A polar vortex dipping down from Siberia is bringing a cold front with frigid temperatures to millions Americans. See maps of ...

because those giant H’s and L’s representing high and low air pressure systems on a weather map are meaningless without understanding their significance. HELP FROM HIGH PRESSURE: How Houston's ...

High pressure often represents stable air, while low pressure can signify instability. On a cold, sunny day there will be a significantly higher atmospheric pressure than when a big storm is ...

The 48 hour Surface Analysis map shows current weather conditions, including frontal and high/low pressure positions, satellite infrared (IR) cloud cover, and areas of precipitation. A surface ...

Toxic smoke and dangerous particulate pollution are spreading far beyond the flames, leaving air quality at unhealthy levels ...