Glenn Burns weather
It's time to put up the jackets, maybe
Well, another winter is in the books and spring has officially arrived … or has it?
This past winter was the 61st coldest on record for our area. December was the warmest month of winter with temperatures averaging nearly five degrees above normal. January was fairly typical with temperatures only .2 degrees below normal. February was a different story. We were nearly seven degrees below normal.
The official snow total at Atlanta’s Hartsfield Jackson International Airport was only a trace, which was 2.1 inches below the 30 year average. However, we all know the ice and snow in our northern counties was substantial, especially the ice storm in February.
From the data I have been seeing, we may have several chances for freezing or near freezing temperatures this month with above average rainfall. In fact, I see cooler than average temperatures continuing until June. I know everyone is cringing about that. Let’s face it, we all want to enjoy the lake on sunny warm days.
Let me explain what is happening. We have a massive area of high pressure in the eastern Pacific Ocean that is now moving. This is causing warm and extremely dry conditions in the western states. In fact, many areas out west only saw about 15 percent of their usual snowfall this past winter. There are some very serious drought concerns. That same high pressure is causing the upper level winds, the steering currents, to go up over that high pressure into western Canada and then blast down into the southern states, bringing us the cooler than average weather.
While we may not want to see cooler temps, they do have a silver lining. First and foremost, cooler temperatures inhibit severe storms. Our spring storms are most violent when we have sharp contrasts between cooler weather to the north and warmer temperatures here. If the cool pattern continues, there are no “weather wars” between air masses. I am not saying we won’t see severe weather this month, just less of a chance. In addition, the pollen season will be more progressive than explosive. I don’t think we’re going to see those 11,000 pollen counts this season.
Based on the past 30 years of weather records, April is the driest month of the year. We average 3.36 inches of rain. However, this year we have a spring El Nino. This throws yet another wrench in the works. The above average sea surface temperatures in the equatorial Pacific Ocean change the global wind patterns. We will likely be dealing with two branches of the jet stream, the cold northern branch and the southern branch coming in across the eastern Pacific, then over Mexico, into the southeast. This southern branch is likely to transport an enormous amount of moisture our way. So, while April is usually the driest month, it may not be the case this go-around.
In any event, spring is here and I personally, am looking forward to a kinder and gentler severe storm season. As always, my team of five meteorologists and I will always keep you informed.
Glenn Burns is chief meteorologist for WSB-TV in Atlanta.
March 2015 column
This month ushers in severe storm season
As I said in last month’s column, I thought February would be the coldest month of the winter. As it turned out, it indeed was. We even set a record low on February 20th of 16 degrees in Atlanta. On that same night, Blairsville, up in the northeast Georgia mountains, dropped to -2 degrees.
The biggest story from last month was the devastating ice storm centered around Lake Lanier and to the north. The set up included a strong area of arctic high pressure that brought in a very shallow later of cold air (below 1800 feet). This cold air wedged itself down the east side of the mountains and “pooled” across northeast Georgia. Temperatures remained just below freezing and never moved. Above ground, at an altitude of 5,000 feet, the temperature was in the mid-40s.
When I saw this setting up, I just cringed. As the snow from the higher clouds fell into the warm layer, the snow melted into rain drops. The rain then fell on to the sub-freezing ground, where it formed a layer of ice on roads and trees. Between a quarter to half inch of ice accumulation was very common. The sheer weight of the ice was just too much for the trees to handle and one by one, they came crashing down on homes and power lines. Many residents were without power for nearly a week.
So now we head into my least favorite season of the year. Aside from the pollen, it’s severe storm season. I do expect a very active season. All winter long we have been dealing with two jet streams over the United States. The cold polar branch has been bringing us the cold arctic air. The southern branch, which has been cruising over the Pacific Ocean, and Mexico, brought us the moisture and our ice storm. It is this southern branch I am most concerned about. When spring storms erupt, these strong upper level winds over the top of the storm bring the storms a tremendous amount of energy. As winds increase from the surface to the top of the storm, this wind shear can cause the air to begin to rotate horizontally. As storm updrafts become stronger, they will tilt that rotating wind into the horizontal. This is the beginning of a tornado.
I don’t see much change in this upper level wind pattern so let’s get ready this month. There are so many ways to receive alerts, and one of the best, is our WSBTV Weather App, available for a free download in the iTunes store. It is also available for Android. We will also have our team of five meteorologists here every day, keeping you ahead of the weather.
February 2015 column
February could bring coldest temps this winter
The dire predictions from some about this winter being cold and harsh have yet to materialize. In December, the average temperature for the month was two degrees above the 30-year norm. Although we had a couple of bouts of cold weather in January, those mid-60 degree days in the middle of the month balanced that out. At press time, we did not yet have the average for January.
This brings us to February. The Climate Prediction Center gives us a 50/50 chance of having above or below average temperatures and precipitation. There may be too many variables to nail it down one way or another. Nevertheless, I have been looking through the coldest winter temperatures ever recorded in the Atlanta and north Georgia areas. Eight of the coldest temperatures ever recorded were during the month of January, as you might expect. The coldest during that month occurred on January 21st, 1985. On that day the temperature dropped to minus 8 degrees. On the list of the coldest Atlanta temperatures was the day we dropped to zero. That was Christmas Day, 1983.
Do you know when the coldest temperature to ever be recorded in Atlanta was? It was in February. On February 13th, 1899 the temperature fell to 9 degrees below zero! In the north Georgia mountains, both Blue Ridge and Blairsville saw the temperature drop to 18 degrees below zero. Both records stand to this day. I am telling you this because I do see signs that we could be in store for a very cold first half of the month. I don’t see anything close to those long standing records so don’t worry!
So, with my humble opinion that we are going to see what may be the coldest weather of the winter this month, it won’t be as cold as it could be. The reason is the lack of snow cover on the ground to our north. Unlike last year, we have just not seen the kind of systems that produce a lot of snow. With the lack of snow to our north, the cold air moving south may get a chance to warm up a little before reaching us. Air warms by conduction. The sun heats the ground and then the ground heats the air above it. Let’s hope this less-snowy winter holds this month.
