Sea breeze showers produced scattered rain

Sea breeze showers are common in southeast Texas during the summer months. As the name implies, the sea breeze blows off the Gulf of Mexico. During the afternoon hours, the warm air over land starts to rise. That creates a void which causes air over the water to move inland. The front edge of this moist and somewhat cooler air is called the sea breeze. It’s like a mini-front. Yet it’s strong enough to kick off scattered thunderstorms as it moves ashore.

Rainfall along the sea breeze is usually scattered and if upper level winds are light the rain can be very heavy since the storms don’t move all that fast. Sea breeze showers also tend to develop about 10-20 miles inland, away from the coast. So communities right along the water sometimes get little rain. For example, during the month of June about an inch of rain fell in Galveston. Yet just up the road in Pearland over ten inches of rain fell last month.

Here are some other rainfall totals for June 2008:

• Bush IAH: 2.06" (-3.29" below normal)
• Hobby Airport: 8.34" (+1.50" above normal)
• Galveston: 1.06" (-2.98" below normal)
• College Station: .29" (-3.50" below normal) *
• Conroe: 1.82" (-2.76" below normal)
• Angleton: 2.35" (-2.41" below normal)
• Tomball: 3.56" (-3.70" below normal)
• Pearland: 10.06" (+2.61" above normal)
• Sugar Land: 1.89" (-3.15" below normal)

* The eighth driest June on record at College Station.

Scattered heavy showers this weekend

One of the presentations last week at the AMS Broadcast Meteorology Conference addressed ways to communicate an uncertain forecast to the public.  A recent poll indicated many people prefer knowing about the uncertainty in the forecast; it helps them prepare.

As fate would have it, there is a lot of uncertainty in the forecast for this weekend.  The big player is an area of low pressure in the upper atmosphere. The models are not consistent in handling the placement or strength of the low and the amount of moisture that will get thrown our way within the circulation. If the low settles west of us, it means more rain will be showing up on our MegaDoppler 13 HD. If the upper low ends up to our south or east, we'll get less rain.

Yesterday, the outcome looked a lot wetter than it does today. But we're leaving the forecast alone at this point so we don't end up going back and forth on the numbers.  We're still forecasting periods of heavy rain during the later afternoon and early evening hours and the likelihood of you getting wet is highest on Friday and Saturday.

During the AMS conference, one of the presenters said, "No forecast is complete without a description of its uncertainty." Anybody who doesn't tell you the forecast for this weekend might change is not telling you the whole story.

Finally! Rain clouds over Houston!

weatherblog.abc13.com

We got a double treat Tuesday evening! First, heavy rain fell in much of the city. A few neighborhoods were soaked with over an inch of much needed rain. Then, the clear sky behind the storm provided a beautiful view of the towering cumulonimbus clouds. The panoramic photo above was captured by Eyewitness Storm Spotter Joel Pirtle in Katy. The photo to the left was taken by Linda Unger in Northwest Houston.

weatherblog.abc13.com

On the back side of the anvil cloud, mammatus clouds formed. These odd looking clouds develop in very unstable air and usually indicate strong vertical wind shear. Several viewers sent us pictures of the clouds. The picture to the right was captured by Tony Tarver in east Harris County.

weatherblog.abc13.com

The photo to the left was shot by Bob Jones.

Here's one more of the sunset from Tom Chitwood in Baytown.

Keep you eye to the sky (and camera ready) on Wednesday. More thundershowers are possible. Hopefully, your yard will get wet this time!

How many ways can you say, "It's humid?"

This is the time of the year when it's humid almost every single day. Once in awhile a slight wind shift might drop the dew points, but that doesn't last long.

Dr. John Nielsen-Gammon sent me an email last week asking my opinion on the different types of humidity we get here in Houston. What?! You didn't know there were different types?  Dr. N-G, as he's known by his students, is a professor at Texas A&M University and co-writes a new blog called "Atmo.Sphere."

"Just as the Inuit have many different names for snow," he wrote, "Houston ought to have many different names for 'hot and humid'."  You can read my response here.

By the way, our own Travis Herzog studied under Dr. N-G and speaks very highly of him. "He's brilliant," Travis explained.

And juding by the quality of his graduates, he's obviously an excellent teacher.

A break from the humidity!

High pressure is settling into north Texas, bringing cooler temps and lower humidity!

The upper level low pressure that brought us scattered severe storms this week is still sitting west of us, in northern Mexico. The counter-clockwise spin around the low will give us a mostly cloudy sky on Saturday. But even without a lot of sunshine, temps will warm into the low 80s. Sunday starts off cool again, but we'll warm up quickly, getting close to 90°.

