November 21 Newsletter

The next SKYWARN meeting is 16-Nov @ 7:00 PM, the third Tuesday of the month.

SKYWARN Breakfast From Mark S
SKYWARN and the Special Deputies are teaming up for a fund raising breakfast on Sunday, 12-Dec. The breakfast at the VFW includes french toast, eggs to order, sausage, coffee, milk, juice and all you can eat pancakes. The price of the breakfast "at the door" is $5.00. SKYWARN gets $2.50 for each ticket sold in advance. 300 VFW Breakfast tickets to be sold will be available to the SKYWARN members at the 16-Nov SKYWARN meeting. If you are unable to make the meeting and would like to sell some tickets please contact Mark Schultz at 451-0468.

SKYWARN Newsletter Index
Do you remember reading something in an SKYWARN Newsletter, but can't remember when? An index of topics was compiled and available as a pdf file. The list provides the "heading" for each topic and the month it appeared in. The index is cross referenced by month and topic.

Absurb MN Weather From Multiple Sources
The fall weather, so far, certainly has been a contradiction. September proved to be the wettest on record, followed by almost two weeks of warm, dry weather in October. The state-average September rainfall total was 6.46 inches, topping the previous high of 6.20 inches from 1900. Don't forget the record number of MN tornadoes, outpacing Tornadoe Alley in 2010.

Then add the record low air pressure combined with high winds. The barometer at Big Fork recorded a new state low at 28.21 inches, equivalent to a Category 3 Hurricane. The previous MN record low barometric pressure in Minnesota was 28.43" in Austin & Albert Lea in Nov-1998. More information is available at NWS Duluth.

Snow Forecasting From Multiple Sources
As the thunderstorm and tornado season pass behind us, it is time to guess about what snow we may encounter tomorrow. A strong La Nina is predicted. This means low sea surface temperatures in the Pacific may result in colder than average winters in the Upper Midwest.

When predicting snow amounts as a winter storm approaches, it's key for meteorologists to know the water content of the snow that's likely to fall. If the atmosphere is waterlogged, it will dump thick, cement-like snow, while a drier atmosphere produces fluffy, powdery snow. Meteorologists at the University of Utah indicate they have a formula that uses temperature and wind speed to predict the water content of snow, and the resulting density.

A nice Popular Science article is available on line about the VORTEX2 project.

Cloud Atlas From Minnesota WeatherTalk
During the 1870s there was increasing use of photography in scientific investigations. In meteorology, one of the pressing needs was to photograph cloud forms and publish a cloud atlas which would illustrate the cloud classification system proposed by Luke Howard in the early 1800s and serve as a reference to meteorological organizations making daily weather observations. Up until that time, drawings and sketches of cloud forms had served as observational guidelines for classifying cloud types. To meet the need of the international meteorological community, English photographer Ralph Abercromby made a series of voyages around the world from 1884 to 1886 with the express purpose of taking as many pictures of different cloud forms as he could. His camera was bulky and unwieldy, using large gelatin plates to capture the images. By 1887 his collection was large and diverse enough to publish the first cloud atlas using photographs. Today, the modern International Cloud Atlas not only contains color photos of cloud types taken from observers on the ground, but also images taken from airplanes and orbiting satellites.

Cloud Shadows From New Scienist
Topographic maps are often generated using laser technology to gather data. Creating this data from camera images is difficult for a variety of reasons. One thought it to utilize the shadows that clouds form on the ground to help make the measurements with a camera. The size of the shadow on the ground changes as the relative height of the cloud changes. When a series of images record the movement, the pixels change color based on the shadow. Once the actual wind speed is factored in, the relative change in the ground height can be calculated.of the shadows. As the shadows move, the and recording the time at which the passing shadows change a pixel's colour they can estimate the distance between each pixel.

What's Moving? From USA Today
Movement is always relative to something else. Do storms move across the earth, or are storms stationary and move becasue of the rotation of the earth? If storms were stationary with the Earth rotating beneath them, then all storms around the Earth would appear to move east to west. We see most storms move from west to east, so they generally are moving opposite of the earth rotation. Storms are often steered by winds at various levels of the atmosphere. Puffy white clouds you see passing by on a summer day are steered by relatively low-altitude winds at the level of their formation. A thunderstorm, which can have a base at 20,000 feet and a top at 50,000 feet, is steered by varying wind speeds and wind directions.

Washington Meridian From Multiple Sources
Most of us recognize the Greenwich meridian as the accepted standard for measurements of longitude. Greenwich was generally accepted prior to its international adoption for nautical measurements due to the prevalence of the British Admiralty charts. Most countries had adopted their own meridian for purposes other than nautical. The original Washington meridian was established as the center of the Capital in 1791. The meridian was redefined as passing through the White House in 1804, the old Naval Observatory in 1850, and lastly at the new naval Observatory in 1897. The Washington Meridian was ultimately abolished in 1912.

Term For The Month From Multiple Sources
Weeping Wing
Ice build up on airplane wings disrupts the flow of air and destroys the lift characteristics of the wing profile. A weeping wing is an aircraft ice protection system. The leading edge of the wing release small amounts of a glycol-based chemical. The fluid flows along the top and bottom surfaces of the wing, leaving a thin coat of fluid to keep the wing surface from icing. Another method of preventing ice build up is a rubber boot. This is an inflatable rubber bladder that breaks up ice by expanding the bladder with compressed air.

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Steele County SKYWARN
Owatonna, MN