Weather Watch

Hail can be a big deal on the Great Plains

Last month, a monster hailstone plummeted to Earth from a slate gray South Dakota sky. It was found by ranch hand Leslie “Les” Scott near a small town of about 100 people named Vivian, on the high plains of South Dakota.

The hailstone was 8 inches in diameter and weighed almost 2 pounds! That broke the previous record for North America, when a 7-inch hailstone smashed down in Aurora, Neb., in June 2003.

I spoke with Leslie Scott about the hailstone discovery at his home near Schoolhouse Hill in Vivian.

That day, Leslie spotted a “finger tornado” while he was working and decided to head home. A few minutes later, Leslie and his wife, Debra, heard what sounded like bricks smashing against their home from an angle. What they heard that evening were enormously large hailstones, which smashed through their roof, leaving baseball-sized holes in their ceiling, and broke out many of their windows.

After the deafening noise stopped, Leslie and Debra ventured outside and saw countless large hailstones lying on the ground.

“One hailstone caught my eye because it had numerous fingers of ice sticking out of it, but there were other stones that size and even bigger that fell,” he said.

Leslie took the hailstone and placed it in his freezer. He told me it melted somewhat because he lost power to his home after the storm.

A meteorologist from the National Weather Service retrieved and sent this record-breaking chunk of ice to the National Center for Atmospheric Research in Boulder, Colo. The National Climate Extremes Committee confirmed the record weight and diameter. By the way, the world record belongs to a 2.25-pound hailstone that fell in Bangladesh in April 1986.

So, how are these monster hailstones formed?

Hail is produced in cumulonimbus clouds, otherwise known as thunderstorms. Strong updrafts within the cloud will keep supercooled raindrops suspended thousands of feet in the sky. Supercooled liquid will freeze on contact with particles like dust or even insects and grow larger and larger in the strong updrafts as they collide with other supercooled liquid droplets.

When the hailstones become too heavy to be supported by the updrafts or carried away by winds aloft, they fall to the Earth. Often in San Luis Obispo County, hail will melt before reaching the ground.

The hailstone that Leslie found probably took violent updrafts that exceeded 160 miles per hour to remain suspended in the cloud over the course of five to 10 minutes!

“It just wasn’t my house. The whole community was hit really hard,” Leslie said.

Today’s forecast

Looking at the surface charts, high pressure covers the midlatitudes of the eastern Pacific while a thermal trough is well established over California's Central Valley.

In the upper levels of the atmosphere, a weak area of low pressure will produce extensive coastal low clouds, fog and drizzle this morning. The coastal stratus will burn off later this morning.

Later today, a weak area of high pressure in the upper atmosphere will build across the southern portion of the state and will produce warmer temperatures and less marine low clouds through Tuesday, especially at locations away from the beaches.

Today’s temperatures will range from the low to mid-60s along the northwesterly-facing beaches (Los Osos and Morro Bay) and high 60s to the low 70s along the southwesterly-facing beaches (Avila Beach and Cayucos). The coastal valleys will range from the mid- to high 70s, with the North County reaching the mid-90s. To the east, California Valley is forecast to reach the low 100s.

The warm to hot interior temperatures will continue through Tuesday, then another trough of low pressure west of California will bring temperatures to below normal for mid-August for all locations by Wednesday.

However, a few of the models do indicate the possibility of monsoon moisture streaming in from the southwest later Tuesday through Wednesday, producing variable mid- to high-level clouds and a chance of thunderstorms over the Santa Lucia mountains.

Today’s surf report Increasing northwesterly (onshore) winds will generate a 3- to 5-foot northwesterly (320-degree deepwater) sea and swell (with a 4- to 10-second period) today and will remain at this height and period through Monday.

The northwesterly sea and swell will turn into 2- to 3-foot (320-degree shallow-water) seas on Tuesday through Wednesday, increasing to 3 to 5 feet (with a 5- to 7-second period) Thursday through Friday.

These northwesterly (320-degree shallow-water) seas will further build to 4 to 6 feet next Saturday and Sunday.

Arriving from the Southern Hemisphere:

A series of storms will develop about 2,000 miles to the west of Chile. The initial Southern Hemisphere (195-degree deep-water) swell from these storms will arrive Friday at 1 to 2 feet (with an 18- to 20-second period), building to 2 to 3 feet (with a 15- to 17-second period) Saturday.

This swell will be overlapped by another 2- to 3-foot (200-degree deep-water) Southern Hemisphere swell (with an 18- to 20- second period) next Sunday and Monday.

Below-normal seawater temperatures will range between 52 and 55 degrees along the immediate shoreline through Saturday.

Conservation tip

To learn more about energy sources that are free of fossil fuels, log on to the NEXT100.com website. It’s supported by Pacific Gas and Electric Co., and provides an in-depth look at the intersection of clean energy and the environment.

John Lindsey is a media relations representative for PG&E. He is also a local weather expert and has lived along the Central Coast for more than 23 years. If you would like to subscribe to his daily weather forecast or ask him a question, send him an e-mail at pgeweather@pge.com.

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