It will start to feel like Houston again on Monday, with warmer temps and higher humidity.

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.

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.

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.

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.

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.

Rainy days and....Thursdays!?

Here's something to think about while you enjoy the beautiful, sunny weather.

Researchers have discovered it rains less on the weekend and more during the week. Using a special tropical rainfall satellite, NASA meteorologist Thomas L. Bell and his colleagues analyzed eight years worth of rainfall data. They discovered rainfall is heavier during the week in the southeast United States. Specifically, Tuesday through Thursday seem to be the wettest days of the week; Saturday is the driest.

What's causing this?  Air pollution.

EPA measurements show particulate matter peaks during the middle of the week and is lower on the weekend when traffic is lighter. The researchers say the pollution initially suppresses cloud development. Instead bigger storms develop and which produce heavier rainfall.

Dealing with the Dryline

The dryline made a rare push into southeast Texas on Thursday. That doesn't happen very often. The dryline marks the boundary between moist air blowing in from the Gulf and dry air from West Texas and Mexico.  It's a semi-regular weather feature in the western part of the state but it doesn't usually get to Houston.

The strong circulation around the large storm moving through the High Plains helped push the dryline into the western part of the ABC13 viewing area on Thursday. The sky cleared out and the dew points dropped in Columbus, Brenham and Huntsville while Houston and other cities east of I-45 stayed cloudy.  If you didn't know better, you'd think that was the cool front moving in.  But the temperatures were warming behind the dryline. A thorough analysis shows the cold front is still out in West Texas.

The movement of the dryline is driven by the heating of the air. It surges eastward during the day and then retreats westward after sunset.  In places like Dallas, Abilene, San Angelo, Amarillo, Lubbock and Midland this movement back and forth can create severe thunderstorms until a cold front moves across the state and finally clears out the moist air.

Those areas in southeast Texas which cleared out earlier, are turning cloudy again as the dry line slides back to the west. But on Friday, the cold front will sweep in and clear us out. A few showers are possible ahead and along the cool front. But after it passes, we're in for a great weekend!

Active weather this week...north of Houston

A major weather system will develop across the middle part of the country later this week.

Severe thunderstorms are possible ahead of the storm while snow will fall in the cold air behind the upper low. This storm will affect a large part of the country as it moves eastward.

A few thundershowers are possible in southeast Texas along a cool front that will push this way on Thursday and Friday. But I expect our atmosphere to be "capped" with a layer of warm air aloft which should limit storm development.

We do get the benefit of the cool front, however. Temps should be in the 70s again this weekend, with low humidity!

Small chance of big showers

A slow moving cool front will push across Texas the next few days. Temperatures in North Texas will drop 10-15 degrees behind the front. We'll be on the warm side with temps topping 81° Friday afternoon.

A line of thundershowers will develop along the front by Friday afternoon and evening. I have a slight chance of rain in the forecast, but that's primarily for the northern counties. Communities like Brenham, College Station, Huntsville, Livingston and Lufkin could get wet on Friday. The chance of rain shifts southward over the weekend, however.

The cool front is aligned parallel with the upper level winds and will stall over central Texas. Small disturbances moving along the front will produce showers both Saturday and Sunday in the Houston area. The chance of rain is pretty low, but IF rain does develop, the showers could be heavy. By then, there will be plenty of moisture in the atmosphere.

What are the chances?

A friend of mine was frustrated by the forecast recently. He had planned to poor some concrete but it poured down rain. “There was only a 30% chance of rain,” he said. “What happened?” The forecast was right. That’s what happened.

A “low chance” of rain is not the same as “no chance” of rain. In this case, there was a 30% chance the atmosphere would produce precipitation somewhere in the area. The percentage does not indicate coverage, or how much of the area will get rain. The “chance of rain” is a personal forecast, the chance that you’ll get wet. Along with the percentage, we usually try and describe the type of rain that could develop: showers, thunderstorms, rain, drizzle, etc. A “30% chance of thundershowers” means there’s a chance of rain with thunder and lightning.  Sure, there’s a better chance you’ll stay dry.  But if a thundershower does develop, the rain could be heavy.

Mud Showers?!

Today you had a great excuse to have a dirty car because last night it rained mud.  Yes, mud.

To be more specific, ash from a large fire in central Mexico along with dirt particles from a dust storm in Monterrey got swept into Texas by yesterday's strong winds.  The ash and dust were carried several thousand feet into the sky where they combined with water droplets in rain clouds over central Texas.  What do you get when mix ash and dust with water?  Well, mud!

