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Pilot's Handbook of Aeronautical Knowledge
Aviation Weather Services

Weather Charts

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Radar summary chart.
Figure 12-17. Radar summary chart.

Intensity levels, contours, and precipitation type symbols.
Figure 12-18. Intensity levels, contours, and precipitation type

Significant Weather Prognostic Charts
Significant weather prognostic charts are available for low level
significant weather from the surface to FL 240 (24,000
feet), also referred to as the 400 mb level, and high-level
significant weather from FL 250 to FL 600 (25,000 to 60,000
feet). The primary concern of this discussion is the low-level
significant weather prognostic chart.

The low-level chart comes in two forms: the 12– and 24–hour
forecast chart, and the 36- and 48-hour surface forecast chart.
The first chart is a four-panel chart that includes 12– and 24–
hour forecasts for significant weather and surface weather.
Charts are issued four times a day at 0000Z, 0600Z, 1200Z,
and 1800Z. The valid time for the chart is printed on the
lower left corner of each panel.

The upper two panels show forecast significant weather,
which may include nonconvective turbulence, freezing levels,
and IFR or MVFR weather. Areas of moderate or greater
turbulence are enclosed in dashed lines. Numbers within these
areas give the height of the turbulence in hundreds of feet
MSL. Figures below the line show the anticipated base, while
figures above the line show the top of the zone of turbulence.
Also shown on this panel are areas of VFR, IFR, and MVFR.

IFR areas are enclosed by solid lines, MVFR areas are
enclosed by scalloped lines, and the remaining, unenclosed
area is designated VFR. Zigzag lines and the letters "SFC"
indicate freezing levels in that area are at the surface. Freezing
level height contours for the highest freezing level are drawn
at 4,000-foot intervals with dashed lines.