I know what you’re thinking. If it’s going to be cold, what would be our chances for snow? That’s the question of the day and a little more difficult to nail down. Pretty much all winter we’ve had a split jet stream. The colder polar jet has remained to our north for the most part, occasionally bringing down shots of cold arctic air to the south. Traveling from west to east we have the sub-tropical branch of the jet stream. This southern branch can sometimes promote storm growth in the Gulf of Mexico. That’s where the “big boys” come from, the ones that can bring us accumulating snows. Needless to say, we will be watching intently this month for the gulf storm and a dip in the polar jet stream. When they meet, it can be very interesting. Stay tuned!
January 2015 column
A plan for winter weather is now in place
As we enter a new year, my thoughts have immediately turned to last year, specifically January of last year. I am hoping we never see anything like that again in north Georgia. We knew the snow was coming. We knew it was going to be around two inches or less in most areas. We also knew cold arctic air would be blasting in as the snow began tapering off. Unfortunately, many people across north Georgia either did not believe the forecast or misunderstood it. Regardless, we all know that minor winter storm created an epic disaster.
In the months following, I was asked to be on the governor’s Winter Weather Task Force, along with leaders from GEMA, GDOT, and the National Weather Service. We looked at the issues involved with this winter weather disaster, made recommendations, and came up with a plan to make sure what happened in January of 2014 does not happen again.
On Monday, January 27th, 2014 we knew winter precipitation was going to move in. It was not an especially big storm and we only expected modest snowfall (most areas would receive 2” or less). The National Weather Service issued a “winter storm watch” that included the metro area. That same night, the NWS canceled the winter storm watch and replaced it with a “winter weather advisory.”
Normally when you go from any type of watch, the next step would be to a warning. So county emergency managers, school superintendents, and most others thought the NWS had downgraded us. That was NOT the case. The advisory was actually an upgrade from a watch because there would be some travel issues. Before school began the NWS and I could see things coming together so that 3:39 in the morning, the advisory was replaced with a “winter storm warning.”
However, that morning, there was no snow falling so people just went about their business. About 11 a.m. the snow began and the arctic air moved in. People began leaving work and school in droves and it did not take long for roads and freeways to become parking lots. Truckers began sliding into cars and blocking freeways. It was mayhem.
From the governor’s task force, new policies have been set. We now have a state meteorologist (my former producer) and will have weather briefings from the NWS that will include all partners so everyone is aware and on the same page. Truckers will be stopped at checkpoints before entering our area and will be told to park until the danger is over. Last winter was a learning process. This year a plan is in place.
I expect winter weather this month and hopefully the problems last year will never be seen again. Stay tuned!
December 2014 column
Blame Nuri for the early cold weather
It began as an area of low pressure southeast of Guam in the western Pacific Ocean. There was little wind shear and a very warm ocean and this area of low pressure began to grow and get much stronger. In less than a week, it became a Super Typhoon named Nuri. And that is the name of the storm that brought us brutal cold in the middle of last month.
Super Typhoon Nuri was powerful and massive, spanning some 800 miles. Winds were sustained, sustained mind you, at 180 miles per hour with higher gusts when it moved just southeast of Japan. As the storm moved northeast into the northern Pacific, it started to tangle with the jet stream and was drawn toward the Bering Sea. As it did so, it began to feed on cold Canadian air and became a massive extra-tropical cyclone. As it headed for the Bering Sea and Alaska it mushroomed into the most powerful storm in recorded history for the region. Ships and crab boats encountered 100 mph winds and waves, get this, over 50 feet high!
As the storm began riding the jet stream into the northwestern United States, it began pulling up so much warm air from the south, and so much cold air from the north, it caused the jet stream to buckle. When that happened, it opened the flood gates to the North Pole and sent the jet stream all the way down to Texas and Gulf Coast. Bitterly cold arctic air sank far south, blanketing areas from the Rocky Mountains to the eastern seaboard with record cold temperatures. While we did not see any record lows here in north Georgia, our temperatures last month, as many of you know, were more typical of mid-January.
As we enter the month of December, I know everyone wants cold weather, and of course, a white Christmas. From what I have seen, now that we don’t have any more typhoons to disrupt the normal weather patterns, we can pretty much look forward to typical December weather. So what is typical December weather? We can and do see thunderstorms and 70s in December. We see sleet and snow too. I think we’ll see the usual progression of warm ups and cool downs with bands of showers along each cold front. I am not seeing anything really extreme.
However, I do see the possibility of an extremely cold January and February. A white Christmas is certainly possible this year but the odds are certainly not in our favor, based on the past 30 years of climatology. We shall see.
I would like to take this time to wish you all a very Merry Christmas and a wonderful, happy, and prosperous New Year. See you again in 2015!
November 2014 column
What El Nino will bring us this winter
El Nino continues to develop in the equatorial Pacific Ocean this month. We continue to see significant warming of the sea surface temperatures. It is likely to be a weak El Nino even for the late fall and winter. That being said, it is still likely to disrupt and change the global wind patterns. So what does that mean for Georgia and the Southeast?
If it behaves like a typical El Nino, our winter is likely to the colder than normal. The Climate Prediction Center is giving north Georgia a 33 percent chance of below average temperatures from December through February. Precipitation however, is a little more uncertain. During a weak or moderate El Nino, central and south Georgia tends to receive much more rain than north Georgia.
Here in north Georgia, we can be divided even further. The mountains would receive less precipitation than counties to the south. There appears to be much uncertainty about this. To that end, the Climate Prediction Center has placed the area north of Macon in the “Equal Chance” category, meaning we have too many variables to make an accurate prediction. In my 30 years of seeing the effects of El Nino, which occurs about every three to five years, I have seen winters where it has been drier than normal and wetter than normal with nearly identical situations.
