Summerlike heat dome to send Southwest temperatures soaring past 100 F
A strengthening heat dome will send temperatures soaring into the 90s and past 100 degrees across the Southwest, threatening records, accelerating snowmelt and raising wildfire risk now, then water supply concerns later.
The end is near for the Death Valley superbloom and Lake Manly as triple-digit heat is forecast for Death Valley next week.
Temperatures will climb well into the 90s, with some areas forecast to top 100 degrees Fahrenheit through this week. While those numbers may not seem extreme for the southwestern United States, they are running one to two months ahead of historical averages and could have implications for wildfire risk and water supplies across the interior Southwest later this year.
A persistent area of high pressure at multiple levels of the atmosphere, known as a heat dome, will intensify in the coming days and may be slow to break down.
Heat will build with a summerlike vengeance this week across the region, reaching levels that typically don't occur until May or June.
From Monday through Thursday, temperatures in downtown Los Angeles are forecast to come within a few degrees of record highs, with some records dating back to 1914.
Across the interior, especially in the deserts of Southern California, Nevada and Arizona, high temperatures will push the 100-degree threshold.
Las Vegas has never reached triple digits before May 1. AccuWeather meteorologists project temperatures will approach the century mark later this week and next weekend.
In Phoenix, the earliest 100-degree reading occurred on March 26, 1988. Multiple days at or above 100 degrees are likely throughout the week, including highs near 101 Wednesday and 104 Thursday. That level of heat is typical of mid-June.
In Death Valley, California, the projected high of 105 Wednesday would not only challenge the record for the earliest 100-degree reading by a day or two, but it would also shatter the record for the earliest 105-degree temperature set on April 1, 1966.
The heat could cause flowers to wilt amid the best superbloom in a decade, while the temporary lake that has formed in Death Valley could quickly dry up.
A superbloom unfolding in Death Valley National Park. (Dr. Elliot McGucken Fine Art Landscape Nature Photography)
The heat will expand across the Sierra Nevada and the Rockies, accelerating snowmelt in the high country. Temperatures may reach 70 degrees at elevations around 7,000 feet in the Sierra this week, and daily record highs are possible.
Denver’s earliest 90-degree reading on record occurred on April 30, 1992. Temperatures are forecast to surge to around 90 degrees later this week in the Mile High City.
Fire risk to increase in some areas, remain elevated in others
The surging heat will dry out vegetation quickly, increasing the risk of wildfire ignition. However, with winds forecast to remain relatively light across much of California, the overall wildfire threat should stay limited in the short term.
Farther east from the Rockies to the High Plains, winds will kick up on occasion, so with the ongoing drought, wildfire risk will be substantially higher this spring.
The surging heat and dry conditions in the Colorado basin may accelerate declines in reservoir and river levels later this spring and summer.
While early-season heat can initially boost runoff and raise stream and river levels, rapid snowmelt may cause that runoff to peak earlier than usual. Once the mountain snowpack is depleted, stream, lake and river levels could drop more quickly later this spring and summer.
With ample Sierra Nevada snow and rain in recent winters, California is likely to avoid critically low water levels this year. However, conditions are more concerning farther inland, where mountain snowpack this winter and in prior years has been below the historical average.
Spring water safety along area streams, beaches
Anyone considering swimming at Southern California beaches or wading in area streams should be aware of the dangers of cold water. Ocean temperatures are near their lowest levels of the year in the North Pacific, and inland streams are barely above freezing as snowmelt fuels runoff. Sudden immersion can trigger muscle cramps and cold-water shock, increasing the risk of drowning.
Some streams will be running high and fast enough to sweep people off their feet easily. Parents should be especially mindful of curious children playing at the edge of streams.
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