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Private Pilot Oral Exam Guide > Weather Information > Flashcards

Weather Information Flashcards

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1
Q

State the general characteristics in regard to the flow of air around high and low pressure systems in the Northern Hemisphere.

A

Low pressure - inward, upward, and counterclockwise

High pressure - outward, downward, and clockwise

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2
Q

If your route of flight takes you towards a low pressure system, in general, what kind of weather can you expect? What if you were flying towards a high pressure system?

A

A low pressure system is characterized by rising air, which is conductive to cloudiness, precipitation and bad weather. A high pressure system is an area of descending air which tends to favor dissipation of cloudiness and good weather.

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3
Q

Describe the different types of fronts.

A

Cold front - occurs when a mass of cold, dense, and stable air advances and replaces a body of warmer air.
Occluded front - A frontal occlusion occurs when a fast moving cold front catches up with a slow moving warm front. two types are cold front occlusion and warm front occlusion.
Warm front - the boundary area formed when a war air mass contacts and flows over a colder air mass.
Stationary front - when the forces of two air masses are relatively equal, the boundary or front that separates them remains stationary and influences the local weather for days. The weather is typically a mixture of both warm and cold fronts.

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4
Q

What are the general characteristic of the weather a pilot would encounter when operating near a cold front or warm front?

A

Cold front - as the front passes, expected weather can include towering cumulus or cumulonimbus, heavy rain accompanied by lighting, thunder and/or hail; tornadoes possible; during passage, poor visibility, winds variable and gusting; temperature/dew point and barometric pressure drop rapidly.
Warm front - as the front passes, expected weather can include stratiform clouds, drizzle, low ceilings and poor visibility; variable winds; rise in temperature.

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5
Q

What is a trough?

A

A trough (also called a trough line) is an elongated area of relatively low atmospheric pressure. At the surface when air converges into a low, it cannot go outward against the pressure gradient, nor can it go downward into the ground; it must go upward. Therefore, a low or trough is an area of rising air. Rising air is conductive cloudiness and precipitation; hence the general association of low pressure and bad weather.

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6
Q

What is a ridge?

A

A ridge (also called a ridge line) is an elongated area of relatively high atmospheric pressure. Air moving out of a high or ridge depletes the quantity of air; therefore, these are areas of descending air. Descending air favors dissipation of cloudiness; hence the association of high pressure and good weather.

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7
Q

What are the standard temperature and pressure values for sea level?

A

15 deg C and 29.92 Hg

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8
Q

What are isobars?

A

An isobar is a line on a weather chart which connects areas of equal or constant barometric pressure.

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9
Q

If the isobars are relatively close together on a surface weather chart or a constant pressure chart, what information will this provide?

A

The spacing of isobars on these charts defines how steep or shallow a pressure gradient is. When isobars are spaced very close together, a steep pressure gradient exists which indicates higher wind speeds. A shallow pressure gradient (isobars not close together) usually means wind speeds will be less.

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10
Q

What causes the winds aloft to flow parallel to the isobars?

A

The Coriolis force.

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11
Q

Why do surface winds generally flow across the isobars at an angle?

A

Surface friction.

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12
Q

At what rate does atmospheric pressure decrease with an increase in altitude?

A

1 Hg per 1000 ft

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13
Q

What does dew point?

A

Dew point is the temperature to which a sample of air must be cooled attain the state of saturation.

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14
Q

When temperature and dew point are close together (within 5 deg), what type of weather is likely?

A

Visible moisture in the form of clouds, dew, or fog. Also, these are ideal conditions for carburetor icing.

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15
Q

What factor primarily determines the type and vertical extent of clouds?

A

The stability of the atmosphere.

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16
Q

Explain the difference between a stable atmosphere and an unstable atmosphere. Why is the stability of the atmosphere important?

A

The stability of the atmosphere depends on its ability to resist vertical motion. A stable atmosphere makes vertical movement difficult, and small vertical air movements tend to become larger, resulting in turbulent airflow and convective activity. Instability can lead to significant turbulence, extensive vertical clouds, and severe weather.

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17
Q

List the effects of stable and unstable air on clouds, turbulence, precipitation and visibility.

A

Clouds - stable (stratiform), unstable (cumuliform)
Turbulence - smooth (stable), rough (unstable)
Precipitation - steady (stable), showery (unstable)
Visibility - fair to poor (stable), good (unstable)

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18
Q

When significant precipitation is occurring at the surface, how thick can you expect the clouds to be?

A

Significant precipitation usually requires clouds to be at least 4000 feet thick. The heavier the precipitation, the thicker the clouds are likely to be.

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19
Q

During your pre flight planning, what type of meteorological information should you be aware of with respect to icing?

A 
Location of fronts - a front's location, type, speed, and direction of movement 
Cloud layers - the location of cloud bases and tops, which is valuable when determining if you will be able to climb above icing layers or descend beneath those layers into warmer air; reference PIREPs and area forecasts
Freezing level(s) - important when determining how avoid icing and how to exit icing conditions if accidentally encountered
Air temperature and pressure - icing tends to be found in low pressure areas and at temperatures at or around freezing
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20
Q

What is the definition of the term freezing level and how can you determine where that level is?

A

The freezing level is the lowest altitude in the atmosphere over a given location at which the air temperature reaches 0 deg C. It is possible to have multiple freezing layers when a temperature inversion occurs above the defined freezing level. A pilot can use current icing products (CIP) and forecast icing products (FIP), as well as the freezing level graphics chart to determine the approximate freezing level. Other potential sources of icing information are: area forecasts, PIREPs, AIRMETs, SIGMETs, surface analysis charts, low level significant weather charts, and winds and temperatures aloft (for air temperature at altitude)

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21
Q

What conditions are necessary for structural icing to occur?

A

Visible moisture and below freezing temperatures at the point moisture strikes the aircraft.

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22
Q

Name the main types of icing an aircraft may encounter in flight.

A

Structural, induction system, and instrument icing

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23
Q

Name the three types of structural icing that may occur in flight.

A

Clear ice - forms after initial impact when the remaining liquid portion of the drop flows out over the aircraft surface, gradually freezing as a smooth sheet of solid ice
Rime ice - forms when drops are small, such as those in stratified clouds or light drizzle. The liquid portion remaining after initial impact freezes rapidly before the drop has time to spread out over aircraft surface
Mixed ice - forms when drops vary size or when liquid drops are intermingled with snow or ice particles. The ice particles become imbedded in clear ice, building a very rough accumulation

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24
Q

What action is recommended if you inadvertently encounter icing conditions?

A

The first course of action should be to leave the area of visible moisture. This might mean descending to an altitude below the cloud bases, climbing to an altitude above the cloud tops, or turning to a different course.

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25
Q

Is frost considered to be hazardous to flight? Why?

A

Yes, because while frost does not change the basic aerodynamic shape of the wing, the roughness of its surface spoils the smooth flow of air, thus causing a slowing of airflow. This showing of the air causes early airflow separation, resulting in a loss of lift. Even a small amount of frost on airfoils may prevent an aircraft from becoming airborne at normal takeoff speed. It is also possible that, once airborne, an aircraft could have insufficient margin of airspeed above stall so that moderate gusts or turning flight could produce incipient or complete stalling.

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26
Q

What factors must be present for a thunderstorm to form?

A

a. Sufficient water vapor
b. An unstable atmosphere
c. An initial upward boost to start the storm process in motion

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27
Q

What are the three stages of a thunderstorm?

A

Cumulus stage - updrafts cause raindrops to increase in size
Mature stage - rain at earth’s surface; it falls through or immediately beside the updrafts; lighting; perhaps roll clouds
Dissipating stage - downdrafts and rain begin to dissipate

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28
Q

What is a temperature inversion?

A

An inversion is an increase in temperature with height a reversal of the normal decrease with height. An inversion aloft permits warm rain to fall through cold air below. Temperature in the cold air can be critical to icing. A ground based inversion favors poor visibility by trapping fog, smoke, and other restrictions into low levels of the atmosphere. The air stable, with little or no turbulence

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29
Q

State two basic ways that fog may form.

A

a. Cooling air to the dew point

b. Adding moisture to the air near the ground

30
Q

Name several types of fog.

A

a. Radiation fog
b. Advection fog
c. Upslope fog
d. Frontal fog or precipitation induced fog
e. Steam fog

31
Q

What causes radiation fog to form?

A

The ground cools the adjacent air to the dew point on calm, clear nights.

32
Q

What is advection fog, and where is it most likely to form?

A

Advection fog results from the transport or warm humid air over a cold surface. A pilot can expect advection fog to form primarily along coastal areas during the winter. Ulike radiation fog, it may occur with winds, cloudy skies, over a wide geographic area, and at any time of the day or night.

33
Q

What is upslope fog?

A

Upslope fog forms as a result of moist, stable air being cooled adiabatically as it moves up sloping terrain. Upslope fog is often quite dense and extends to high altitudes

34
Q

Define the term wind shear and state the areas in which it is likely to occur.

A

Wind shear is defined as the rate of change of wind velocity (direction and/or speed) per unit distance; conventionally expressed as vertical or horizontal wind shear. It may occur at any level in the atmosphere but thee areas are of special concern:

a. Wind shear with a low level temperature inversion
b. Wind shear in a frontal zone or thunderstorm
c. Clear air turbulence (CAT) at high levels associated with a jet stream or strong circulation.

35
Q

Why is wind shear an operational concern to pilots?

A

Wind shear is an operational concern because unexpected changes in wind speed and direction can be potentially very hazardous to aircraft operations at low altitudes on approach to and departing from airports

36
Q

What types of weather information will you examine to determine if wind shear conditions might affect your flight?

A

a. Terminal forecast - any mention of low level wind shear or the possibility of severe thunderstorms, heavy rain showers, hail, and wind gusts suggest the potential for LLWS and microbursts
b. METARs - inspect for any indication of thunderstorms, rain showers, or blowing dust. Additional signs such as warming trends, gusty winds, cumulonimbus clouds should be noted
c. Severe weather watch reports, SIGMETs, and convective SIGMETs - severe convective weather is a prime source for wind shear and microbursts
d. LLWAS (low level windshear alert system) reports - installed at 110 airports in the U.S; designed to detect wind shifts between outlying stations and a reference centerfield station
e. PIREPs - reports of sudden airspeed changes on departure or approach and landing corridors provide a real time indication of the presence of wind shear

37
Q

What is the primary means of obtaining a weather briefing?

A

The flight service station (FSS) is the primary source for obtaining preflight briefings and inflight weather information. The FAA provides the Flight Service program through FSS’s (both government and contract, 1-800-WX-BRIEF), and via the internet, through direct user access terminal system (DUATS), and lockheed martin flight services (DUATS II)

38
Q

What are some examples of other sources of weather information?

A

a. Telephone information briefing service, or TIBS (FSS)
b. Weather and aeronautical information available from numerous private industry sources
c. DUATS and lockheed martin flight services via the internet. Pilots with a current medical certificate can receive preflight weather data and file domestic VFR and IFR flight plans
d. In alaska, transcribed weather broadcast (TWEB and telephone access to the TWEB, or TEL-TWEB

39
Q

You’re planning a cross country flight. Does the weather data provided by commercial and/or third party vendors satisfy the preflight action required by 14 CFR 91.103?

A

Pilots and operators should be aware that weather services provided by entities other than FAA, NWS or their contractors (such as the DUATS and lockheed martin flight services DUATS II) might not meet FAA/NWS quality control standards. All operators and pilots contemplating using such services should request and/or review and appropriate description of services and provider disclosure. When in doubt, consult with an FAA flight service specialist.

40
Q

What types of weather briefings are available from an AFSS/FSS briefer?

A

Standard briefing - request when you are planning a flight and you have not received a previous briefing or have not received preliminary information through mass dissemination media (TIBS, TWEB in alaska only)
Abbreviated briefing - request when you need information to supplement mass disseminated data, update a previous briefing, or when you need only one or two items
Outlook briefing - request whenever your proposed time of departure is six or more hours from the time of the briefing; for planning purposes only
Inflight briefing - request when needed to update a preflight briefing

41
Q

What pertinent information should a weather briefing include?

A

a. Adverse conditions
b. VFR flight not recommended
c. Synopsis
d. Current conditions
e. Enroute forecast
f. Destination forecast
g. Winds aloft
h. Notices to airmen (NOTAMS)
i. ATC delay

42
Q

What is HIWAS?

A

Hazardous inflight weather advisory service is a continuous broadcast of inflight weather advisories including summarized aviation weather warnings, SIGMETS, convective SIGMETs, center weather advisories, AIRMETs and urgent PIREPs. HIWAS is an additional source of hazardous weather information which makes this data available on a continuous basis. Navaids with HIWAS caoabukutt are depicted on sectional charts with an H in the upper right corner of the indentation box. Where implemented, HIWAS alerts are broadcast on all except emergency frequencies once upon recept by ARTCC, terminal facilities, and FSS

43
Q

What is a flight information service?

A

Flight information service - broadcast (FIS-B) is a ground broadcast service provided through the automatic dependent surveillance - broadcast (ADS-B) services network over the 978 MHz UAT data link. The FAA FIS-B system provides pilots and flight crews of properly equipped aircraft with a flightdeck display of aviation weather and aeronautical information

44
Q

Can onboard datalink weather (FIS-B) be useful in navigating an aircraft safely around an area of thunderstorms?

A

Weather data linked from a ground weather surveillance radar system is not real time information; it displays recent rather than current conditions. This data is typically updated every 5 minutes, but can be as much as 15 minutes old by the time it displays in the cockpit. Therefore, FIS aviation weather products are not appropriate for tactical avoidance of severe weather such as negotiating a path through a weather hazard area

45
Q

While en route, how can a pilot obtain updated weather information?

A

a. FSS on 122.2 and appropriate RCO (remote communication outlet) frequencies
b. ATIS broadcasts along your route of flight
c. HIWAS (hazardous inflight weather advisory service)
d. Datalink weather - cockpit display of FIS-B information
e. ATC

46
Q

What is a METAR and what are the two types?

A

A METAR is an hourly surface observation of conditions observed at an airport. There are two types of METAR reports - a routine METAR report that is transmitted every hour and an aviation selected special weather report (SPECI). This is a special report that can be given at any time to update the METAR for rapidly changing weather conditions, aircraft mishaps, or other critical information

47
Q

Describe the basic elements of a METAR.

A

A METAR report contains the following elements in order as presented:

a. Type of reports - the METAR, and the SPECI (aviation special weather report)
b. ICAO station identifier - 4 letter station identifies; in the conterminous U.S., the 3 letter identifier is prefixed with K
c. Date and time or report - a 6 digit date/time group appended with Z (UTC). First two digits are the date, then two for the hour, and two for minutes
d. Modifier (as required) - if used, the modifier AUTO identifies the report as an automated weather report with no human intervention. If AUTO is shown in the body of the report, AO1 or AO2 will be encoded in the remarks section to indicate the type of precipitation sensor used at the station
e. Wind - 5 digit group (6 digits if speed is over 99 knots); first three digits = wind direction, in tens of degrees referenced to true north. Directions less than 100 degrees are preceded with a zero; next two digits are the average speed in knots, measured or estimated (or, if over 99 knots, the next three digits)
f. Visibility - surface visibility in statute miles, space, fractions of statute miles (as needed), and the letters SM
g. Runway visual range (RVR), as required
h. Weather phenomena - broken into two categories: qualifiers, and weather phenomena
i. Sky condition - amount/height/type (as required) or indefinite ceiling/height (vertical visibility). Heights are recorded in feet AGL.
j. Temperature/dew point group - 2 digit format in whole degrees celsius, separated by a solidus. Temperatures below zero are prefixed with M
k. Altimeter - 4 digit format representing tens, units, tenths, and hundredths of inches of mercury prefixed with A. The decimal point is not reported or stated
l. Remarks (RMK), as required - operational significant weather phenomena, location of phenomena, beginning and ending times, direction of movement

48
Q

Describe several types of weather observing programs available.

A

a. Manual observations - with only a few exceptions, these reports are from airport locations staffed by FAA personnel who manually observe, perform calculations, and enter their observations into the communication system
b. AWOS - automated weather observing system; consists of various sensors, a processor, a computer-generated voice subsystem, and a transmitter to broadcast local, minute by minute weather data directly to the pilot. Observations will include the prefix AUTO in data
c. ASOS/AWSS - automated surface observing system/ automated weather sensor system; the primary U.S. surface weather observing systems. AWSS is a follow on program that provides the identical data as ASOS. Both systems provide continuous minute by minute observations that generate METARs and other aviation weather information. Transmitted over a discrete VHF radio frequency or the voice portion of a local NAVAID, and are receible to a maximum of 25 NM from the station and a maximum altitude of 10,000 feet AGL. Observations made without human intervention will include the modifier AUTO in the report data

49
Q

What are PIREPS (UA), and where are they usually found?

