Signals Summary: Record heat and heat waves are among the clearest signals of climate change. In the Western US, a study found that up to 90 percent of local monthly temperature records are due to climate change.
Article Excerpt: For most of April, a high-pressure system has been situated over the Gulf of Alaska, but it has now shifted into the western Lower 48 states. This is allowing a dome of hot air to build over the Southwest, which will then spread into the Rockies and parts of the Southern Plains this week. Many parts of the West will have their hottest temperatures so far this year.
Daily record highs starting falling in the Southwest last Friday and continued to be eclipsed last weekend.
Phoenix recorded its first 100-degree day of the year Sunday, soaring to a daily record of 102 degrees. They reached 102 degrees again Monday.
Daily records were tied Sunday in El Paso, Texas (95 degrees); San Diego (88 degrees); and Tucson, Arizona (99 degrees).
The National Weather Service has issued excessive heat warnings for parts Arizona, southeastern California and southern Nevada, including the cities of Las Vegas, Phoenix and Tucson, Arizona.
Much of the West will have highs 10 to 25 degrees above average through Wednesday.
By late in the week, the most-above-average warmth will spread into the Rockies and Plains.
Highs in the 80s will be common in the Rockies later this week, including Denver, and a few triple-digit highs are possible in parts of western Texas and southwest Oklahoma late this week.
Las Vegas has never reached 100 degrees before the first of May. Phoenix could approach its all-time April record high of 105 degrees, set most recently in 2012.
Amarillo, Lubbock and Midland, Texas, could each reach 100 degrees for the first time in 2020 late this week. In the northern Texas and Oklahoma Panhandles, any 100s from this heat wave would be their record hottest so early in season.