These "mud showers" developed over San Antonio and moved east into Houston early Thursday morning.  Thankfully most of the gunk rained out before it got here, but there were still enough ash and dust particles mixed in with the rain to leave a fine coating of dirt on everything outside once the rain water dried up.

Sometimes called a "dirty rain," mud storms are fairly common in west Texas and the panhandle where dust storms occur frequently, but last night's muddy mess is a rarity for us.

Now that you know you why your car suddenly got dirty last night, it's time to think about washing your car.  You can't use this excuse for long!

Record high temps on Friday!

The clouds should clear out this afternoon allowing temps to hit the upper 80s, setting a new record in Houston! The old record is 86° set in 1936. Strong southwest winds will send our temperatures soaring. Winds will be blowing 15-25 mph with stronger gusts. In south Texas, temps could reach the upper 90s around Laredo! The weather map is starting to look more like summer all of a sudden.

A wind shift early Saturday will bring our temps down a little bit, but it will still be warmer than normal. The average high this time of year is 73°. We'll cool off a little more by Sunday.

It looks like a strong storm system will be developing early next week. There's a possibility of severe weather with heavy rain on Monday and Tuesday. Watch for updates on that forecast.

Sunshine returns Tuesday

High pressure will build into the area on Tuesday. That will help clear out the sky and bring back sunshine by mid-morning. Temps will be cooler than normal, but still very comfortable. As an added bonus, a northeast wind will keep the humidity down.

Several small weather systems will be moving across Texas this week. I'm expecting a mostly cloudy sky with a few showers on Thursday as an upper air disturbance passes south of us. Another weak front on Saturday could produce a little rain.

You can always check MegaDoppler 13 radar on your cellphone at www.abc13now.com

North winds blowing in a winter chill

The north winds will blow in colder air tonight. We'll be down in 30s over most of the area by Friday morning.

The low pressure that brought us heavy rain will move away from Texas tonight, but there will be enough moisture wrapping around the backside of the storm to keep us cloudy.

Space

Temperatures will be about 20 degrees colder than normal on Friday, with a high near 50°. And the gusty north winds will put an additional chill in the air. It's going to feel like it's in the 30s all day.

Now for the good news: we warm up quickly this weekend! And it will be sunny!

Winter returns this week

Spring doesn't officially begin until March 20th, but we've already had a few beautiful, sunny days.

Wednesday was another good one! It started off in the upper 30s. However, a south wind and sunny sky helped us warm into the low 70s by late afternoon.

Meanwhile in the northern part of the state another cold front is on the move. Temps were in the 40s in the Panhandle. By Friday some parts of southeast Texas will have highs in the 40s as well!

Our exclusive FutureTrack illustrates what the satellite and radar will look like Thursday evening. Clouds will gather ahead of the front with some scattered showers early in the day. Strong storms are possible along the front during the evening as the front approaches Houston.

I expect more light rain on Friday with much colder temperatures.

Near freezing Wednesday morning

Did you visit the garden center this past weekend? Those tender plants will not like the weather coming up this week.

A cold front will blow through early Tuesday. Gusty north winds will keep us cool...about 15-20° cooler than it was on Monday! The winds will relax Tuesday night which will allow temps to cool even more. By Wednesday morning we'll be near freezing in Houston and below freezing in some outlying cities. 

It will be a light freeze, with temps below 32° for an hour or two. But you should still cover up newly planted flowers and vegetables.

Foggy start to Friday

Areas of dense fog will cover parts of southeast Texas early Friday morning. Visibility could be less than one mile in some spots, especially near the coast.

A stationary front is sitting across the area separating cool air to the north from warm, humid air to the south. A few more showers could develop along the front during the day Friday. But gradually the front should drift east of the area, allowing cooler temperatures to return...for a day.

The weekend will be sunny and warm with highs in the 70s! Perfect.

Changes in the weather, changes in the forecast

We've made some changes in the forecast for this weekend. What looked like a cold, wet weekend a few days ago, now looks warm...but still wet.

In yesterday's post, I wrote about the different weather features that will affect our weather this weekend. The upper level low is staying way out west and the cold front won't push through until Sunday now. We'll be on the warm side of the front on Friday and Saturday so temperatures will not be as low as originally forecast.  The sky will be cloudy on Friday with scattered showers throughout the day.  The rain will be light, with isolated heavier thundershowers possible. The cold front arrives late Saturday night and early Sunday. That's when we expect the strongest storms, and possibly severe weather.

3-6" of rain could fall across the area over the next three days. Some flooding could develop in those areas with poor drainage.

Provided the front keeps moving, we'll clear out on Sunday afternoon.

Recipe for a mess

Big changes are coming in the weather this weekend. For a few days now we've been mentioning that some parts of Texas could have wintry precip on Saturday and Sunday.

There are several weather features coming together that will determine what kind of precipitation falls: rain, sleet, snow...or all of the above:

• Cold front arrives on Friday: Strong thunderstorms will develop along the cold front when it first arrives on Friday. The front will turn stationary near the coast on Saturday and Sunday.
• Low pressure in the lower atmosphere: Low pressure will develop along the stalled front and then move to the northeast, pumping moisture into south Texas. The counterclockwise spin will also pull freezing cold air into Texas on the backside of the circulation.
• Low pressure in the upper atmosphere: 15,000-25,000 feet above the ground, another low pressure will develop. This adds lift to the atmosphere and promotes the development of precipitation.
• These weather features are moving: The weather will be changing hour-by-hour in some parts of the state. What might start off as rain in one area, could mix with some sleet or snow. Or vice versa.

A few days ago, it looked like enough cold air would be pulled into the storm that sleet and/or snow could fall in the Hill Country and even the northern parts of our viewing area. Lately, the forecast models are positioning the upper-level low pressure farther and farther to the west. That should keep the snow and ice in far west Texas and the Panhandle. Temps will be too warm in the Houston area. We'll get rain....and lots of it.

Strong Cold Front Tonight

Temperatures are dropping about 30° behind a strong cold front now moving across Texas. While some of us in southeast Texas got to see a peek of sunshine today, this front will bring back cloudy, wet weather for Wednesday.

None of the forecast models have a good grasp on the strength of the cold air coming in. All the models forecast temps behind the front at least five degrees too warm. Since the model data isn't accurately depicting the weather that is actually developing, today's forecast requires greater skill. 

We write our own forecast at ABC13 so you'll probably see different numbers during our weathercasts compared to other radio and TV stations. Our forecast calls for much colder weather Wednesday, Thursday and Friday...much colder than what we previously forecast. A little sun might break through the clouds on Thursday, but we're still keeping the chance of rain pretty high through the weekend.

Wet all week

The weather pattern I blogged about last week has developed. There's rain in the forecast every day this week and into next weekend.

Most of the rain on MegaDoppler 13 will be light to moderate, although a few heavier showers are possible. We are not expecting any widespread flooding problems at this time. This rain is more of a nuisance...more of a bummer, really.

The first chance for a sunny day will be next week.

More rain next week!

The weather pattern for next week does not look good. A flat, west-to-east zonal flow will develop in the upper atmosphere by Monday. Usually when this happens, we get stuck with wet weather that lasts for several days.

The jet stream will be positioned right over Texas and blowing horizontally across the map. Moisture will keep us cloudy while ripples moving along the jet stream will bring us rain.

Dry air will not have a chance to drop into Texas until the upper wind flow changes. And that might not happen until next weekend!

Sharp clearing on satellite

We saw something interesting on the visible satellite on Thursday. As the sky cleared, the clouds had a very distinct edge. Normally, clouds are a little fuzzy. Not today. Look at the area between Conroe and Liberty. The edge of the cloud bank was almost a straight line!

The sharp clearing brought sunshine back to most areas until more clouds rolled in from the southwest. The new clouds were your typical, fuzzy type of clouds.

Wet and Cold by Wednesday

Monday started off sunny, but the clouds are back. Our exclusive FutureTrack shows heavy rain in the Houston area by early Wednesday morning.

Right now, moisture is moving into Texas in the upper atmosphere; the clouds are over 20,000 feet above the ground. But an area of low pressure will be moving along the Gulf coast this week. This will pump some low-level moisture in the Houston area which will cause the clouds to thicken and eventually rain will fall.

There's a 30% chance of rain late Tuesday. Overnight Tuesday into early Wednesday morning, I expect heavy rain to fall with 2-3 inches in some locations.

This will be the first big rain of the new year. So far, only .04" of rain has fallen at Bush Intercontinental Airport since January 1, 2008.

Forecasting with FutureTrack

One of the forecasting tools available to us at ABC13 is our own FutureTrack computer model. As far as I know, we're the only local TV station running their own in-house forecast model. Four times a day, a computer in the weather center analyzes the current status of the atmosphere and then predicts how those conditions will change every 15-minutes over the next 60 hours. You commonly see the future satellite and radar data in our weathercasts.

For example, the image to the left shows the FutureTrack forecast for 9 AM Thursday morning. Our forecast called for a less than 20% chance of rain for Houston, and a 30% chance of rain for communities east of Houston and along the coast where we felt more of the rain would develop.

The image to the right shows the actual radar and satellite at 9 AM Thursday morning. There's an excellent match between the two regarding the strength and location of the heaviest rain. The clearing behind the storm is also accurately forecast.

FutureTrack also forecasts future temperatures, wind, humidity and air pressure at ground level, as well as the future upper air changes. Taken together, the computer can assess the possibility of severe weather, rainfall amounts and flooding potential. With new data available every six hours, ABC13 meteorologists compare the data output from each update and check for consistency in the track and intensity of storms. If the outcome is similar with each update, we have confidence in the forecast. FutureTrack is accurate enough at predicting storms that we can usually show you where the rain will fall, when it will start, when it will stop and how much will fall.

More weather facts from 2007

The year 2007 was the sixth wettest in Houston and the ninth warmest in Galveston. Here are the numbers for last year:

Houston | Bush Intercontinental Airport

• Average High 79.7°
• Average Low 60.4°
• Average Temp 70.1° (+1.3° warmer than normal)
• Rainfall 65.52" (+17.80" wetter than normal)

Galveston | Scholes Field

• Average High 77.6°
• Average Low 65.8°
• Average Temp 71.7° (+0.5° warmer than normal)
• Rainfall 50.92" (+7.08" wetter than normal)

Altogether, eight record high temperatures were either broken or tied in Houston, with only one record low all year. In Galveston, there was also only one record low set or tied in 2007. But twenty record high temperatures were tied or broken, with eight records set in December alone.

Here are some additional rainfall totals reported by the National Weather Service Co-Op volunteers for the year 2007:

• Alvin 62.11"
• Anahuac 61.02"
• Angleton 59.62"
• Baytown 73.73"
• Bellville 51.77"
• Brenham 56.68"
• Cleveland 51.61"
• Columbus 62.09"
• Conroe 53.37"
• Danevang 58.27"
• Freeport 54.47"

The most rain fell in Houston Heights last year. A total of 90.56" of rain was reported.

Hard Freeze Tonight

Temperatures will drop below freezing in Houston around midnight and stay below freezing for about 8 hours tonight. We'll probably drop to about 29° in the city. Galveston and other areas right along the coast will stay just above freezing with a low in the mid 30s.

There's a thin blanket of cirrus clouds moving in from the west. This will provide some insulation during the cooling tonight. Without the clouds, we'd be another 3-5° colder!

This will be the coldest night of the week. We'll stay above freezing tomorrow night. By the weekend, our highs will be near 80° again!  Such is winter in Houston.

Setting up your home weather station

So you got a new weather station for Christmas?!

Welcome to the world of weather watching! Soon, you'll be making your own forecasts. (And you'll discover it's not as easy as you thought!) My grandfather was a farmer and tracked storms using an old aneroid barometer. Things have changed a lot over the years. Now, electronic sensors allow you to precisely monitor what's happening in your neighborhood.

Here's some things to keep in mind as you set up your home weather station:

• You are trying to measure the weather, not the effects of the weather.
• The thermometer/hygrometer probe must be in a shady location where the air flows freely.
• The anemometer should also be placed in a location where the wind flows without obstruction in all directions.
• The rain gauge should be out in the open, away from trees or buildings.
• The barometer is usually built into the display panel since air pressure varies little inside and outside.

To make sure your weather station is reading correctly, you might want to compare it with the "official" data recorded at National Weather Service observation sites around the area.

Photo courtesy of Davis Instruments.

Travel problems this weekend

A strong storm will be moving across the county this weekend and that could create some problems for folks traveling outside of the Houston area.

Heavy snow will fall north of the storm track from Colorado, Kansas, Iowa and into the Great Lakes. Strong thunderstorms are possible in Arkansas, Louisiana and into the Tennessee Valley. We might have a few showers around here early Saturday, but most of the action will be well north and east of Houston.

Flying out of town? You can check airport delays on the FAA website.

To get a detailed forecast for any place in the country, go the weather section of our web page. Under the video window, you'll see a place to enter the city name or zip code of your travel destination.

Front Coming, Freeze to Follow!

While winter weather has been raging in December from the plains to the northeast, it seems that record highs in Houston have been falling faster than the leaves!  In fact, if the month ended today, it would be the 3rd warmest December on record.

But the weather here is about to turn on a dime, and by Sunday morning we expect fall's first official freeze in Houston!  Since Tuesday we have been forecasting a light freeze behind the front, and right or wrong, we see no reason to change that forecast.  In fact, now we're confident that Monday morning will be even colder, with a hard freeze likely for communities north of Houston.  So throw some logs on the fire this weekend, and stay warm!

Ice storm to our north

My Mom sent me an email from eastern Iowa where the ice storm is hitting them pretty hard. She wrote, "It is really a mess here. Trees are breaking and everything is coated with ice. We have been lucky so far and have not lost our lights. Parts of Cedar Rapids have been without lights all day. I'm shutting down my computer now because our power keeps surging."

My Dad bought a generator for storms like this. They use it to power some lamps if they lose power. There's no need to keep the refrigerator going. They just set the food outside to keep it cold.

ABC News reports the storm temporarily grounded the presidential candidates who are running all over Iowa trying to generate votes before the January caucus.

The front separating Houston from the cold air is slipping south again. It will push into southeast Texas early Wednesday morning. A graph of our temperatures over the next 24 hours shows it getting colder all day Wednesday. I expect it to be windy and wet with some scattered showers. Just rain around here; the ice will stay up north.

The photo above from ABC News shows the effect of the ice storm as it moved through Oklahoma earlier this week.

Tale of two seasons

There's a big contrast in the temperatures over southeast Texas. A stationary front separates a winter chill in the north from summer-like heat and humidity in the south and east.

An arctic cold front has been sinking southward the last couple of days. By 10AM Monday morning, the cold front was as far south as Hobby Airport. Then it stopped and started drifting north again. The front is parallel to the upper level winds so it's going to meander across Texas for a couple of days. This is the front I talked about on the blog last week.

Temps across the whole area will return to above normal levels overnight. We'll stay sticky through Wednesday. Early Thursday morning the front will surge south again, bringing back the cooler temperatures.

Wetter Weather Ahead

A shift in the jet stream will bring near record temperatures this weekend! It's also going to get humid again. All this heat and humidity will be gathering ahead of a strong cold front that will begin to push across the state on Sunday.

Thunderstorms are possible beginning Sunday and continuing into next week. Some of the rain will be heavy. The front will turn stationary which will bring repeated rain to parts of the state. If the front settles around here, the rain could stick around till next Wednesday!

North of the cold front temperatures will be cold enough that sleet and snow could fall in the Panhandle and parts of north Texas. While south of the front, it will stay warm...and wet.  That's the type of weather I expect we'll see in the Houston area.

A cold, frosty morning

Low temperatures dropped below freezing in some parts of southeast Texas early this morning. The ABC13 forecast called for a low of 35° in Houston, while our competitors followed the National Weather Service and forecast 32°. The low at Bush IAH was 33° last night while Hobby Airport dropped to 37°.

Here's some of the other low temperatures from this morning:

• Brenham 27°
• Conroe 29°
• Galveston 44°
• Huntsville 30°
• Pasadena 37°
• Pearland 36°
• Palacios 34°
• Sugar Land 34°
• Tomball 31°

We expect tonight to be rather chilly, but not as cold as last night.

Edited to reflect new low at Bush IAH.

Freeze Warning Tonight

The National Weather Service has issued a Freeze Warning for all but the coastal counties in southeast Texas. With a clear sky and light winds, temperatures will drop quickly tonight. Many areas north and west of Houston will be near or below freezing for a couple of hours. Folks living closer to the coast will stay above freezing tonight.

The Freeze Warning does include Harris County. We're forecasting a low of 35° for the city of Houston. However, outlying parts of the county could be near freezing. Places like Conroe and Lufkin could drop into the upper 20s by daybreak.

We'll warm up quickly on Tuesday. Temps will be in the mid 60s by late afternoon!

Weekend rainfall amounts

A slow moving storm dumped 4-6" of rain across parts of southeast Texas this past weekend. Radar estimates show the heaviest rain fell across central Harris County.

Our FutureTrack correctly forecast the timing of the rain and the maximum rain totals. However, we expected more rain near the coast. Only .81" of rain fell at Scholes Field in Galveston. That's partly because the secondary low on Sunday tracked east of Galveston which produced heavy rain in the Beaumont area and throughout southern Louisiana.

We're incorporating some new model physics in our FutureTrack forecasting system. I'm fairly happy with how the model performed with this storm. My goal is to consistently and accurately forecast when the rain will start, when it will stop, how much will fall and where the heaviest rain will fall. We're almost there.

Heavy rain in the Houston area this weekend

Rain will start to fall in southeast Texas by early Saturday morning and will continue through the afternoon. While showers might taper off Saturday evening, another round of heavy rain will develop early Sunday. Flooding is possible!

Our exclusive FutureTrack shows the potential for 4-6 inches, with the heaviest amounts near the coast, closer to the low pressure that will develop offshore. Rainfall totals will ultimately depend on where the strongest storms train, or track one after the other.

There could be some thunderstorms and small hail. The main threat, however, will be the potential for flooding.

Blue Norther' blowing across Texas!

As of Wednesday afternoon, the temperatures across Texas ranged from the low 40s in the Panhandle to the low 90s in the Valley.

The cold front we've been talking about since last week is pushing across the state. When the front goes through your neighborhood temperatures will drop 15-20° and gusty winds will turn in from the north.

We'll be down near 60° by 10PM here in Houston. Our low tonight will be in the upper 40s... twenty degrees colder than last night!

Ahead and along the front, strong thunderstorms could produce damaging winds and large hail. This could affect your travel plans this evening. Check the traffic before heading out.

The rest of the holiday weekend looks cold and wet. More rain will fall on Saturday and Sunday. Those showers could be heavy!

Heavy rain soaks the Houston area

For the first time in more than a month, heavy rain fell in Houston this past weekend. Our Eyewitness Storm Spotters measured 2-5" of rain from the storms that started late Saturday and continued almost non-stop through early Sunday morning.

Joe Pirtle in Katy called in with over 4 1/2" of rain and mentioned that a few fences were blown down in his neighborhood. Everett Crayne in Sealy also had about 4 1/2" of rain, but just north of him the rainfall map shows over 6" of rain fell in northern Austin County and northern Colorado County. Keith Lang said Wharton had 6.5" of rain. The map above shows healthy rain fell across the whole area.

We appreciate the efforts of our Storm Spotters. These folks volunteer to put their community on the map by reporting rainfall and severe weather. I started the Spotters network over three years ago and it's still the only organized group of TV weather observers in this area.

Wetter Weather

The weather pattern is changing for the wetter. Low pressure in the upper atmosphere will slide across Texas this weekend. These type of weather systems move very slowly. Even after this one moves out, another low will develop early next week, bringing even more rain.

But that's OK. The last time we had a good, soaking rain in the Houston area was over a month ago. Almost five inches fell way back on October 15. Very little rain has fallen since.

Our exclusive FutureTrack, a forecast model that we run in-house at ABC13, shows pockets of moderate to heavy rain starting to move toward the Houston area by Saturday evening. More showers could fall on Sunday. Up to 1-2" of rain could fall in some yards this weekend.

I expect this wet weather to clear just in time for Thanksgiving. Temperatures should drop again as well. I'm thinking highs could be in the 60s, maybe even the low 60s by then!

15 degrees cooler!

The north winds are blowing cool, dry air into Houston. And doesn't it feel great!?! It's sweater time again. I always kid Melanie Lawson on Live at 5 about her turtle-neck sweaters. As soon as it turns cool, Mel wears a turtle-neck. I think she has one of every color.

Temperatures today will be about 15 degrees cooler than yesterday. On Wednesday, we had a near record high of 86 degrees. (The record is 87 set in 1989.) Today's high will be about 70. And while you might get by with a light turtle-neck today, you'll need something heavier Friday morning. Temps will drop into the low 40s tonight.

From Sweating to Sweaters

The high temperature on Tuesday will reach the mid 80s! The record high is 87° set in 1989. And it will feel just a touch warmer when you factor in the high humidity.

The warm weather is about to end. A series of cool fronts will push through southeast Texas over the next two weeks. Instead of near record highs, we'll average closer to normal...even a little cooler than normal on a few days.

The graph to the left is a plot of the daily high temperatures over the next two weeks. This gives you an idea of the temperature trend ahead. I left the specific temperatures off the graph since the exact numbers are likely to change. But right now, the early outlook for Thanksgiving is for cooler temperatures, at least 20-25 degrees cooler than the near record high you'll feel on Tuesday.

Forecast Comes Into Focus

Last week Chief Meteorologist Tim Heller blogged about the uncertainty in this week's weather pattern.  The weather pattern is no longer in question, and the European forecast model comes away the clear winner. 

Instead of a potent upper-level storm coming through early this week, a much weaker version will pass overhead early in the weekend.

What does this mean for your forecast?  Rain chances for the week are down significantly, and record highs could fall before cooler air arrives on Thursday.  Unusually warm fall weather is common for us in a strengthening La Nina, so don't be surprised if you're still wearing shorts in December!

Uncertain forecast next week

You can count on us to tell you when we're not sure about the forecast. We could have heavy thunderstorms early next week...or nothing. The forecast is uncertain.

Right now, we expect a trough of low pressure in the upper atmosphere to move into the central part of the country by Tuesday. Strong thunderstorms, perhaps even severe weather could develop if this happens.

But...

The European forecast model has been consistently forecasting a completely different scenario, with storms staying out west. Yet another model places the low half way between! In the past, when there's a disagreement among the models, the European usually outperforms the others. However, if it's wrong we could end up with severe weather.

We're playing it safe and forecasting a chance of strong storms early next week while also stressing the forecast could change.

Cold front will cool us off Tuesday

A cold front will move through southeast Texas early Tuesday morning. Temps might start off warm, but we won't be warming up!  If this same cold front came through later in the day, we'd feel a 10-15 temperature drop. But since it will arrive during what it typically the coolest part of the day, temps will hold steady and then slowly fall.

Ahead of the front, a trough of low pressure will turn the winds in from the north. (The trough is shown as the dashed blue line on the map above.) But the cold air won't arrive until 2-3 hours after the wind shift, with the cold front.  Many meteorologists miss the trough when analyzing weather maps. They look for the wind shift and assume the north wind marks the position of the cold front. But you have to examine the temperatures and dew points to accurately locate the cold front.  The pressure pattern and wind flow will help identify a trough.

I've found that most of the time a trough will develop 100-200 miles ahead of cold fronts as they move into north Texas. As the cold air mass pushes south, the cold front eventually overtakes the trough.

The cold front should reach the coast by Noon Tuesday. Temps will hold steady throughout the afternoon and then start falling. We'll be 15-20 degrees colder by Wednesday morning!

Halloween weather a real treat!

No tricks. Just treats this Halloween. The great weather continues! There will be a little more humidity in the air, but temps will be pleasant enough so the kids will not need a jacket when they head out.

And it won’t be quite as dark for trick-or-treaters this year. The sun doesn't set until 6:40 PM…an hour later than it did last Halloween. Last year we were already back to Central Standard Time and the sun set at 5:40 PM. Beginning this year, Daylight Saving Time lasts through the first Sunday in November. We’ll set our clocks back this coming Saturday night. By the way, idea of "saving daylight" was first proposed by Benjamin Franklin in 1784.

Two sides of the same weather system

The high pressure system that is producing a cool, dry wind here in Texas is also fanning the wildfires in California. Winds blow clockwise around high pressure. With the high centered over the Rocky Mountains, we have a north wind blowing across Texas while the wind in southern California is blowing from the west, out of the deserts and mountains.

As the wind blows out of the mountains into lower elevations, it is compressed. That warms the air and dries it out. This in turn dries out the ground. Once fires start, they are hard to contain because of the all dry vegetation and strong, gusty winds which can blow 50-60 mph, or more.

The weather in California should improve over the next several days. Cooler air and weaker winds will help. A few showers could develop early next week. But there won't be enough rain to completely erase the dry conditions.

October Deluge

Yesterday is the perfect example of what can happen when a weak October cold front dives into Texas but stops short of clearing the coast: Torrential, flooding rains.  Northern Harris county picked up 5-6 inches of rain from the stalled front while folks on the southeast side of town received hardly a drop.

October is no stranger to major rain events.  In fact, the top two wettest months ever recorded in Houston happened in October 1949 and October 1984.  That's impressive considering that tropical storms and hurricanes almost never contribute to our October rain totals. 

These October rain events occur when deep tropical moisture interacts with a stalling cold front, sometimes for days at at time.  This was the case from October 16th-18th, 1994, when up to 30 inches of rain fell across southeast Texas, causing both Lake Houston and the Brazos River to crest at their highest levels ever.

Bush airport picked up 4.95" of rain after the storms finally ended early this morning, pushing our yearly rainfall total up to 57.57".  As it stands now, it will only take another 5.27" of rain this year to place 2007 on Houston's list of top 10 wettest years.

China Plans to Control the Weather During 2008 Olympics

Blue skies will dominate the 2008 Olympics held in China.  At least that's what Beijing's Weather Modification Office hopes to accomplish during the historically wet month of August.  Recently the office held a practice run for the summer games by attempting to blast ominous clouds out of the sky with rockets carrying a payload of silver iodine and dry ice. 

It is claimed that "seeding" clouds with this chemical combination can induce rainfall, dissipate clouds, and bring on the sunshine.  Some Texans tried cloud seeding a few years ago in hopes of bringing rain to the drought-stricken Edwards Aquifer, which serves as the main water supply to residents of San Antonio.     

Skeptical? Attempting to modify the weather is nothing new. Matthew Moore, producer of our Weather Extremes weather special, asked us if cloud seeding could work on hurricanes, and the answer is that it has already been tried.