The summer heat dome

The weather will certainly feel like summer this week. High temperatures are expected to climb into the 90s across many areas here in the Inland Empire. Up until this point, there hasn’t been a 90-degree day for the 2020 season at Cliff’s station in Coeur d’Alene. However, Spokane did hit 90 degrees last Thursday.

The warmest temperature in Coeur d’Alene occurred last Saturday and Sunday with a reading of 88 degrees. According to Cliff’s records, there was one year when we didn’t have a 90-degree day. That occurred in 1991. The warmest temperature that year was on July 17 with a high of 89 degrees.

Many of us have already heard about the incredible heat across the southern U.S., especially the Southwest, over the past few weeks. All-time heat records have fallen across parts of Texas and the Southwest.

According to weather.com, Borger, Texas, which is about 40 miles northeast of Amarillo, hit an incredible 116 degrees on July 11. That beat its old all-time record of 113 degrees on June 26, 2011. Del Rio, Texas, hit 112 degrees on July 13. And, talk about not getting much relief at night, Midland, Texas, had a low of 85 degrees on July 14, a new low maximum record. That’s only three degrees cooler than our warmest afternoon this summer.

Other locations in the desert Southwest topped the 110-degree mark earlier this month. Phoenix, Ariz., hit 116 degrees on July 12. Of course, the hottest weather is in the desert regions as Death Valley had a scorching 128-degree high temperature on July 12. Their minimum temperature on that date was 100 degrees! This was the hottest temperature on the planet in over 3 years. Back in May of 2017, a blistering 128.7-degree reading was reported in Turbat, Pakistan.

It’s not uncommon to see high temperatures in Death Valley top the 120-degree mark. The region holds the record for the hottest temperature on Earth of 134 degrees which was set on July 10, 1913. However, there are some meteorologists and climatologists who have questioned or disputed this old temperature record. Data from nearby weather stations on that date did not record temperatures that would support that kind of extreme heat. Other weather experts say that the hottest temperature for Death Valley is 129 degrees set on July 1, 2013. That would tie the supposed warmest Earth’s temperature as Kuwait also hit 129 degrees on July 21, 2016. But, the official record still stands at 134 degrees.

Much-warmer-than-normal weather this summer has not only made headlines in the southern U.S., but in other parts of the world as well. A recent study shows northern Siberia has seen milder-than-average conditions for most of 2020. In fact, there was an all-time record of 100.4 degrees that occurred on June 20 at a station north of the Arctic Circle called Verkhoyansk. Many scientists say that global warming from human activities is the cause for the warmer temperatures in the Arctic.

The recent hot spell in the southern U.S. has been the result of a massive “heat dome.” This mountain of hot air is a large high pressure system that combines with other influences, such as a La Nina sea-surface temperature pattern, that results in hot air getting trapped under the big dome.

According to NOAA, heat domes are likely to be caused by a strong gradient, or change in ocean temperatures from the west to the east in the tropical regions of the Pacific Ocean during the previous winter season. Our planet is constantly trying to equalize itself and when there is a difference in air pressure caused by a difference in temperature, then winds are generated. Over time, the winds will move the hotter air from west to east from the ocean to the land areas. As the northern jet stream moves northward at this time of year, the hot air sinks, especially over the southern U.S., and gets trapped under the high pressure system resulting in these heat waves.

In terms of our local weather, we’re now in the drier and warmer-than-normal weather pattern as most precipitation is staying to our far north or to the northeast. However, there is a slight chance of some moisture creeping into the Inland Northwest around the end of the month.

On average, July is our driest month as we only receive .92 inches of rain. So far, our July total is .57 inches, so I think we’ll end up a little below normal. However, if a thunderstorm moves over the region late this month, then rainfall totals could be higher.

August is expected to start out drier than normal, but moisture is expected to increase toward the end of next month. The normal August precipitation is 1.23 inches. If sea-surface temperatures continue to cool down over the next 4-6 weeks, then September’s rainfall should increase to above average levels.

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Contact Randy Mann at randy@longrangeweather.com