After this summer’s frequent heavy rains, newcomers to Colorado may have a hard time believing that we live in a semi-arid climate. How unusual was our wet summer, and what does Mother Nature have in store for us this winter?

It’s interesting to note that although Denver International Airport recorded more rain than usual this summer, Castle Pines North received even more than Denver.

Castle Pines North received 15 inches of moisture from April through August. This was about 5 inches more than during the same months last year. Although CPN had a dry winter, the wet spring and summer means that we are already ahead of Castle Rock’s average for the whole year.

In contrast, Denver also had a “wet” summer, but Denver’s winter was so dry that the total for the year is still below average.

Cold and Snowy Winter Ahead?

Many residents around the state have assumed that the wet summer will lead to a wet winter, and have noted “folklore” indications of a cold and snowy winter (the aspen are changing early, skunk cabbage have grown tall, etc.) But what do the weather professionals have to say?

Colorado State University research climatologist Nolan Doesken says, “The fact is, long range prediction is difficult. There is some chance we could have a tough winter. Extreme winter cold blasts have been rare in recent years. We are ‘overdue.’ But chances are less than 50-50 that it will actually happen.”

The National Weather service (NOAA) has stated their prediction for this coming winter is that it will be “normal.”

Dr. Thomas Corona of Metro State College, says, “Predicting winter precipitation based on what we’ve seen so far is tricky.” He noted the return of El Nino, which causes some portions of the country to receive more moisture than normal while other areas receive too little.

To shed some light on CPN’s weather patterns, we talked with a familiar face on local TV and in the neighborhood. Dave Fraser, Chief Meteorologist at WB2 News and a resident of CPN, said “We’re seeing a trend towards a wetter pattern, but moisture and associated weather are cyclical, and the dry pattern will come back.” According to Fraser, we appear to be heading for a “normal” winter.

What is “Normal?”

“During a typical winter, the Denver area sees about 60 inches of snow, with the usual storm bringing three to six inches,” said Fraser. Newcomers should know that March and April are usually our snowiest months, and that while most winter storms are relatively mild and short-lived, on occasion the Denver area will see a good-sized storm. (Remember March 18 – 20, 2003?)

Historical weather data tells us that, while snow may “average” 60 inches per year, actual snowfall varies widely from year to year. Dating back to 1948, Denver’s annual snowfall totals have ranged from 27 to 100 inches. Castle Rock has an “average” snowfall similar to Denver, but has an even wider range, from 11 to 115 inches a year.

What’s the history for total moisture for a year? (Moisture is the sum total of rainfall plus the water content in snow.) Denver receives an average of 15.5 inches of moisture per year, and Castle Rock gets slightly more — about 17 inches. But actual moisture totals can vary widely, with very wet and very dry years skewing the averages.

CPN had a “dry” winter, where we had only about 3 inches of moisture. Then we had a “wet” spring and summer (15 inches from April to August). The total for 2004 (through August) is nearly 18 inches — already an inch ahead of our 17-inch average for an entire year.

The official year-to-date readings for Denver, on the other hand, were only 11.3 inches, so Denver has not yet reached its “average” for the year. (In a normal year, Denver receives 12 inches of moisture by the end of August).

Fraser said the up-slope conditions created by Monument Hill and Surrey Ridge make CPN ideal for receiving higher snowfall amounts than in the city of Denver. Therefore, CPN residents can typically expect higher amounts of snowfall than is forecasted.

How does CPN compare?

Thanks to a new Colorado State University weather-tracking program, it is possible to start looking at variations for CPN and other specific locations throughout the state. Data from CPN shows that this summer, we received more moisture than other nearby areas, with 15 inches. During the same time period, a weather tracker in Highlands Ranch reported 13.93 inches; and a station at Cherry Creek Dam Road reported 12.45 inches.

How much do precipitation levels vary even within CPN? We should have that data soon. In the last issue of The Connection, we asked for additional rain trackers to cover the northern and western portions of the CPN community, and a couple of residents have expressed interest. If you would like to set up your own observation station, contact Tim Gamble at webmaster@cpnhoa.org to find out more about how to get started.

For more information

For a quick summary of CPN’s recent moisture totals, and links to web sites with detailed historical data, click on “Moisture Stats.”

Also, check out Dave Fraser’s weather forecasts, which can be viewed on WB2 Sunday through Thursday, or strike up a conversation with Dave when you see him in the neighborhood. Fraser and his wife, Kathy, live in CPN’s GreenBriar neighborhood with their two sons. Kathy and Dave met while working for competing stations as broadcast weather forecasters in Sioux Falls. The Fraser family has called CPN home for more than three years.

There is a story on the 9News website about NOAA’s winter weather outlook. Click here to read the article in its entirety.

NOAA has also posted a 2004-2005 winter outlook on its website. Click here to view it.

Will El Niño bring more snow this winter and spring? (Denver Post, 11/13/04)

Drought may be fading (Rocky Mountain News, 11/24/04)