Extreme Temperature Diary- Saturday June 19th, 2021/ Main Topic: Detailing Heatwave Alpha (Day 6)

The main purpose of this ongoing blog will be to track planetary extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials)😉

Main Topic: Detailing Heatwave Alpha (Day 6)

Dear Diary. Historic Heatwave Alpha is in full swing across the Southwest as of this Saturday. Yesterday we saw this temperature regime during the middle of the afternoon:

Thankfully, the 597+ decameter heat dome which spawned this heatwave has diminished, so conditions won’t get much hotter than those of Friday across the Southwest the next few days:

What has me worried here is that for the last couple of days model scenarios have changed such that the western ridge will begin to build up again with another cool system digging into the eastern U.S. Such a forecast, if it verified, would prolong and exacerbate the western heatwave and delay the onset of the monsoon. If the heat dome were to build in the more traditional area of the southern Plains, the system would usher Gulf moisture westward into much of the Southwest, which by this point needs more than a good dowsing to break its drought,

If this chart verified our Heatwave Alpha would spread northward into the Pacific Northwest a week from today:

Next week the monsoon will try to work its way into the Rockies and may get as far west as Utah and Arizona, but if the above chart were to verify the visit would be very brief. On top of that any isolated storms are likely to be of the dry variety and could set off fires.

Here is another article from the Washington Post with more updated details concerning Heatwave Alpha:


Capital Weather Gang

‘Mega-heat wave’ is peaking in the West, breaking records and intensifying drought, fires

Climate change has made the situation worse

Forecast highs Thursday in the Southwest from the National Weather Service. Boxed temperatures would be record highs. (WeatherBell)

By Jason Samenow and Diana Leonard June 17, 2021 at 9:55 a.m.

One of the most extreme heat waves ever observed in the western United States this early in the season is near its climax. The punishing blast of heat, which began Sunday, has set hundreds of records while simultaneously worsening a historically severe drought, intensifying fires and degrading air quality.

About 40 million Americans have endured triple-digit heat and more than 50 million have been under excessive-heat warnings this week.

After focusing in the northern and central Rockies earlier in the week, the core of the heat has shifted into the Desert Southwest and California’s Central Valley, where scores of additional records are predicted to fall through Saturday.

California’s Independent System Operator, which manages the state’s flow of electricity, is encouraging residents to reduce their energy use Thursday evening.

While it’s just mid-June and the hottest time of the year is historically still weeks away, temperatures have matched their highest ever observed levels in parts of Utah, Wyoming and Montana. Salt Lake City; Sheridan and Laramie, Wyo.; and Billings, Mont.; all made history Tuesday, soaring to 107, 107, 94 and 108 degrees, respectively.

On Wednesday, the mercury in Las Vegas swelled to 116, just one degree shy of its highest temperature ever recorded. Death Valley, Calif., famous for holding the world record for heat, hit 125 degrees, the highest temperature reached this year in the United States. Denver hit the century mark for a second-straight day Wednesday, the earliest in the season it has reached 100 twice in a row.

“What we are seeing in the Western U.S. this week — I’d be comfortable calling it a mega-heat wave because it is breaking 100-plus-year records, and it is affecting a wide region,” said Mojtaba Sadegh, a professor at Boise State University who specializes in climate extremes.

The “mega-heat wave” is being supercharged by climate change, scientists say. “Currently, climate change has caused rare heat waves to be 3 to 5 degrees warmer over most of the United States,” Michael Wehner, a climate scientist at Lawrence Berkeley National Laboratory, wrote in an analysis published Tuesday.

Forecasters fear that the longevity and intensity of the heat, which is the leading cause of weather-related deaths in a typical year in the United States, will take a toll on people’s health. They continue to issue dire warnings: “This magnitude and duration of heat is dangerous! Limit outdoor exposure and drink plenty of water!” the National Weather Service Las Vegas posted on its website Thursday.

The interaction of the blistering heat and a toxic soup of air pollutants has resulted in pockets of poor air quality, the worst in years in some locations. Parts of Phoenix saw the worst air quality since at least 1980 on Tuesday, tweeted Ryan Stauffer, an air quality expert at NASA. On Wednesday, several areas east of Los Angeles also experienced unhealthy air.

In a vicious, self-reinforcing cycle, the heat has intensified the historic drought plaguing the West, which has, in turn, exacerbated the heat. Nearly 55 percent of the West is experiencing an “extreme” or “exceptional” drought, according to the U.S. Drought Monitor. Soil moisture is at or near the lowest levels seen in more than 120 years in many areas, so energy that would normally go into evaporation is directly heating the air and surfaces instead.

Meanwhile, the hot, dry air has created tinderbox conditions, and blazes have erupted in several states. The fire risk on Thursday is particularly worrisome because of the prediction for dry lightning in parts of the West, which is a major ignition source.

Excessive heat warnings in effect Thursday. (National Weather Service)

Excessive heat warnings Thursday blanket much of California outside coastal and mountainous areas, southern Nevada, western and southern Arizona, and southern Utah. In many of these areas, high temperatures are forecast to exceed 100 and even 120 degrees in desert areas of Southern California.

  • In Phoenix, the high the next three days is expected to reach 116 or 117 degrees, probably breaking daily records on Thursday and Friday.
  • In Las Vegas, highs are predicted to reach 113 or 114 through Saturday, near daily records.
  • Tucson is forecast to reach 114 or 115 degrees through Saturday and about 110 Sunday. It has already hit 110 on five consecutive days and threatens to extend the streak to eight or nine days, breaking the record for its longest such streak of six days.
  • The Weather Service in Las Vegas says both Arizona and Nevada have a chance to challenge state records for their highest temperatures ever observed of 128 and 125 degrees, respectively.
  • Death Valley, Calif., is predicted to have forecast highs between 125 and 126 degrees through Saturday, just a few degrees shy of its highest June temperature on record of 129 degrees, set in 2013.
  • Fresno and Bakersfield, Calif., are predicted to have highs of 107 to 110 degrees Thursday through Saturday, near record levels.
  • Sacramento is predicted to see highs near 110 on Thursday and 107 on Friday, near record levels.

In some areas, exceptionally high nighttime low temperatures represent even a greater danger than the sizzling afternoon highs, particularly for vulnerable groups, such as the homeless, who lack air conditioning. Thursday morning’s low temperature in Las Vegas was just 91 degrees, which would be the earliest that a low temperature that warm has been recorded.

Some relief will gradually arrive. By Sunday and into next week, the heat is predicted to transition from record-challenging to simply above-normal.

Heat and drought combine to create volatile fire conditions

In the meantime, the sweltering heat, low humidity and moisture-starved land surface make for dangerous background conditions for the spread of fires.

Already parched vegetation — by many measures at peak-season dryness and breaking records for June — is going to be even more flammable both during and after this heat wave.

Since Sunday, wildfires have erupted in Arizona, California, Montana, Utah and Wyoming, and conditions are ripe for more. Red-flag warnings for high fire danger are still in effect in Montana, Utah and Wyoming.

On Thursday, the Weather Service’s Storm Prediction Center is predicting possible dry lightning over broad region of the West, which could spur fast-moving blazes. And this will become an even greater concern deeper into fire season when winds increase.

“My expectation is that we are going to have a dramatic fire season this year,” Sadegh said.

Thursday’s fire outlook from the National Weather Service. The zone shaded in brown is at risk for dry lightning strikes, which could ignite fires. The fire danger is elevated in much of the West. (NWS)

In vulnerable parts of California, the ground is as dry and vegetation flammable as it was last year ahead of its worst wildfire season on record. “Live fuel moistures remain at or near historic lows at all sites for June 15 … meaning live fuels in the unit are current as dry as they were during July 15-Aug 1 window last year,” Cal Fire’s San Mateo-Santa Cruz unit tweeted Wednesday.

Intensifying California drought promises ‘very concerning’ fire season

The climate change connection

The heat wave and drought are happening against a backdrop of rising temperatures caused by the burning of fossil fuels. Simultaneous heat waves and droughts are on the rise, with climate change not only intensifying them, but increasing their extent.

In a study published in September, Sadegh and his colleagues show that extreme heat and extreme dryness are overlapping with increasing frequency, and that rare, high-end events have had an “alarming” jump since 1993. For example, dry-hot extremes that should happen only once every 75 years occurred three or four times in the past 25 years in some regions. The most widespread and significant changes are found in the western United States.

Sadegh said that as droughts worsen heat waves and heat waves worsen droughts, people should not expect this cycle of warming and drying to break until there is a significant shift in weather patterns. “We’re still in June, so expect a lot more heat waves coming this summer,” he said.

Humidity and heat extremes are on the verge of exceeding limits of human survivability, study finds

Image without a caption

By Jason Samenow is The Washington Post’s weather editor and Capital Weather Gang’s chief meteorologist. He earned a master’s degree in atmospheric science and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association.  Twitter

Here are some of Friday and Saturday’s “ET’s“:

Today I will be adding notes about Heatwave Alpha in the space below:

Here is more climate and weather news from Saturday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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