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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.

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Partly cloudy with light showers today, temps to drop below freezing tonight

Published: Thursday, April 19, 2018 @ 3:21 AM
Updated: Thursday, April 19, 2018 @ 12:07 PM

Gradual warm up towards the weekend.

Freeze Warning will go into effect at 2 a.m. Friday for Montgomery, Greene, Warren, Preble and Butler Counties.

>> Live Doppler 7 Interactive Radar

QUICK-LOOK FORECAST

  • Gradual clearing, breezy and cool today 
  • Freeze warning tonight for some
  • Slow warm up this weekend

DETAILED FORECAST

Today: High pressure will slowly move in through the day and clouds will gradually decrease. Temperatures will remain below normal with highs around 50 degrees. It will feel cooler at times due to the winds that may gust over 20mph this afternoon. Later tonight clear skies and lighter winds will allow temperatures to drop quickly. Overnight lows expected around 30 degrees. A freeze warning will go into effect at 2am through 9am tomorrow for our southern counties. Covering sensitive plants outside or bringing them indoors if possible is suggested to keep them from getting damaged.

WHIO Weather App

Friday: Temperatures will be below freezing, making for a chilly morning. There will be plenty of sunshine through the afternoon and temperatures will finally get closer to normal, reaching the upper 50s.

Saturday: Skies will be sunny with highs around 60, making for a beautiful start to the weekend.

Sunday: It will be another nice day with highs in the low 60s, which is back to normal. We’ll see sunshine through the afternoon.

>> County-by-County Weather 

Monday: The dry stretch continues. Highs will reach the mid-60s with sunshine and a few clouds.

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Clear skies in time for the Lyrid Meteor Shower this weekend 

Published: Thursday, April 19, 2018 @ 6:13 AM

The Lyrids peaks this weekend! Meteorologist Kirstie Zontini talks about where and when to look.

Dry and pleasant weather returns just in time for the Lyrid Meteor Shower this weekend, said Storm Center 7 Meteorologist Kirstie Zontini.

RELATED: Tips for viewing a meteor shower

The meteor shower peaks before dawn April 22. The waxing crescent moon will have sets around 2:30 a.m. Sunday morning, meaning the sky will be darker to watch for meteors. Grab a blanket and go outside Saturday night/Sunday morning!

RELATED: SkyWitness7

The Lyrids usually produce 10 to 20 meteors per hour, but can have outbursts which produce around 100. The radiant point, which is the point where the meteors look to come from of the Lyrid shower, is the constellation Lyra. 

Give yourself 30 minutes outside to let your eyes adjust to the darkness and enjoy the show! You might also see some meteors before dawn on the 21 and 23. Don't forget to use the hashtag #SkyWitness7 if you snap a picture.

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WPAFB Thursday Weather: Possible snow showers to start the day 

Published: Thursday, April 19, 2018 @ 12:20 AM

WRIGHT PATTERSON AIR FORCE BASE—A quick blast of wintry weather will start the day with a chance for snow showers, according to Storm Center 7 Chief Meteorologist Eric Elwell.

RELATED: 5-Day Forecast

Little, if any snow accumulation is expected. After starting in the 30s, clearing skies this afternoon will allow temperatures to rebound into the upper 40s. It will be blustery through the day.

RELATED: County-by-County Weather

A steady warming trend will get underway Friday with sunny skies. Highs will rebound into the 50s. Dry weather will stick around through the weekend with highs reaching up to 60 degrees by Sunday.

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Rain and snow possible overnight

Published: Wednesday, April 18, 2018 @ 3:36 AM
Updated: Wednesday, April 18, 2018 @ 7:00 PM

Rain and snow return later today.

    It will be blustery and turn colder overnight, Storm Center 7 Chief Meteorologist Eric Elwell said. Passing rain or snow showers are possible before daybreak, with little, if any, snow accumulation. Temperatures will fall into the middle 30s.

    QUICK-LOOK FORECAST

    • Colder air moving in overnight

    • Chance for rain/snow showers again by morning

    • Calmer, milder weather this weekend

     

    >> Live Doppler 7 Interactive Radar

Meteorologist Kirstie Zontini looks at how the pollen count will change this week.

WHIO Weather App

DETAILED FORECAST

Thursday: Expect a mix of rain or snow showers in the morning. A coating of snow will be possible on grassy and elevated surfaces in the morning, mainly north. Skies will clear in the afternoon with blustery, cool conditions. Temperatures will hold in the upper 40s.

>> County-by-County Weather 

Friday: Sunshine returns to end the week with milder temperatures in the middle 50s.

Brigitte Taylor, takes advantage of the nice weather on Wednesday to work in her yard

Saturday: Partly cloudy skies will start the weekend with temperatures reaching back into the middle to upper 50s.

Sunday: Dry weather will end the weekend with some high clouds and sunshine. Highs will top out in the lower 60s.

Monday: A bit more cloud cover is expected with highs reaching into the middle 60s.

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