is the jet stream retreating poleward, leaving the then cut-off system behind. Whether or not the system is of high- or low-pressure variety dictates the weather that the block causes. Precisely this situation occurred over the southern United States during late spring and early summer of 2007, when a cut-off-low system hovering over the region brought unusually cool temperatures and an extraordinary amount of rain to Texas and Oklahoma (see June 2007 Texas flooding), and a cut-off-high near the coast of Georgia that caused a drought in the Southeast that same year. Rainy, cooler weather results if the block is a low in the US. Hurricane Ian in the last week of September 2022 drifted northward and its remnants became detached from the jet stream, resulting in a stationary low pressure system spinning off the Northeastern US and bringing several days of precipitation until a front finally moved through on October 6. Blocking high If the block is a high, it will usually lead to dry, warm weather as the air beneath it is compressed and warmed, as happened in southeastern Australia in 2006 and 1967 with resultant extreme droughts. However, when a blocking high is situated in the Tasman Sea it can cause torrential rains in eastern Australia, as in the cases of the 2021 and 2022 flood events. In Australia, blocking highs generally occur in the Great Australian Bight and the Tasman Sea, which are powerful high-pressure systems that usually develop further south than normal. They stay virtually unmoving for an lengthy period (i.e. several days to weeks) and thus block the regular easterly motion of weather systems across southern Australia. Cold air damming Blocking of atmospheric systems near the surface of the Earth occurs when a well-established poleward high pressure system lies near or within the path of the advancing storm system. The thicker the cold air mass is, the more effectively it can block an invading milder air mass. The depth of the cold air mass is normally shallower than the mountain barrier which created the cold air damming, or CAD. Some events across the Intermountain West can last for ten days. Pollutants and smoke can remain suspended within the stable air mass of a cold air dam. Midlatitude cold waves In the middle latitudes of the Northern Hemisphere, areas on the eastern side of blocking anticyclones or under the influence of anomalous flows from colder