May 2Ø11 Newsletter

The next SKYWARN meeting is 17-May @ 7:00 PM, the third Tuesday of the month.

SKYWARN Workshop
Based on the picture below, 17 members made the trip to the MN SKYWARN workshop on 09-Apr.

Looking for a bit more current local information? Click on over to the WBØVAK WX Station. A link was added to the Steele County SKYWARN Home Page

Rotating Vortices From
Rotating columns of air come in many flavors, from tornadoes to dust devils. Some of the variations include:

  • Dust Devil - The dust devil forms on sunny days when the land surface gets much hotter than the air above ground. Some dust devils can become strong enough to produce EF0 or perhaps EF1 damage (and definitely at least eye damage from the blowing dust).
  • Fire Devil - A fire whirl or fire devil forms due to intense heating from fires. They can also reach EF0 or EF1 intensity. The generic term for these rotating air columns is whirlwind.
  • Waterspout - These are usually associated with a growing cloud, occasionally with thunderstorms. The waterspout has the potential to become even stronger than its whirlwind cousins.
  • Steam Devil - Steam devils form as bitterly cold air is heated by unfrozen water. They may also form over thin ice at a temperature much warmer than the air.

Hurricanes From Multiple Sources
Although we don't have to worry about hurricanes in Minnesota (at least not yet). Atlantic hurricane activity waxes and wanes over a cycle of several decades. Scientists have worked to develop models to predict the number of storms each seasons. Many researchers think conditions like rising sea-surface temperatures might affect the number of storms and their intensity. This animation illustrates the damage that can occur from different category storms.

Lightning and Nitrates From USA Today
A lightning strike can produce nitrates (also known as fixed nitrogen) that can be used by plants. It is estimated that 5 to 8% of the nitrates in the biosphere are fixed by lightning and carried to Earth by rainfall. However, any improvement in grass or plant growth following a thunderstorm may simply be due to the influx of rain and not necessarily tied to an increase in nitrates in the soil.

Farmer's Forecast From Minnesota WeatherTalk
The Weather Channel, in partnership with Monsanto, deliver better agricultural weather information to American farmers via their web site. includes forecast information on rainfall, soil moisture, wind, temperature and UV index, along with severe weather alerts. It will be updated several times each day.

Fair Weather Cumulus Clouds From USA Today
Clouds that form out-of-the-blue clouds are often referred to as fair-weather cumulus. They often show pop up around noon after the day typically begins clear. Clear skies result in plenty of sunshine. The earth's surface heats unevenly depending on what is being heated. For example, a parking lot will heat quicker than a grove of trees. As parcels of air are heated above these surfaces, they rise. Rising air breeds condensation, and sinking air breeds evaporation.

Great Lake Tides From USA Today
There is apparently some disagreement among experts as to whether the Great Lakes have tides, but there is no doubt that, even if they do, they are miniscule (1 to 4 cm) compared to tides experienced at coastal locations on oceans (particularly the Atlantic Coast). The relatively small volume of water (even in Lake Superior) as well as the fact that the Great Lakes are essentially closed off from other bodies of water affect the magnitude. Restrictions to the free flow of water have an impact on tidal cycles. For example, while the East Coast of the U.S. has semi-diurnal tides (two high/two low each day), the Gulf Coast only has diurnal tides (one high/one low each day). This has to do with the fact that ocean water can only enter or exit the Gulf of Mexico through the narrow Yucatan Channel or the Florida Straits.

Term For The Month From Multiple Sources
Anabatic Winds
Anabatic winds are ascending or upslope winds, often the result of heating along valley slopes. These winds are prevalent in many landscapes with pronounced topography, especially during the daylight hours. Balloonists and pilots of gliders and sailplanes often use these winds to maintain or gain altitude. There is even a type of sailplane called an Anabat.

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Steele County SKYWARN
Owatonna, MN