by Robert K. Peters, Ph.D. - National Weather Service Cooperating Observer
The month of August 1998 was warmer and wetter than normal. Through month's end, forty-four days this season had reached or exceeded 100 degrees. This ties the Summer of 1998 with that of 1930 for the warm season with the greatest number of days at or above 100. Daytime heating and some weak air mass boundaries allowed for scattered shower and thunderstorm activity during much of the month. This provided localized relief for the dry conditions, which have persisted since March. Essentially, the summer-time upper air high pressure ridge was the most important factor in the August 1998 weather over East Texas.
In comparison with August 1997, last month was 3.6 degrees warmer, and 0.49 inch wetter. Through August 31, 1998, rainfall is 25.28 inches. This is 10.72 inches less than through August 31, 1997. Rainfall over the past twelve months is 42.79 inches--about 94 percent of normal. The thirty-day outlook for the month of August had called for above normal temperatures and below normal precipitation.
The first week in August saw the breaking of the heat-wave, which had gripped the region since early-July. Temperatures during the week averaged near normal, and rainfall was 200 percent of normal. A cold front moved into the region on the 4th, with showers and thunderstorms occurring daily between the 2nd and 7th. The front ended the string of 20 consecutive days at or above 100 degrees in Tyler, which established a new record for consecutive 100-degree days. Severe weather occurred in parts of the area on the 3rd and 4th. Unofficial reports indicate that as much as two and one-half inches of rain fell in forty-five minutes in southeast Tyler on the afternoon of the 4th.
The second week in August saw temperatures one degree above normal and rainfall about 75 percent of normal. The upper air high built back over the area early in the week, and then retreated back to the west on the 10th. Another cold front dropped to Red River, and was reinforced on the 13th. The combination of this front, upper air disturbances in the northwest flow aloft, low-level moisture from the Gulf of Mexico and high-level moisture from the remnants of Pacific Hurricane Frank, brought shower and thunderstorm activity daily from the 10th through the 14th.
The third week in August saw temperatures three degrees above normal and rainfall about 200 percent of normal. All except 0.01 inch of the rain fell on the afternoon of the 15th as a result of an upper air disturbance and a strong sea- breeze front. Otherwise, upper atmospheric high pressure was in control. Haze was present much of the week, as the area was under an ozone advisory from the 16th.
The final week in August saw temperatures about five degrees above normal, and near normal rainfall. The upper air high pressure ridge had weakened slightly. This allowed for late-day showers many days around the region. The continued presence of the ridge did allow for more very warm to hot temperatures.
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
AUGUST 1998, RECORDS AND SUMMARY: