November 2010 was mostly quiet across North Texas in general and in Denton County in particular. Overall, November was significantly warmer and drier than normal.
By the numbers: Denton’s average high was 68, the average low was 43, which works out to an average monthly temperature of 56 degrees, about 2 degrees above normal. Precipitation was 1.32”, which is 1.5” below normal. Although rain occurred on six days, the only two significant rains we had were November 2nd (.74”) and the 12th (.48). The other four days, we received a trace to .05”.
So far this year, we’ve accumulated about 32” of rainfall which is close to normal for this point of the year, however those figures are misleading. Included in our yearly precipitation total is September’s nearly 9 inches of rain including a record 5.2” received September 8th. Since September, we received about half our normal rainfall quotas in October and November.
What was normal about November was our first freeze, which ended the growing season right on schedule. The average first killing freeze or frost in North Texas is generally established as November 22nd. Any freeze within one week of that date is considered normal. Our first freeze was Thanksgiving morning, the 25th, when we reached 30 degrees. The next day, Black Friday, we dipped to 27 and the following Saturday, we touched 26 degrees.
Our drier and warmer-than-normal conditions are consistent with the development of cooler-than-normal waters in the Pacific, known as La Nina. The oscillating pattern of ocean temperatures and currents affects the wave pattern of jet streams around the Northern Hemisphere. Because of La Nina, we expect more relatively dry and warm conditions through at least the first quarter of 2011.
That’s not to say we won’t have any winter weather this year, it’s just less likely. Our most likely outcome will be a persistent increase in fire danger. Dormant vegetation left dry by our fall mini-drought and recent freeze, plus dry air, warmer-than-normal temperatures and occasional gusty winds, will leave much of the North Texas landscape vulnerable to fires. If anything, prepare for a growing shortage of surface and ground water and the increasing need to use it.