The next SKYWARN meeting is 17-Aug @ 7:00 PM, the third Tuesday of the month.
Letter To The Editor
From People's Press
Dave KCŘUVY wrote a nice Letter To The Editor in July:
I want to thank the Owatonna People’s Press for their excellent coverage of the recent severe weather that hit Steele County. It is easy to forget about it once the storm clouds are gone. But the damage from these tornadoes will impact lives for years to come.
I especially want to thank the members of Steele County SKYWARN. These dedicated volunteers donate their time and resources (including their own vehicles and fuel) to protect and warn the citizens of Steele County when severe weather strikes. Working hand in hand with the National Weather Service, dispatch, law enforcement, fire departments, and the local media outlets (KOWZ, KRFO, Charter, and the Owatonna People’s Press), we saved lives. The destruction from this storm was incredible and yet there was no loss of life in Steele County.
We can’t prevent a tornado (or three) from hitting our county. Nor can we force people to take shelter when severe weather strikes. But we will continue to do our very best to monitor and track severe weather and to provide timely and accurate alerts so that you can take action and be safe.
If you are interested in joining Steele County SKYWARN, please leave your name and contact information with Bonnie Hermel at the Owatonna Fire Department (774.7232). We will be very happy to notify you when we schedule our next Spotter training class.
Isolated vs. Scattered Thunderstorms
From USA Today
Precipitation probablilities are factored by the actual chance of precipitation and the percentage of the area that will see the precipitation over the forecast area. The terms isolated and scattered are based on the probabilities of measurable precipitation. The National Weather Service uses this terminology to relate probabilities:
- 10% probability: Slight chance, isolated or none.
- 20% probability: Slight chance, isolated
- 30-50% probability: Chance,scattered
- 60-70% probability:Likely, numerous
- Over 80%, the forecast will be categorical, such as "rain this afternoon."
From NASA Tech Briefs
For decades, scientists have struggled in vain to find such pockets where lightning might be initiated. Florida researchers developed a technique to remotely measure thunderstorm electric fields on the ground. By measuring small radio pulses made by cosmic-rays passing through these storms, they calculate that they can reconstruct the electric fields along the high-energy particles' paths. One idea is that thunderstorms generate big electric fields capable of making sparks, but those strong fields are localized in very small pockets - too small to be easily detected by the balloons and aircraft sent into thunderclouds to measure the fields. The scientists are conducting experiments to search for these lightning initiation pockets.
June typically means the beginning of hurricane season. The conventions used for naming hurricanes has changed over the years, and differs between regins around the globe. For example, saints were used in the West Indies, based on the saint's day when the hurricane occurred. The US began using women's names around WWII. The international phonetic alphabet was used for two years in the early 1950s and reverted back to women's names. Men's names were added in the late 1970s, and continue today. The World Meteorological Organization (WMO)
maintains several lists. Not every letter of the alphabet is used. The Atlantic storm list, for example, does not utilize names that begin with Q, U, X, Y or Z. If there are more than 21 named storms, the Greek alphabet (Alpha, Beta, etc.) is used. The lists are rotated over multiple years, with up to eight lists of names for a particular region. Occassional changes in the names occur for various reasons. You can find lists of
current names for every region of the globe and
retired Atlantic nameson the NHC Web site.
From New Scientist
Have you ever seen a photograph of a raindrop splash? We see the drop flattens into a thin sheet that then bounces to form a crown shape. The splash is affected by the size of the drop and the air pressure around it. Computer simulations show a drop compresses air in front of it a few microseconds before hitting a solid surface, causing the raindrop to flatten and spread out. In a practical experiment, researchers used alcohol in a vacuum chamber and came up with similar results. The lower the air pressure, the less the liquid splattered.
Great Balls of Fire
Ball lightning has been the subject of much scientific scrutiny over the years. The exact cause and nature of ball lighting has yet to be determined; there may be several different types, confusing matters further. But generally it manifests as a grapefruit-sized sphere of light moving slowly through the air which may end by fizzling out or exploding. Since the mid-60s, the U.S. military has been exploring ways that the phenomenon. One researcher suggests a donut-shaped mass of moving plasma would generate the required fields which would be completely stable and self-sustaining. Short-lived plasmoids from "chicken egg to softball" size were created in the laboratory in the 80s.
Two hundred years ago, the warship HMS Warren Hastings was struck by a weird phenomenon: "three distinct balls of fire" fell from the heavens, striking the ship and killing two crewmen, leaving behind "a nauseous, sulfurous smell," according to the Times of London. Ball lighting is still mysterious two hundred years later… and the next time a warship gets struck by weird fireballs they will probably be as baffled as the sailors on the HMS Warren Hastings.
But is it really all in your mind? Some physicists suggest that lightning strokes could stimulate people’s brains and cause them to hallucinate bright blobs of light. Repetitive (20-60) strokes can form magnetic fields that are very similar to those used in a brain-stimulation technique called transcranial magnetic stimulation (TMS). TMS is used to
treat some neurological and psychiatric conditions by the application of magnetic fields. During treatment, some patients report seeing blobs of light in their field of vision. The explanation for seeing light when light is not actually entering the eye, are known as phosphenes. One common example is when you see light when you rub your closed eyes hard.
Oil Spill Trajectory
As the Newsletter is being written, things continue to look optimistic for keeping the oil spill capped. The bigger problem is what is going to happen to the oil alredy released. NOAA scientists are trying to determine where the oil will go by modeling. They are estimating the oil movement using historical wind patterns and ocean currents. You can find more information at the
NOAA web site.
Term For The Month
From Minnesota WeatherTalk
Atmospheric pressure is normally not the consistent across all altitudes. Stacking can develop with large, slow moving low pressure systems. The air pressure tends to be the same near the surface and above with little distortion in the pressure field horizontally. Satellite images may show large white blobs of clouds rotating.