How does front movement affect temperature, dew point, and wind on a map?

• A. Fronts do not affect any weather variables.
• B. Temperature and dew point shift across the front; winds may shift direction.
• C. Winds shift direction, but temperature and dew point remain constant.
• D. Temperature and dew point usually shift across the front; winds typically shift direction; pressure pattern changes near the front.

Answer: (D)

Fronts mark the boundary between air masses with different temperatures and humidity, so as a front moves across a map you see a sharp change in temperature and dew point right along the boundary. Ahead of the front the air is usually warmer and moister, and behind it it becomes cooler and drier, creating clear gradients in both temperature and dew point on the map. Winds tend to shift direction as the front passes because the region’s pressure field and air mass characteristics reconfigure, leading to a change in the prevailing flow. The passage of a front also brings changes in the nearby pressure pattern, such as shifts in pressure gradients or the development of troughs, near the front. This combination—T and dew point changing across the front, winds changing direction, and pressure pattern adjustments—is why this option is the best description.