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.

MegaDifference!

The severe weather that developed around the Houston area on Thursday, May 3 gave us a chance to see what MegaDoppler13 can detect during a severe weather event.

When the hook echo developed over eastern Montgomery County it was clear that a tornado was forming. The counterclockwise spin of the storm pulled rain around the back side of the circulation, creating the "hook echo." Tornadoes form in the inflow of thunderstorm, which is right over New Caney in this radar image. Numerous trees were knocked over and at least four homes suffered significant damage.

This is what the same storm looked like on another local TV station which uses low resolution NEXRAD data. It's nearly impossible to see where the tornado is forming in this image.

We used the Doppler mode to show inbound and outbound windflow. The green colors show winds blowing toward the radar, while red shows outbound winds. The brighter the colors the stronger the wind. Notice the bright red and greens right over New Caney marking the circulation in this tornadic thunderstorm.

It's a bird! It's a... BIRD!

I thought it was pretty cool when we discovered our new high-speed, high powered Doppler radar could pick up jets flying into local airports. (See an earlier post on this blog.) But last night, ABC 13 meteorologist Travis Herzog discovered flights of birds on MegaDoppler13!

After doing a little research, we found out various species of Warblers are migrating across Texas right now. The birds are stopping in Houston after traveling across the Gulf of Mexico from the Yucatan. Eventually, these little songbirds will end up in the northern U.S. and Canada.

According to the good folks at the Russ Pitman Nature Center in Bellaire, the Warblers roost during the day in heavily wooded areas around Houston and then take off around sunset.

The thousands of birds are easily picked up by our new megafast, megawatt MegaDoppler13. On Monday night, we saw several flocks take off from around Piney Point just south of the Katy Freeway and fly northwest. We also identified a couple of other bird hotspots, near Memorial Park and in southwest Harris County.

Turns out bird watchers have been using the National Weather Service's NEXRAD to track bird migration for years.  Clemson University has a very extensive website on radar ornithology (that means the study of birds, by the way.) The Gulf Coast Bird Observatory also tracks bird migrations along the Gulf coast.

We also have a case study on how we tracked the birds on MegaDoppler13.

This is just the beginning of the migration season. Expect to see flocks of birds flying over Houston now thru the end of April.

Doppler Winds

The thunderstorms on Tuesday gave me a chance to try out the different scanning modes on our new MegaDopppler13. This image shows the movement of raindrops in relation to the radar. The shades of green indicate raindrops moving toward the radar while the red indicates raindrops moving away. The brighter the colors and the closer they are to each other, the tighter the rotation. This is the what "Doppler" radar is all about: the ability to see the wind.

After tracking the rotation on this storm for several minutes, I did a cutin warning residents of Fort Bend County about the possibilty of damaging winds. The National Weather Service issued a Severe Thunderstorm Warning a few minutes later.

It's a bird! It's a plane!

Our new megawatt, MegaDoppler13 is so sensitive it's picking up bugs, birds and airplanes!  At first I wasn't sure what the bright blips were on the radar. But after time-lapsing the data for several hours, I realized we were picking up planes flying into and out of Hobby Airport.

We could see our first thunderstorms on MegaDoppler 13 late Sunday and Monday.

MegaDoppler 13

After a year of planning and development and days of heavy lifting, we flipped the switch on our new MegaDoppler 13 weather radar today. The name refers to the power of the radar; it detects rain and wind using a megawatt, or million watt radar pulse.

Our old SuperDoppler 13 radar served us well for several years but parts were starting to wear and the electronics were outdated. We spent a lot of money last year keeping it running. It was time to trade it in.

When it came time to take down the old radar we discovered it was in worse shape than we thought. The floor of the radome was made out of wood and was rotting! Field technicians actually sawed off the top of the dome and lifted it to the ground. That gave them access to the pedestal and antenna which were pretty flimsy compared to the new radar.

We were able to use the same tower, but everything on top was replaced. And of course, all the electronics are new. It amazes me how MegaDoppler 13 can take a 240 volt electrical current, convert that to a one million watt radar pulse which is amplified up to almost 20 gigawatts by the antenna and how that invisible electromagnetic wave can detect rain.

There's a ton of material on our website about the new radar. You can view a slide show of the installation, check out the technical specs of MegaDoppler 13, review case studies and even download some wallpaper for your computer! Click here to start your tour.

I'm also very excited about our exclusive county-by-county MegaDoppler 13 website maps. You can also view these maps on your phone. Be sure and bookmark this page.

Now, you have a million more reasons to get your weather from ABC13!