Definition
A low-level Significant Weather Prognostic Chart that forecasts weather conditions from the surface up to 24,000 feet (Flight Level 240). It depicts expected fronts, pressure systems, areas of IFR and MVFR conditions, turbulence, and freezing levels for a specific valid time, typically issued in 12-hour and 24-hour forecast panels.
Plain English
A weather forecast map showing what the weather is expected to look like from the ground up to 24,000 feet at a specific future time. It highlights things pilots flying below 24,000 feet need to know about, like bad visibility, turbulence, and where it will be cold enough for ice to form.
Context Anchor
Seen during preflight weather planning in FAA weather chart discussions, especially when reviewing significant weather prognostic charts.
Derivation
SFC is the standard aviation shorthand for 'surface' (the ground). 240 refers to Flight Level 240, which is 24,000 feet. So 'SFC-240' literally means 'from the surface up to 24,000 feet' — the altitude band the chart covers.
Why Pilots Care
It helps pilots anticipate turbulence, icing, cloud cover, and other conditions that affect flights in the lower altitudes.
Intuition Check
Do not read 240 as 240 feet or as a time. In this chart label, 240 means about 24,000 feet.
Example Sentence 1
During flight planning, the pilot reviewed the SFC-240 chart and saw a band of moderate turbulence forecast along the planned route.
Example Sentence 2
According to the SFC-240 chart, moderate turbulence was expected below 18,000 feet.