May 2008 Newsletter

The next SKYWARN meeting is 20-May @ 7:00 PM, the third Tuesday of the month.

Local News

  • Dale WBPKG updated the WX Dashboard with additional outlooks on precipitation and flooding.
  • The MN SKYWARN Conference was held on 05-Apr. Steele Couty was represented by Deuel NSL, Marv NFJP, Bill KDDJZ, and Tom NUW.
  • Skywarn was honored at the 22-Apr meeting of the Steele County Board of Commissioners as part of Severe Weather Week.

HY-Vee WX Radio - Part 2
Hy-Vee Owatonna is having a second WX Radio sale/event on Saturday May 10th from approx. 8:30AM to 3:00PM. Please contact Deule NSL (451-8975) if you can help. If no answer leave amessage.

Also Hy-Vee in Faribault is having a WX Radio sale/event on Saturday May 3rd with approximately the same hours. Deuel is in contact with a Skywarn person in Rice county and recruiting help from Rice county to program radios. Contact Deuel if you are willing to help at Faribault.

Weather Predictions With Coffee From USA Today
The newsletter has atlked about Groundhog Day and other animal folklore. How about that morning cup of coffee? If bubbles in a hot cup of strong, black coffee form in the middle of the cup, fair weather is in the offing. However, if bubbles migrate to the edges of the coffee surface, stormy weather is on the way. The scientific explanation is the relationship between atmospheric pressure and surface tension. Relatively high atmospheric pressure (fair weather) creates a concave surface such that the bubbles migrate to the center. Low pressure, on the other hand, creates a convex surface such that the bubbles move to the walls of the cup. Anecdotal evidence concludes that strong brewed coffee works the best, with the oil from the coffee beans plays a role in the liquid's surface tension. The editor has tried to see if this is true, but his eyes usually don't open up until after the coffe cup is empty.

Lightning Strikes From Multiple Sources
Scientists know lightning forms between layers of positive and negative charges within a cloud. Theories suggest that lightning should remain inside the cloud, trapped between the charged layers. Researchers say they have finally worked out how lightning forms, how it escapes the storm cloud, and whether it will form a "bolt from the blue". Layers of positive and negative charges inside a cloud are redistributed by altitude, intra-cloud lightning, and cloud-to-ground lightning. Direction depends on how the charges were initially distributed inside the cloud, their magnitude, and the weird fact that charges move upwards more readily than they move towards the ground. Lightning jets initially moving up get re-routed by charges lining the sides of the cloud. A bolt-from-the-blue results when the lightning exits the cloud sideways, hitting the ground more than 40 kilometres away from a storm.

Citizen scientists From USA Today
Project Bud Burst, a national field campaign for "citizen scientists," is designed to help record how the planet is warming by tracking the dates that 60 plant species leaf and flower this spring and summer. After a trial run in 2007 that included reports from 26 states, the project is in full swing this year with thousands of people signed up. Become a member of the Project BudBurst community to save your observation sites and plants that you are monitoring throughout the year and for coming years.

Earthquake Clouds From New Scientist
CAN unusual clouds signal the possibility of an impending earthquake? Geophysicists noticed a gap in the clouds in satellite images from December 2004 that precisely matched the location of the main fault in southern Iran. It stretched for hundreds of kilometres, was visible for several hours and remained in the same place, although the clouds around it were moving. At the same time, thermal images of the ground showed that the temperature was higher along the fault. Sixty-nine days later, on 22 February 2005, an earthquake of magnitude 6.4 hit the area, killing more than 600 people. In December 2005, a similar formation again appeared in the clouds for a few hours. Sixty-four days later, an earthquake of magnitude 6 shook the region.

The researchers suggest that hot gases erupting from inside the fault could have caused water in the clouds to evaporate. Another researcher recently demonstrated that when rocks are squeezed, positively charged ions form in the air above. The trouble is that ions usually help to form clouds, not dissipate them. Weather this observation could be used for prediction remains to be seen. There is no physical model explaining why something would suddenly occur two months before an earthquake, and then shut off and not occur again.

Hurricane Forecast From Minnesota WeatherTalk
The atmospheric scientists at Colorado State University issued a North Atlantic Hurricane Season Forecast. They estimate up to 15 named storms, with eight becoming hurricanes and four of the hurricanes may be major. The North Atlantic Hurricane Season runs from June 1st to November 30th and on average produces about 10 named storms and six hurricanes.

Laser Lightning From National Geographic
Scientists say they have triggered early stages of lightning by shooting lasers into clouds over New Mexico. Lightning occurs when storm clouds separate negative and positive electrical charge. In cloud-to-ground lightning, a "leader" sends a hot, negative charge downward. If the electrical field on the ground is strong enough, a positive charge rises up to meet the leader, completing an electrical circuit that is visible as a lightning bolt. Scientists can already trigger lightning with rockets, but is cumbersome and only works about half of the time. Laser beams free electrons from atoms in a long, thin channel of airmaking it easy for an electrical charge to pass through the air between a cloud and the ground. During two thunderstorms in September 2004, researchers sent ultrafast laser pulses into clouds and measured electrical activity using antennas around the experiment site. The team now intends to build a transportable laser to trigger a full-scale cloud-to-ground lightning bolt in the next few years.

Tornado Forcasts From NOAA Storem Prediction Center
Tornado forecasting does not have a simple answer. Here is a very generalized view from the perspective of a severe weather forecaster.

When predicting severe weather (including tornadoes) a day or two in advance, we look for the development of temperature and wind flow patterns in the atmosphere which can cause enough moisture, instability, lift, and wind shear for tornadic thunderstorms. Those are the four needed ingredients. "How much is enough" of those is not a hard fast number, but varies a lot from situation to situation -- and sometimes is unknown. A large variety of weather patterns can lead to tornadoes; and often, similar patterns may produce no severe weather at all. To further complicate it, the various computer models we use days in advance can have major biases and flaws when the forecaster tries to interpret them on the scale of thunderstorms.

As the event gets closer, the forecast usually (but not always) loses some uncertainty and narrows down to a more precise threat area. There is a transition from outlook to mesoscale discussion. Real-time weather observations from satellites, weather stations, balloon packages, airplanes, wind profilers and radar-derived winds become more and more critical. The models become less important as the thunderstorms are expected to arrive. To figure out where the thunderstorms will form require finding out the location, strength and movement of the fronts, drylines, outflows, and other boundaries between air masses which tend to provide lift. Moisture and temperatures (both near ground and aloft) are also looked at since they will help storms form and stay alive. Wind structures in the atmosphere are also important because they can make a thunderstorm rotate as a supercell, then produce tornadoes. Finally, make an educated guess when and where the most favorable combination of ingredients will be and draw the areas and type the forecast.

2010 Twins Opener
Have your tickets to the 2010 Twins opening game in the new stadium? Just remember the weather on the opener this year in the Dome -- 6 inches or more predicted. Late March/early April snow is no stranger to Minneapolis.

Word For The Month From Minnesota WeatherTalk
Crosshair Signature is used by meteorologists to identify a spatial pattern signature in the data used to assess how much snow may fall from a storm. It refers to a vertical zone or area where atmospheric lift will be maximum right in an area of abundant moisture and dendritic ice crystal formation. Under such circumstances the crosshair signature implies that snowfall rates may range from 3 to 4 inches per hour, an extremely high snowfall rate and rare for the Western Great Lakes area.

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Steele County SKYWARN
Owatonna, MN