The heat is on in Three Rivers (and more weather news)

Monsoon-related thunderstorm activity builds up over the Sierra on Monday, July 22.

Update: Thursday, July 25— Three Rivers experienced wind throughout the afternoon, an unusual weather pattern for this canyon. The wind was a result of the storminess in the mountains. Precipitation fell at 1,500 feet and above. Areas in the higher elevations of Sequoia and Kings Canyon National Parks received deluges of up to two inches per hour, according to the National Weather Service-Hanford.

While the high country deals with heavy rainfall and residual debris flows, the San Joaquin Valley is under a heat advisory through the weekend. It is best to take precautions to avoid overheating.

Common symptoms of heat-related illnesses include profuse sweating, headache, extreme tiredness, weakness, dim or blurred vision, nausea, dizziness, and/or cold, damp skin or hot, dry skin. If someone is in need of emergency medical attention, call 9-1-1.

ŸIn Three Rivers, the “cooling center” available is Three Rivers Library during regular business hours. Tulare County and incorporated cities offer Cooling Centers during the hot daytime hours for those who don’t have air conditioning. The list of Cooling Centers countywide is available anytime here or by calling 2-1-1.

Never leave any person or animal in a parked vehicle. Temperatures can exceed 120 degrees within 10 minutes, even with the windows down, resulting in serious illness or death. Also, keep in close contact with friends and family who may be at greater risk of heat illness, such as infants and young children, the elderly, and those with health risks to ensure their health and safety.

Sierra thunderstorms

Monsoon moisture originating in the Desert Southwest is making its way into California. This monsoonal residue will impact the region with cloudiness in the foothills and thunderheads forming over the High Sierra when the warm air mass collides with the cold air mass.

Backpackers, of which there are less in the Sierra so far this year, will feel the brunt of this warm-meets-cold collision as they dodge lightning, rain, and hail. These storms usually build up during the day, then let loose with a fury for a few hours in the afternoon.

Those hardy mountaineers who endure these summer deluges receive a grand reward. The cloudy skies create epic sunsets. Pinks, oranges, and reds paint the granite peaks with a broad brush, creating a scene that causes a scramble for cameras in an attempt to capture this unforgettable, short-lived phenomena known as alpenglow.

Snow in the high country

Besides the first thunderstorms of the summer, high-country hikers are also still dealing with snow at 10,000 feet and above. All the high mountain passes are still clogged with snow as are the approaches. Some of the highest lakes haven’t completely thawed. Water crossings are higher than usual for this time of year; some remain treacherous.

Summer heatwave

At the lower elevations in the Sierra foothills and the San Joaquin Valley, triple-digit heat has parked itself over the region with no letup in sight. The 15-day forecast shows daytime high temperatures at, near, or above the century mark for the next two weeks.

This is the first major heatwave for the region this summer. Like the other weather phenomena, it’s late in its arrival too.

Dangerous rivers

The river levels are slowly trending downward while the water temperature is rising somewhat. But there is still a lot of snow that needs to melt and will be making its way down the various forks of the Kaweah River so conditions will remain hazardous.

Fortunately, there have been no drownings this season. Drowning is a leading cause of accidental death in this area; high water years such as 2019 usually claim the most casualties.

There have been several close calls and rescues, in Three Rivers, Sequoia, and Kings Canyon. But no fatalities. This is, due in part, to the National Park Service taking an aggressive proactive role in water safety. Anyone who enters Sequoia National Park can’t escape the large, lighted sign board that warns of the rivers’ dangers and advises visitors to stay well away from water’s edge.

Sequoia’s River Rovers have been out in full force this year too. This group of volunteers is the front line for visitor information about all things water. They contact visitors at river access points to explain the dangers and deceptiveness of the local waterways that may look inviting and calm in one area when just around the bend there is a narrow, rocky, steep, whitewater channel from which no one would be able to escape.

Where have all the flowers gone?

Three Rivers enjoys its wildflower season during the spring months. But the wildflowers don’t go away, they just head for the high country. Current peak bloom is at about 8,000 feet, so no windshield tours here. Flower enthusiasts will have to park the car and take an uphill walk to enjoy the color.

California’s wildfire outlook

This time of year, the long-range forecast becomes an important predictor of what the future holds for California since the two most destructive wildfires the state has ever experienced occurred in the fall of 2017 and 2018. These predictions begin with examining the water temperature of the high-latitude oceans. Currently, the water temperature near Nome, Alaska, is four degrees warmer than that off Ocean Beach in San Francisco; it’s the ocean warmth that holds implications of a warmer-than-normal fall and winter.

According to Daniel Swain, climate scientist with the Institute of the Environment and Sustainability at UCLA: “The seasonal models are actually in pretty good agreement that the September through November period will be significantly warmer than average for most of the West. In California, a key question will be, will these projected warm autumn temperatures coincide with frequent and/or strong offshore wind events? At the moment, it’s too early to say. But if so, we could well experience another severe autumn fire season given the prodigious growth of grass and brush due to the cool/wet conditions this past spring.”

Breathing easy

For the most part, the air quality this summer has been uncharacteristically good. Even when there was a prescribed burn in Sequoia causing smoke to linger in the air, the Real-Time Air Quality Advisory Network of the San Joaquin Valley Air Pollution Control District has only dipped to 3 a few times on its scale of 1 to 5 (1-Good; 2-Moderate; 3-Unhealthy for Sensitive Groups, 4- Unhealthy, 5- Very Unhealthy).

With the run of hot weather, the air quality usually deteriorates rapidly with the stagnant air mass caused by the high-pressure buildup. But the last few days have consisted of clear, crisp, blue skies. Now with the surge of monsoon-related thunderstorm activity, the air movement should help keep the sky blue and the mountain views crystal clear.

Lake Kaweah is shrinking

As of Monday, July 22, at 3 p.m., the Lake Kaweah reservoir, administered by the U.S. Army Corps of Engineers, contained 133,797 acre-feet of water, 72 percent of its capacity. The 10-year average for the lake level on this day is 78,853 acre-feet, meaning it is usually substantially a much smaller lake at this time of year.


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