The National Weather Service says a kink developing in the jet stream may bring a good chance of thunderstorms on Wednesday and Thursday in Southeast Missouri and Southern Illinois. Some of the storms may become severe, forecasters said.

"The upper air dynamics of the atmosphere will be pretty good for the development of thunderstorms, and some of them may get up to the severe level," said Guy Tucker, forecaster with the weather service office at St. Charles. "The system that's developing out west right now bears close watching when it gets into this area around mid-week."

Meanwhile, temperatures in the Cape Girardeau area, which have been averaging over 2 degrees below seasonal norms for the first half of June, are expected to warm to near mid-June and mid-July levels, says the 30-day outlook.

Al Robertson, professor of earth science and climatologist at Southeast Missouri State University, said the actual average temperature for Cape Girardeau for June 1-14 was 72.2 degrees, down 2.3 degrees from the long-term average of 74.5 degrees.

Rain for the same period at the airport totaled 2.09 inches, a little over half of the long-term monthly average of 3.88 inches, Robertson said.

The most noticeable weather feature during the first half of the month was the absence of 90-degree temperatures. During the period the high was 85 degrees, on June 12 and 15. In contrast, the daily high during June 1991 was at or above 90 degrees on the first four days of the month. The high for the month last year was 96 degrees on June 30. There were 10 days in June last year when the high was at or above 90 degrees.

Robertson said the El Nino effect continues to play a major role in the weather pattern across the Midwest.

Since last year, El Nino has caused the Polar Jet Stream to remain far to the north, in a generally west to east flow near the Canadian border, while the sub-tropical jet stream remains along the Gulf Coast states. It is only when rare kinks develop in the polar jet, allowing it to dip down into Missouri, that the weather becomes wet and more active in this area, Robertson said.

In addition to keeping a lid on severe weather this spring, El Nino has also caused dangerously dry conditions to develop in Missouri, northwest of a line from St. Louis to Nevada. Four counties in north Missouri have had less than an inch of rain in the five weeks preceding June 7. Most counties in the dry area have received less than 2 inches of rain since May 1.

Grant Darkow, an atmospheric scientist at the University of Missouri-Columbia, says the ocean surface temperatures in the southern Pacific Ocean, which help power El Nino, continue unchanged. He said El Nino has not been this strong since 1983, but in that year the pattern broke and was followed by a summer with normal rain, except for a brief and normal dry spell in August.

Robertson said last month he also expects El Nino to begin weakening sometime this year.