by Robert K. Peters, Ph.D. - National Weather Service Cooperating Observer
The month of January 2001 was colder and wetter than normal. For most of the month, the southern branch of the jet transported disturbances across the area. These combined with ample moisture to produce precipitation. Temperatures did moderate slowly through the month from the very cold levels of mid- and late-December to near normal by month's end. Compared with January 2000, last month was 6.8 degrees colder, and 3.64 inches wetter. Precipitation during the past twelve months is Precipitation during the past twelve months is 134.4 percent of normal. The thirty-day outlook for January 2001 had called for near normal temperatures and above normal precipitation.
The week December 31-January 6 saw temperatures nine degrees colder than normal, and precipitation about one-third normal. The week began cold, with 2.5 inches of snow falling on the afternoon of the 31st. Snow remained on the ground through the 3rd, melting with warm temperatures on the afternoon of the 4th. The week ended warm. A Chinook moved into the area on the morning of the 4th behind a weak low pressure trough. This was responsible for the rise in temperatures. A weak cold front on the 5th brought only a brief wind shift, and mild daytime readings continued through the 6th. Snows on the 31st ranged from about one inch in the Lufkin area to as much as six inches over the extreme northeast. Since the precipitation was snow, it did not worsen existing electric power problems.
The week January 7-13 saw temperatures four degrees below normal, and precipitation 75 percent of normal. The week began with Tropical Maritime air over the area, which was quickly replaced by Polar Maritime and then modified Polar Continental air. This resulted in the below normal temperatures. An upper air storm crossed at mid-week, bringing the precipitation. Another, and weaker, storm crossed at late-week. It brought rain on the 13th, which was reported with the following week's total. Some light sleet accompanied the rainfall of the 10th because of wet-bulbing, as the precipitation fell through very dry air. There was, however, no ice accumulation. Tyler reported an overcast for 108 consecutive hours, between 6 p.m. on the 9th through 6 a.m. on the 14th. During this period, temperatures varied only 13 degrees.
The week January 14-20 saw temperatures seven degrees below normal, and rainfall about 450 percent of normal. A slow-moving upper air storm between the 16th and 18th brought widespread rains, which averaged between three and five inches. A cold air mass trapped near the surface beneath an overrunning layer of warmer and more moist air again held temperatures within a narrow range of five degrees on these days. A strong cold front moved into the area on the 19th, ending the rainfall and bringing a brief shot of Polar Continental air.
The week January 21-27, 2001 saw temperatures two degrees below normal, and rainfall about one-tenth of normal. Three weak storms crossed during the week--on the 21st, 23rd, and 26th. That of the 21st brought the rainfall, which was mixed with sleet and snow. With temperatures a few degrees above freezing, there was no accumulation. The morning of the 22nd brought freezing fog. Ground water left by the rains of the previous week caused the fog to develop in a stable atmosphere. The fog lingered into late-morning. The other two storms produced only very light amounts of rain, which were not general. The air masses behind these two were Polar Maritime, and did not bring significant cooling. Tropical Maritime air was over the area on the afternoon of the 26th, which allowed for warming into the lower 70s until the cold front arrived that evening.
The reporting period for temperatures and phenomenon on each day is for the twenty-four hours ending at midnight hours GMT--6 p.m. CST and 7 p.m. CDT. The reporting period for precipitation is for the twenty-four hours ending at noon GMT--6 a.m. CST and 7 a.m. CDT. All times are given using the twenty-four hour clock, and are expressed in Greenwich Mean Time.
Observations are from NWS Station 41/9207/4 in Tyler, Texas. The term "normal" refers to averages from the standard climatic period 1971-2000.
MX MN OBS PCPN REMARKS
January 2001, RECORDS AND SUMMARY: