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December 2008 - Report and Summary

by Robert K. Peters, Ph.D. - National Weather Service Cooperating Observer

After two dry years in 2005 and 2006, 2007 and 2008 have been wet. Rainfall in 2007 was 57.81 inches, and 2008 nearly equaled that total at 57.65 inches. The latter months of 2007 and first months of 2008 were dry, but significant rainfall began in June, and continued into the Autumn. On the early-morning of August 12, 6.47 inches of rain fell in the city, which set a record for the wettest day in August, and helped make August 2008 the second wettest August in the 113 years of weather records for Tyler.

The latter months of 2008 were drier than normal.

The biggest bad weather event was the remnant of Hurricane Ike, which moved rapidly northward through the area on September 13. A peak wind gust of 47 mph was clocked, and there were widespread power failures. Ike brought 2.70 inches of rain to the city. The remnant of Hurricane Gustav crossed about 100 miles east of Tyler on the morning of the 2nd. Only 0.99 inch fell with that system. Normal rainfall for Tyler is 45.27 inches. The year's highest temperature of 103 came on August 2, with the coldest, 22, on December 22.

The growing season was also about 10 days shorter than normal at 235 days. It began March 8, and ended October 27.

The warm season was also shorter than normal this is the period between the first and last occurrence of 90-degree temperatures. The normal period is 146 days; in 2008 it was 125 days between May 9 and September 11.

The temperature reached or exceeded 100 degrees on seven days about normal, and reached or exceeded 90 on 88 days. This is below normal. The temperature reached or fell below freezing on 43 days during the year more than normal. The cool season of 2007-2008 was about normal, with 101.0 percent of normal heating degree-days.

The 2008 warm season saw only 95 percent of normal cooling degree days. The year 2008 saw an average temperature of 65.3 deg., which was 0.9 deg. Cooler than 2007, and the coolest year since 1993 when the average was 65.1 deg. 2008 was 1.2 deg. Cooler than the 1971-2000 climatic average. The month of December 2008 saw slightly below normal temperatures, and rainfall about one-fourth normal. Arctic air masses were present for much of the first two-thirds of the month, with moderating temperatures towards month's end. Compared with December 2007, the month was 3.1 deg. Cooler, and 2.10 inches drier. The thirty-day outlook for December 2008 had called for above normal temperatures and near normal precipitation.

The week November 30-December 6 saw temperatures about 7 degrees below normal, and only a trace of rain. Polar Continental air dominated the area for much of the week, except for a brief warm-up at mid-week when a storm system and accompanying cold front crossed. This brought scattered showers, with the trace amount falling in the city, though 0.62 inch fell at Pounds Field. There were a couple of severe thunderstorms on the afternoon of the 2nd over Cass, Morris, and Bowie Counties. Conditions were windy daily from the 30th through the 4th, with winds finally diminishing on the evening of the 4th. The week's average temperature was 44.7 deg., which was which was 9.8 deg. Cooler than the previous week. The week was 12.1 deg. Cooler and 0.08 inch drier than the same week in 2007.

The week December 7-13 saw temperatures about 4 degrees below normal, and rainfall about one-half normal. The week began warm, until an Arctic air mass arrived on the 9th, holding temperatures below normal until week's end. At that warming resumed, ahead of another Arctic air mass early in the following week. Snow fell over the southern counties near Lufkin on the night of the 10th. Light sleet fell in Tyler on that day, but there was no ice accumulation. The week's average temperature was 45.8 deg., and rainfall was 0.58 inch. This was 1.1 deg. Warmer than the previous week. Compared with the same week in 2007, the week was 7.0 deg. Cooler, and 1.18 inches drier.

The week December 14-20 saw temperatures about 3 degrees above normal, and rainfall under 10 percent of normal. As was the case with the previous week, it began warm, but Arctic air arrived on the morning of the 15th. Light freezing rain and freezing drizzle occurred on the afternoon of the 15th and morning of the 16th, but there was no accumulation. Strong warming began the afternoon of the 17th, taking temperatures to near 20 degrees above normal by week's end. Light rain occurred as the warmer air overrode the cool layer. Another Arctic cold front arrived the evening of the 20th. The week's average temperature was 52.4 deg., and precipitation was 0.08 inch. This was 6.6 deg. Warmer than the previous week. Compared with the same week in 2007, the week was 1.9 deg. Warmer, and precipitation was identical.

The week December 21-27 saw near normal temperatures and precipitation about 60 percent of normal. The week saw a roller-coaster ride of temperatures. With very cold readings at the start of the week, a strong warming through the 24th, then slight cooling, then another strong warm-up before another front crossed on the afternoon of the 27th. Spotty light freezing drizzle and freezing rain occurred on the morning of the 23rd as the Arctic front of the 20th retreated northward. Wind damage occurred on the afternoon of the 27th with gusty winds accompanying that day's cold front. The average temperature was 48.2., which was 4.2 deg. Colder than the previous week. Precipitation was 0.72 inch. Compared with the same week in 2007, the week was 6.1 deg. Warmer, and 0.84 inch drier.

The month and year ended with near to slightly below normal temperatures. A very dry air mass permitted a wide diurnal variation, with a cold front early on the morning of the 31st reinforcing the cool air mass already in place.

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.




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