by Robert K. Peters, Ph.D. - National Weather Service Cooperating Observer
The month of April 1998 saw near normal temperatures and below normal precipitation. In the upper air flow, a split pattern was over North America for much of the month. This kept the storm track either well to the south or well to the north of the region. Temperatures warmed seasonally during the month.
April 1998 was 2.5 degrees warmer and 6.28 inches drier than April 1997. Year-to-date rainfall through April 30 is 4.14 inches less this year than last. Rainfall over the past twelve months is 48.47 inches--107 percent of normal. The thirty-day outlook had called for near normal temperatures and near normal precipitation.
The first week in April saw temperatures near normal and rainfall about three percent of normal. Polar Maritime air was over the area much of the week following passage of a storm system and cold front on the 2nd. Tropical Maritime air returned on the 6th, causing strong warming on the 7th. The rainfall reported during the week actually fell behind a departing storm feature on March 31st.
The second week in April saw temperatures three degrees warmer than normal and rainfall about one-half normal. Upper air high pressure controlled the weather for most of the week. A disturbance crossing in the southern branch of the jet stream early in the week brought the rainfall. The third week in April was cool and dry, with temperatures three degrees below normal and rainfall about one- fourth normal. Surface and upper atmospheric high pressure were in control. One storm crossed well to the south early in the week, but brought little rainfall.
The final nine days of the month saw temperatures three degrees below normal and rainfall about 25 percent of normal. A weak storm feature crossed on the 27th-28th, bringing the week's only rainfall. Cool air both preceeded and followed this storm feature.
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 1998, RECORDS AND SUMMARY: