Our Q&A blog series answers common questions about aviation and Southwest Airlines. Our first question about Turbulence is answered by Southwest’s Chief Meteorologist Rick Curtis. Have a question of your own? Leave us a comment!
Most airplane flights experience some form of turbulence between takeoff and touchdown, but luckily most of the time it’s either very light or simply an irritation for a few seconds or minutes. Despite advances in technology and forecasting techniques avoiding turbulence is still very difficult. Think about it for a second—when we are on a boat or ship in the ocean we can easily see the waves ahead of us. The wave’s interaction and impact will greatly depend on the size of our boat. Since the atmosphere is also a fluid (like the ocean) the same holds true with airplanes. Turbulence that has a large impact on small airplanes may only provide a gentle “bump” to a commercial airliner.
When an airplane travels through the sky, the air around that plane is also moving. Air surrounding the aircraft can not only be moving towards or away the airplane, but also be rising or sinking. The same is true with ocean currents in our boat example. However, while airplanes have radar detection instruments, which help Pilots “see” turbulence, identifying turbulent air versus water is much more difficult.
There are a few basic types of turbulence and each has a different source; however, their effects on the comfort of your flight can be the same. One of the most common types of turbulence is found around thunderstorms. Airplanes obviously avoid and fly around thunderstorms; however, updrafts, downdrafts, and outflows from thunderstorms can have a turbulence impact on airplanes many miles away from a storm. Another common type of turbulence is experienced when flying over mountainous terrain. When the surface winds interact with mountains, the winds cause many fluctuations in the atmosphere and can “bounce around” thousands of feet about the mountain tops.
Another type of turbulence is often experienced is due to “thermals,” or rising air from the surface. As the sun warms the air at the surface it becomes lighter and begins to rise. This rising of air then becomes an “updraft,” which will impact an airplane in the form of turbulence when encountered.
Lastly, clear air turbulence is one of the toughest types to predict. Clear air turbulence is usually caused by wind shear in the atmosphere. Wind shear is the difference in wind speed or direction over a horizontal or vertical distance. As you can imagine detecting clear air turbulence can be difficult as we do not have the observing network in the air that we have on the surface.
Turbulence, although very common, is still one of the more difficult forecasts for a meteorologist to make. Our forecast models and observations are always trying to move to high resolution information, but we a still a very long way from being able to fully “see” and prediction turbulence on a very localized scale.
More and more commercial airplanes are beginning to automatically report turbulence (at last check, Southwest was up to 127 reporting aircraft). These additional reports greatly assist with the detection and forecast of turbulence. Over time, Southwest will be expanding our automated turbulence reporting capacity, which will greatly help forecasters identify and predict turbulence.
So the next time you are flying and feel those “bumps,” know they can be caused by a variety and combination of many different variables. Many efforts are taking place “behind the scenes” and within the flight deck to minimize the encounter of turbulence on your flight as much as possible.
Photo by BWI Flight Attendant Michael Demouy
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A series of very slow moving weather system have been responsible for some very wet weather across much of the eastern half of the country during the past few weeks. These systems have been responsible for major flooding, bouts of severe weather, and many significant air travel disruptions.
So now that we enter the first full weekend of the summer 2014, will any changes take place, or will the wet weather pattern continue? Unfortunately, the answer to that question will really depend on just exactly where you are this weekend.
You’ve probably heard about the flooding in Minnesota and the record rainfall totals there over the past few weeks. In fact, thus far in June, Minneapolis has officially recorded 10.85 inches of rain which is over three and a half times the normal for the month. That rain, when combined with unusually heavy snowpack, swelled river levels well past flood stage.
The Chicago area has also been very wet with many stretches of daily precipitation this month. As of today, 5.44 inches of precipitation have fallen at Chicago-Midway which is over two inches greater than normal amounts this month. Rainfall totals have also been high in Ohio with Cleveland already at 5.41 inches of rain, which is more than double the June average, and Columbus more than 1.5 inches already over their June normal.
Parts of Texas have also experienced a very wet June with the Houston area receiving double the average rainfall so far this month; however, drought conditions continue to exist in much of the state including Austin, San Antonio, Corpus Christi, and Dallas.
A series of “cut-off,” low-pressure storm systems and some very slow moving cold fronts have been responsible for much of the weather in the east. Gulf moisture continues to fuel smaller storms in much of the south and southeast. As we progress through the end of this week, a cold front will move off the east coast Thursday. This will bring more seasonable weather over the weekend to metro D.C. and New York City with afternoon high temperatures in the mid-80s, with just the threat of afternoon thunderstorms. Isolated thunderstorms will also be in the weekend forecast in both Chicago and St. Louis with afternoon highs in the mid-to-upper 80s.
Most of Florida will continue to experience typical afternoon and evening thunderstorms, and further to the north, more isolated coverage of showers and thunderstorms will be found around Atlanta.
Meanwhile, out west it will be hot with afternoon highs between 105 and 110 in Phoenix and Las Vegas and highs in the mid to upper 90s in Sacramento. Expect typical morning low ceilings in southern California with seasonable temperatures in the mid-to-upper 70s along the coast and the mid-to-upper 80s inland.
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At Southwest Airlines, our Meteorology Team is small, but mighty. Our four-person Team helps to support the weather-related strategic decision process here at Southwest; however, we also are involved with many other industry efforts and projects. One example is our strong partnership with both Aeronautical Radio Incorporated (ARINC) and the National Oceanic and Atmosphere Association (NOAA).
About five years ago, we were asked by ARINC and NOAA to participate in a particularly exciting initiative that had the potential to help revolutionize weather forecasting—gathering and reporting real-time atmospheric humidity information from our airplanes. Today, Southwest has water vapor sensing systems (WVSS-II) on 87 of our aircraft as part of this project, and it is truly benefiting the entire worldwide meteorology community.
For decades, meteorologists have routinely gathered wind, temperature, and humidity data (and continue to do so) via the use of weather balloons. These balloons, however, are launched just twice daily from fewer than 90 locations across the entire United States. These updates are not nearly frequent enough or in enough locations. It was the best we had to work with, due to both cost and technology limitations. What we needed was more data that was reported more often to produce better and more accurate forecasts. Updated temperature, wind, and humidity readings from the atmosphere are crucial during the forecasting process—especially during severe weather events and winter storms. The WVSS-II project provides an extremely cost-effective way to obtain this information that was not previously available. Through this public-private partnership, this data is available much sooner with far greater coverage. In fact, just over the past 24 hours, our 87 equipped airplanes have reported more than 40,000 weather observations.
A precise forecast is important to an airline in many ways, including the operation of flight schedules and ontime performance, as well as reducing flight diversions and efficiently handling cancellations. Forecasters can use WVSS-II data in many ways such as helping to determine fog formation and timing, marine layer depth, the changing level of atmospheric instability, and winter weather precipitation types. This data also is used in National Weather Service (NWS) forecast models and within local NWS offices across the country—all for the purpose of improving forecasts to help us all better prepare for weather events.
We are very excited to be part of their effort, and we continue to work with ARINC and NOAA to try and obtain funding for additional aircraft installations. It serves as a great example of how we can take advantage of technology and use the extensive Southwest flight schedule to truly advance the science of meteorology—something that benefits everyone.
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After a series of storms in the west over the past several days, cold air will finally start to drop southward into the western half of the country over the weekend. It will start to feel like December in at least part of the country! Sunday’s high temperatures will only be in the upper 20’s or low 30’s in the northern plains—OMA, DSM, and MSP—while relatively mild conditions persist in the Southeast and Northeast. With the colder weather, accumulating snow will be possible late in the weekend in SLC, DEN, and MSP. Here are this weekend's weather highlights:
Rain will spread from the upper Plains Thursday and into the Midwest and Great Lakes Friday. Some early morning snow may mix in Friday morning in MKE, PIT, and BUF. Rain showers will move into metro NYC and New England Friday afternoon and evening. Showers will continue through the weekend, with likely periodic showers Saturday and Sunday. Periods of snow showers are expected in GEG Thursday and Friday. Light accumulations may occur, due to colder temperatures on the way for the weekend. Snow showers are likely Saturday in BOI and SLC, and will spread into DEN and MSP overnight into early Sunday. Light snow accumulations are likely. Persistent late night/early morning low ceilings and fog are once again likely in coastal southern California through the weekend. Expect rain showers both Saturday and Sunday in the Southeast.
Have a great rest of the week! This information is not intended for dispatching purposes.
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This week, most sections of the country are enjoying more seasonable temperatures and are receiving some very welcome relief from what has been a very long and hot summer. Things are also starting to quiet down from a severe thunderstorm standpoint as well, with only a few areas with strong thunderstorm potential throughout the week. However, we are starting to enter into the peak of “Hurricane Season” as we transition through the end of August into September. We are watching a tropical wave in the middle of the Atlantic, which shows signs of strengthening early this week. Otherwise, we are expecting a fairly nice, late August weather week for most of our system. Here are this week’s weather highlights:
A very slow moving weather system continues to bring showers and isolated thunderstorms in the Northeast Monday and Tuesday, with clearing expected midweek. It’s monsoon season in the southwest with periods of rain and thunderstorms likely around LAS, PHX, TUS, and ABQ through most of the week. The weather will remain active in much of Florida this week with scattered coverage of thunderstorms likely each day. Expect morning low ceilings and patchy coastal fog in both northern and southern California throughout the week. As mentioned earlier, there is a fairly high likelihood that the tropics will become active this week. The next storm will be named Isaac, and we’ll continue to monitor things and issue updates accordingly.
Enjoy the nice weather!
This information is not intended for dispatching purposes.
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