Turbulent motions between differing air masses create undulating clouds as seen over rural Kansas in the early morning hours of April 28, 2006. Meteorologists are proposing these clouds be designated as the first new cloud type to be named in over 50 years: Undulus Asperatus.

The Cloud Appreciation Society has designated the clouds as “Undulus Asperatus” or alternatively, “Undulatus Asperatus.”  The Latin term translates loosely as “turbulent undulation.”  Such clouds are relatively rare, but have been photographed in several areas around the world.

Turbulent motions between differing air masses create undulating clouds as seen over rural Kansas in the early morning hours of April 28, 2006. Meteorologists are proposing these clouds be designated as the first new cloud type to be named in over 50 years: Undulus Asperatus.

The ominous-looking clouds have been particularly common in the Plains states of the United States, often during the morning or midday hours following convective thunderstorm activity.  These clouds are not considered a precursor to severe weather, rather appear to form following rain or thunderstorm activity.

Jane Wiggins of Cedar Rapids, Iowa recently captured several spectacular images of the new cloud type as viewed from a downtown office building.  Several of her images have recently been published by National Geographic Magazine – an honor which Wiggins does not take lightly.

This turbulently undulating cloud photographed over Cedar Rapids Iowa may soon be designated as the first new cloud type named in over 50 years: Undulus Asperatus. Source: Jane Wiggins

This turbulently undulating cloud photographed over Cedar Rapids Iowa may soon be designated as the first new cloud type named in over 50 years: Undulus Asperatus. Source: Jane Wiggins

“It is a bit like looking at the surface of a choppy sea from below,” said Gavin Pretor-Pinney, founder of the Cloud Appreciation Society, who first identified the asperatus cloud from photographs that were being sent in by members of the society.

“We try to identify and classify all of the images of clouds we get in, but there were some that just didn’t seem to fit in any of the other categories, so I began to think it might be a unique type of cloud.

This turbulently undulating cloud photographed over Cedar Rapids Iowa may soon be designated as the first new cloud type named in over 50 years: Undulus Asperatus. Source: Jane Wiggins

“The underside of the clouds are quite rough and choppy. It looks very stormy, but some of the reports we have been getting suggest that they tend to break up without actually turning into a storm.”

The Royal Meteorological Society is now gathering detailed weather data for the days and locations where the asperatus clouds have been seen in an attempt to understand exactly what is causing them.

Wind turbines along the Buffalo Ridge in rural southwest Minnesota (2004)

A relatively new wind energy farm in central Wisconsin has created a newly-discovered, puzzling side effect:  interference with the local National Weather Service doppler radar.

The Butler Ridge wind farm was constructed in February of this year and contains a total of 36 wind turbines, each standing about 300 feet above ground level.  These windmills were build on a ridge line that is about 1100 feet above sea level, placing the turbines in an optimal location to benefit from the highest wind speeds in the region.  Coincidentally, the location is in the sight of the local doppler radar tower in Sullivan, WI that is approximately 30 miles south of the wind farm.

This image from April 1, 2009 displays the location and reflecdtivity of the wind farm 30 miles north of the radar site. Credit: NOAA

Doppler radar functions to detect atmospheric phenomena by sending out an electromagnetic signal and simultaneously “listening” for the signal to return if it is bounced off of an object.  Many objects will reflect the radar beam, most notably rain droplets, ice crystals, and snowflakes.  But as we reported earlier this year, doppler radar can also detect bats, birds, aircraft, surface traffic, and even tragedies like 9/11 and the Columbia disaster.  They are even believed to have the potential to alter the weather.

In the case of the Butler Ridge wind farm, the radar beam is being reflected by the large blades on the spinning turbines.  This electromagnetic energy is then reflected back to the radar dome and the radar detects the object.  The turbine blades then appear on the radar image.  This seemingly innocuous interference could have significant ramifications in the upcoming severe weather season though.

This image from the National Weather Service demonstrates how wind turbines can be mistaken for storms on doppler radar. Credit: NOAA

Doppler radar is arguably one of the most critical tools at the disposal of the National Weather Service when they look to provide timely watches and warnings of severe thunderstorms and tornadoes.  By examining the output of doppler radars, meteorologists are able to detect and forecast thunderstorms that may become severe and where they may track.  But if the radar image is masked by interference such as the wind turbines, it is feared that severe weather watches and warnings may be less robust.

The National Weather Service Radar Operations Center has enlisted the help of the wind energy industry to try to alleviate these problems in the future by locating the wind farms in places that would not interfere with such radar signals.  They have published an extensive analysis of the problem.  The map below displays the locations (in red) of the doppler radar sites that may be impacted.  The yellow regions are those in which the radar beam travels close enough to the ground that it could be impacted by windmills constructed in those regions.

This map displays the locations of all National Weather Service radar locations (red) and the regions in which the radar beam is low enough to the ground that it may be impacted by windmills (yellow). Credit: NOAA

Meteorologists may be able to write software code that is able to filter out this interference, but such work can be costly and time-consuming.  The primary concern is that filtering the data to remove such interference may also increase the risk of filtering out true radar echoes – those of actual storms that must be detected for public safety.

With the mushrooming popularity of wind energy around the country, this problem is one that is sure to warrant further study and creative mitigation attempts.

Damage to the CNN building in downtown Atlanta, GA following a tornado on the evening of March 14, 2008.

A recent study by experts on land-atmosphere interactions suggests a connection may exist between large urban population centers and the intensity of tornadoes that impact these areas.

The urban heat island effect is the term given to the hot, dry conditions generated by large expanses of buildings, asphalt, and other human-made conditions that alter the landscape otherwise covered by fields, forests, and bodies of water.  Decades of research have indicated that large urban areas reach higher temperatures during the day, stay warmer at night, and tend to have drier air surrounding them, as there is little open water or moist soil to provide atmospheric moisture.

Atlanta Tornado of 2008

The study indicates a connection between the intensity of the 2008 urban Atlanta tornado and the heat island effect suggests that the hot, dry urban conditions may have led to a larger discrepancy with the surrounding atmospheric conditions, enhancing stability and thus intensifying the storm as it approached the city.

This map published by the Atlanta National Weather Service office describes the track and intensity of the tornado that struck Atlanta, GA on 03/14/2008. Click for a high resolution image (Credit: NOAA / NWS)

The recent research has taken our understanding of the urban heat island one step further by connecting its impact to severe weather.  “Urban regions create their own weather,” said Dev Niyogi, a climatology professor at Purdue University in Indiana and the lead author of the study, which was funded by the National Aeronautics and Space Administration. “As we are becoming bigger and bigger in terms of our urban footprint, there’s a distinct probability we are going to see cities have their own weather patterns.”

However, not all meteorologists and climatologists agree.  Harold Brooks, a research meteorologist at the federal government’s National Severe Storms Laboratory, in Norman, Okla., said it is already widely accepted that wet ground breeds tornadoes, and noted that strikes on urban areas aren’t rare. There is no evidence suggesting downtown areas are hit “any less or more than any other area of the same size,” Mr. Brooks said. In the past decade, tornadoes have hit Nashville, Tenn.; Fort Worth, Texas; and Miami, as well as Atlanta, he said.

Urban Tornadoes

A tornado strikes downtown Salt Lake City, UT in 1999.

The myth that tornadoes are less likely to strike urban areas continues to remain pervasive, even in the face of evidence to the contrary.

It is a common – and definitely false myth that tornadoes do not strike downtown areas. The odds are much lower due to the small areas covered, but paths can go anywhere – including over downtown areas.  St. Louis, MO, for instance, has been struck 4 times in the last century.

It may seem tornadoes impact urban areas less frequently than rural areas simply because urban population centers cover a much smaller fraction of land area than rural areas.  As such, any given tornado is more likely to impact a rural wheat field in Kansas rather than the urban core of a city such as Wichita or Kansas City.

However, tornadoes impacting large urban areas are far from rare.  Beyond the 2008 Atlanta tornado, violent tornadoes have also impacted other large urban centers:

• Omaha, NE (F5, 03/23/1913)
• Topeka, KS (F5, 06/08/1966)
• Lubbock, TX (F5, 05/11/1970)
• Nashville, TN (F3, 04/16/1998)
• Little Rock, AR (F3, 01/21/1999)
• Salt Lake City (F2, 08/11/1999)
• Fort Worth, TX (F3, 03/28/2000)

For a more exhaustive list and details, see the table compiled by Roger Edwards and Joe Schaefer of the Storm Prediction Center on downtown tornadoes.

A crippling duststorm shrouded the Saudi capital of Riyadh on Tuesday, halting transportation for hours. (Credit: Jad Saab/AP)

Airport traffic was halted completely for over three hours while the dust settled and the air cleared, allowing planes to again arrive and depart without disruption.

The storm was actually sufficiently forecast as to allow public schools to be closed in sufficient time to permit students to get home safely ahead of the storm.

Sandstorms are caused by strong winds blowing over dry, loose sand and soil, picking up enough of the sand and soil such that the air is filled and visibility is substantially reduced.

The Saudi Arabian capital city of Riyadh was blasted by an intense sand storm this week, dropping visibility to zero and bringing transportation to a standstill after causing dozens of automobile accidents and other disruptions.

Hot and dry conditions that are frequent in the Arabian Peninsula routinely create the type of atmospheric instability that lends itself well to sandstorms.  When the soil and sand are dry, they heat up much more quickly under intense sunlight.  Such rapid heating causes air close to the ground to rise rapidly into the upper levels of the atmosphere, sweeping the sand and soil to higher altitudes.

A Saudi covers his face with his traditional headdress as the sandstorm colors the sky. Source: AP

While such sandstorms were more frequent in the drought-stricken areas of the 1930′s dust bowl era, they are much more rare today as widespread agricultural irrigation has reduced the overall areal coverage of soil that can sufficiently dry to create the conditions necessary for a dust storm.  The smaller scale events that may still occur in the desert southwest are often referred to as dust storms in the United States.

A crippling duststorm shrouded the Saudi capital of Riyadh on Tuesday, halting transportation for hours. (Credit: AP).

The move would eliminate at least 30 and as many as 80 forecasting positions currently occupied at the nations busiest airports.  Instead, the forecasting duties would be consolidated at already-existing multi-purpose National Weather Service facilities in Kansas City, MO and College Park, MD.

But the National Weather Service Employees Organization argues the move may reduce the accuracy and effectiveness of forecasts made available to traffic controllers:

“It’s a public safety issue,” said Dan Sobien, president of the National Weather Service Employees Organization.  It doesn’t mean a plane will crash tomorrow, but it could happen one day if sufficient weather information isn’t available, he said.

FAA spokesman Paul Takamoto confirmed that the agency is looking for ways to cut costs, but he insisted that any changes will not affect the ability of air traffic controllers to get weather guidance. Weather will be available on radar, he said, and controllers will be able to consult forecasters, just not face-to-face.

And Weather Service spokesman Chris Vaccaro said that any plan that is finally agreed to will ensure the safety of the aviation industry is maintained.

The recommendation may make it’s first public appearance next week and be open to review as the new congress convenes in January.

When compared to the 30-year probability of a White Christmas, it is evident that many regions that have relatively low odds of a White Christmas are in fact enjoying one this year.  These regions include much of the middle of the country in a swath extending from Kansas and Missouri stretching into Northern Ohio.  Additionally, the costal areas of western Oregon and Washington areas traditionally enjoy only a 10-20% chance of seeing snow on the ground on Christmas Day but recent strong winter storms have blanketed the Pacific Northwest in white (see more on Seattle’s snowy road woes).

This is a significantly larger area covered by snow than in many previous five years. The NOHRSC has been plotting this snow analysis map since 2003 and 2008 ranks as the snowiest thus far. See the maps below for the comparative snow cover for Christmas Day of 2003 through 2007.  Click each map for a larger view.

2003:

2004:

2005:

2006:

2007:

Established in 1982, the channel initially attracted an audience of devoted meteorology enthusiasts. But it has gained a broader following by showing “docudramas” such as Storm Stories which recreate the exploits of people hit by extreme weather. It reaches 96m households.

A “broader” audience? Perhaps. A smaller audience after losing true weather enthusiasts and meteorologists? Likely. They had a solid schedule that repeated every hour, including the local forecasts on the 8s. That is about the only remnant that has remained, with most live programming having been replaced by sensationalistic, tabloid-style programming instead of current weather analysis and forecast discussions.

A round-the-clock American weather forecasting channel, renowned for its intrepid rain-drenched reporters standing in the eye of hurricanes, is up for sale with an estimated price tag of $5bn (£2.5bn).

The Weather Channel has been put on the block by its parent company Landmark Communications, which is owned by the Virginia-based Batten family.

Among those reportedly expressing interest are General Electric, Comcast and Rupert Murdoch’s News Corporation.

Some 110 meteorologists are employed by the network, which supplies forecasts to 157 newspapers and to on-line portals such as Yahoo and MSNBC. The channel and its offshoots generated $1.75bn (£887m) in revenue last year, with sales even generated by a selection of compact discs of music played during forecasts.

In a news story Fake tornado picture embarrasses newsrooms, an Australian news agency admits to having publicized a “photoshopped” image of a tornado. A woman sent it to them as a joke thinking there wouldn’t be a chance it’d be aired on TV or online. She was wrong.

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