The next SKYWARN meeting is 18-Nov @ 7:00 PM, the third Tuesday of the month.
About 8 members attended the 21-Oct meeting. Topics discussed included:
- Discussion on the antenna work completed on 18-Oct.
- Coordinating SKYWARN and Amateur Radio classes in the Spring.
- Identifying and documenting good observation spots.
There was no actation in September.
Most of the 21-Oct SKYWARN meeting centered around idnetifying "swett spots" for spotters to use during activation. Dave KCØUVY sent an e-mail out asking for suggestions and received no responses. The group reviewed a county map and identified several possibilities. Over the next several months, suggested locations will be surveyed. Worthy locations will be documented with:
- Location (address, E911, Latitude-longitude).
- Accessability and escape routes.
- Shelter options.
- Estimated radio coverage.
Anyone interested in helping with the surveying across the county should contact Dave KCØUVY. The first planned expedition will start from the Happy Chef restaurant on Saturday 08-Nov at 10:30 AM, immediately following the OSCAR meeting.
MN Citizen Corps Conference
The 2008 Minnesota Citizen Corps Conference, Friday and Saturday, November 14-15, 2008. The agenda is evolving, but the location is set. The conference will be held once again at the U of M Continuing Education and Conference Center on the AG Campus in St. Paul. Check MN HSEM for more information about the conference. Pre-registration is required.
From Multiple Sources
The 2008 tornado season is on track to set a record for the number of tornadoes in the USA, according to National Weather Service data. Through July, 1,390 tornadoes were officially recorded in the first seven months of a year — the most ever. The annual record for tornadoes in the USA is 1,817, set in 2004. Official numbers from the weather service's Storm Prediction Center since Aug. 1 aren't available yet, but preliminary reports for the period since then show as many as 300 tornadoes could be added. On top of that, October and November are usually very active for tornadoes, what's known as the nation's "second tornado season" after the main season in spring.
Although the number of reports has risen sharply since the early 1990s, many of the weaker tornadoes probably would not have been recorded in earlier decades. An increase in national Doppler radar coverage, population sprawl into previously little-occupied areas and greater attention to reporting have contributed to the rising number of tornado reports. During the past 55 years, there has been little trend in the frequency of strong to violent tornadoes, those at EF-3 or higher on the Enhanced Fujita Scale of Tornado Intensity. As for future tornado trends in the USA because of climate change, a warning was sounded in 2007, when two separate studies predicted there would be an increase in the frequency and intensity of severe thunderstorms and tornadoes in the USA due to global warming by the year 2100.
From USA Today
Winds seem to be stronger and more consistent in the Fall. The strength of fall winds derives from the migration of the mid-latitude jet stream. This river of air, six to nine miles high in the atmosphere, forms along the boundary between cold, polar air and warm, subtropical air. The jet stream is typically located across the southern USA in the winter and shifts toward the Canadian border during the summer. During the transitional seasons of spring and fall, this ribbon of strong winds aloft often roars across the continental USA. This jet stream increases the speed of all winds above the Earth's surface. In early fall, there is still enough daytime heating to create warm air pockets that rise vigorously from the ground. Strong winds aloft sink to replace this rising air, creating gusty winds.
Why Leaves Fall Off Trees
From Telegraph (UK)
The reason that leaves fall off trees has been discovered. All tree leaves have 'thermostat' that maintains temperature. Deciduous (falling) trees use an elaborate cellular mechanism to part company from their leaves, which act as "solar cells" in the summer but become superfluous in the darker winter months. At the base of each leaf is a special layer called the abscission zone. When the time comes in autumn to shed a leaf, cells in this layer begin to swell, slowing the transport of nutrients between the tree and leaf. Once the abscission zone has been blocked, a tear line forms and moves downwards, until eventually the leaf is blown away or falls off. A protective layer seals the wound.
Rubber Duckies In Science
Those famous yellow, rubber ducks that we play in the tub with are being put to work by NASA. NASA recently dropped a total of 90 ducks into the Jakobshavn Glacier between Greenland and Canada. This particular glacier is Greenland's fastest moving glacier in Baffin Bay and discharges nearly 7% of all ice coming off of Greenland. If found, the duckscould provide crucial information on how water moves through the ice and provide information about the movement of glaciers. There are still lingering questions on why glaciers speed up and head towards sea during the summer. Science Experiment is written on each duck with an email address in different languages. There is a reward for reporting the missing ducks, but nobody has contacted NASA, so far.
Percent Possible Sunshine
From Minnesota WeatherTalk
This is a standard climate measurement made at National Weather Service Offices, but it is often misunderstood as a indicator of solar energy. It is the ratio of the actual duration of bright sunshine (unobstructed sunlight measured by a sunshine recorder) in hours and minutes compared to the astronomically possible duration of sunshine in hours and minutes taken from sunrise and sunset times for the local station (latitude specific). Thus, in the winter when only 8 hours of sunshine is possible for the Twin Cities, 7 hours of actual sunshine would equal 87.5 percent possible sunshine, while in summer when 15 hours of sunshine is possible, 7 hours of actual sunshine would only equal about 47 percent possible sunshine.
Incidentally, long term climate averages show that it is this time of year that we see the maximum percent possible sunshine in Minnesota (typically the last few days of September and first few days of October). My former colleague and mentor Dr. Don Baker wrote about this topic decades ago, but his findings are still valid today.
From USA Today
With the first snow appearing in Owatonna, it is appropriate to reflect on the frost line. The frost line marks how far down frost will penetrate soil. The beams of a structure that establish the foundation, known as footings, are placed below this point during construction to minimize movement. Areas have different frost lines, depending on air temperature above the soil, sun exposure, ability to reflect light, snow cover, as well as the heat conductivity, thickness, and water content of the soil. This map shows the frost lines for all states across the nation. Northern Maine and northern Minnesota have the deepest frost lines in the lower 48 states, with an average frost depth of more than five feet.
Word For The Month
From Minnesota WeatherTalk
In the subtropical climates subject to a distinct monsoon (rainy) season, the medical profession routinely gears up for increased patient loads due to cold, fever, and cough. The onset of this season can come suddenly and may tax the body's ability to acclimate. In addition, the higher humidity and persistent wet landscape favors the development of certain disease carrying insects and organisms. Fresh water supplies are sometimes contaminated by monsoon floods and the high humidity causes stored foods to spoil more rapidly. Under such environmental conditions it is no wonder that humans are exposed to a variety of ailments.