January’s weather defied the accepted La Nina pattern that controlled our weather trends during most of 2010. Virtually every month since last April had been predictably warmer and drier than normal due to the presence of colder water temperatures in the central Pacific which changed the wave pattern of the jet stream in the Northern Hemisphere.
But Denton’s average temperatures dipped below normal during January.
Daily highs averaged 53 degrees, slightly below the normal high of 54. Overnight lows were significantly lower, averaging 27 degrees, a full 4 degrees below the normal average 31 degrees. Precipitation was 1.4” for the month, slightly drier than normal (1.6”).
So what happened? Two other long-term weather factors trumped La Nina. The North Atlantic Oscillation placed a blocking high near Greenland in early December, which led to a deepening jet stream trough over the eastern United States. And the Arctic Oscillation kept throwing Arctic air masses down into that trough over the eastern U.S., resulting in repeated outbreaks of wintry weather even before the winter solstice arrived.
The most powerful of those winter storms was bearing down on North Texas Monday night, January 31st, leading to some of the coldest temperatures here since the winter of 1996.
Denton recorded its highest precipitation for the month on January 9th (1.3”). Every other day we had rain or a threat of freezing drizzle, January 14, 15, 16, 18, 20, 25 and 31, we had small amounts between a trace and .05”.
Despite the recent outbreak of harsh winter weather in North Texas in early February, the long-range computer models continue to persist in forecasting average temperatures that are above normal throughout the Southwest and Texas. We’ll see. Rainfall chances of above or below normal look about even at this point.