The month of July 1998 was much warmer and much drier than normal. July 1998 is the warmest July and the warmest month of record. The average temperature was 89.7F. This is 6.8 degrees above normal. Rainfall totaled 0.37 in., 2.38 inches drier than normal. The previous record warmest Month is July 1930, when the average temperature was 88.1. August 1951 was close behind at 88.0. July 1998 is but the fifth month of National Weather Service records for the Tyler Metropolitan Area (which date to 1896) wherein the average maximum temperature has exceeded 100 degrees. The others are: July 1930 101.1, August 1951 100.6, August 1954 100.3, and July 1954 100.0.
During the heat wave of 1980, the average July maximum in Tyler was 99.4, and the monthly average temperature was 87.3--2.4 degrees cooler than the month just ending. August 1980 cooled to an average temperature of 86.0. The 77.8 degree average minimum is the warmest ever for any month. In July 1945 the average minimum was 76.4, and in August 1934 76.0. The temperature reached or exceeded 100 degrees on twenty-six days during the month. This establishes new records for the most number of 100-degree or higher days for July (previous record 22 in 1930 and 1954,) and for any month (previous record 24 in August 1954.) The mercury was in triple digits on each of the last 17 days of the month.
July 12, 1998 saw the highest temperature in nearly 20 years when the mercury reached 105. The same thing happened last on July 15, 1978. The mercury again reached 105 on the 31st. Though rainfall was scant, it is not the driest July. Indeed, it ranks third in that category. In July 1993, 0.02 inch fell, while 0.15 inch fell in 1954.
July 1998 was 5.5 degrees warmer than July 1997, and 0.71 inch drier. Showing the effects of the drought which began in mid- March are two precipitation figures. Year-to-date precipitation through July 31, 1998 is 20.57 inches. This is 11.31 inches less than that through July 31, 1997. Rainfall over the past twelve months is 41.30 inches. This is about 93 percent of normal. The thirty-day outlook had called for above normal temperatures and near normal precipitation. The first week in July saw temperatures eight degrees above normal and no rainfall. Upper atmospheric high pressure was in control of the region's weather through the week. A tropical disturbance crossed to the west of the region through Central Texas on the 3rd-5th. It brought widely scattered late-day showers to the area on the 3rd and 4th, but rain did not fall in Tyler.
Temperatures during the second week in July were eight degrees above normal, and rainfall was about one-half normal. Throughout the week, the upper air high pressure ridge dominated. This caused several temperature records. On the 12th, Tyler reached its warmest temperature since July 15, 1978 when the mercury hit 105. A weak low pressure trough crossed from north to south on the night of the 12th, causing widespread thunderstorm activity. There were widely scattered late-day showers and thunderstorms on the afternoons of the 13th and 14th as well, but rain did not occur in Tyler. The temperature was at or above 100 degrees on five of the seven days, and reached 98 on the other two. The rain on the night of the 12th-13th broke a string of thirty-five consecutive days without rainfall in Tyler. Though by no means a record, it was an unusually lengthy rainless period. The rainless string re-commenced the next day, with no more rainfall through month's end.
Temperatures during the third week in July averaged seven degrees above normal and there was no rainfall. Maxima reached or exceeded 100 degrees each day during the week. Nighttime lows were a bit cooler, due probably to slightly more soil moisture from widely scattered to scattered late-day thunderstorms which occurred on most days. The upper air high pressure ridge continued its dominance of the area's weather.
The final ten days of the month saw temperatures six degrees above normal and no rainfall. Again, the persistent upper air high pressure ridge controlled the region's weather.
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
July 1998, RECORDS AND SUMMARY: