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‘Dangerously hot conditions’ prompt rare February heat alert in Los Angeles

The Washington Post logo The Washington Post 2/8/2022 Matthew Cappucci, Jacob Feuerstein
The National Weather Service's expected temperature anomalies on Thursday. Highs will range 15 to 20 degrees or more above average. (WeatherBell) The National Weather Service's expected temperature anomalies on Thursday. Highs will range 15 to 20 degrees or more above average. (WeatherBell)

We may be in the heart of winter, but that isn’t stopping the atmosphere from cooking up some extreme heat for parts of the West Coast. Multiple National Weather Service offices in California have opted to issue excessive heat watches ahead of climbing temperatures beginning Wednesday, an unusual measure that may be a first of its kind for February.

The Weather Service warns of “dangerously hot conditions with temperatures up to 90 degrees possible,” noting that visitors from other states unaccustomed to the toasty weather may be at a greater risk for heat-related illnesses. The Super Bowl is Sunday at SoFi Stadium in Inglewood, Calif., with the Cincinnati Bengals facing the Los Angeles Rams.

Excessive-heat watches are issued when “extremely dangerous” heat appears likely within one to three days, according to the Weather Service. Sixteen million people reside within the alert areas.

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Southern California is no stranger to hot weather — Los Angeles averages five days annually that hit 90 degrees or higher — but such temperatures are particularly unusual at this time of year. In fact, the city has recorded only seven 90-degree days during the winter months of December, January or February since 1948. That last time it happened was Jan. 31, 2003, when the high was 91 degrees.

The excessive-heat watch covers coastal Orange, Riverside and San Bernardino counties, as well as the interior valleys. The San Gabriel and San Fernando valleys are included in the watch, as is downtown Los Angeles. Burbank, Anaheim, Santa Ana and Newport Beach are all within the watch area.

A look at the past excessive heat watches issued by the Weather Service in Los Angeles. Notice the unusual nature of Tuesday's. (WeatherBell) A look at the past excessive heat watches issued by the Weather Service in Los Angeles. Notice the unusual nature of Tuesday's. (WeatherBell)

It’s the first time since at least 2006, when software began tabulating weather alert issuance, that an excessive-heat watch has been hoisted during February in Southern California. In fact, all other excessive-heat watches issued by the Weather Service office in Los Angeles have fallen between May and October; for the San Diego office, between April and October.

The setup isn’t exactly a classic one for extreme heat in Southern California, but it does meet the requirements for warming offshore flow. Multiple areas of high pressure are banked to the north, one in southern British Columbia and the other over Saskatchewan and Manitoba. That, coupled with weak low pressure draped across the southern United States, will funnel air westward over the Sierra Nevada.

The Weather Service's prediction for highs on Thursday. (WeatherBell) The Weather Service's prediction for highs on Thursday. (WeatherBell)

As air slides downhill into the lowlands and the Inland Empire and deserts of Southern California, it will undergo a process called adiabatic compression — greater air pressure near sea level will squeeze and compress the air, which induces a warming and drying. By the time parcels of air make it to Los Angeles between Wednesday and Friday, they’ll be sitting in the upper 80s to near 90 degrees.

A look at the broader weather map for the West reveals high pressure to the north and weak low pressure to the south. Air will likely funnel westward between the two and slide downhill in California. (WeatherBell) A look at the broader weather map for the West reveals high pressure to the north and weak low pressure to the south. Air will likely funnel westward between the two and slide downhill in California. (WeatherBell)

The dry atmosphere will be ineffective at trapping heat overnight, permitting temperatures to fall into the upper 50s and allowing some respite from the day’s anomalous warmth.

The Weather Service expects Los Angeles to snag highs of 87 degrees on Wednesday and Friday and perhaps make it up to 89 degrees on Thursday. That would flirt with record territory Wednesday and Friday and beat out Thursday’s record of 85, set in 2016. Record-keeping dates to 1944.

Average highs in Los Angeles for early to mid-February range between 65 and 66 degrees. Afternoon temperatures late in the workweek will soar 15 to 25 degrees or more above average.

Los Angeles International Airport has never logged a reading above 92 degrees during February. It’s improbable, but not impossible, that monthly records will be tied in a few areas.

Oxnard, Calif., farther northwest, is likely to remain a few degrees below records. The predicted highs for are 80 on Wednesday, 82 on Thursday and 77 on Friday; 88, 84 and 87 are the numbers to beat.

The Weather Service office in Los Angeles, in its online technical forecast discussion, did note that the forecasts do not necessarily meet the conventional requirements for pulling the trigger on an excessive-heat warning (typically issued after a watch when dangerously hot conditions are imminent), but it emphasized the hazard posed by the heat nonetheless.

“Heat risk grids are quite a bit below thresholds, in part due to relatively cool overnight temperatures in most areas,” the NWS wrote. “But the afternoon highs will pose heat risks for people enjoying outdoor activities each afternoon [Wednesday] through Friday.”

A look at temperature departures from average simulated by the American GFS model reveals an enormous swath of heat in the western U.S. (WeatherBell) A look at temperature departures from average simulated by the American GFS model reveals an enormous swath of heat in the western U.S. (WeatherBell)

The hot weather may persist into the weekend, with highs in the mid- to upper 80s forecast in Southern California. The heat may well coincide with the Super Bowl, with kickoff set for 3:30 p.m. local time. However, SoFi Stadium features a state-of-the-art roof made up of multiple operable panels that can open or close to facilitate cooling.

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The heat is occurring on the heels of California’s second-driest January on record. Dry conditions tend to intensify hot weather as a land surface stripped of its moisture heats up more readily. Three of California’s five driest Januarys on record have occurred in the past eight years.

The hot weather fits into a larger pattern of human-induced climate warming. Average winter temperatures in Los Angeles have increased two degrees since 1948 — a trend that’s been mirrored dramatically across all seasons in Southern California and more broadly across the United States and much of the planet.

A hot year in North America ... and the world A graph depicting rising winter temperatures in Los Angeles over time. (XMacis) A graph depicting rising winter temperatures in Los Angeles over time. (XMacis)
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