
2) Mature - MOST dangerous stage
begins when precipitation (rain or hail) starts to fall, lots of up/down drafts
3) Dissipating - strong downdrafts, cell starts to die off
What are the 5 types of fog? RAISU
1) Radiation - clear calm nights ground cools rapidly, when cooling causes air to reach saturation, fog forms.
2) Advection - warm, moist air moved by wind, over a colder surface, causes air to become saturated
3) Ice - forms when temp. is well below freezing and humidity = 100% ; only in colder regions
4) Upslope - moist, stable air forced up over terrain & cooled down to its dew point by adiabatic cooling
5) Steam - cold, dry air moves over warm water. When water evaporates, it rises and forms steam/smoke.
What are the 3 Types of Icing?
1) Clear (2 deg ~ -10 deg C) Most dangerous
2) Rime (-10 deg ~ -20 deg C)
3) Mixed (-15 deg ~ -20 deg C)
Do we have De-icing or Anti-icing?
Anti-icing, pitot tube & cabin heat to prevent windshield from frosting with ice
What to do when you fly into icing conditions?
1) Pitot heat ON
2) AVIATE and COMMUNICATE for deviation or lower altitude
3) If ATC delays you, declare and emergency and ask for vectors
4) If icing conditions are all around you, land as soon as practicable
What are the 3 Kinds of Icing?
1) Structural: ice accumulating on a/c structure
2) Induction: carburetor icing & airbox icing (when iced over, alternate air door will open and lets unfiltered air in decreasing rpm)
3) Critical Systems - when instruments ice up, pitot etc.
What (2) Anti-Icing measures do we have?
1) Pitot Heat - electrically heated, turn on when below 10 deg C in clouds
2) Windshield defroster - cabin heat pointed at windshield
What De-Icing measures do we have?
None
A/C have: pneumatic boots, weeping wings, bleed air, electrically heated, and electro impulse etc.
What are Isobars?
Lines of same or similar pressure, tells us about the pressure gradient force
What is a pressure gradient force?
change in pressure over a given distance, measured by the space between isobars
closely spaced isobars = strong winds
further spaced isobars = light winds
What are the 4 types of Fronts?
1) Cold front: bad weather, occurs when a mass of cold, dense, and stable air replaces a body of warmer air. B/c the air is so dense it acts like a snowplow, sliding under warmer air & forcing the less dense air aloft. Moves faster than warm fronts. (25 to 30 mph)
2) Warm front: good weather, poor vis. warmer air slowly overtaking the colder air. Brings higher humidity. Depending on the stability of a warm front, after being overtaken by a cold front, if warm front is stable, clouds will form, if air is not stable, thunder storms and squall lines would form.
3) Occluded front: cold front catching up to a warm front. Strong wind heavy precipitation
4) Stationary front: neither air mass overtaking each other hence “stationary”, stationary clouds