FAA Part 107 Remote Pilot (UAG)WeatherEasy
An evening forecast calls for the temperature/dew point spread to narrow to just 2°F overnight with light winds. What weather condition is most likely to develop by early morning?
- AA line of severe thunderstorms is likely to develop
- BFog or low stratus clouds are likely to form
- CGusty, turbulent winds will develop rapidly
- DVisibility will improve significantly by sunrise
Show answer & explanationAnswer & explanation
Correct answer: B. Fog or low stratus clouds are likely to form
A narrow temperature/dew point spread means the air is close to saturation. With light winds and calm conditions overnight, radiational cooling can bring temperature down to the dew point, producing fog or low stratus clouds by morning.
Why the other options are wrong
- A. Thunderstorms require instability and lifting mechanisms, not just a narrow spread with light winds.
- C. Light winds and a narrow spread are associated with calm, stable conditions, not gusty turbulence.
- D. Narrowing spread indicates worsening, not improving, visibility conditions.
Temperature/Dew Point Spread
The difference between air temperature and dew point; a small spread indicates air is near saturation and prone to fog or low clouds.
- Spread near 2-3°F signals high fog/low cloud potential
- Clear skies and light winds favor radiational cooling and fog
- Wide spreads (>5°C) indicate low humidity and low fog risk
Memory trick: 'Small spread, socked-in ahead' — narrow spread means fog is near.