The month of November 1998 was warmer and wetter than normal. A rather strong northern branch of the Westerlies held Arctic air masses above the Canadian border throughout the month. The upper air flow pattern was split for most of the month. During the first half, active weather was beneath the southern branch; it shifted to the northern branch during the last half.
November 1998 was 4.7 degrees warmer and 2.89 inches wetter than November 1997. Year-to-date rainfall through November 30 was 1.12 inch less this year than last. Rainfall during the twelve months ending November 30, 1998 was 51.49 inches; this is about 113 percent of normal. November marked the fourth consecutive month of above normal rainfall. This has more than made up for the rainfall deficit between early-Spring and mid-Summer. The thirty-day outlook had called for near normal temperatures and above normal rainfall.
The first half of the month saw four very wet storms cross the region. The result was temperatures four degrees below normal, and rainfall 300 percent of normal. The wettest of the four was the last--crossing between the 12th and 14th. Between two and five inches of rain fell on the 12th-13th, with rain steady in Tyler from 6 a.m. on the 12th through 11 a.m. on the 13th. No major cold air masses penetrated the region during these two weeks, though scattered light frost occurred on the 6th. Tyler established a new rainfall record on the 13th when 3.23 inches of rain fell. The previous record was 1.32 in 1957 and 1972.
The second half of the month was in sharp contrast to the first. Temperatures were about six degrees above normal, and rainfall was about one-half normal. The reason for the change was that the northern branch of the Westerlies had become the focus for active weather during the latter half of the month, whereas that had been in the southern branch during the first half. In fact, most of the last half of the month's rain fell on the 30th when the southern branch again became active. With a strong northern branch, Arctic air masses were held above the Canadian border. No freeze had occurred in Tyler by the 30th--well after the normal first freeze date of the 15th.
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
November 1998, RECORDS AND SUMMARY: