These conditions made way for a massive Rex block,[25][2] that is more often formed during La Niña years.[3] In this situation, a high-pressure area stays there for a long time and does not let cyclones pass through it, which could have cooled the region.[22] As the Pacific Northwest, just as the Southwest, experienced severe drought conditions, the already warm air was heating more quickly than usual,[26] which intensified the ridge so strongly it caused a heat dome.[6] Indeed, on June 27, the height at which 500 hPa air pressure was sustained (geopotential height) was reported at 5,986 m (19,639 ft) in Prince George, British Columbia – the highest ever recorded in the area; adjacent stations have similarly reported record-high values.[27] The downslope winds from the Cascades and other mountain ranges further warmed the air in the valleys.[8][9][28][29]