Weather Flashcards
What is the primary means of obtaining a weather briefing?
The primary source of preflight weather briefings is a briefing from a briefer at the AFSS/FSS. These briefings are available through 1-800-WX-BRIEF.
What are some examples of other sources of weather information?
Weather and aeronautical information from numerous private industry sources.
FSS
Where can you find a listing of FSS and weather information numbers?
In the Chart Supplement
What type of weather briefings are available from an FSS briefer?
a. Standard Briefing
b. Abbreviated Briefing - when you need an update to a previous briefing or only one or two items.
c. Outlook Briefing - When your proposed time of departure is six or more hours from the time of the briefing.
d. Inflight Briefing - request when needed to update a preflight briefing.
What pertinent information should a weather briefing include?
S – Synopsis
A – Adverse conditions
Cr – Current weather
E – Enroute forecast
D – Destination terminal forecast
Wi – Winds aloft
Nd – Notams
(SACrED WiNd)
What is an ATIS?
Automated Terminal Information Service
It’s a continuous broadcast of recorded non-control information in selected high activity terminal areas. Its purpose is to improve controller effectiveness by automating the transmission of routine information.
What type of information is provided in an ATIS broadcast?
a. Time of the latest observation
b. Wind (direction & speed)
c. Visibility (distance sm)
d. Cloud Layers & Ceiling (AGL)
e. Temperature and Dewpoint
f. Altimeter
g. Instrument approach & runway in use
What is a METAR?
A routine weather observation of the conditions at a given site and time.
What information is contained in a METAR?
a. ICAO station identifier
b. date and time of report
c. wind (direction and speed)
d. visibility
e. weather phenomena
f. sky condition
g. temperature/dew point
h. altimeter
i. remarks
Describe the various types of weather observing programs now in use.
a. Manual observations - made by FAA or NWS personnel.
b. AWOS - automated weather observing system
c. ASOS - automated surface observing system. Can be transmitted over VHF radio or the voice portion of a NAVAID.
What are PIREP’s?
What information is required with them?
PIREP’s are reports made by pilots enroute, about concerning weather observations / experiences.
L - Location
A - Altitude
T - Time
T - Type of Aircraft
O - Observation
LATTO
What are terminal aerodrome forecasts?
TAFs, or Terminal Aerodrome Forecasts, provide weather forecasts for the area within five statute miles of the center of an airport’s runway complex.
They are valid for a 24-hour period and updated four times a day.
- What is a convective SIGMET?
- What conditions must be present for a convective SIGMET to be issued?
- Convective SIGMET implies severe or greater turbulence, severe icing, and low-level wind shear.
- a. severe thunderstorms due to: surface winds greater than or equal to 50 kts, hail at the surface greater to 3/4 inches in diameter, tornadoes
b. embedded thunderstorms
c. A line of thunderstorms
d. thunderstorms that produce precipitation levels greater than or equal to heavy intensity precipitation, affecting 40% or more of an area at least 3000 mi.²
- What is a SIGMET, and how long is it valid?
- What conditions would require a SIGMET to be issued?
- A SIGMET advises non-convective weather that is potentially hazardous to all aircraft. The maximum forecast is four hours.
- a. severe icing not associated with a thunderstorm
b. severe or extreme turbulence or a clear air turbulence not associated with thunderstorms
c. Dust storms or sandstorms lowering surface or in-flight visibility’s to below 3 miles
d. Volcanic ash
- What is an AIRMET?
- What conditions would require an AIRMET to be issued?
- What are the different types of AIRMETs?
- An AIRMET is an advisory of significant weather phenomenon for conditions at intensities lower than required for issuance of SIGMETs, issued every six hours.
- Issued for IFR conditions, moderate turbulence, strong surface winds (30+ kts), icing (moderate & freezing), mountain obscuration.
