Weather

Question 1

What is a METAR and what are the two types?

Answer 1

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).
(AC 00-45)

Question 2

Describe the basic elements of a METAR.

Answer 2

A METAR report contains the following elements in order as presented:
a. Type of report (METAR/SPECI)
b. ICAO station identifier
c. Date and time of report (DDHHMM)
d. Modifier (AUTO = no human intervention)
e. Wind (HHHKK)
f. Visibility
g. Runway Visual Range (RVR)
h. Weather phenomena
i. Sky condition (Ft AGL)
j. Temp/Dewpoint
k. Altimeter
l. Remarks
(AC 00-45)

Question 3

Describe several types of weather observing programs available.

Answer 3

a. Manual
b. AWOS
c. ASOS/AWSS (Produces METAR)
(AIM 7-1-12)

Question 4

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

Answer 4

The two types of PIREPs (routine, or “UA,” and urgent, or “UUA”) contain information concerning weather as observed by pilots en-route. Required elements of all PIREPs are message type, location, time (UTC), flight level (MSL), type of aircraft, and at least one weather element encountered.
(AC 00-45)

Question 5

What are Radar Weather Reports (SD)?

Answer 5

A radar weather report (SD/ROB) contains information about precipitation observed by weather radar. It is a textual product derived from the WSR-88D NEXRAD radar without human intervention.
(AC 00-45)

Question 6

What are Terminal Aerodrome Forecasts (TAFs)?

Answer 6

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 of the center of the airport’s runway complex. The TAFs use the same weather codes found in METAR weather reports, in the following format:
a. Type of report (TAF, TAF AMD, or TAF COR)
b. ICAO station identifier
c. Date and time of origin
d. Valid period date and time
e. Forecasts
(AC 00-45)

Question 7

Define “area aviation forecast.”

Answer 7

Abbreviated as “FA,” this is a forecast of specified weather phenomena covering a flight information region or other area designated by the meteorological authority. Used to determine en-route weather and to interpolate conditions at airports that do not have a TAF. FAs are issued 3 times daily for each of the 6 areas in the contiguous US.
(AC 00-45)

Question 8

What information is proved by an FA?

Answer 8

a. Synopsis - brief discussion of synoptic weather during 18-hour valid period.
b. Clouds and weather - coverage, bases/tops, precipitation, visibility, sustained winds over 20 knots.
c. 12-18 hour categorical outlook - IFR, MVFR, or VFR.
(AC 00-45)

Question 9

What are Inflight Aviation Weather Advisories (WST, WS, WA)?

Answer 9

Inflight aviation weather advisories are forecasts to advise en-route aircraft of development of potentially hazardous weather in 3 types: the SIGMET, the convective SIGMET, and the AIRMET. All heights are MSL with the exception of ceilings (AGL).
(AIM 7-1-6)

Question 10

What is Convective SIGMET (WST)?

Answer 10

Convective SIGMETs imply severe or greater turbulence, severe icing, and low-level wind shear. The forecast is valid for up to 2 hours.
a. Severe thunderstorm (surface winds over 50 knots, hail over 3/4 inches, tornados).
b. Embedded thunderstorms.
c. A line of thunderstorms.
d. Thunderstorms producing heavy precipitation or worse over 40% or more of a 3000 square mile or greater area.
(AC 00-45)

Question 11

What is a SIGMET (WS)?

Answer 11

A SIGMENT advises of non-convective weather that is potentially hazardous to all aircraft. The maximum forecast period is four hours.
a. Severe icing not associated with a thunderstorm.
b. Severe or extreme clear air turbulence not associated with TSs.
c. Dust or sand storms reducing visibility below 3 miles.
d. Volcanic ash.
(AC 00-45)

Question 12

What is an AIRMET (WA)?

Answer 12

Advisories of significant weather phenomena that describe conditions at intensities lower than those which require the issue of SIGMETs. They are issued on a scheduled basis every 6 hours beginning at 0245 UTC.AIRMETs contain details about IFR, extensive mountain obscuration, turbulence, strong surface winds, icing, and freezing levels.
(AC 00-45)

Question 13

What are the different types of AIRMETs?

