Weather Wednesday — Hurricane Season Outlook

Tropical Storm Ana earlier this month aside, June 1st marks the beginning of the “official” Atlantic Hurricane season. So what can we expect this year? Exact predictions are always iffy, but noted expert Dr. William Gray and his colleague Philip Klotzbach, both of Colorado State University, predict 7 named storms, three hurricanes and one major hurricane. If true, this would be one of the quietest hurricane seasons in the last 60-years. The long term average is for 12 named storms, six hurricanes and two major hurricanes. Some recent years have seen in excess of 20 named storms.

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NOAA

Why the smaller numbers? One factor is the development of a strong El Nino in the equatorial Pacific Ocean. Historically, El Nino years have fewer hurricanes along with other effects. The Weather Channel has created a nice page and video explaining this.

It is extremely important to note, however, that it only takes one major landfalling hurricane to cause vast damage and many casualties. Just because the long range hurricane forecast seems to be encouraging, we’re not out of the woods.

Hurricane-Sandy-stormsurgediagramIn preparation for the 2015 hurricane season, the National Hurricane Center is unveiling a new system of communicating storm surge threats and vulnerabilities. As has been seen over and over, some of the most devastating damage from hurricanes is not always from strong winds but from storm surge, the wall of water that is pushed out in advance of the center of the hurricane.

20121106-hurricane-sandy-new-jersey-shore.jpg.662x0_q100_crop-scale Hurricane Sandy is one of the more recent demonstrations of this mighty force.

This week, May 24-30, is national Hurricane Preparedness Week.  For those of you who have a role educating others about hurricanes here’s a link to FEMA’s toolkit.   And here is material from the National Hurricane Center/NOAA.

 

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National Dam Safety Awareness Day is May 31st. That date is the anniversary of the failure of the South Fork Dam which resulted in the infamous Johnstown (PA) flood. More than 2,200 lives were lost in what is considered the worst dam failure in the history of the United States according to FEMA.

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Missouri Institute of Science and Technology

The National Dam Safety Program is led by FEMA and a partnership of states, federal agencies and other stakeholders. Dams are part of an aging infrastructure and continued attention is vital in averting future catastrophic failures.

Weather Wednesday – May through July Outlook

The Climate Prediction Center recently issued its 90-day outlook for temperature and precipitation for the U.S. It also updated the drought monitor tool.

off01_tempIn general the outlook calls for the next three months to feature above normal temperatures in the western third of the country and in the far southeastern states. Alaska and the Pacific Northwest will also be warmer than usual. Below normal temperatures are confined to much of Texas and areas of adjoining states. Most of the country will see an equal chance for above or below normal temperatures.

 

off01_prcpMuch of the nation may experience above normal precipitation from the southeast through the gulf states to the western plains and Rockies along with a good portion of Alaska. The above normal rainfall may bring drought relief to Texas and the four corners area. The Great Lakes states will see below normal precipitation and the potential of a developing drought. Lake levels and fire danger may be impacted.

 

drought 90The drought monitor shows little change in the near term for the hardest hit areas of the west, parts of Texas, and parts of the Dakotas, Minnesota and Wisconsin. Over the 90 day period of the outlook, the drought may ease in Texas and areas northwest of there. However, drought conditions may expand in the Great Lakes. Unfortunately, little or no relief is seen for California.  Just this week water use restrictions of from 8% to 36% were enacted for some municipalities.

Late breaking news.  Tornadoes in Germany!

There was a fairly broad outbreak of severe weather including tornadoes in Germany on Tuesday, May 5.  Here’s coverage from the British newspaper, The Guardian.

Weather Wednesday – First Tornado Captured by Radar

62 years ago this month, April 9, 1953, about 3 miles from where I am sitting, a tornado was caught by radar for the first time. Scientists and electrical engineers at the Illinois State Water Survey at the University of Illinois at Urbana-Champaign had modified a former WWII airborne radar for use in estimating amounts of precipitation falling from storms.

Don Staggs, an electrical engineer, was preparing the radar for later field tests. He started to notice what we now call “hook echo” returns in the scans of the storm. As afternoon turned to evening, a strong thunderstorm developed just north of Champaign, about ten miles from the radar site at the university-owned Willard Airport. The storm image included a pronounced hook on the bottom rear flank much as we see hook echoes on modern Doppler radar.

first radar image of a tornado
Illinois State Water Survey via The News Gazette

Still photos and a 16mm film of the images on the scope captured that moment. A team of meteorologists and technicians were able to study the image capture. Later, Dr. Ted Fujita the creator of the tornado strength measurement scale that bears his name, sketched over 200 of the frames of the film in his own hand. All of this can be seen in a terrific article from Colorado State University.  Note especially the photos of the tornado and the well-developed wall cloud.

We now know that the radar captured the early stages of an F3 tornado that eventually traveled about 160 miles and dissipated near Albany, IN. There were two fatalities and about $4-million in property damage in Illinois. The path of the storm took it across mostly rural areas.

Next week, we’ll discuss current use of radar and what may be the next generation of this important forecast tool.