The Weather Wire
November 2010 Volume 17 Number 11
Avg High - 69.7
Avg Low - 40.9
Snow - 0.0"
Season Snow - 0.0"
Precipitation - 0.54"
Avg High - 51.5
Avg Low - 23.5
Avg Snow - 10.7"
Avg Precip - 0.98"
Winter Weather Definitions...
With winter looking like it will make a visit to Colorado this month it is time to review all the winter weather definitions since we will be seeing a lot of these over the coming winter months.
The National Weather Service issues many different types of watches and warnings during the winter months. Here is what they mean:
WINTER STORM WATCH:
A winter storm watch is issued when winter storm conditions are possible within the next 12 to 36 hours, but the timing, intensity, or occurrence may still be uncertain.
WINTER STORM WARNING:
A winter storm warning is issued when heavy snow is occurring or will develop in the next 18 hours. The heavy snow may be accompanied by wind and blowing snow.
A blizzard warning is issued when the following conditions are expected for at least 3 hours: Sustained winds of 35mph or greater with considerable falling and/or drifting snow lowering visibilities to less than 1/4 mile. Remember, snow does not necessarily need to be falling and dangerous wind chills are often observed during blizzard events.
WINTER WEATHER ADVISORY:
A winter weather advisory for snow is issued when these general snow accumulations are expected: Between 4 and 8 inches in 12 hours in the mountains. Between 3 and 6 inches in 12 hours at lower elevations, such as Denver Metro.
A winter weather advisory for snow and blowing snow is issued when falling snow is accompanied by blowing snow to cause travel problems due to lowered visibilities and drifting snow.
A winter weather advisory for blowing snow is issued when wind blown snow will occasionally reduce visibilities and create a hazard for travelers.
Below freezing temperatures are expected and may cause significant damage to plants, crops, or fruit trees in areas unaccustomed to freezing temperatures. Usually issued for first frost/freeze of season and again in spring for late frost/freezes.
HIGH WIND WARNING:
wind warning is issued for the following conditions: Sustained winds of
50mph for at least 1 hour, or gusts to 75mph for any duration in the
mountains and foothills. Sustained winds of 40mph for at least 1 hour, or
gusts to 58mph for any duration at lower elevations away from the
We as weather forecasters use different wording or terms when we describe a snow event. Whether it is just some flurries or a large winter storm we use different words that best suit the snow event that is expected.
- Light snow falling for short durations. No accumulation or light dusting
is all that is expected.
Rain drops that freeze into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. However, it can accumulate like snow and cause a hazard to motorists.
Rain that falls onto a surface with a temperature below freezing. This causes it to freeze to surfaces, such as trees, cars, and roads, forming a coating or glaze of ice. Even small accumulations of ice can cause a significant hazard.
Snow and or severe cold can be potentially life threatening and every year we see cold and snow related deaths.
Everyone is potentially at risk during winter storms. The actual threat to you depends on your specific situation. Recent observations indicate the following:
Frostbite is damage to body tissue caused by that tissue being frozen.
Frostbite causes a loss of feeling and a white or pale appearance in
extremities, such as fingers, toes, ear lobes, or the tip of the nose. If
symptoms are detected, get medical help immediately! If you must wait for
help, slowly re-warm affected areas. However, if the person is also showing
signs of hypothermia, warm the body core before the extremities.
When CAUGHT in a Winter Storm...
Do not eat snow: It will lower your body temperature. Melt it first.
IN A CAR OR TRUCK
in your car or truck. Disorientation occurs quickly in wind-driven snow and
Make yourself visible to rescuers:
Exercise from time to time by vigorously moving arms, legs, fingers, and toes to keep blood circulating and to keep warm.
AT HOME OR IN A BUILDING
Stay inside. When using ALTERNATIVE HEAT from a fireplace, wood stove, space heater, etc.:
and drink. Food provides the body with energy for producing its own heat.
Keep the body replenished with fluids to prevent dehydration.
Colorado sees it share of snow during the winter months. The best time to prepare for the next snow is now while the weather is mild and dry. Take an inventory of you winter supplies both for the car and the home and stock in items that you need. Be prepared and the winter snows will be a lot less bothersome this year.
Dry conditions since mid August have brought areas of drought to much of Colorado again.
The map below shows forecasted temperature deviances for November 2010. As can be seen, above normal temperatures are expected statewide for the month.
The map below shows forecasted precipitation deviances for November 2010. Below normal precipitation is expected across southern Colorado for November, with normal precipitation northern Colorado.
Some areas of drought have returned and are likely to persist across north central Colorado.
October of 2010 continued to produce above normal temperatures and below normal precipitation. Temperatures have actually been above average every month since May with the last two months of September and October being more than 4 degrees above the monthly mean temperature. There were only two days with a temperature below freezing compared to nearly 9 days on normal years. The warm and rather dry October resulted in only the 15th October since 1872 without even a trace of snow reported in Denver. Without snowfall at all this season we are currently 6.2" below average as of the 1st of November. Total precipitation for the month was 0.54" measured at DIA compared to 0.99" on average. Currently year to date the precipitation deficit has grown to 2.2" below normal with 11.15" so far this year and 13.35" on average. There were a few windy days towards the end of the month with a peak wind gust of 51mph reported on the 25th, otherwise October of 2010 was fairly quiet without any scary weather for Halloween which really happens more years than not contrary to popular belief.
The trend of abnormally warm and dry weather is expected to continue through the first half of the month with a more active weather pattern as the month comes to a close. Typically November is Denver's 2nd snowiest month of the year behind March with 10.7" on average and 3 "significant" snows of greater than 1". This year below normal snowfall is expected with 1-2 snow events of greater than 1". Temperatures really begin to drop off in November with 51.5 degrees for an average high and 23.5 for an average low with a mean temperature of 37.5 degrees. November of 2010 will likely end up significantly warmer than average. Enjoy the pleasant weather while it lasts as the weather pattern here in Colorado can turn on a dime and there will be a period where conditions are equally as cold and snowy.
Sunrise/Sunset (July - Dec Denver area)
Sept 2010 to May 2011