Above average winter precipitation during an El Nino is highly dependent on the position of the southern branch of the jet stream. It will travel from the Pacific Ocean, through California, the southern states, and into Georgia. It could waver only 50 miles north or south and completely change our weather. It is definitely a fine line of variability.
While we all wait for winter weather, I must remind you November is a “transition month.” As we transition from autumn to winter, we can and often do, face devastating severe storms, like we did last month. Six tornadoes touched down on October 14th. Insured losses were more than $6 million.
The tornadoes were spawned along the leading edge of a squall line called a QLCS (quasi-linear convective system). They are extremely difficult to detect on radar. We did spot them and we did track them and because of the technology we have, no one was hurt. That is and always will be our goal. I would expect to see several more systems like the October outbreak this month, especially with the changing southern branch of the jet stream over us.
So, with that in mind, take a little time to enjoy the remaining fall color. The holiday season is upon us and winter is looming. November is a month of transition so get ready for stronger cold fronts, stronger storms ahead of those cold fronts, and the freezing temperatures that will no doubt follow.
October 2014 column
Remembering the hurricane that hit Atlanta
At the beginning of the month, we were looking at the long-range models for this October. The patterns are showing a warmer than average month with about equal chances of above or below average rainfall. As we were pondering the rainfall, one of our meteorologists reminded me of the night of October 4th and 5th, 1995.
I remember that night all too well. Category 4 Hurricane Opal was spinning in the Gulf of Mexico. Although satellite observations showed some weakening, it was still a very formidable tropical cyclone. What bothered me the most was its fast forward speed. Opal was moving at nearly 30 miles per hour and aiming for the Florida Panhandle, heading almost due north.
When tropical systems move inland they are usually moving about 5-10 miles per hour. As they move over land they no longer have the energy from the ocean to maintain their strength. That is the way things are supposed to work. This was not the case with Opal. The hurricane was maintaining its heading and speed. It would only take eight hours at that speed to move from the panhandle into the Atlanta metro area. This would not be enough time for the storm to substantially weaken. It was going to be a very long night.
I watched the eye move inland and make a bee line up the Georgia-Alabama state line. Squalls in the outer bands were already producing torrents of heavy rain and spinning up many tornadoes. When Opal moved into the western part of the metro area, we clocked winds at 79 miles per hour. Opal was still a hurricane!
As the outer bands continued to swirl, warnings for winds and tornadoes were coming in fast and furiously. Damage reports flooded our newsroom. Thousands of trees were down. Power was out for many. At the height of the storm, nearly 400,000 people had no power. However, Opal was not quite finished. Winds on the ground are slowed by friction. The higher up in the storm, the stronger the winds. When those winds hit the north Georgia Mountains, it was mayhem. Thousands upon thousands of trees, some more than 100 years old, snapped like twigs. It wasn’t until Opal reached Tennessee that it was downgraded to a tropical storm. When it was all said and done, 43 counties in Georgia were under a state of emergency. There were several deaths from tornadoes and fallen trees. All totaled, there was $5.1 billion in damage in the Southeast. It was one of the scariest nights I have ever had forecasting the weather.
When our fall cold fronts move south of Georgia they will tend to stall in the Gulf of Mexico during the month of October. So far, the giant Sahara dust cloud has kept the Atlantic quiet. I hope never to see another storm like Opal. Rest assured we will be watching the Gulf intently this month. Aside from possible tropical development this month, October is my favorite month of the year. I hope the blue sky, low humidity, cool morning lows and warm daytime highs will prevail. Expect the fall color to peak around the third week of the month and continue through early November.
September 2014 column
A strange summer comes to close this month
Summer ends this month. Fall officially begins on September 22 at 10:29 p.m. I have to say, this has been one of the strangest summers I have ever seen. It seemed to be a season of extremes. Rainfall was certainly not a problem. We had pop-up afternoon storms somewhere in Georgia just about every day. The storms this summer produced some of the most intense lightning we have seen in Severe Weather Center 2. Trees would get struck and would crash onto houses. People in their living rooms were hit. There were numerous attic fires from lightning every time a storm popped up.
On the other end of the spectrum were the temperatures. This summer our temperatures were below average by 2-3 degrees. There were several major cold fronts that moved through in July and August. When we track a summer cold front, we usually just see a shift in the wind from the south to the northwest. The northwest wind will tend to bring in some slightly drier air. However, the cold fronts this summer were actually cold fronts. We set low temperature records on several occasions in July! 59 degrees in Atlanta was the coolest low temperature record. Many mountain communities saw low temperatures in the upper 40s in July. I have never observed that in my 32 years here at WSB.
It is about this time of year when I begin to receive inquiries about our winter weather. As we all remember, last winter was brutally cold and we had two major winter weather events. Winter patterns don’t usually set up until late October or November. However, if I were to make a prediction now, I would make that prediction on persistence. What I saw last winter, to some extent, actually continued into the summer. I am not seeing a major pattern change as we head into September. That being said, I would think our upcoming winter might be another cold one. I cannot comment on whether or not there will be any snow or ice, as they are random events.
Temperatures this month should still be warm with plenty of time to enjoy more time on the lake. If you are out on the lake on the night of September 8th, you’ll be in store for a real treat. The full Harvest moon will rise in the east at around 9:30 pm. It is a little early this year.
I hope you’ve enjoyed your summer. Seasons are changing this month and I will be here, as always, to get you through the transition. Enjoy!
August 2014 column
An explanation of 'dog days'
All last winter, all I heard was how cold it was. Everyone was wishing for an early summer. Guess what’s happening now? You got it! Everyone is now asking when it is going to cool down! I can assure you, it won’t be in the month of August. We are in the Dog Days of Summer.
I have heard many north Georgia residents say it is the time of year that drives dogs mad because it is so hot and miserable. This is NOT the case. You might have heard of a constellation named Orion. Often referred to as “The Hunter,” Orion is a prominent constellation visible throughout the world. Nearby is the constellation Canis Major, which is Latin for “greater dog.” According to constellation lore, Canis Major is one of Orion’s hunting dogs.
Located in Canis Major is a star named Sirius, also called the “Dog Star.” With the exception of our sun, Sirius is the brightest star visible from Earth. The brilliant, blue-white star’s name comes from the Greek word for “searing” because Sirius is so bright. It was easy to track even for early astronomers. During April and early May, Sirius was visible in the southwest after sunset. But by the time mid-summer would come along, Sirius would rise and fall with the sun and get lost in the daytime light.
However, the ancients knew that the “Dog Star” was still there, up in the sky with the sun during the hottest time of the year. They reasoned that since Sirius was so bright and up there with the sun, it must be adding to the heat to produce the hottest time of the year. Of course we all know Sirius is still there, it just does not produce any heat. So that is the true story of how the Dog Days got its name.
While we all simmer through the Dog Days, we have a real treat coming this month. If you happened to miss the Super Moon in July, don’t worry. The best is yet to come! The August Super Moon will be the closest the moon comes to earth all year, and should be the best of the five Super Moons of 2014 as it passes within 221,765 miles of us. The next Super Moon is on August 10th. September 9th is the last Super moon. The “Super Moon” is a relatively new term to refer to the “perigee full moon” or new moon, basically, when the moon comes to the closest point in its orbit to earth. (The moon’s orbit is an ellipse, not circular) “Super Moon” usually refers to any of a number of times the moon orbits earth that fall within the closest 10 percent of orbits. I don’t think there is anything quite as beautiful as a full moon rising over Lake Lanier on a warm, Dog Days of Summer night. Enjoy!
July 2014 column
When sunglasses fog up, it's one of those days
It is early morning and the sun has been up for about an hour. When you walk out the door to get into your car, your sunglasses immediately fog up. You know it’s going to be one of those days you wish you could hang out by the pool. It’s already stiflingly hot.
Far above the ground, where you see the jets flying, it is very cold. As the sun continues to bake the ground, the air over the ground begins to heat up, becoming lighter and very buoyant. A column of warm, sticky, tropical air begins to rise. With the air around this column being very cold, it begins to rise faster and faster until the water vapor in the air condenses to form a cloud. Our cloud stops rising as it encounters a layer of warm air. Overnight, the heat we absorbed all day escapes and rises. It forms what we call a “cap.” Our little cumulus cloud tries to climb higher but there is no longer any cold air around it to help push it upward. By early afternoon a weakness forms in the cap and the air rushes upward at tremendous velocity. The cloud continues to grow with huge towering branches of cumulus clouds. Trillions of water droplets begin to get super-cooled, remaining liquid below 32 degrees. Some water droplets begin to freeze into small hailstones.
Gravity begins tugging at the hail pulling it toward the ground. On their way, they collide with the super-cooled water droplets and grow larger. But the updrafts coming from the ground are relentless. They bring the hailstones back up, high into the cloud, coalescing into even larger and larger hailstones. The rain and the hail begin to collide in the stronger upper level winds. And then it begins with the first crack of lightning.
A summer storm is born and it’s a big one. In the middle of this storm the updraft of warm and humid air continues to supply the storm with energy. It continues to grow larger. Looking down from space, our satellite imagery shows what looks like a large cotton ball, towering over surrounding clouds. Our radar shows a large core of hail and very heavy rainfall. As we switch modes on the radar to show wind velocities, we can see straight-line winds on the edge of the thunderstorm at 60 mph. We are also detecting hail the size of quarters. The National Weather Service radar operator issues a Severe Thunderstorm Warning. Our storm is now reaching its mature stage. All hell is breaking loose on the ground. Rain, hail, high winds and severe lightning, as many as 100 strikes in 10 minutes are occurring.
As the rain and hail continue to fall, the air below the storm begins to cool. The updraft of hot humid air that was once feeding the storm with energy is being overwhelmed by the rain and hail-cooled air. It is scrounging for energy but there is none. When the storm can no longer continue there is a last downward rush of cold air. The air rushes toward the ground at nearly 80 miles per hour. As it hits the ground it fans out in all directions, causing roof shingles to peel away, lawn furniture is scattered everywhere and several trees are blown down in this wet microburst. From the time the storm first formed to its last death throws, 45 minutes have passed! This was a typical “pulse type” thunderstorm frequently found during the month of July. This is why you need to pay particular attention to the weather forecasts and have a weather app or weather alert radio when you want to spend a day on the lake.
Be safe this July my friends. Summer storms can be deadly.
June 2014 column
Summer could bring interesting weather
At 6:51 a.m. on Saturday June 21st, summer officially begins. Summer 2014, from what I have seen, could be a very interesting summer.
If you will recall, last summer was absolutely miserable. We had showers and thunderstorms pretty much every single day and consequently, cooler than average temperatures. While the above average rainfall was certainly great at keeping the lake level up, it was not so great for those of us wanting to enjoy the lake. So, the question of the day is, are we going to see a re-peat performance.
Hurricane season begins June 1st and continues to the last day of November. During June, the most likely area for tropical development is in the Gulf of Mexico. By July, the favored area is the Caribbean, and in August and September, that area shifts to the Atlantic, where the major hurricanes are likely to form.
Since 1970, according to the U.S. Geological Survey, there has been an increase in the amount of Sahara dust streaming across the Atlantic Ocean. Last hurricane season, the dust clouds were especially thick as storms in Africa tossed the dust high into the atmosphere. We saw it as high as 15,000 feet! Sahara dust clouds have a chilling effect on the ocean, preventing the formation of the tropical waves that push off the west coast of Africa. Normally, these waves will evolve into tropical depressions or tropical storms. However the Sahara dust clouds prevent incoming sunlight for warming the ocean to the levels that would support tropical system formation. Hurricane experts believe that will happen again this season so a much fewer number of systems will likely develop.
Another reason this tropical season will be below average has to do with what is happening on the other side of the world, in the equatorial Pacific Ocean. It appears we may have a very strong El Nino developing, the likes of which we have not seen since 1997. El Nino is a warming of the sea surface temperatures in the Pacific that will result in a changing of the jet stream and wind patterns across the globe. The effects of El Nino in the winter months for north Georgia are more pronounced, with cooler temps and above average precipitation. However, in the summer months, it will also have a major impact.
Scientists studying El Nino development believe we just might have a cooler than average temperatures this summer as a result. Last summer, because of the rain, we only had a handful of days where temperatures reached 90 degrees. It may be the same this summer because the jet stream will be at a much lower latitude, supplying us will little shots of cooler air. Will we see above average rainfall? It will all depend on how quickly El Nino forms. I can say from past experience, summer storms will likely be stronger because of the increased wind shear.
My summer forecast then, will be for cooler than average temperatures. I cannot definitively say much about increased rainfall yet. We will be watching as things continue to evolve.
May 2014 column
Last month was quiet on the storm front
April was an incredibly quiet severe weather month across the country. The number of tornadoes was 46 percent of normal. Here in Georgia, we average four tornadoes statewide in April. We only had one tornado and it actually occurred from a heavy shower and not a thunderstorm. There were several minor injuries and damage to two homes just to the northwest of Griffin in Spalding County.
In the month of May, the average number of tornadoes in Georgia is three. This is based on the past 30 years of weather records. From what I have seen in the long-range models, rainfall in May should be below our 3.67 inch average. Maybe the below average severe storm season will continue. Beyond that, the Climate Prediction Center is giving us equal chances of above or below average rainfall. That prediction was made before signs of a developing El Niño.
It appears that an El Niño is in the works right now and it might be a big one. El Niño can boost the odds of extreme weather (droughts, typhoons, heat waves) across much of the planet. If current forecasts stay on track, El Niño might end up being the biggest global weather story of 2014. The most commonly accepted definition of an El Niño is a warming of the tropical Pacific Ocean south of Hawaii, lasting for at least five consecutive three-month “seasons.” A recent reversal in the direction of the Pacific trade winds appears to have kicked off a warming trend during the last month or two. That was enough to prompt U.S. government forecasters to issue an El Niño watch last month.
Forecasters are increasingly confident in a particularly big El Niño this time around because, deep below the Pacific Ocean’s surface, off-the-charts warm water is lurking. Currently there is a huge sub-surface wave of very warm water that currently spans the tropical Pacific Ocean – big enough to cover the United States 300 feet deep. That’s a lot of warm water. As that blob of warm water moves eastward, propelled by the trade winds, it’s also getting closer to the ocean’s surface. Once that happens, it will begin to interact with the atmosphere, boosting temperatures and changing weather patterns.
In the United States, this could bring welcome rains to our western states suffering from severe drought. While residents there might be very happy about this, these rains may be so heavy as to cause more flooding and mudslides. In Georgia, we may see a benefit. In fact, this may be good news for eastern coastal states. An El Nino will create strong easterly winds across the Atlantic. With so much wind shear, Atlantic hurricanes will have a VERY tough time developing. Colorado State University hurricane forecasters, including Dr. Bill Gray, is prediction only three hurricanes to form this season, one of which will be a major hurricane. Certainly good news!
April 2014 column
Spring is like a split personality
April is a month I like to call a Jekyll and Hyde month. For the most part, the weather this month is mostly tranquil and serene. In fact, it is the driest month of the year in north Georgia. We have abundant sunshine, the plants and trees are still in bloom, and temperatures continue to warm. However, things can frequently turn ugly in a heartbeat.
I remember back in 1987 when temperatures were warming and we were on a fast track to warmer spring weather. Then I noticed this huge area of cold arctic high pressure barreling out of Canada. At the same time, there was a stalled out cold front in the Gulf of Mexico. A low pressure area was forming along the front. It looked like a typical winter storm scenario. As new computer model data continued to stream in, it was now apparent the moisture and the cold were about to meet up at the same time, and right over Georgia. Even though we were well into the 70s, I had to make a prediction. Within 48 hours, we had 4-6 inches of snow from the mountains in to the northern suburbs of Atlanta. Two days later, we were back in the 70s! The latest I believe it ever snowed in our area was April 25 when 1.5 inches fell in 1910, also the heaviest for the month, and the latest-ever freeze.
While April can be very pleasant, and on rare occasions even snowy, it is a month that has spawned violent weather. The Dunwoody Tornado was a significant tornado that tore across the northern suburbs of metro Atlanta on April 9, 1998. It struck parts of the four most populous counties in Georgia: Cobb, Fulton, DeKalb, and Gwinnett. The most severe damage was in the Dunwoody area, where the storm reached a high-end F2 on the Fujita scale, making it one of the strongest and most damaging recorded to have hit that area.
The thunderstorm was part of a major outbreak that started in the south-central United States on April 6. The particular supercell which produced it also spawned the tornado that ripped through western suburbs of Birmingham just a few hours prior, on the evening of April 8. That storm was rated F5 and killed 32 people.
March is usually the time we see the most severe storm activity and tornadoes. However, the abnormally cool air we had, severe storms never materialized. I don’t believe I have ever seen a March go by without a single severe storm. I am hoping severe storm season just isn’t getting a late start. We shall see in the Jekyll and Hyde month of April. Be prepared.
March 2014 column
Residents need to take warnings seriously
February 2014 may go down as one of the most bizarre weather months I have ever seen. After “Snowpocolypse” in late January, an even stronger winter storm developed in the Gulf of Mexico and ran right into a wedge of cold arctic air. It was amazing to see the different types of precipitation we endured over that 36-hour period.
We were a lot more prepared for the second one. Our 1-2 inch snowfall on January 28th turned into the worse traffic nightmare since “Snowjam” 1982. People were stuck on the roads and in schools for up to 24 hours. Most everybody blamed the government for its lack of preparedness. I beg to differ. We all knew we were going to see 1-2 inches of snow followed by an arctic cold front. We knew it was going to develop in the late morning and continue into the evening. However, people chose to go to work. Schools chose to have class. Then it began to snow and everyone left work and school at the same time. All the traffic on the roads caused a massive snow melt which abruptly turned into ice with the cold arctic air moving in. Trucks to treat the roads could not get to their destinations and then the public said the government should have been more prepared. It was actually the residents of north Georgia that were not prepared and did not take our forecasts seriously and caused the chaos.
When we were forecasting the snow, sleet, and ice again two weeks later, people heeded the warnings and we avoided a repeat performance. Gov. Nathan Deal in the days after the January 28th storm, appointed a task force, of which I am a member. We have met several times and have made some excellent suggestions on how to address future winter storms. I am also doing a lot of the forecasting too. Although winter is just about over, I have reminded the task force about March 13, 1993! While seeing another “Storm of the Century” is not likely, you never know, especially with this weather pattern we are in.
Speaking of weather patterns, it is likely we are going to see the strong southern branch of the jet stream continue to traverse the southern United States through the spring. It wasn’t a week after our snow, sleet, and ice that we were under a tornado watch with violent overnight storms causing trees to crash into homes. I suspect we are going to have a very active tornado and severe storm season if the pattern holds. I cannot emphasize enough that we all need to be prepared. You need an app that has a warning alert for your smart phone. We have a great weather app that I think is the best in the country. It is free on iTunes. If you don’t have a tablet or smart phone, you need to get a weather alert radio. Whenever there is a severe storm threat, you will have critical weather information when you need it, even if the power goes out. Take for example our first round of severe storms back in February. They moved in during the middle of the night when most of us were asleep. Getting a warning from your smart phone, tablet, or weather alert radio can and does save lives.
February 2014 column
So just what is a 'polar vortex'?
As we move out of a record setting cold January for much of the eastern two thirds of the country, our long-range models show we can expect a nice warming this month.
Last month we all heard ridiculous headlines like “the polar vortex is set to devour the Midwest and Northeast.” I think a little explainer about the polar vortex is in order. I believe we all know or have at least heard of, the Bermuda High. In the summer, it’s a semi-permanent area of high pressure centered near Bermuda. It’s what keeps us warm and muggy during the warm months. It’s also a guide for hurricane movement. In the winter, the Bermuda High migrates eastward across the Atlantic and sets up near the Azores. It then becomes known as the Azores High. It’s pretty much the same thing with the Polar Vortex. It’s a semi-permanent area of low pressure centered near Baffin Island. The polar vortex, as it sounds, is circulation of strong, upper-level winds that normally surround the north pole in a counterclockwise direction – a polar low-pressure system.
These winds tend to keep the bitter cold air locked in the Arctic regions of the Northern Hemisphere. It is not a single storm. On occasion, this vortex can become very weak and can become distorted and dip much farther south. When this weakening occurs (called a negative north Atlantic Oscillation) frigid arctic air is allowed to plunge much farther to the south than normal. This is why we saw the record cold across much of the country, including a 6 degree record low here in Atlanta earlier last month.
The north Atlantic Oscillation models show it going into the positive range this month and therefore, we can expect a nice warming trend, at least for the first week or two. That is as far as the model data goes out. The Climate Prediction Center is a little more confident, indicating above average temps for the entire month. So, if you like warm temperatures, this is certainly good news for you.
On the other hand, this may not be such good news for those of us in the meteorological community. When we see a rapid thaw after harsh cold, we tend to see above average severe weather. Climatologically, severe storm season begins this month along the southern gulf coast states, from Louisiana to the Florida Panhandle. The reason being is this geographic area tends to get warmer first. That being said, we have certainly seen our fair share of violent storms and tornadoes in Georgia in February. With temperatures warming, and it could be a significant warming, the battle zone between cold air and warm air could be accelerated northward. There has also been another weather feature we have taken great note of this winter. Our jet stream is split over the continental United States. The cold polar branch wavers across the country like a snake bringing down the cold arctic air. The southern branch of the jet stream is riding hell-bent across the Mexican Baja into the southeast. This river of air running at nearly 80 miles per hour churns through the atmosphere at around 18,000 feet. When these strong upper level winds cruise over thunderstorms, they add a tremendous amount of energy and wind shear. Tornadoes and severe thunderstorm winds will now be our focus of attention. After such an active winter, we will have to wait to see how weather patterns continue to evolve.
My best advice, be prepared. Severe storm season is almost here.
January 2014 column
'Neutral' conditions make weather predictions difficult
Last month I attended a winter weather seminar at the Georgia Tech Research Institute. Along with Atlanta TV meteorologists, attendees included representatives from Georgia Emergency Management Agency, county emergency managers, and meteorologists from the Atlanta National Weather Service. The goal of the seminar was to look back at past winter weather events and to see how the National Weather Service, GEMA, and county emergency managers handled these events. We went over how soon winter weather advisories, watches, and warnings should be issued, if the warning terms or parameters should be changed, and what would make the public more aware of impending winter weather. Then a GEMA representative dropped the bomb and asked Keith Stellman, Meteorologist-In-Charge of our National Weather Service, what he thought we could expect this winter.
There was about five minutes of head scratching. Stellman finally replied that he was just not sure. He went on to say predicting long term weather in a “neutral pattern” was extremely difficult. When we have an El Nino, which is above normal sea surface temperatures in the eastern or central equatorial Pacific Ocean, we know we’re going to have a wet and cool winter. When we have a La Nina, which is ocean cooling in the Pacific, we know we generally have warmer and drier winters. However, since we don’t have either this winter season, the predictions are a little more difficult. Stellman said, based on the latest long-range model guidance, we might see some wintry weather during the third or fourth week in January. Climatologically, that IS when we get most of our snow or ice.
The problem I have been dealing with in my own forecasts is the jet stream, or should I say jet streams. Moving from west to east across the country is a river of air containing powerful upper level winds. The jet stream separates cold air from warm air. The bigger the difference between the cold air and warm air, the stronger the jet stream winds. We always look at the position of the Polar Jet to determine when cold air will move into north Georgia. This winter season, we are dealing with the Polar Jet and also the southern branch of the jet stream called the Sub-Tropical Jet Stream.
While the polar jet brings in cold air, the sub-tropical branch has been transporting storms from the Pacific Ocean through the southern states. It was responsible for that big ice storm across Texas last month. Stellman and I agree that because there is so much cold air and snow on the ground to our north, we will see the Polar Jet driving farther south during the month of January. With the southern jet bringing in one pacific storm after the other, it will only be a matter of the cold air and a pacific storm meeting up here.
My bet for wintry precipitation this month will be ice and snow. Timing of course, is everything. We’ll continue to watch the weather and will always keep you once step ahead.
Until then, I hope you all have a wonderful and prosperous 2014.
December 2013 column
More artic fronts predicted this winter
It is hard to believe that another year is coming to a close. Last spring’s tornado season was much quieter than normal. The Atlantic hurricane season turned out to be a non-hurricane season, despite dire predictions. However, this past fall turned out to be devastating for many people in the United States and around the globe. From Super Typhoon Haiyan in the Philippines to the 80-plus tornadoes that slammed the Midwest in November, this past autumn brought a great deal of destruction. So far, we in Georgia have fared well this fall severe storm season. However, we all know strong and severe storms can occur any time of the year. We have seen many tornadoes in late December and January.
I have been doing a great deal of research on something with the folks at NASA’s Jet Propulsion Laboratory in California. Scientists working at NOAA, the National Oceanic and Atmospheric Administration found a conclusive link between the alignment of two weather patterns in the Northern Hemisphere and the formation of an “atmospheric river” headed for California. The results were obtained in part from data provided by NASA’s 11-year-old Aqua weather satellite.
Atmospheric rivers are narrow bands of wind, often a mile high that can pack the punch of a hurricane. As they move over the ocean, they become laden with water vapor and can carry with them as much water as the Mississippi River dumps into the Gulf of Mexico in an average week! An example of the power of such an atmospheric river event was seen in 1999, when a winter storm hit California and caused 15 deaths and $570 million in damage. The two weather systems studied were the Arctic Oscillation and Pacific/North American teleconnection. The weather patterns rarely align in a certain way, but when they do the result is intense weather for California. Most troubling is that the weather events have the possibility of playing out over an extended period of time – such as the winter storms in 2010-2011.
So why should we be concerned with storms on the opposite side of the country? Let’s take a look back at what has happened this past fall. Normally, we see five to six true arctic cold fronts every season. By late November, we already had three. The arctic high pressure systems have been setting up across New England for the most part. This position sets up that wedge of cold air that drains down the Appalachian Mountains into north Georgia and sits there for days on end. There has also been a very strong southern branch of the jet stream traveling from California, across Texas, and into the Southeast. So, if we have strong southern storms moving from California into the Southeast and there is a “wedge of cold air” in place, the end result could be a major ice storm. On average, north Georgia is likely to see a major ice storm once every 10 years. We are way overdue.
I would like to wish you and your family and very Merry Christmas and a happy and wonderful New Year. And I will end this article with the question that everyone wants to know. What our winter weather should be like. Unofficially, my prediction is for temperatures to be slightly below average with several more major arctic fronts with above average precipitation. The official forecast from the Climate Prediction Center is for equal chances for above or below average temperatures. That being said, the CPC is predicting above average temperatures from Alabama westward through the desert Southwest. Being in such close proximity to the warmer than average temperature prediction, I would think we are going to have temperatures near normal to slightly above normal. The forecast for precipitation is for below average precipitation from December through February.
November 2013 column
Yes, it was a typical October
October certainly lived up to its expectations. Our summer humidity moved out. Temps for the most part, were typically cool, and we did not see a lot of rain. I was concerned about Tropical Storm Karen in early October, not so much from the wind, but from the heavy rains tropical systems could potentially bring. With our moist soil from the summer rains, a heavy rain-maker could have caused some serious issues.
Fortunately, after states of emergency were declared from Louisiana to Alabama, hundreds of thousands of dollars spent on moving boats inland, and the news media outlets just about calling it the storm of the century, Tropical Storm Karen only brought a few rain showers to the gulf coast with winds in 20 mph range before it completely fell apart.
I certainly loved the kind of weather we had during October. However, I also know October is the calm before the storm. November is a month of transition. Winter weather patterns begin to become more defined. Cold fronts continue to get stronger and more frequent. It is time for the autumn weather wars to begin, the time for air masses to collide. The battle ground this month is the Southeast.
During the month of November we often see lines of storms developing ahead of approaching cold fronts. Most of us know these as squall lines. They are in fact, what we call a QLCS or quasi-linear convective system. They are powerful, often containing “bow echoes,” which indicate strong straight line winds. On occasion, when we get enough wind shear (changing wind speed or direction with height) we will get a tornado spinning up on the leading edge of the bow echo. They are extremely difficult to find because they are very small. They do however create powerful winds of more than 100 miles per hour. These systems will often cross states ahead of a cold front and are easily tracked by our radar. Fortunately, with the new technology we have, we can spot the rotation much better. We can even see if it is lofting debris in the air. Even without a tornado, winds can reach 70 mph in the bow echo straight line wind area. These are dangerous thunderstorms. I just want all of you to be aware November can produce the kind of storms we see in the spring.
With that being said, November certainly has its fair share of magnificent weather days. It will be getting colder and on average, our first frosts and freezing temperatures can be expected during the first couple of weeks of the month. I know you all want to know if it will be a cold winter. I wish I could answer that right now. However, as I mentioned, weather patterns are just now taking shape for the winter. The Climate Prediction Center gives us, once again, a 50-50 chance of above or below average temperatures and rainfall this winter. I know what you are thinking but we have to cut the CPC a little slack. We don’t have an El Nino or a La Nina right now. When those conditions exist it makes winter weather predictions much easier. We are currently in a neutral pattern, which tends to complicate things.
You may recall last spring when all the tropical weather experts were saying how bad the hurricane season was going to be. As it turned out, the tropics were as quiet as Lake Lanier during as ice storm! If you would like my humble opinion, I think the western United States will be warmer than average while we here in the Southeast enjoy a good old-fashion, normal Georgia winter with occasional cold fronts, a couple of days of flurries or snow showers, and no doubt a few days of sunshine and 70s thrown in from time to time.
No matter how it turns out, I wish you and your family a happy Thanksgiving and a great November. I am sure by next month, weather patterns will have established themselves and we’ll know more as we head into winter.
October 2013 column
The feel of fall is in the air
October is without a doubt, my favorite month of the year. Cool fronts become stronger and more frequent resulting in that “feel of fall” in the air we all enjoy. October is also the second driest month of the year, averaging 3.41 inches. (April is the driest month, averaging 3.36 inches).
The fall color is certainly making its presence known this month, especially the last week of the month. Everyone is asking what my prediction for fall color will be. Based on my experience, I think the above average rainfall we have had would mean less brilliant fall color this year. That being said, I also believe the good soil moisture we still have will mean a longer season.
Speaking of above average soil moisture, my thoughts quickly turn to the tropics. It has been a rather unusual tropical season this year. We have seen an increase in dry air and dust from the Sahara keeping the Atlantic in check and really limiting tropical storm development. However, in October, the most likely area for tropical storm development is much closer to home, in the Gulf of Mexico. As I pointed out, cool fronts will be moving through north Georgia with greater frequency this month. As they move through, they have a tendency to stall out in the Gulf of Mexico. Often times, we see low pressure areas develop along these stalled boundaries. These low pressure areas can sometimes “spin up” into tropical systems. With the Gulf being very warm and with many warm water eddies, there is plenty of fuel for a tropical system to develop and get stronger. I am not so much concerned with the wind from any developing system as I am for the rains they can bring. In recent conversations with our state hydrologist, a system that has the potential to bring 5-10 inches of rain to our area could be devastating. So, we’ll certainly be keeping a watchful eye on what happens this month.
I know you are all wondering what this fall and winter will be like. I am wondering too! This year we are in what we call a neutral pattern. That means we have no Pacific Ocean cooling, ( La Nina) or Pacific Ocean warming, (El Nino) to change the global wind patterns. We know what type of weather a La Nina or El Nino tends to bring. However, in a neutral pattern we really can’t make a winter weather prediction until we begin to see how weather pattern across the globe are evolving. As of right now, the Climate Prediction Center is forecasting near average or slightly above average temperatures for the winter months. The CPC is also forecasting drier than average weather for the winter. I would assume this is subject to change so stay tuned!
Enjoy the beautiful blue October skies, the mild temperatures, and the beautiful colors of Autumn.
September 2013 column
Records set in rainfall, cool temps
Last month was one of the strangest weather months I have ever seen. Our wet pattern continued and on August 19th, we surpassed our average annual rainfall total of 49.68 inches! The weekend of August 17th, we saw the coolest high temperature ever recorded for the date, which was 66 degrees. We shattered the old record of 74 previously set in 1892!
So what is going on with our weather? The first observation I can make involves the position of the Bermuda High. The Bermuda High is a semi-permanent area of high pressure that, in the winter months, is centered in the eastern Atlantic Ocean near the Azores. During the summer, it migrates across the Atlantic and sets up near Bermuda. I have seen its position a little farther west than the past couple of years. Normally during the summer we get a southwest wind off the Gulf of Mexico, which sets us up with afternoon thunderstorms. With the Bermuda High being a little farther west, we have not only seen moist air coming off the Gulf, but moisture coming in from the deep tropics. In essence, we have become a tropical rain forest this summer. The air is so loaded with moisture that extreme rainfall, sometimes two to three inches per hour, is the result.
With the position of the Bermuda High being a little farther west than in previous years, there is great concern among the southeastern meteorological community. We are now in the peak of the Atlantic hurricane season (the actual peak is September 15th). If the Bermuda High was centered more toward the east, then tropical systems that develop in the Atlantic would ride around the western ridge of the high and then run parallel to the east coast, most remaining well off shore. However, given the Bermuda High’s current westward position, the western ridge would bring tropical systems right up through the Gulf of Mexico, across the Florida Panhandle, and right up into Georgia. This would not bode well for us at all.
Our groundwater tables are full. The lakes are full. The soil is already saturated. Many areas have seen so much runoff from the tropical rains, massive tree roots are now exposed. Our National Weather Service hydrologist, Kent Frantz, is extremely concerned about mud slides. The worst case scenario would be a storm like Hurricane Opal. We would not only see heavy tropical rains but tornadoes and severe wind damage. I cannot imagine the number of trees that would go down in north Georgia. That being said, we could also get a storm like Tropical Storm Alberto in July of 1994. It was a weak storm as far as winds go, but the rains it brought, especially to south Georgia, were catastrophic. Either scenario is something we need to be prepared for.
I do have a bit of good news. The long-range 90 day weather outlook takes the above average rainfall and brings it more to our west and northwest. The Climate Prediction Center gives us 50/50 odds of having above or below average rainfall over the next 90 days. We shall see.
In any event, cooler temperatures will be arriving by the end of the month as we close out a summer for the record books. The first day of fall is Sunday, September 22nd, at 4:44 pm.
The full Harvest Moon is September the 19th. Hope you have a wonderful September. I