A

A pilot report (PIREP) provides valuable information regarding the conditions as they actually exist in the air, which cannot be gathered from any other source. Pilots can confirm the height of bases and tops of clouds, locations of wind shear and turbulence, and the location of inflight icing. There are two types of PIREPS: routine or urgent. PIREPS should be given to the ground facility with which communications are established. Altitudes are MSL, visibility SM, and distance NM.

50
Q

What are terminal aerodrome forecasts (TAFs)

A

A terminal aerodrome forecast (TAF) is a concise statement of the expected meteorological conditions significant to aviation for a specified time period within five statue miles (SM) of the center of the airport’s runway complex (terminal). The TAFs use the same weather codes found in METAR weather reports, in the following format:

a. Type of reports - a routine forecast (TAF), an amended forecast (TAF AMD), or a corrected forecast (TAF COR)
b. ICAO station identifier - 4 letter station identifiers
c. Date and time of origin - the date/time of forecast follows the terminal’s location identifier. It contains the day of the month in two digits and time in four digits in which the forecast is completed and ready for transmission, with a Z appended to denote UTC
d. Valid period date and time - the first two digits are the day of the month for the start of the TAF followed by two digits indicating the starting hour (UTC). The next two digits indicate the day of the month for the end of the TAF, and the last two digits are the ending hour (UTC) of the valid period. Scheduled 24 and 30 hour TAFs are issued four times per day, at 0000, 0600, 1200, and 1800Z
e. Forecasts - wind, visibility, significant and vicinity weather, cloud and vertical obscuration, non convective low level wind shear, forecast change indicators (FM, TEMPO, and PROB)

51
Q

Define aviation area forecast.

A

Abbreviated as FA, this is a forecast of specified weather phenomena covering a flight information region or other area designated by the meteorological authority. Pilots should use the area forecast (in conjunction with AIRMETs, SIGMETs, convective SIGMETs, CWAs), to determine forecast en route weather and to interpolate conditions at airports that do not have a terminal aerodrome forecast (TAF). FAs are issued 3 times daily for each of the 6 areas in the contiguous 48 states. FAs are also issued for the Gulf of Mexico, the Caribbean, Hawaii, and Alaska. Most areas forecasts were cancelled in 2017, replaced by GFAs.

52
Q

What information is provided by the FA?

A

Area forecasts are issued for the conterminous U.S. and cover the airspace between the surface and 45,000 feet MSL. They include:
a. Synopsis - brief discussion of the synoptic weather affecting the FA area during the 18 hour valid period
b. Clouds and weather - description of the clouds and weather for the first 12 hour period for each state or group of states, including:
cloud amount (SCT, BKN, or OVC) for clouds with bases higher than or equal to 1000ft AGL and below FL 180
cloud bases and tops (AMSL) associated with the above
precipitation
visibility between 3 and 6 SM and obstrucion(s) to visibility
sustained surface winds 20 knots or greater
c. 12 to 18 hour categorical outlook - IFR, marginal VFR (MVFR), or VFR, including expected precipitation and/or obstruction(s) to visibility

53
Q

What is a graphical forecast for aviation (GFA)?

A

The GFA is intended to provide the necessary aviation weather information as a complete picture of the weather that may impact flight in the continental U.S. The webpage includes observational data, forecasts, and warnings that can be viewed from 14 hours in the past to 15 hours in the future, including thunderstorms, clouds, flight category, precipitation, icing, turbulence and wind

54
Q

What are the four types of inflight aviation weather advisories?

A

Inflight aviation weather advisories are forecasts to advise enroute aircraft of the development of potentially hazardous weather in four types: the SIGMET (WS), the convective SIGMET (WST), the AIRMET (WA; text or graphical product), and the center weather advisory (CWA). All heights are reference MSL, except in the case of ceilings (CIG) which indicate AGL.

55
Q

What is a convective sigmet?

