February 212 Newsletter

The next SKYWARN meeting is 19-Feb @ 7:00 PM, the third Tuesday of the month.

SKYWARN Newsletter Editor
The current SKYWARN Newsletter editor is retiring after the March-2013 issue. Anyone that is interested in continuing this line of communications should contact Dave.

Amateur Radio Class
Owatonna Steele County Amateur Radio is once again sponsoring a license class. The class will prepare you for the (no code) Technician operating license. There will be eight class sessions, about two hours each. Class begins on 19-Feb at 7:00 PM. Classes will be held on Tuesday and Thursday nights on the 1st floor of the Owatonna Fire Station (107 W. Main Street). The license exam will be given on the last night of class, 14-Mar.

The class is free. The ARRL Ham Radio License Manual (2nd Edition) is being used as the study guide. The book is normally $29. OSCAR is offering a $5 discount if the book is ordered and paid for prior to the beginning of class. A $15 fee is charged for taking the exam.

For more information can be read at the OSCAR web site. Contact Tom NUW 507-444-9133 for more information or ordering the License Manual.

SKYWARN Spotter Class
The next Steele County spotter class will be held on Tuesday, 19-Mar. The class starts at 7:00PM on the 3rd floor of the Owatonna Fire Station. All spotters must take the class every two years to be current.

Average Temperature Calculation From Multiple Sources
Daily temperature averages are computed by adding the daily high and daily low , then dividing by two. If the daily high is 32°F with a low of -10°F, then the daily average is 21°F. (32 - 10) / 2 = 42 / 2 = 21.

Monthly averages are a bit more complicated. The average high temperature is calculated by adding all of the daily high temperatures and dividing by the number of days. Similarly, The average daily low temperature is calculated by adding the daily low temperatures together and dividing by the number of days. The average daily high and low are added together and divided by 2.

How Do Winter Storms Form? From Multiple Sources
Just like storms at other times of the year, the right combination of ingredients is necessary for a winter storm to develop. Winter storms have various components, including low pressure centers, warm fronts, and cold fronts. These components are generally driven by the jet stream. The jet stream determines the trajectory of a relatively warm air mass bringing moisture from the south. It also brings a sufficient amount of cold polar air flowing down from the north.

The components provide the three ingredients:

  • Cold air. Below freezing temperatures in the clouds and near the ground to make snow and/or ice.
  • Lift. Raises the warm moist air to form the clouds and cause precipitation.
  • Moisture. The final ingredient to form clouds and precipitation

The intensity of a storm depends upon several items, such as the strength and positioning of the jet stream and associated upper air disturbances, the related strength of the horizontal temperature gradients, and the availability of moisture.

Term For The Month From Multiple Sources
Rarely used anymore, hythergraph found in the old glossary of meteorology refers to a climate diagram which shows temperature along one axis and some form of moisture, such as humidity or precipitation along the other axis. It may also be called a climagraph. The hythergraph is often used to characterize the climate of a region using mean monthly values. The model could be used to estimate how a specific crop variety might perform. HVAC engineers use a varient of the hythergraph called the Comfort Chart. The comfort Chart is used to identify what temperature/humidity combinations people may feel comfortable in.

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Steele County SKYWARN
Owatonna, MN