Slow moving cool front keeps rain in the Houston forecast

Usually when you see a cool front on the weather map, it's moving fairly quickly. Not so this week.

The cool front sitting across Texas right now is parallel with the jet stream winds in the upper atmosphere so it's barely moving. Furthermore, a deep low pressure in the upper atmosphere over New Mexico is also sending out small disturbances which move along the front and keep it active with periods of rain and thunderstorms.

One round of severe weather moved across southeast Texas early Wednesday. Trees were knocked down in Burleson, Walker and San Jacinto counties. Heavy rain got as far south as northern Harris County, but most of the city and those cities south of I-10 got only light rain, if even that.

Because of this slow moving front, there's still a chance of severe thunderstorms on Thursday. Heavy rain and large hail are likely. There's also the slight risk of a few funnel clouds.  Most of the computer models are forecasting drier conditions for Friday. Our exclusive FutureTrack still shows additional rain in the area of Friday. So the ABC13 forecast calls for a 40% chance of leftover thundershowers.

Hurricane names Dean, Felix and Noel are retired

The hurricane committee for the World Meteorological Organization retired the names of three major hurricanes that develop during the 2007 season. The names Dean, Felix and Noel will never be used again for tropical cyclones that develop in the Atlantic basin because of the devastation they caused.

While most people in the United States consider last hurricane season a "quiet year," over 300 people died in Central America and the Caribbean because of hurricanes. Both hurricanes Dean and Felix made landfall as category 5 hurricanes, something that has never happened since records began in the mid 1800s. Dean hit the Yucatan peninsula where 32 people died. Felix was responsible for 130 deaths in Nicaragua and Honduras. Noel was a late season storm that only reached category 1 strength, but killed over 160 people in the Caribbean and Bahama islands. Noel also produced widespread power outages and coastal flooding as it moved along the northeast coast of the U.S. and eastern Canada.

Altogether, 70 names have been retired since tropical cyclones were first named in 1953. The names Dean, Felix and Noel will be replaced with Dorian, Fernand and Nestor.

Heavy Rain Ahead

Updated Tuesday Afternoon:

I'm still expecting some heavy rain on Wednesday and Thursday. The showers are developing along a slow moving cool front which should push through Houston on Thursday.

Storms that develop ahead and along the cool front could produce heavy rain. Given the amount of moisture in the air, most of us will probably get about 2" of rain over the next few days. Some isolated locations could have twice that amount.

There's also the possibility of some large hail and damaging winds with these storms. Isolated tornadoes are possible, but not likely, in the Houston area.

Previous Discussion Follows:

A shift in the jet stream will bring a slow-moving storm this way by midweek.

Scattered showers will develop on Tuesday as a warm front surges northward across the the area. The rain starts in earnest on Wednesday and Thursday with a cool front pushing this direction. Low pressure in the upper atmosphere will keep the weather active with repeated storms moving along the front.

A north wind on Friday should reduce the chance of rain. But I'm concerned about another upper level storm setting up west of us which could bring even more rain.  I'm forecasting dry weather for Saturday at this time, but that could change depending on how the storm develops later this week.

Stay up with this forecast this week. While many parts of southeast Texas are still pretty dry, several hours of rain could saturate the ground and cause some isolated flooding problems.

New jet stream maps on ABC13

We're using some new jet stream maps on 13 Eyewitness News. Instead of just showing a bunch of arrows on a map, we're showing you real data now.

In the sample image to the right, the gray lines indicate the wind flow and the color shading designates the wind speed at about 25,000 feet above the ground. The shades of red and orange represent winds blowing over 100 mph. We overlay the satellite imagery on top of the wind data so you can see the direct effects of the jet stream.

What you'll notice right away, is that the jet stream is not one continuous river of wind. Rather the winds in the upper atmosphere move along in streaks. These powerful bursts of wind play an important role in the intensity and movement of storms crossing country. 

Tell me what you think about the new jet stream maps. Do you like them? Are they confusing? Post your comments below.

Is it a record high, or not?

According to the National Weather Service the record high for Saturday is either 92° or 94°.  The online database, which we've been referencing all week, lists the record for May 10 as 92° set in 2003.  Then today, the NWS issued a climate statement listing the record for May 10 as 94° set in 1927.

So I called them.  Apparently, there are two different databases being used here. One list shows the record temps recorded at Bush IAH and the other database shows the all time record observed at the "official" recording site, regardless of where that site was located. From 1889 through the 1960s, the "official" data was collected in downtown Houston. The "official" site moved to the big airport in 1969.

Either way, Saturday is going to be a hot day. Just by chance, my forecast calls for a high of 93°, which will be a record high or a near record high.  A wind shift on Sunday will drop the temps back into the 80s and bring us lower humidity. Just for you, Mom.

Updated Saturday Evening: The National Weather Service issued a statement regarding my questions on the record temps:

NCDC (the National Climatic Data Center) has issued a new set of records for Houston which go further back in time than the previous set. We are in the process of updating this information on the NWS HGX website. The correct records can be found in the daily climate products.

So the new record high for May 10 is 94° set in 1927. The official high at Bush IAH on Saturday was 91°, a near record high. Until we hear otherwise....

Air pollution and weather

Already this spring we’ve had a couple of days when the air pollution has been unhealthy. The amount of pollution released into the air doesn’t change much from day to day. But the weather patterns affect how much pollution collects in the lower atmosphere and whether it makes the air unhealthy to breathe.

High pressure might bring us a sunny sky, but it also produces weak winds. That allows the air to become stagnant. In turn, the sunshine bakes the pollution which creates noxious ozone. Although ozone is invisible, the pollution that creates the ozone gives the sky a brown, hazy appearance.

While pollution is a problem for all of us, it’s especially hard on folks with heart and lung ailments, the elderly and very young. When the air quality becomes unhealthy, avoid being outdoors during the afternoon and early evening hours when pollution is usually worse. Stay indoors where the air conditioner will help filter the air you breathe.

Watch for the "Weather and Health" reports on ABC13 and on our 24-hour weather channel Comcast 315. We report the expected allergy levels, the UV Index and the Air Quality Forecast.

Satellite shows flooding from Myanmar hurricane

The death toll continues to climb in Myanmar in the wake of a major hurricane. Cyclone Nargis hit over the weekend with 130 mph winds. As of late Tuesday, the death toll had climbed to 22,000, with twice as many people believed to be missing.

High resolution satellite imagery shows how much of the low-lying area was affected by the storm. In the top picture, taken April 15, you can clearly see the ocean and rivers in blue, as well as the fields and wetlands in green and brown.

SPACE

The next image was taken on Monday. The blue shading shows floodwater covering about 20,000 square miles of Myanmar. Yangon, a city similar in population to Houston, is almost completely surrounded by water.

Nargis was the equivalent of a strong category 3 hurricane and moved in from the west. The storm was near peak intensity when it made landfall on May 2. The strong winds and a broad counter-clockwise circulation pushed a huge swell of ocean water into the Gulf of Martabon. As the eye made landfall south of Bassein, the 12-foot storm surge inundated the area which is barely above sea level. Most of the victims drowned.

It's "SKOALS," not "SHOALS" Airport in Galveston

Jim O'Donnel from the Jamaica Beach Weather Observatory sent me an email about the name of the airport on Galveston Island:

The correct pronunciation is "SKOALS" (like the chewing tobacco).  It is pronounced just like most other words that begin with "SCH" such as school, scholastic, schooner, schedule, etc.

It is probably due to the fact that a "shoal" is closely associated with the coast that the airport name is always mispronounced.

I trust Jim. But to be sure, I called the airport in Galveston and the lady who answered the phone said, "Good afternoon, Scholes (SKOALS) Airport."  I said, "Thank you. You just answered my question."  After I explained why I was calling, she told me no one pronounces it correctly.

O'Donnel worked at the Scholes Airport weather office for many years. He said the airport was named about Robert D. Scholes who was a longtime airport manager. Apparently, some family members still live in the Galveston area and would prefer we pronounce the name of the airport correctly.

A few lifelong Houstonians who work in our newsroom had trouble believing this. "Everyone pronounces it "SHOALS," they said!  How could so many people be so wrong?

Heavy rain soaks parts of Houston

We needed the rain, and we got it!  At least, some of us got it.

Showers developing along a warm front produced heavy rainfall across parts of southeast Texas. Five to eight inches of rain were reported in northern Washington, Waller and Harris Counties.

Lee Sulecki, our Eyewitness Storm Spotter in Tomball is also a volunteer fireman at the Rosehill Fire Department.  He reported late Monday afternoon that creeks and streams in his area were still within the banks.

On the other hand, on the other side of the warm front, only a few sprinkles fell in southern Harris, Fort Bend, Brazoria and most of Galveston County.

Behind the scenes of the morphing weather video

Several people have asked me how we filmed the "All Weather Man" commercial, now showing on ABC13. 

During the 30-second spot, you first see me walking down a sunny street in a short sleeve shirt, talking about a change in the weather. Suddenly, I change...or rather "morph" and you see me wearing a rain jacket. The weather keeps getting worse with gale force winds and torrential rain. Then just as quickly, the rain stops and I walk back into the weather center, dry and wearing a suit.  All in a day's work!

CLICK HERE TO WATCH THE VIDEO

The truth is, the whole commercial was shot in a TV studio, in front of a chroma-key "green screen." This is the same method we use to put the weather maps behind me during the news. The color green is electronically removed from the video. For the commercial the green is replaced with shots of Houston. The weather was digitally added during editing.

SPACE

The morphing shot was the most difficult to film. The director had me deliver the lines while walking on a treadmill so the editors could match up my walk and talk. I had to say the lines several times, first dressed in casual clothes and then again while wearing a rain jacket. And the lines had to be delivered exactly the same way everytime. That sequence alone took about four hours to set up and shoot.

SPACE

Then we got to have some fun. The production crew sprayed me down with water to make it look like I was walking in the rain.  When the "weather takes a turn for the worst," they shot the scene using high powered fans and a water sprayer to create the perfect storm. The director kept yelling, "More wind! More rain!" Again we did several takes, over and over.

SPACE

Sure, we could have filmed the commercial outside, using real weather. But it would have taken weeks to shoot. This way the producers could control the camera shots...and control the weather. I got soaked, but everyone else (and all the camera equipment) stayed completely dry.

This was a big time, Hollywood style production. We had a crew of about 10 people working behind the scenes, including lighting and audio technicians, assistants and grips.  It was a lot of fun. But it was work, more for the crew than me!. For my part, there was a lot of standing around and waiting while the camera shot was set and the lights adjusted. And then, "Action!"

All photos from Mike McGuff. Used with permission.

Gravity waves in the clouds

The satellite captured an image of gravity waves moving through the clouds early Friday morning. If you look carefully at the image to the left, you'll see ripples in the clouds which look similar to waves you see in the ocean.

This unique pattern is caused by wind moving up and down in waves. A trough of low pressure moved through the area which caused a wind shift and triggered the wave. Gravity waves are more common in the mountains and around thunderstorms where updrafts can cause sudden vertical displacement of the air.

Storm Spotters are 4 years old!

The Eyewitness Storm Spotters have been reporting the weather in their neighborhood for four years now! It is still the only network of volunteer weather observers on TV in southeast Texas.

About 35 communities are well represented by folks who love the sound of thunder and don't mind running outside during a storm to see how much is in the rain gauge. In addition to rainfall reports, the Spotters also call ABC13 whenever they spot severe weather or when wind damage or flooding are reported in their area.  The Storm Spotters are the eyes and ears of our weather team, allowing us to monitor the weather in locations outside of Houston.

While we have many areas well covered, there are still a few spots open. If you love tracking the weather and see an open spot on the map above, send me an email!  I'll tell you more about the Storm Spotter program and you can decide whether you'd like to put your town on the map.  You can write me at tim.heller@abc.com

Thanks to all the Storm Spotters who serve their communities so well! You are another reason ABC13 is Houston's Severe Weather Leader.

New boss at Houston NWS

Congratulations to Gene Hafele, the new Meteorologist-in-Charge at the Houston-Galveston National Weather Service office! Gene replaces Bill Read who left to direct the National Hurricane Center.

Gene has been the Warning Coordination Meteorologist since 1993. He also worked for about ten years in NASA's Spaceflight Meteorology Group, providing weather guidance for nine shuttle missions.

The media works very closely with the National Weather Service during severe and tropical weather events. Gene will provide stability in the local office and maintain our great working relationship.

Contrails crossing over Houston

On almost any sunny day, you can look up and see contrails crossing the sky.  These "condensation trails" are produced by jets flying across the country. When hot, humid air in the jet exhaust mixes with the cooler air temperatures aloft, the moisture condenses and creates an artificial "cloud."

The length of a contrail and the amount of time it takes to dissipate depends on the weather conditions aloft. If the atmosphere at flight level is humid, the contrail will last for hours; if it's dry, the contrail will dissipate more quickly. Also, since the temperature, humidity and wind vary greatly throughout the atmosphere, contrails can be dashed, jagged, wavy, short, long, fat and skinny. And depending on the direction planes are flying when they pass over Houston, the contrails can sometimes create interesting patterns in the sky, like the "X" you see in the TowerCam snapshot above.

Over the years these patterns have captured the attention of some folks who believe the white streaks are not contrails, but rather chemtrails. Conspiracy theorists believe our government is spraying chemicals, viruses and cancer into the air. Once such believer called the ABC13 weather center last week when the "X" pattern seen above showed up over Houston.

Giving the caller the benefit of the doubt, I immediately checked the flight paths over Houston. The image to the right is from FlightAware and was captured at the same time as the TowerCam snapshot above. The map shows the position of every passenger plane in the air. If you look carefully, you'll see several paths crossing each other in an "X" pattern. (Contrails can be much longer than the lines shown on the map which only indicate position reports received from the planes.)

There could be a real concern about contrails, however it has nothing to do with our government trying to kill us. The man-made cirrus clouds could block sunlight during the day and hold in the heat at night. As air traffic increases in the future, more studies will need to be done to determine if contrails cause a general cooling or warming of the atmosphere.

As always, you can post your comments below.

Stormy Weekend

Updated Sunday morning: The front is moving slower than originally forecast, but it's still coming. Scattered thundershowers are developing ahead of the front which will push through the area this afternoon.

The threat for severe weather is diminishing. Due to the weak flow ahead of the front, damaging winds are less likely, but there could still be a little hail in some of the stronger storms. I'm still expecting very heavy rainfall because the storms will be moving slowly.

Lower pressure in the Gulf has turned the winds in from the north, dropping the dew points at the surface. However, there's still enough moisture aloft for heavy rain in storms that develop ahead and along the cool front. Showers will also linger in the cooler air this evening.

The previous discussion follows:

We had three great weekends in a row-- with sunshine and mild temperatures! This weekend, on the other hand, will be stormy. Our lucky streak of great weather is over.

A cool front is pushing across Texas. Scattered showers will develop ahead of the front on Saturday while a squall line will blow into town early Sunday when the front pushes through.

Our exclusive FutureTrack computer model shows active storms on Saturday. Some of the rain will be heavy because upper level winds are light. An inch of rain wouldn't be unusual from any single storm that develops. And if a storm sits in one location long enough, we could see more than three inches of rain with isolated flooding problems.

I'm also concerned that a few of the storms could produce large hail and damaging winds.

The front will meander around the area on Saturday, even shifting north again before it finally plows through early Sunday. There could be a few showers ahead of the front very early Sunday. But at this time, it looks like the worst of the weather will develop after 6 AM Sunday. The front will hit Houston about 10 AM. The rain should end in Houston shortly after Noon, and by 2 PM in Galveston.

Very strong winds will blow in behind the cool front. Temps will probably be in the upper 60s most of the day Sunday, with a brief high in the low 70s. But with 20-30 mph northwest winds, it will feel much cooler.

Lights out Houston!

Have you ever looked at our beautiful skyline at night and wondered whether somebody is really working late in all those offices? Truth is, some of the lights around town are on all night even when nobody's there.

This Friday, commercial property owners, managers and tenants are being asked to shut off the lights when they leave for the day.  According to organizers of Lights Out Houston, "by eliminating just 50% of the lights routinely left on overnight and on the weekends, we can save 8.4M KW-Hours annually. That equals to almost $1 million annually."

Astronomers have been trying to get us to shut off the lights for years. We can't see the stars over Houston because of light pollution. From space, it's easy to pick out large cities because of all the lights, many which are aimlessly pointed toward the sky where the light (and energy) is wasted.

No one is asking you to shut off lights that keep your home and neighborhood secure. But look around your office and your house. If you don't need the lights on, shut them off. Didn't your Dad always tell you that?

Isolated shower produces heavy rain

Here's why we put a 20% chance of rain in the forecast.

Sure, chances are you'll stay dry. But there's enough moisture in the atmosphere that if a shower does show up on Live MegaDoppler13, the rain could be heavy.

That happened on Tuesday. An isolated thundershower developed in northern Harris County and just sat there for over an hour. Winds in the mid-levels of the atmosphere were weak so the storm didn't move much. The image to the left shows the radar rainfall estimate. The dark green shading represents more than 3 1/2" of rain!

The chance of rain will be going up this weekend. A stronger storm will be pushing across the state on Saturday and Sunday. Again, some of the rainfall will be heavy. I'm also concerned some of the storms could produce isolated wind damage.

Today is Earth Day. Try Something New!

I did something scary this weekend: I rode my bike to the store.

I just needed a few things and in honor of Earth Day, I decided to try and bike it. So I put on a backpack and my helmet and set off to maneuver through the traffic. That's the scary part-- traffic.

It's not a long trip; I only live about four city blocks from the store. And honestly, all the drivers I encountered left me plenty of room as I peddled along, going a fraction of their speed.

However, I made up time in the parking lot. I could move much more quickly than the big lumbering SUVs most people were driving. I was cautious while passing through the rows of parked cars, knowing most drivers backing out would be looking for cars, not bikes.

I was in/out of the store and back home in no time. An added bonus: I used my backpack to carry the things I bought, saving a grocery bag.

It worked so well I tried it again Sunday night. I needed a cable for my computer. So once again, I hopped on my bike and peddled off to the store.

I could get used to this! The second trip was easier than the first. And I'm sure if I do this more often, I will get accustomed to cars zipping around me. And if more people start biking, the folks driving cars will get accustomed to sharing the road with bicyclists.

What are YOU doing for Earth Day?

Subtropical jet stream right over Houston

We'll feel a lot of heat and humidity in Houston this week. But despite all the moisture in the air, there won't be much rain.

The map to the left shows the wind speed at about 30,000 feet above the ground. The main branch of the jet stream is well north of Houston right now. However, the weaker subtropical jet is directly overhead. The little bump, or ridge right over Texas, represents higher pressure which should keep us mostly dry. Small disturbances moving with the upper level winds could still produce some isolated showers through Thursday, but the chance that you'll get wet is less than 20%.

By Friday a shift in the jet stream will bring a stronger storm to the middle part of the country. That could produce a few more showers around Houston as well.

Chaos Theory Effects Weather Forecast

The man who developed the concept of the "Butterfly Effect" died last week.

Edward Lorenz, 90, discovered that even the smallest discrepancy in data can produce vastly different results when using computer models. This, he explained in a paper published in 1963, is why weather is unpredictable.

Later in 1972, Lorenz gave a presentation titled, "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas?"  The "Butterfly Effect" suggests a small flicker of a butterfly's wings can set off a chain of events that can eventually grow into a major disturbance.

Celebrate Earth Day at the Weather Museum

Earth Day is Tuesday, April 22 and the John C. Freeman Weather Museum will celebrate with a day of family fun.

The date also marks the second anniversary for the Weather Museum, the nation’s first and only museum dedicated to weather. 

The doors will be open from 10 AM to 7 PM and admission is free on that day. The Weather Museum, is located at 5104 Caroline Street in the Museum District.

Houston E-Cycles for Earth Day

The second ABC13 E-Cycle Drive was another huge success...thanks to YOU!

I don't have specific numbers.  But from the looks of it, you donated as much, if not more, electronic waste as last year. Folks dropped off their old computers, laptops, monitors, printers, cell phones, fax machines and computer mice. We also have a huge pile of power cords now.

Everything you donated will be taken apart and reused. As a whole your old computer and e-waste probably isn't worth anything. But the individual components have value and can be reused. Even the smallest capacitors and resistors can be reused.

Special thanks also to all the volunteers who helped unload the e-waste from cars as they drove through the ABC13 parking lot. Crews will be working into the night to separate the waste, pile it on palettes and prepare it for shipping to the recycling center.

I hope the spirit of the day stays with you. During a special program that aired from 9-10 AM Friday morning, Casey Curry and I gave you lots of ideas on how to "stay green" every day. 

Earth Day is Tuesday, April 22. Let's celebrate!

E-cycle Drive at ABC13

We want your junk!  Well, not all of it. Just the old electronic junk that's collecting dust in your attic or garage.

ABC13 will host an E-Cycle Drive this Friday, April 18.  Stop by the KTRK studios on 3310 Bissonnet anytime between 6 AM and 2 PM.

We’ll take your old computer monitors, keyboards, mice, routers, printers, fax machines, power cords and telephones. If you want to E-cycle your old computer or laptop, we ask that you erase or remove the hard drive before you drop it off.

Also, join meteorologist Casey Curry and me for a live Earth Day program from 9-10 AM, Friday morning. We'll focus on clean living!  It's easy to be "green."  We'll show you how.

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.

Learning about hurricanes

Over 350 local fifth graders got to step into the cockpit of a WP-3 Hurricane Hunter today. The airplane landed at Scholes Field in Galveston for the 2008 Hurricane Awareness Tour.
The students got a lesson hurricane safety and met meteorologists and engineers who fly into the eye of hurricanes...on purpose.
Hurricane Hunter data is used to pinpoint the location and strength of the storm. Measurements collected from instruments dropped from the plane while inflight are used in forecast models to project where the storm is going. The plane that landed in Galveston has made 82 penetrations, including flights into Felix in 2007 and Rita and Wilma in 2005.