- a. Sierra describes IFR conditions and/or extensive mountain obscuration
b. Tango describes turbulence, surface winds of 30 knots or greater, or non-convective low-level windshear
c. Zulu describes moderate icing and provides freezing level heights
What valuable information can be determined from a Winds and Temperature Aloft Forecast (FB)?
How often is the Winds and Temperatures aloft forecast issued?
Most favorable altitude, areas of possible icing, temperature inversions, turbulence.
Winds and temperatures aloft are forecast 4 times daily.
What is a center weather advisory (CWA)?
An unscheduled, short-term weather advisory issued by ARTCC to warn pilots of hazardous weather conditions.
Issued as needed (not scheduled like SIGMETs or AIRMETs) & valid up to 2 hours (but can be extended).
Covers localized hazardous weather, such as severe turbulence or icing, LLWS, thunderstorms, reduced visibility.
What is a convective outlook (AC)?
What time period is it valid, and how is it categorized?
Convective Outlook is a flight planning tool used to avoid thunderstorm areas.
It describes the prospects for general thunderstorm activity during the following 24 hour periods. Categorized by risk levels (Slight Risk, Moderate Risk, High Risk).
What is a surface analysis chart?
A surface analysis chart overlays weather conditions on a map at the surface & low altitudes.
Pilots use it to get a visual understanding of phenomena like pressure, temperature, wind, and precipitation in the area at a given time.
Pressure lines (isobars) indicate areas of equal pressure.
Other features on the chart include highs and lows, troughs, ridges, dry lines, squall lines, and tropical waves.
What is a radar summary chart?
It displays areas of precipitation along with information about type, intensity, configuration, coverage, echo top, and cell movement of precipitation.
What is a winds and temperatures aloft chart?
How often is winds and temperature aloft issued?
A computer generated chart showing observed and forecast winds and temperatures aloft from 6,000 to 39,000 feet MSL.
4 times daily.
What are significant weather prognostic charts (SIGWX)?
A chart that shows forecasted weather conditions.
It shows fronts, precipitation, pressure systems, and low ceilings.
They’re issued 4x/day and valid for 12, 24, 36 and 48 hours.
What altitude range does a low-level significant weather prog chart cover?
Surface to 24,000 feet (400mbs)
What is a convective outlook chart?
This chart shows areas forecast to have the potential for any convection, and/or extreme weather events such as tornados, wind gusts 50 knots or greater, or hail 3/4 inch diameter or greater for the next three days.
What are NOTAMs ?
Notices to Airmen. Time critical information which is not printed on any aeronautical chart.
What type of information might a NOTAM contain?
Airport or runway closures, changes of navigational aids, ILS’s, radar service, or other essential information for planning a flight.
What are the four basic groups of NOTAMs?
a. (D) NOTAMs - pertain to enroute nav aids, public-use airports listed in the Chart Supplement, facilities, services, and procedures.
b. FDC (Flight Data Center) NOTAMs - regulatory information such as changes in IFR charts, procedures, and airspace usage (e.g. TFR’s).
c. POINTER NOTAMs - issued by a FSS to highlight or point out another NOTAM.
d. MILITARY NOTAMs - pertain to military nav aids and airports
Where can NOTAMs be obtained?
a. flight service station
b. authorized third party site / EFB.
c. FAA’s NOTAM website
What are the two major classifications of thunderstorms?
Air mass thunderstorm
Steady state thunderstorm
What is an air mass thunderstorm?
a. Results from surface heating
b. Only lasts an hour or two
c. Occurs in random unstable air
What is a steady-state thunderstorm?
a. Usually forms in lines
b. Lasts for several hours
c. Produces heavy rain, winds, and possibly tornados
d. Normally associated with weather systems
Give some examples of charts and reports useful in determining the potential for and location of thunderstorms along your route.
a. Convective outlook
b. Radar summary chart
c. PIREPs
What are microbursts?
Small-scale intense downdrafts which, on reaching the surface, spread outward in all directions. They cause both horizontal and vertical wind shears which can be hazardous to all aircraft.
