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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WPAFB Thursday Weather: Rain showers continue through weekend 

Published: Thursday, February 22, 2018 @ 12:41 AM

WRIGHT PATTERSON AIR FORCE BASE—A soggy morning is expected although rain will move out fairly quickly, according to Storm Center 7 Chief Meteorologist Eric Elwell.

RELATED: 5-Day Forecast

Temperatures will start out the day in the middle 30s and make it back into the middle 40s during the afternoon with lingering clouds. After some brief dry time tonight, rain will return to the area Friday morning with on and off rain likely to continue through Saturday. The rain may be heavy at times with a few thunderstorms possible.

RELATED: County-by-County Weather

Rainfall amounts will range from 2 to 4 inches through Sunday morning. Despite the rain, temperatures will rebound to near 60 degrees for highs both Friday and Saturday before cooling into the lower 50s to end the weekend.

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Warm temperatures lead to record-breaking week

Published: Wednesday, February 21, 2018 @ 3:14 AM

Meteorologist Kirstie Zontini looks at how the numbers have broken down for this warm week in February.

The Miami Valley saw record-breaking warmth this week.  

On Monday, temperatures climbed to 70 degrees, tying the record for the warmest day set back in 1939. The week continued to get warmer, and Tuesday morning temperatures never dropped below 61 degrees. This set a record for the warmest low temperature in Dayton for Feb. 20. The old record was 49 degrees set back in 1930.

>> WHIO Doppler 7 Interactive Radar

Things continued to heat up in the afternoon. Tuesday, the high temperature soared to 75 degrees smashing the old record for the warmest high temperature of 69 degrees which was set in 2016. The warmest February day ever on record is 76 degrees from February 24, 2017, making Tuesday the second warmest February day on record in Dayton.

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WPAFB Wednesday Weather: On, off rain showers through the day 

Published: Wednesday, February 21, 2018 @ 12:40 AM

WRIGHT PATTERSON AIR FORCE BASE—Rain will start the day today with on and off showers lasting through the day, said Storm Center 7 Chief Meteorologist Eric Elwell.

RELATED: 5-Day Forecast

Temperatures will be warmer in the morning but fall through the 50s into the 40s this afternoon. A quick break in the precipitation is expected this afternoon before another wave of rain arrives later tonight. As temperatures drop into the 30s, the rain may change to freezing rain after 3am. Some slick spots will be possible early Thursday with temperatures hovering near the freezing mark.

RELATED: County-by-County Weather

The showers will taper off as temperatures rise into the 40s. More rain arrives Friday and will last into Saturday. The rain may be heavy at times to end the week and start the weekend, which could lead to high water in spots.

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WPAFB Tuesday Weather: Warm weather continues; showers expected tonight

Published: Tuesday, February 20, 2018 @ 12:21 AM

WRIGHT PATTERSON AIR FORCE BASE—Unseasonably warm weather will continue today with temperatures soaring into the 70s this afternoon, according to Storm Center 7 Chief Meteorologist Eric Elwell.

RELATED: 5-Day Forecast

Skies will be partly sunny with gusty winds over 20mph at times. Showers and even a few thunderstorms will push into the area late tonight and linger into Wednesday. Temperatures will slowly drop through the 60s tonight and continue to fall through the 50s Wednesday. A brief break in the precipitation is expected Wednesday afternoon before another wave of rain pushes into the area Wednesday night.

RELATED: County-by-County Weather

As temperatures drop into the 30s early Thursday morning, rain may mix with sleet or change to freezing rain early Thursday before temperatures rebound above freezing Thursday afternoon. 

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