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.

WPAFB Friday Weather: Patchy morning fog; highs near 80

Published: Friday, July 28, 2017 @ 1:10 AM

WRIGHT-PATTERSON AIR FORCE BASE — Patchy fog will be around to start the day with lingering clouds, Storm Center 7 Chief Meteorologist Eric Elwell said. 

RELATED: WHIO Interactive Radar 

Some passing showers will develop as we head into the afternoon. 

RELATED: Sky Witness 7

Drier air will work its way in later this evening with lowering humidity and clearing skies tonight, Elwell said. 

Highs today will be near 80 degrees, but will fall into the upper 70s with mostly sunny skies for the weekend. 

Dry weather is expected to stick around through much of next week.

Occasional showers and storms through Friday

Published: Thursday, July 27, 2017 @ 4:39 AM
Updated: Thursday, July 27, 2017 @ 11:30 PM

A soggy Thursday with a few storms. Drying out towards the weekend.

Showers taper off overnight. Some breaks in the clouds are expected but patchy fog will be likely, Storm Center 7 Chief Meteorologist Eric Elwell said. Temperatures will drop into the upper 60s.

RELATED: WHIO Interactive Radar 

QUICK-LOOK FORECAST 

  • Showers taper off overnight
  • Muggy with patchy fog possible late
  • Sunshine, comfortable for the weekend

RELATED: Sky Witness 7  

Friday's Planner

DETAILED FORECAST 

Friday: There still will be a chance for passing showers and a few thunderstorms. Showers should taper off by late afternoon. Clouds will linger through the day with highs in the upper 70s. 

Rain falls on Smithville Road on Thursday afternoon

Saturday Some patchy fog will be possible in the morning with skies becoming mostly sunny in the afternoon. It will be comfortable with lower humidity and highs in the upper 70s.

Sunday: Lots of sunshine is expected with highs near 80 degrees.

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Monday: Mostly sunny skies will start the workweek with highs in the lower 80s.

Tuesday: Partly cloudy skies expected along with a slow warming trend. Highs will be in the lower 80s.

Wednesday: Partly cloudy skies are in the forecast with highs in the middle 80s.

Space Glossary

Published: Monday, April 24, 2017 @ 7:39 AM

FILE - In this early morning, Aug. 13, 2013 file photo, a meteor streaks past the faint band of the Milky Way galaxy above the Wyoming countryside north of Cheyenne, Wyo., during a Perseids meteor shower. On Thursday night, Aug. 11, 2016 into early Friday morning, the Perseid meteor shower is expected to peak with double the normal number of meteors. Scientists call this an outburst, and they say it could reach up to 200 meteors per hour. (AP Photo/The Wyoming Tribune Eagle, Blaine McCartney)
FILE - In this early morning, Aug. 13, 2013 file photo, a meteor streaks past the faint band of the Milky Way galaxy above the Wyoming countryside north of Cheyenne, Wyo., during a Perseids meteor shower. On Thursday night, Aug. 11, 2016 into early Friday morning, the Perseid meteor shower is expected to peak with double the normal number of meteors. Scientists call this an outburst, and they say it could reach up to 200 meteors per hour. (AP Photo/The Wyoming Tribune Eagle, Blaine McCartney)

 

Asteroid: A large space rock that stays in space. These rocky objects orbit the sun and are much smaller than planets.

 

Bolide: The light emitted by a large meteoroid or asteroid as it explodes in the atmosphere.

 

Comet: A solid body made of ice, rock, dust and frozen gases. As they fracture and disintegrate, some comets leave a trail of solid debris. 

 

Fireball: A very bright meteor. It is brighter than the planet Venus. There are several thousand meteors that are bright enough to be fireballs each day. Most occur over the ocean. 

 

Meteor: Sometimes called shooting stars. These are space objects that can as small as dust or as large as a rock. Once they enter the Earth’s atmosphere they are heated by friction burn up. 

 

Meteorite: A meteor is able to survive the hot entry into the Earth’s atmosphere and reach the ground. 

 

Meteoroid: A smaller asteroid or space rock that can orbit the sun and become meteors if they enter the Earth’s atmosphere.

 

Meteor Shower: An annual event, when the Earth passes through a region having a great concentration of debris, such as particles left by a comet. From Earth, it looks like meteors radiate from the same point in the night sky.

Solar Eclipse: When the Moon moves between Earth and the Sun and the 3 celestial bodies form a straight line: Earth–Moon–Sun. Solar eclipses only occur during a New Moon.

Total Solar Eclipse: When the Moon completely covers the Sun, as seen from Earth.

Partial Solar Eclipse: When the Moon only partially covers the disk of the Sun.

Annular Solar Eclipse: When the Moon appears smaller than the Sun as it passes centrally across the solar disk and a bright ring, or annulus, of sunlight remains visible during the eclipse.

Hybrid Solar Eclipse: A rare form of solar eclipse, which changes from an annular to a total solar eclipse, and vice versa, along its path.

 

Lunar Eclipse: When Earth comes between the Sun and the Moon and blocks the Sun's rays from directly reaching the Moon. Lunar eclipses only happen at Full Moon.

Total Lunar Eclipse: When Earth's umbra – the central, dark part of its shadow – obscures all of the Moon's surface.

Partial Lunar Eclipse: When only part of the Moon's surface is obscured by Earth’s umbra.

Penumbral Lunar Eclipse: When the Moon travels through the faint penumbral portion of Earth’s shadow.

WPAFB Thursday Weather: Showers, thunderstorms today

Published: Thursday, July 27, 2017 @ 12:40 AM

WRIGHT-PATTERSON AIR FORCE BASE — Clouds will thicken up through the morning as a cold front slowly pushes into the area through the day.

RELATED: WHIO Interactive Radar 

Expect showers and thunderstorms to develop with occasional heavy rain at times. There is also a marginal risk that one or two storms could be strong. Damaging wind would be the main threat outside of the flooding threat.

RELATED: Sky Witness 7

Temperatures will be head down to around 80 degrees with the clouds and showers.

Some occasional rain will stick around into Friday before tapering off Friday night.

Clearing skies are expected for the weekend with more comfortable temperatures.