Microclimates mean readings vary

Many folks live in the Inland Northwest because of its scenic beauty. Within short distances, there are many lakes, mountains and valleys that offer a variety of climates. With its four distinct seasons, many observers have reported temperature and precipitation figures that greatly vary from the so-called “official reporting stations” used by the National Weather Service.

These “microclimatic” divergences are basically caused by topographical features, including latitude, longitude and, of course, altitude, which often dictates amounts of snowfall and precipitation.

The proximity to water, especially large bodies like Lake Coeur d’Alene, Badger Lake, Hayden Lake, Lake Pend Oreille, Liberty Lake and others, also results in wide climatic differences in neighboring regions. For example, during the summer months, residents near the lakes often experience milder nights and cooler days due to the moderating effects of the water. Readings may differ as much as 3 to 5 degrees.

During the winter season, however, towns away from these lakes have been as much as 10 to 20 degrees colder during the nighttime hours. Some area towns sit in tiny valleys where cold air will often settle, resulting in much more frigid conditions than in slightly higher areas.

Within a wide range of at least 40 to 50 individual “microclimates” in this area alone, snowfall amounts vary significantly. Towns near or in mountain locations usually receive anywhere from two to three times the amount of snow in the winter months compared to ones at lower elevations. Even below 2,500 feet, there have been many instances when towns near a particular lake would receive only “traces” of the white stuff, while just a few miles away, as much as 3-6 inches of snow will fall. This type of event will often occur in Coeur d’Alene.

Spokane receives much less precipitation than Coeur d’Alene, which is only about 33 miles to the east of Washington’s second largest city. The Cascades block air masses that originate in the Pacific Ocean. Storms that move in directly from the west have to rise over the Cascades, resulting in heavier amounts of precipitation as the air condenses. But, as the storms “descend” from those mountains on the other side, the air is compressed and ultimately warms up and dries out. This phenomenon is commonly known as the “rainshadow effect.” However, as one moves closer to Idaho mountains, the air is once again forced upward. As a result, rain and snow becomes more abundant in these regions.

In 2006, the Spokane International Airport recorded 21.02 inches of moisture, compared to the normal of 16.67 inches. A station at Otis Orchards in the Spokane Valley picked up 25.89 inches of rain and melted snow. The normal for that particular spot is 22.92 inches. In Coeur d’Alene, total precipitation for 2006 was 33.97, compared to a normal of 26.11. This was the fourth wettest season in that area, despite having the driest late spring and summer in history.

As we move through the first month of 2007, January will probably be the coldest month of the winter season. A frigid Arctic air mass has already sent temperatures plummeting. More cold weather is expected later this month as well. We should continue to have drier weather for at least three to five more days, but conditions should start turning snowier late next week, or during the early portion of the following week, as the storm door swings open once again to the northwest.

Also, El Niño, the warm-water phenomenon in the south-central Pacific Ocean, is now weakening at a rapid rate. (More on this next week.) Despite this change, I still see February turning drier again as it’s been for the last several years. Only scattered, quickly melting snows will fall across the area lowlands in March and early April. Then, another in a long series of very wet and cool spring seasons will be likely, but not quite as damp as last year.