A

Convective SIGMETs (WST) implies severe or greater turbulence, severe icing and low level and wind shear. They may be issued for any convective situation which the forecaster feels is hazardous to all categories of aircraft. Convective SIGMET bulletins are issued for the Eastern (E), Central (C) and Western (W) United States (convective SIGMETs are not issued for Alaska or Hawaii). Bulletins are issued hourly at H+55. Special bulletins are issued at any time as required and updated at H+55. The text of the bulletin consists of either an observation and a forecast, or just a forecast. The forecast is valid for up to 2 hours.

a. Severe thunderstorm due to surface winds greater than or equal to 50 knots, hail at the surface greater than or equal to 3/4 inches in diameter, tornadoes
b. Embedded thunderstorms
c. A line of thunderstorms
d. Thunderstorm producing greater than or equal to heavy precipitation that affects 40% or more of an area at least 3,000 square miles

56
Q

What is a sigmet?

A

A SIGMET (WS) advises of weather that is potentially hazardous to all aircraft. SIGMETs are unscheduled products that are valid for 4 hours; SIGMETs associated with tropical cyclones and volcanic ash clouds are valid for 6 hours. Unscheduled updates and corrections are issued as necessary. In the conterminous U.S., SIGMETs are issued when the following phenomena occur or are expected to occur:

a. Severe icing not associated with thunderstorms
b. Severe or extreme turbulene ore clear air turbulence (CAT) not associated with thunderstorms
c. Widespread dust storms or sandstorms lowering surface visibility to below 3 miles
d. Volcanic ash

57
Q

What is an AIRMET?

A

Advisories of significant weather phenomena that describe conditions at intensities lower than those which require the issuance of SIGMETs, intended for use by all pilots in the preflight and enroute phase of flight to enhance safety. AIRMET information is available in two formats: text bulletins and graphics. They are issued on a scheduled basis every 6 hours beginning at 0245 UTC. Unscheduled updates and corrections are issued as necessary. Each AIRMET bulletin includes an outlook for conditions expected after the AIRMET valid period. AIRMETs contain details about IFR, extensive mountain obscuration, turbulence, strong surface winds, icing, and freezing levels.

58
Q

What are the different types of AIRMETs?

A

There are three AIRMET types: Sierra, Tango, and Zulu:

a. AIRMET Sierra describes IFR conditions and/or extensive mountain obscurations
b. AIRMET Tango describes moderate turbulence, sustained surface winds of 30 knots or greater, and/or non convective low level wind shear
c. AIRMET Zulu describes moderate icing and provides freezing level heights

59
Q

Describe the winds and temperature aloft forecasts.

A

Winds and temperature aloft forecasts are computer prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations. They are produced 4 times daily for specified locations in the continental United States, Hawaii, Alaska and coastal waters, and the western pacific ocean. Amendments are not issued to the forecasts. Wind forecasts are not issued for altitudes within 1,500 feet of a location’s elevation. Some of the features of FBs are:

a. Product header includes date and time observations collected, forecast valid date time, and the time period during which the forecast is to be used.
b. Altitudes up to 15,000 feet referenced to MSL; altitudes at or above 18,000 feet are references to flight levels (FL)
c. Temperature indicated in degrees Celsius (two digits) for the levels from 6,000 through 24,000 feet. Above 24,000 feet, minus sign is omitted since temperatures are always negative at those altitudes. Temperature forecasts are not issued for altitudes within 2500 feet of a location’s elevation. Forecasts for immediate levels are determined by interpolation
d. Wind direction indicated in tens of degrees with reference to true north and wind speed is given in knots. Light and variable wind or wind speeds of less than 5 knots are expressed by 9900. Forecast wind speeds of 100 through 199 knots are indicated by subtracting 100 from speed and adding 50 to the coded direction. For example, a forecasts of 250 degrees, 145 knots, is encoded as 7545. Forecast wind speeds of 200 knots or greater are indicated as a forecast speed of 199 knots. For example, 7799 is decoded as 270 degrees at 199 knots or greater

60
Q

What valuable information can be determined from winds and temperatures aloft forecasts?

A

Most favorable altitude - based on winds and direction of flight
Areas of possible icing - by noting air temperatures at +2 deg C to -20 deg C
Temperature inversions
Turbulence - by observing abrupt changes in wind direction and speed at different altitudes

61
Q

What are center weather advisories?

A

A center weather advisory is an aviation warning for use by aircrews to anticipate and avoid adverse weather conditions in the en route and terminal environments. The CWA is not a flight planning product; instead it reflects current conditions expected at the time of issuance and/or is a short range forecast for conditions expected to begin within 2 hours of issuance. CWAs are valid for a maximum of 2 hours. If conditions are expected to continue beyond the 2 hour valid period, a statement will be included in the CWA.

