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Elwell: Rare meteorology event brought severe winds to region

Published: Monday, July 17, 2017 @ 7:27 PM

Feeling like the 90s all week with a few storms at times.

One week ago, a very interesting and rare weather phenomenon occurred in a small, but populated part of the Miami Valley.

On July 11th, severe storms erupted across Indiana and began moving eastward very slowly. The storms were responsible for numerous severe weather reports around Indiana including funnel cloud sightings. However, as the storms moved closer to the Miami Valley, they began to weaken, and weaken fast. By the time the storms reached the Ohio state line around 1:30 p.m., they were producing little if any lightning strikes.

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As the storms fell apart, a wake low was formed producing wind gusts over 60 mph. So, what is a wake low? Well - first, let’s go back to what was happening at the time.

Early in the afternoon, a band of light to moderate precipitation pushing into the Miami Valley. At first glance on radar, nothing looked to ominous - but then - as the area of rain was pushing into Wayne County, Ind. - both meteorologist McCall Vrydaghs and I started to notice the wind speed being measured on doppler radar started to ramp up quickly. The wind speed about 2,000 feet off the ground was blasting through at nearly 80 mph. While typically wind speeds at this level of the atmosphere don’t usually make it to the ground, one way they can is with falling rain.

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MORE: Soaking rains keeping summer heat in check, for now

In a small geographical area about 40 miles wide and 80 miles long, the line of decaying storms started to bow outward in advance of the approaching line of rain, which helped bring down the higher winds being generated at higher altitudes. When this occurred, wind damage reports and power outages began to be reported. By the end of the wind event, over 50,000 people lost power across the Miami Valley. Dayton Power and Light said this was the worst storm related outage since the derecho windstorm of 2012.

So, if the storms were quickly weakening, what caused the severe winds? This is where the meteorology gets a bit more complicated, but let me see if I can explain what happens. Likely in school you remember learning about high pressure and low pressure on weather maps. You likely know that high pressure generally means good weather and low pressure typically means bad weather. You may or may not also remember that air typically moves from high pressure to low pressure. It turns out that these pressure differences can occur on a much smaller scale.

These big clusters of thunderstorms that form can generate mini- low and high-pressure systems. Both falling rain and the evaporation of rain create sinking air. This sinking air creates high pressure. Since air is being forced downward where it is raining, the area immediately behind the falling rain rises to “replace” the air moving into the mini-high pressure system. This becomes a cycle. This process begins to create a low-pressure system where the rain was expected. Sometimes the pressure gradient can increase rapidly which in turn, increases the wind speed. The higher the pressure gradient, the higher the wind speed .

It is believed that this is what happened in the Miami Valley last Tuesday. According to meteorologists from the National Weather Service, this rare weather event typically happens once every few years but is more common in the Plains. The legendary Ted Fujita, who is credited for coming up with the scale to measure tornadoes, is also credited for first describing wake lows back in 1955. For those who spent much of last week without power, I imagine they are hoping it is several more years (or longer) before we experience this event again.

Eric Elwell is WHIO StormCenter 7 Chief Meteorologist. Contact him at eric.elwell@coxinc.com or follow him on Facebook and Twitter.

Hurricane Maria knocks out power in Puerto Rico, takes aim at Dominican Republic

Published: Saturday, September 16, 2017 @ 9:16 PM
Updated: Thursday, September 21, 2017 @ 3:13 AM

The latest track on hurricane Maria shows a major hurricane near the Bahamas early Friday.

Hurricane Maria has caused 100 percent of Puerto Rico to lose power. 

RELATED: FEMA facing third major relief effort

As of early Thursday morning, Maria regained strength and is a Category 3 hurricane near the eastern Dominican Republic.

>> RELATED: Hurricane Maria live updates

See our WHIO Dopple 7 Interactive Radar

It could take months for power to be restored, and anyone who has power on the island is using a generator, according to reports.

>> RELATED: Maria destroys homes, triggers flooding in Puerto Rico

Maria is not a threat to the mainland U.S., according to the storm’s latest track. Maria is expected to curve back out to sea by the weekend, but there will be plenty to track. 

>> PHOTOS: Hurricane Maria slams Caribbean

Maria became the fourth major hurricane of the 2017 Atlantic season on Monday. Maria is the second storm in the 2017 Atlantic Hurricane Season to become a Category 5 storm. 

 

>>>LIVE Storm Chasers

Several islands were already severally damaged from Hurricane Irma. Rain totals could reach as high as 20 inches in some of those spots producing life threatening flash flooding and mudslides. Hurricane and tropical storm force winds extend out from the center of the storm. 

On Monday, there were three active named storms in the Atlantic for the second time this season. Tropical Depression Lee was also active. 

Touchdown 7 Forecast: Week 5

Published: Friday, September 15, 2017 @ 12:00 AM
Updated: Thursday, September 21, 2017 @ 11:38 AM

NewsCenter 7's Sports Director Mike Hartsock and StormCenter 7 Meteorologist McCall Vrydaghs talk about the forecast and the games featured on this week 5 of Touchdown 7.

Looking ahead to a warm night for Touchdown 7 Football across the Miami Valley this Friday.

Friday is the first official day of Fall, but it will feel like summer, so no need for blankets or sweatshirts this week, Storm Center 7 Meteorologist McCall Vrydaghs said.

WHIO Doppler 7 Interactive Radar

Sports Director Mike Hartsock says nothing beats this warm weather when it comes to playing football. The Game of the Week is Franklin at Valley View and will be one to watch.

Your 5-Day Forecast

For full highlights of this week's games, be sure to watch Channel 7 Friday night at 11:13 p.m.

Disaster declared in Puerto Rico after Hurricane Maria devastates island

Published: Thursday, September 21, 2017 @ 11:21 AM

Hurricane Maria Makes Landfall In Puerto Rico

President Donald Trump on Thursday declared a federal disaster in Puerto Rico after Hurricane Maria brought pounding rain and punishing winds to the island, knocking out power and causing widespread flooding and landslides.

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The declaration allows for federal resources to be used for Puerto Rico’s recovery efforts.

The island is reeling after Maria made landfall Wednesday as a Category 4 hurricane. With maximum sustained winds measured at 155 mph, according to the National Hurricane Center, Maria was the strongest hurricane to hit Puerto Rico in more than 80 years.

People walk next to a gas station flooded and damaged by the impact of Hurricane Maria, which hit the eastern region of the island, in Humacao, Puerto Rico, Wednesday, September 20, 2017. The strongest hurricane to hit Puerto Rico in more than 80 years destroyed hundreds of homes, knocked out power across the entire island and turned some streets into raging rivers in an onslaught that could plunge the U.S. territory deeper into financial crisis. (AP Photo/Carlos Giusti)(Carlos Giusti/AP)

"Months and months and months and months are going to pass before we can recover from this," Felix Delgado, mayor of the northern coastal city of Catano, told The Associated Press.

Videos posted on social media showed swift floodwaters and powerful winds brought to Puerto Rico by Maria.

Maria knocked out power to the entire island and its 3.4 million residents, officials said Wednesday.

Ricardo Ramos, CEO of the Puerto Rico Electric Power Authority, told CNN that it could be as long as six months before power is restored.

“The system has been basically destroyed,” he said.

Maria continued to churn over the Atlantic Ocean as a major Category 3 hurricane on Thursday afternoon with maximum sustained winds measured at 115 mph, the National Hurricane Center said in an 11 a.m. advisory. Officials warned that the storm, which is expected to turn to the north early Friday, could still strengthen over the next day or two.

Jupiter visible in the night sky through Saturday

Published: Thursday, September 21, 2017 @ 6:53 AM

Meteorologist Kirstie Zontini explains how to find Jupiter over the next few mornings.

The moon will help you again this weekend to find a bright planet. 

Jupiter will be visible in the night sky right after sunset until Saturday.

RELATED: Dayton Interactive Radar - WHIO Doppler 7

On Thursday evening, the sun will set around 8:42 p.m., on  Friday at 9:13 p.m., and on Saturday at 9:46 p.m. Look to the western horizon and make sure you have a clear view free of trees or buildings that would block your view. When you find the waxing crescent moon, look toward the horizon for Jupiter. 

The two will be the closest together on Thursday and Friday. Jupiter will be to the bottom right of the moon Friday and Saturday evening. 

RELATED: 5-Day Forecast

Don't forget to use the hashtag SkyWitness7 when sharing pictures.

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