ATLANTA (AP) _ Willis Swint usually strolls behind his feed store every morning to measure rainfall, but he hasn't done that much lately in this drought-stricke n area.

In fact, until thunderstorms rumbled through the area Thursday, there hadn't been any rain to measure in two weeks.

''We measured a quarter of an inch,'' Swint said Friday. ''It helped a little bit.''

''If we know there are no visible signs of rain, we don't go back there,'' said Swint, 59, an official rain watcher for the National Weather Service for 38 years in Jonesboro, just south of Atlanta. Before he started, his father had measured rainfall since 1940.

Swint said Jonesboro's monthly rainfall totals since 1941 are recorded on ''one big cardboard sheet'' that hangs in his feed store. He also keeps a daily record, which he mails to the weather service in Atlanta each month.

The Jonesboro area is close to being short one year's worth of rain, he said.

Swint said the area was 6.4 inches short on rainfall for the year through May, and was short a total of 34.21 inches for the previous four years. That means Jonesboro, which usually gets 50.30 inches of rain in a year, is missing 40.61 inches for the 4 1/2 -year period through May, he said.

''We just had an inch and 94 hundredths (of rain) in May, so it's pretty dry.''

Much of northern Georgia is dry. Officials from Atlanta and six metropolitan counties agreed Thursday to adopt a uniform set of outdoor watering regulations to conserve water. State Natural Resources Commissioner Leonard Ledbetter said the agency probably will have to ban all outdoor watering and begin water rationing unless there is substantial rainfall in the area in the next two or three weeks.

A committee of representatives from Georgia, Florida and Alabama decided Thursday to recommend that barge traffic on the lower Chattahoochee River and the Apalachicola River in Florida be restricted because of low water. The Corps of Engineers warned that barge traffic may have to be suspended altogether next month.

Swint said the area could catch up on some of its rainfall deficits this month if it gets an average June rainfall of 3.71 inches.

''If we just got the average, we'd still catch up,'' he said. ''These four years in a row is what's really hurt. That's hurt the moisture way down in the ground, you see.''

Swint said there have been drier years than this one - namely 1954, 1981 and 1986 - so water demand plays more of a role in this season's drought than rainfall.

''In 1986 through May, we were ... about twice as short then as it is now,'' he said. ''There's more demand for water now.''

But the early conservation efforts being implemented by local governments are helping, Swint said.

''Authorities are trying not to wait until they get to the last dipperful to start conserving,'' he said. ''That's my thinking on it, anyway.''