December 24th brought an end to a nearly month long dry spell across the Topeka area with 0.07 inches of precipitation measured in the rain gauge. The last measureable precipitation of 0.01 inches occurred on November 23, 2010. This places the Topeka area in 21st place for 29 consecutive days without measurable precipitation since records began in 1887, which is considered to be a minimum of 0.01 inches. The last significant rainfall that occurred was recorded on November 12th with 1.07 inches measured. Since November 12th, the Topeka area has only received 0.18 inches of precipitation.
Annual precipitation so far for 2010 is 36.38 inches, which is 0.88 inches above the normal amount of 35.50 inches. However, the period of October 2010 through December 2010 has been quite dry with only 2.64 inches of precipitation recorded; the majority of that recorded on or before November 12th. This currently places the Topeka area in 16th place for the driest October through December period. December has been particularly dry with only 0.07 inches of precipitation recorded, which fell on the 24th. This currently ties the Topeka area in 6th place for the driest December on record which also occurred in 2001 and 1908. The driest December on record is shared with 1996 and 1889 with only 0.03 inches of precipitation recorded. However, our current status could change with chances for precipitation returning to the forecast this week.
Snowfall has also been quite scarce for the Topeka area during the fall season. On average, the area will receive 5.9 inches of snow for the three month period of October through December. So far, the Topeka area has only received a trace of snowfall which is not considered measureable. At least 0.1 inches of snow must fall in order for it to be considered measureable. In comparison to the 2008 and 2009 fall season, the area received 5.6 inches of snow in 2008 and 19.2 inches of snow in 2009. The last time the Topeka area did not receive measureable snow in December was in 2001.
What has caused the extended dry period across the area?
Essentially, the country has been dominated by two large pressure systems with a broad ridge of high pressure across the western half of the nation and a trough of low pressure across the eastern half. This has caused the main storm track to remain north of the area for much of the latter half of the fall season. This is a fairly typical La Nina pattern, which has been forecasted by the Climate Prediction Center to become moderate to strong through the Spring of 2011. La Nina patterns typically lead to dry but warm conditions across the western high plains of Kansas and Colorado; especially during the winter months. There is a bit more variability in the weather patterns over eastern Kansas over the course of various La Nina years, but we appear to be much drier this fall season due to the global scale influence of the La Nina signal. However, the Climate Prediction Center is forecasting equal chances for precipitation over the Topeka area for the January through March 2011 period. This means, there is no significant for probability precipitation over the area to be either above or below normal.
Unfortunately, the recent lack of precipitation has resulted in abnormally dry conditions across much of Topeka and the surrounding area. Soil moisture conditions are even drier from south central Kansas and extending northeast into Coffey County, where drought conditions have reached the moderate category. Fortunately, the forecasted trend for the area suggests that conditions are not expected to worsen or persist through March 2011, but drought conditions are expected to persist across much of western Kansas and eastern Colorado, which is typical for the La Nina signal and resultant weather pattern.