How Do High Pressure and Low Pressure Affect Our Weather?

Tools

By By Steve Pool

SEATTLE - You're well familiar with our "H" and "L" designations on weather maps for areas of high and low pressure, but what do they mean in regards to what weather's coming?

High pressure situations are generally associated with fair, sunny weather. As high pressure is an area of sinking air, and air tends to dry out as it sinks, leaving sunny skies.

Low pressure areas are generally cloudy/rainy areas -- where strong areas of low pressure bring our stormiest weather. That's because it's an area of rising air, and as air rises, it condenses into clouds and rain. Air moves from higher pressure to lower pressure, so if you have a high and a low nearby, it can be windy as air rushes between the two.

Your Photos

YouNews Rainbow Lightning Rainbow Lightning
Driving across I 205 bridge from Portland OR to Vancouver WA.
YouNews Various shades of Mt. Rainier Various shades of Mt. Rainier
No great sunset but lots of different cloud formations on
Thursday. The clouds eventually enveloped the entire mountain view.