62
Q

Give some examples of the various NWS weather charts you will use during preflight planning.

A

a. Surface analysis chart
b. Weather depiction chart
c. Short range surface prognostic chart
d. Significant weather prognostic chart
e. Convective outlook chart
f. Constant pressure analysis chart

63
Q

What is a surface analysis chart?

A

Surface analysis charts are analyzed charts of surface weather observations. The chart depicts the distribution of several items including sea level pressure, the positions of heights, lows, ridges, troughs, the location and character of fronts, and the various boundaries such as drylines, outflow boundaries, sea level breeze fronts, and convergence lines. The chart is produced eight times daily.

64
Q

What information does a weather depiction chart provide?

A

The weather depiction chart contains a plot of weather conditions at selected METAR stations and an analysis of weather flying category (VFR, MVFR, IFR). It is designed primarily as a briefing tool to alert aviation interests to the location of critical or near critical operational minimums at terminals in the conterminous U.S. and surrounding land areas. The chart is issued eight times daily.

65
Q

Define the terms: LIFR, IFR, MVFR and VFR.

A

LIFR Low IFR - ceiling less than 500 feet and/or visibility less than 1 mile
IFR ceiling 500 to less than 1000 feet and/or visibility 1 to less than 3 miles
MVFR - Marginal VFR - ceiling 1000 to 3000 feet and/or visibility 3 to 5 miles inclusive
VFR ceiling greater than 3000 feet and visibility greater than 5 miles; includes sky clear

66
Q

What are short range surface prognostic charts?

A

Short range surface prognostic charts provide a forecast of surface pressure systems, fronts and precipitation for a 2-1/2 day period. They cover a forecast area of the 48 contiguous states and coastal waters, and are prepared by the NWS weather prediction center (and available on the AWC website). Predicted conditions are divided into five forecast periods: 12, 18, 24, 48 and 60 hours. Each chart depicts a snapshot of weather elements expected at the specified valid time. Charts are issued four times a day and can be used to obtain an overview of the progression of surface weather features during the included periods.

67
Q

Describe a U.S. low level significant weather chart.

A

The low level significant weather (SIGWX) charts provide a forecast of aviation weather hazards primarily intended to be used as guidance products for pre flight briefings. The forecast domain covers the continental U.S. and the coastal waters for altitudes Flight level 240 and below. Each depicts a snapshot of weather expected at the specified valid time. The charts depict weather flying categories, turbulence, and freezing levels, and are issued four times per day in two types: a 12 hour and a 24 hour prog

68
Q

Describe a mid level significant chart

A

The mid level significant weather chart provides a forecast and an overview of significant en route weather phenomena over a range of flight levels from 10,000 feet MSL to FL450, and associated surface weather features. The chart is a snapshot of weather expected at the specified valid time and depicts numerous weather elements that can be hazardous to aviation. The AWC issues the 24 hour mid level significant weather chart four times daily.

69
Q

What is a convective outlook chart?

A

The convective outlook chart depicts areas forecast to have the potential for severe (tornado, wind gusts 50 knots or greater, or hail 3/4 inch diameter size or greater) and non severe (general) convention and specific severe weather threats during the following three days. The chart defines areas of slight risk (SLGT), moderate risk (MDT) or high risk (HIGH) of severe thunderstorms for a 24 hour period beginning at 1200 UTC. The day 1 and day 2 convective outlooks also depict areas of general thunderstorms (GENTS TMS), while day 1, day 2, and day 3 convective outlooks may use SEE TEXT for areas where convection may approach or slightly exceed severe criteria.

70
Q

What are constant pressure analysis charts?

A 
Any surface of equal pressure in the atmosphere is a constant pressure surface. A constant pressure analysis chart is an upper air weather map where all information depicted is at the specified pressure of the chart. From these charts, a pilot can approximate the observed air temperature, wind, and temperature dewpoint spread along a proposed route. They also depict highs, lows, troughs, and ridges aloft by the height contour patterns resembling isobars on a surface map. Twice daily, five constant pressure charts are issued from observed data obtained at 00Z and 12Z:
850mb           5000 ft
700mb           10,000 ft
500mb           18,000 ft
300mb           30,000 ft
200mb           39,000 ft

Private Pilot Oral Exam Guide (8 decks)

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