Aviation Weather Services

Question 1

How to determine the thickness of a cloud layer ?

Answer 1

First find the base in MSL by adding the field elevation to the reported base, then subtract this total from the tops.

Question 2

What is meant by the Special METAR weather observation for KBOI?
SPECI KBOI 091854Z 32005KT 1 1/2SM RA BR OVC007 17/16 A2990 RMK RAB12

Answer 2

The SPECI report for KBOI is reporting a visibility of 1 1/2 SM in rain and mist (1 1/2SM RA BR), and the remarks indicate that the rain began at 12 min. past the hour, or 1812Z (RMK RAB12). Also, the report states temperature is 17°C and dew point is 16°C, which implies a temperature-dew point spread of 1°C. Note the time of the SPECI is 1854Z.

Question 3

Terminal Aerodrome Forecasts (TAF) are issued how many times a day and cover what period of time?

Answer 3

Four times daily and are usually valid for a 24-hour period.

Question 4

What single reference contains information regarding a volcanic eruption, that is occurring or expected to occur?

Answer 4

A SIGMET, which is a type of in-flight weather advisory, will contain information regarding a volcanic eruption that is occurring or expected to occur.

Question 5

What is the upper limit of the Low Level Significant Weather Prognostic Chart?

Answer 5

24,000 feet.

Question 6

Describes the purpose of convective SIGMETs (WST)?

Answer 6

They consist of either an observation and a forecast or just a forecast for tornadoes, significant thunderstorm activity, or hail greater than or equal to 3/4 inch in diameter.

Question 7

What chart shows the observed temperature, wind, and temperature/dewpoint spread be determined at a specified altitude?

Answer 7

Constant Pressure Analysis Charts.

Question 8

What significant cloud coverage is reported by this pilot report?
KMOB

UA/OV 15NW MOB 1340Z/SK 025 OVC 045/075 OVC 080/090 OVC

Answer 8

The PIREP describes three overcast layers. The first layer has a base of 2,500 feet and a ceiling of 4,500 feet. The second layer has a base of 7,500 feet and a ceiling of 8,000 feet. The third layer begins at 9,000 feet.

Question 9

Which chart provides a ready means of locating observed frontal positions and pressure centers?

Answer 9

Surface Analysis Chart.

Question 10

How to determine the approximate height of the cloud bases ?

Answer 10

Divide temp/dewpoint spread by lapse rate of 2.5°C per 1,000 ft. (3 C adiabatic rate - .5 C dewpoint rate)

Question 11

What does the Hazardous Inflight Weather Advisory Service (HIWAS) broadcast service over selected VORs provide ?

Answer 11

continuous broadcast of inflight weather advisories.

Question 12

What flight planning information can a pilot derive from Constant Pressure Analysis Charts?

Answer 12

Winds and temperatures aloft.

Question 13

Which weather chart depicts conditions forecast to exist at a specific time in the future?

Answer 13

12-hour Significant Weather Prognostic Chart.

Question 14

RMK FZDZB42 WSHFT 30 FROPA

Answer 14

The remark is decoded as freezing drizzle that began at 42 min. past the hour (FZDZB42) and a wind shift at 30 min. past the hour due to frontal passage (WSHFT 30 FROPA).

Question 15

During preflight preparation, weather report forecasts which are not routinely available at the local service outlet (FSS) can best be obtained by means of contacting whom ?

Answer 15

weather forecast office (WFO).

Question 16

Weather Advisory Broadcasts, including Severe Weather Forecast Alerts (AWWs), Convective SIGMETs, and SIGMETs, are provided by

Answer 16

ARTCCs on all frequencies, except emergency, when any part of the area described is within 150 miles of the airspace under their jurisdiction.

Question 17

What type of In-Flight Weather Advisories provides an en route pilot with information regarding the possibility of moderate icing, moderate turbulence, winds of 30 knots or more at the surface and extensive mountain obscurement?

Answer 17

AIRMETs and Center Weather Advisories (CWAs).

Question 18

In-Flight Aviation Weather Advisories include what type of information?

Answer 18

Forecasts for potentially hazardous flying conditions for en route aircraft.

Question 19

What wind conditions would you anticipate when squalls are reported at your destination?

Answer 19

Sudden increases in windspeed of at least 16 knots to a sustained speed of 22 knots or more for at least 1 minute.

Question 20

What does Hatching on a Constant Pressure Analysis Chart indicate ?

Answer 20

windspeed 70 knots to 110 knots.

Question 21

What type of In-Flight Weather Advisories provides an en route pilot with information regarding the possibility of moderate icing, moderate turbulence, winds of 30 knots or more at the surface and extensive mountain obscurement?

Answer 21

AIRMETs and Center Weather Advisories (CWAs).

Question 22

From which of the following can the observed temperature, wind, and temperature/dewpoint spread be determined at a specified altitude?

Answer 22

Constant Pressure Analysis Charts.

Question 23

What is the meaning of the terms PROB40 2102 +TSRA as used in a Terminal Aerodrome Forecast (TAF)?

Answer 23

Between 2100Z and 0200Z there is a forty percent (40%) probability of thunderstorms with heavy rain.

Question 24

Which chart provides a ready means of locating observed frontal positions and pressure centers?

Answer 24

Surface Analysis Chart.

Question 25

How is a stationary front represented on a prognostic chart ?

Answer 25

The alternating red semicircles and blue triangles represent a stationary front, which is a front between warm and cold air masses that is moving very slowly or not at all.

Question 26

The U.S. High-Level Significant Weather Prognostic Chart forecasts significant weather for what airspace?

Answer 26

25,000 feet to 63,000 feet.

Question 27

What does the contraction VRB in the Terminal Aerodrome Forecast (TAF) mean?

Answer 27

Wind speed is variable throughout the period.

Question 28

Which chart provides a ready means of locating observed frontal positions and pressure centers?

Answer 28

Surface Analysis Chart.

Question 29

The Surface Analysis Chart depicts

Answer 29

actual frontal positions, pressure patterns, temperature, dewpoint, wind, weather, and obstructions to vision at the valid time of the chart.

Question 30

At what rate do temperature and dewpoint converage at ?

Answer 30

2.5 deg C per 1000 ft

Question 31

What is the upper limit of the Low Level Significant Weather Prognostic Chart?

Answer 31

24,000 Ft

Question 32

Name one thing the Surface analysis chart does not include ?

Answer 32

Forecast.