Where are microbursts most likely to occur?
Almost anywhere there is convective activity.
What are some basic characteristics of a microburst?
Size: less than 1 mile in diameter as it descends from the cloud base. Can extend to 2.5 miles near ground level.
Intensity: downdrafts as strong as 6,000 ft. per minute. Horizontal winds near the surface as strong as 100 kts.
Duration: Usually lasts 5 - 15 mins.
How can microburst encounters be avoided?
Check weather forecasts, such as TAFs and SIGMETs, for convective activity and reports, such as METARs and PIREPs, for wind shear and sudden airspeed changes in the airport area.
Define wind shear
A sudden change in wind speed or direction. It can be vertical or horizontal.
State the areas where wind shear is most likely to occur.
a. Low-level temperature inversion
b. In a frontal zone or thunder storm
c. Clear air turbulence at high levels associated with a jet stream or strong circulation.
Why is wind shear an operational concern to pilots?
Unexpected changes in wind speed and direction can be potentially hazardous to aircraft operations at low altitudes on approach to and departing the airport.
The sudden change in wind direction can cause a drastic loss of altitude.
What airplane characteristics will be observed in a wind shear with a sudden increase in headwind?
Increase in airspeed and altitude along with a nose-up pitching tendency.
What airplane characteristics will be observed in a wind shear with a sudden decrease in headwind?
Decrease in airspeed, altitude and pitch attitude.
What is the proper action from the pilot when wind shear is encountered?
For either an increase or decrease in headwind, the pilot should add power and increase pitch attitude to maintain proper airflow over the wings.
Concerning wind shear detections, what does LLWAS indicate?
Low-Level Wind Shear Alert System. It uses sensors located around an airport to compare wind direction and speed to detect a wind shear.
Where does most weather occur?
What is that altitude range?
In the troposphere, which can extend to 36,000 feet
Define dewpoint
The temperature at which air is saturated with water vapor and can’t hold any more water. 100% humidity.
A small temp/dewpoint spread means…
…clouds, dew and fog is likely.
Stable atmosphere has (4 qualities)
Stratiform clouds
Smooth air
Steady precipitation
Fair to poor visibility
Unstable atmosphere has (4 qualities)
Cumuliform clouds
Rough air/turbulence
Showery precipitation
Good visibility
Low-Pressure systems - what direction do the winds move?
Inward, upward and counterclockwise
High-Pressure systems - what direction do the winds move?
Outward, downward and clockwise
What is an Occluded Front?
When a fast-moving cold front catches a slow-moving warm front
Describe a Trough
Areas of low pressure that are associated with cloudiness and precipitation.
Usually associated with bad weather.
Describe a Ridge
Areas of high pressure that are associated with warm air and decreased precipitation.
Usually associated with good weather.
A Cold Front weather passage has…
As the front passes - cumulus or cumulonimbus clouds.
Heavy rain, lightning, thunder, gusty winds, rapid temperature drop.
A Warm Front weather passage has…
Stratiform clouds, drizzle, poor visibility and rise in temperatures.
What does the weather associated with a front depend on?
- Moisture content (more moisture leads to more severe weather)
- Stability of the atmosphere (unstable air supports stronger convection)
- Speed of the front (faster moving [eg cold] fronts create more intense wx, slower moving prolong precipitation)
- Temperature contrast (greater temp diff between air masses increases wx intensity)
- Terrain effects (mountains can enhance lifting
What is the typical icing temperature range for each icing type? Describe the icing types.
0°C to -20°C
Clear Ice (0°C to -10°C): Large supercooled droplets freeze slowly, forming smooth, hard ice.
Rime Ice (-10°C to -20°C): Small supercooled droplets freeze instantly, creating rough, opaque ice.
Mixed Ice (-10°C to -15°C): A combination of clear and rime ice, forming irregular shapes.
How are the different Convective Outlook probabilities defined? (5)
MRGL - Marginal (green)
SLGT - Slight (yellow)
ENH - Enhanced (orange)
MDT - Moderate (red)
HIGH - High (magenta)
What altitude range does a High-level Significant Weather Prognostic chart show?
24,000 to 60,000 MSL
Describe VFR conditions (ceiling & visibility)
Ceiling: greater than 3000 feet AGL
Visibility: greater than 5 statute miles
Describe MVFR conditions (ceiling & visibility)
Ceiling: 1000 to 3000 feet AGL
Visibility: 3-5 statue miles
Describe IFR conditions (ceiling & visibility)
Ceiling: 500 to 1000 feet AGL
Visibility: 1-3 statute miles
Describe LIFR conditions (ceiling & visibility)
Ceiling: Less than 500 feet AGL
Visibility: Less than 1 statute mile
Where can windshear can be found?
Around thunderstorms or convection
Low-level temperature inversion
Clear Air turbulence with Jet Stream
Frontal zone
What are the 3 stages of a Thunderstorm?
Cumulus
Mature
Dissipating
What may be omitted from ATIS?
Ceiling and Sky if ceiling is above 5000 feet
What important risk factor is not shown by radar?
Fog and clouds
If windshear increases your headwind what happens and what action do you take?
Causes an increase in airspeed, altitude and pitch
Action is to increase airspeed and pitch
If windshear decreases your headwind what happens and what action do you take?
Causes a decrease in airspeed, altitude and pitch
Action is to increase airspeed and pitch
How to avoid turbulence around thunderstorms
DO NOT
- fly under anvil
- fly under a T-Storm
- fly without airborne radar into clouds with embedded T-storms
- assume ATC can help
- use ADS-B wx for tactical maneuvering around T-storm
How to avoid thunderstorms if you do not have onboard T-storm detection
- Nexrad, but that may be 15-20 minutes old
- ask ATC for radar navigation and deviation
- listen to ATC for aircraft deviating
- monitor PIREPs
- avoid areas with 6/10 T-storm coverage
- avoid areas with vivid and frequent lightning
Risks of relying on ATC for in-flight assistance avoiding Thunderstorms
ATC radar limitations
Frequency congestion
Separation of traffic is their primary concern
What can you expect when flying towards a low-pressure system?
Rising air
Cloudiness
Precipitation
Bad weather
How can you determine the stability of atmosphere?
Analyze the temperature lapse rate, comparing the actual temperature change with altitude (usually 2C / 1000ft) to a standard “dry adiabatic lapse rate” (usually 3C / 1000ft).
If the air cools faster than the dry adiabatic rate, it’s considered unstable. If it cools slower, it’s considered stable.
If air near surface is warm and moist, suspect instability.
How is the vertical extent of clouds determined?
Stability of the atmosphere
Under what conditions is Carb Icing likely?
With visible moisture
A close temp/dew point spread
What is the definition of a Ceiling?
The lowest broken or overcast layer.
5/8 to 7/8 sky coverage = broken. 8/8 = overcast.
Describe Multi-cell Thunderstorms
A cluster of cells at different stages of their life-cycle.
A new cell takes place of one that moved downwind.
Describe a Supercell
Single quasi-steady cell
Rotating updraft for an extended period
Updraft up to 100knots / 9000 FPM
Where are PIREPs available from?
ATC
FSS
Aviationweather.gov
EFBs
What is the FIS-B frequency
978 MHz
It has weather and aeronautical information
How can you get weather while enroute?
FSS on 122.2
ATIS
ADS-B in
ATC
Describe Airmet Zulu
Moderate icing
Freezing level heights
(last thing you will see if you mess it up - icing)
Describe Airmet Tango
Turbulence - moderate
Windshear
Surface winds - 30+ knots
Describe Airmet Sierra
Low visibility conditions
Ceilings less than 1,000 feet or visibility less than 3 miles
Mountain obscuration
