Radar X-Ray detects small, but powerful storms

ABC13's exclusive Radar X-Ray identified several thunderstorms that were topping out over 50,0000' Wednesday afternoon. 

Radar X-Ray slices through thunderstorms to see what's inside the clouds. The image above shows a cluster of storms east of Lake Livingston, as seen during 13 Eyewitness News at 6. 

The first line on the graph indicates a height 20,000' above the ground. Each additional line represents another 10,000'. The storm on the left side is about 35,000' tall, while the stronger storm on the right is about 55,000' high!  Thunderstorms this tall often produce large hail and gusty, damaging winds along with extremely heavy rainfall. You can also see how the upper level winds have displaced the top of the thunderstorm to the east of the rain core.

Here's a screen capture of the thunderstorm that was rumbling along the West Loop about 8:30 PM Wednesday. The main rain core was only 35,000' high. But looking out the window, you could see clouds bubbling up over other clouds, which Radar X-Ray also shows here. Another cluster of storms over eastern Liberty County is visible on the right side of the image.

This radar analysis tool allows us to show you when thunderstorms are getting stronger or weaker and gives you advance warning of a possible severe storm. And you'll see it only ABC13.

MegaDoppler 13 detects smoke from Gallery Furniture fire

The heat and smoke from the fire at Gallery Furniture was so intense we could see it on MegaDoppler 13 radar.

Mattress Mack's landmark furniture store is just off the North Freeway in northern Harris County. The warehouse behind the showroom caught fire about 8:45 PM Thursday evening. 

As the fire spread, the billowing flames emitted intense heat into the air along with thick smoke.  Scanning the horizon with one million watts of power, MegaDoppler 13 detected the plume as the light wind pushed the smoke to the west/southwest.

MegaDoppler 13 is located in northeast Fort Bend county. It is the most powerful radar in Houston. In addition to being able to punch through intense thunderstorms and detect tornadic winds, our radar is also sensitive enough to identify small targets in the atmosphere like birds, bats and particles of smoke.

MegaDoppler 13 is now LIVE on the web!

The most powerful radar in Houston is now "live" on the internet!  During severe weather we often stream MegaDoppler 13 on our website. Now it's available 24/7, regardless of the weather.

Our popular county-by-county radar maps are still posted on our webpage. These maps are updated about every three minutes and can be animated so the data loops, showing you the direction storms are moving.

Live MegaDoppler 13 HD is still the only high-resolution, high-definition radar in Houston. Operating full-time with one million watts of power, our radar can scan the sky over your house every 10-seconds during severe weather.

Radar Xray looks inside Hurricane Dolly

A 3D slice of Hurricane Dolly clearly shows the slanted eyewall as the cyclone nears the Texas coast Wednesday morning.

Radar Xray is a weather analysis tool available exclusively in the Houston area on ABC13. This image was captured about 9 AM while the storm was still about 40miles east of Brownsville.

The first line of the grid represents 20,000 feet, then each additional line is another 10,000 feet. The precipitation with Dolly extended about 35,000 feet above the ground. That's lower than severe thunderstorms which can top out above 55,000 feet, but it's pretty typical for tropical weather systems.

The 3D cross-section also shows the bands of heavy rain east of the eye separated by dry slots. At the same time, rainfall in the eyewall is heavy over a wide area. Rain was falling at the rate of 4" per hour!

Mesocyclone seen on MegaDoppler 13

A small, but powerful, counter-clockwise spinning thunderstorm moved right over Houston Wednesday afternoon. The circulation only lasted a few minutes. No warning was issued and no severe weather was reported. But the view in the sky and on the radar was quite ominous.

The image to the left is a screen capture from our own MegaDoppler13 HD. The small hook echo developed at 1:57 PM. By 2:02 PM the circulation was wrapped in rain and the storm weakened. The thunderstorm was drifting to the west which, interestingly, puts this hook at the leading edge. The hook echo usually appears on the trailing edge of a supercell.

A shear marker popped up on this storm for exactly 2 minutes which indicates a lock on the low-level and mid-level rotation.

We also saw the storm pass by our TowerCam. You can see a lowering of the cloud base in the screen capture to the right. (The height of the camera makes the storm appear closer than it really is.)  The view from the TowerCam matches what we were seeing on MegaDoppler 13.

You can watch a timelapse video of the storm here.

Mesocyclones form in the updrafts of strong thunderstorms. Although tornadoes can form in these types of storms, a study in the late 1990s revealed less than 25% of mesocyclones produce tornadoes. I think today's storm weakened because the circulation was at the front of the storm. The rain falling out of the storm cut off the inflow which disrupted the circulation after a few minutes.

Radar class for TV meteorologists

Here's something that will make your head spin: the mathematic equation that explains how MegaDoppler 13 HD sees a single raindrop as it falls through the atmosphere.

This, among other things, was covered during an all-day radar class at the American Meteorological Society conference in Denver on Wednesday. Only about 60 TV meteorologists enrolled in the class for which we receive professional development credit. I was the only meteorologist from the Houston area who took the class.

The class also covered the modernization of the National Weather Service NEXRAD which will take place over the next five years. There are currently no plans to make that data available to the public or TV stations. So it will be even more important that local TV stations have their own live radar. With MegaDoppler 13 HD we're ahead of the game... and leading the way.

A few HEAVY showers likely

There haven't been many showers on the radar lately. But where the rain has developed, a few people have gotten soaked.

Take a look at this snapshot from MegaDoppler13 HD from Monday afternoon. Heavy rain was falling along I-10 and the East Beltway. A yards were getting a good drink of water, but most of the area was dry.

Don and Pat sent me this email:

"You blew it again. Almost drowned this weekend.. you have been wrong about 80% of the time!!!"

Actually, the forecast has been very accurate lately. This is an easy pattern to predict: partly sunny with a slight chance of rain.  We simply adjust the "chance" up or down depending of the expected movement of the sea breeze, outflow boundaries and the strength of the cap.

This is the type of weather pattern we're in. Widespread rain is not in the forecast. But scattered showers are still possible. Since there's no cold front or warm front kicking off the rain, there's no pattern as to who gets wet and who doesn't.

In almost every single weathercast you'll hear me say, "We're not expecting to see too many showers on the radar. But where it does rain, the rain will be heavy."

Of that, I'm 100% certain.

Bats and Birds on MegaDoppler13 HD

When the weather is quiet, our MegaDoppler 13 radar is very sensitive to anything moving through the air. Bats and birds show up very clearly on the radar.

The image to the left, shows MegaDoppler 13 HD at 8:00 PM Wednesday. Initially, just a small echo showed up as the bats emerged from underneath the Waugh Drive Bridge just west of downtown. According to the Houston Parks and Recreation Department there are about 250,000 bats living under the bridge. As the bats fanned out across the city, we saw an expanding area on the radar that eventually stretched north beyond Bush Intercontinental Airport.

The smaller areas of reflectivity in western Harris County are migrating birds flying in from Mexico. They roost in the trees along I-10, between the West Loop and the Beltway.  Like the bats, the birds start to move around sunset.

Not all storms are created equal

I got an email from a viewer today expressing concern about MegaDoppler 13 HD. He wrote, "I am disappointed in the contrast of the new Doppler as compared to the old. When I look at it, it all has a 'blob' look."

That's a fair observation. But what you see on MegaDoppler 13 HD is what you get. Statiform precipitation is created by  large-scale uplift of the atmosphere. The result is widespread areas of light to moderate rainfall which does look like a "blob" on the radar. (See the image to the right.)

Convective precipitation, on the other hand, develops in unstable conditions.  Stronger updrafts and downdrafts produce stronger storms, with greater contrast when seen on radar.

While we're on the subject of MegaDoppler 13 HD, the video processor on the radar interprets the intensity of the rain based on the strength of the echo received by the antenna. Here's what you can expect based on the colors you see on the radar:

• Light Blue: Sprinkles or very light rain; you probably do not need your umbrella.
• Green: Light rain coming down heavy enough that you will need your umbrella.
• Yellow: Moderate rainfall; will quickly produce puddles on streets and sidewalks.
• Orange: Heavy rain usually associated with severe weather.
• Red, Magenta and Pink: Extreme rainfall and/or hail produced by severe thunderstorms.

By the way, if you have a question about the weather send me an email: tim.heller@abc.com

Buy Your Own Radar on Ebay

Here's your chance to buy your very own radar antenna!  This new listing on eBay indicates the antenna is an RCA AVQ-21. I don't know what that means either, but I'm impressed and your friends will be too! Its not MegaDoppler13, but how many people do you know who have their own radar?!

Look at the listing closely. It doesn't include any of the electronics that generate the radar signal and then process the received data. You'll also need a tower and a radome to protect your investment.  Oh yes, the FCC will require you to obtain a license if you ever want to turn on your new radar.

Father's Day is coming! Hint. Hint.