Answer 13

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 nonconvective low-level wind shear.
c. AIRMET Zulu describes moderate icing and provides freezing level heights.
(AIM 7-1-6)

Question 14

Describe winds and temperature aloft forecasts (FB).

Answer 14

Computer prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations. Some of the features of FBs are:
a. Product header includes date and time observations collected, forecast valid date ad time, and the time period during which the forecast is to be used.
b. Altitudes up to 15,000 are MSL; altitudes at or above 18,000 are FL.
c. Temperature above 24,000 is always negative.
d. Winds are indicated with two digits for heading (tens of degrees) and two digits for wind speed. Light or variable winds are expressed as 9900. Winds of 100-199 knots subtract 100 from the wind speed and add 50 to heading. 230 degrees at 150 would be 7350. Winds above 199 knots are indicated as 199 knots.
(AC 00-45)

Question 15

What valuable information can be determined from Winds and Temperatures Aloft Forecasts (FB)?

Answer 15

a. Most favorable altitude.
b. Areas of possible icing (+2 to -20 degrees C).
c. Temperature inversions.
d. Turbulences (abrupt wind changes at different altitudes).

Question 16

Give some examples of current weather charts available at the FSS or NWSO used in flight planning.

Answer 16

a. Surface analysis chart
b. Weather depiction chart
c. Radar summary chart
d. Short-range surface prognostic chart
e. Significant weather prognostic chart
f. Convective outlook chart
g. Constant pressure analysis chart
(AC 00-45)

Question 17

What is a surface analysis chart?

Answer 17

This is a computer-prepared chart that covers the contiguous 48 states and adjacent areas. The chart is transmitted every three hours. The surface analysis chart provides a ready means of locating pressure systems and fronts. It also give an overview of winds, temperatures, and dew point temperatures at chart time.
(AC 00-45)

Question 18

What information does a weather depiction chart provide?

Answer 18

The weather depiction chart is computer-generated (with a weather observer’s analysis of fronts) from METAR reports. This chart gives a broad overview of the observed flying category conditions at the valid time of the chart. The chart is transmitted at three hour intervals. Plotted data for each station includes: sky cover, cloud/ceiling height, weather and obstructions to visibility.
(AC 00-45)

Question 19

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

Answer 19

LIFR: below 500/1
IFR: 500-1000/1-3
MVFR: 1000-3000/3-5
VFR: above 3000/5
(AIM 7-1-7)

Question 20

What are radar summary charts?

Answer 20

Computer generated graphical display of a collection of automated radar weather reports (SDs). Displays areas of precipitation as well as information about type, intensity, configuration, coverage, echo top, and cell movement. The chart is available hourly.
This chart aids in preflight planning by identifying general areas and movement of precipitation and/or thunderstorms. Only displays precipitation so an absence of echoes does not guarantee clear weather.
(AC 00-45)

Question 21

What are short-range surface prognostic charts?

Answer 21

Called “progs,” these charts portray forecasts of selected weather conditions at specified valid times (12, 24, 36, 48 hour progs).
(AC 00-45)

Question 22

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

Answer 22

With two forecast periods, 12 hours and 24 hours, the chart is composed of four panels. The two lower panels depict the 12 and 23 hour surface progs and then two upper panels depict the 12 and 24 hour significant weather progs. It is issued four times a day.
(AC 00-45)

Question 23

Describe a mid-level significant weather (SIGWX) chart.

Answer 23

The mid-level SIGWX 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. It is issued four times daily.
(AC 00-45)

Question 24

What is a convective outlook chart?

Answer 24

The convective outlook chart depicts areas forecast to have the potential for severe (tornado, gusts over 50 knots, fail over 3/4 inch) and non-severe (general) convection 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) for severe thunderstorms.
(AC 00-45)

Question 25

What are constant pressure analysis charts?

Answer 25

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.