By Robert K. Peters, Ph.D. - National Weather Service Cooperating Observer
The month of April 2007 was cooler and wetter than normal.
In fact, it was the coolest and wettest April since 1997. April 2007 was in sharp contrast with April 2006, which was the fifth warmest April, and was also unseasonably dry. April 2007 was 9.9 deg. Cooler and 3.87 inches wetter than April 2006. Year-to-date rainfall through month's end was 3.24 inches greater in 2007 than in 2006. The twelve-month precipitation percentage was 92.0 in 2007, compared with 64.3 in 2006 showing improvement in the drought. It even snowed once during April 2007, with a trace observed. There have been only five April months in which wintry precipitation has occurred in Tyler since government weather records began in 1896. The thirty-day outlook for April 2007 had called for near normal temperatures and near normal precipitation.
The week April 1-7 saw temperatures about 4 degrees cooler than normal, and rainfall about 75 percent of normal. The week saw active weather, with a severe weather event on the 4th followed by sharp cooling and much below normal temperatures at week's end. A line of strong to severe thunderstorms affected the northern half of the area during the early-morning hours of the 4th, with wind and lightning damage. Tyler clocked a peak gust of 67 mph at 1:01 a.m., and temperatures climbed to as high as 92 in a microburst at Mount Vernon and 81 in a microburst at Crockett. A strong cold front accompanied the upper air low which produced the severe weather. This lowered temperatures to about 20 degrees below normal by the end of the week as a 1050-mb. High pressure ridge containing Arctic air built southward from Central Canada. Record low maximum temperatures occurred on the 7th along with light snow. Though there was no accumulation, it marked the third latest date for observed snowfall. The latest was April 9, 1928, followed by April 8, 1938. Had the snow which occurred in Tyler stuck, the city would have received about one-half inch. The week's average temperature was 59.7 deg., which was 10.7 deg. Cooler than the previous week. Precipitation was 0.65 inch. Compared with the same week in 2006, the week was 12.3 deg. Cooler, and 0.65 inch wetter.
The week April 8-14 saw temperatures about 9 deg. Cooler than normal, and near normal rainfall. Temperatures moderated during the week until another strong cold front crossed on the 14th, sending temperatures back to well below normal levels. Two storm systems crossed, one on the 10th and another on the night of the 13th. The latter brought severe weather to much of the region to the west and north of Tyler. The week's average temperature was 57.2 deg., which was 2.5 deg. Cooler than the previous week. Precipitation was 0.81 inch. Compared with the same week in 2006, the week was 12.5 deg. Cooler, and 0.81 inch wetter.
The week April 15-21 saw temperatures about 5 degrees cooler than normal, and rainfall about 10 percent of normal. Temperatures warmed slowly through the week as Tropical Maritime air gradually replaced Polar air. A weak storm crossed on the 17th, bringing the week's only rainfall. The week's average temperature was 62.3, which was 5.1 deg. Warmer than the previous week. Rainfall was 0.10 inch. Compared with the same week in 2006, the week was 14.3 deg. Cooler and 0.63 inch drier.
The week April 22-28 saw near normal temperatures, and rainfall about 400 percent of normal. A major storm crossed on the morning of the 25th, bringing severe weather and flooding rains. Temperatures cooled slightly following this storm and its associated cold front. Readings warmed at late-week as a weak storm and front on the 28th had little effect on temperatures and generated only a few light showers along Red River. The week's average temperature was 69.1 deg., and rainfall was 4.00 inches. A daily rainfall record was established on the 25th. The week was 6.8 deg. Warmer than the previous week. Compared with the same week in 2006, the week was 0.2 deg. Cooler, and 3.04 inches wetter.
The month ended warm under upper air high pressure, with another storm system moving in late on the 30th with scattered thunderstorms.
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
APRIL 2007, RECORDS AND SUMMARY: