The National Weather Service paid David Powell's airplane ticket to Washington three weeks ago so the president of the weather service's employee organization could spend two days hashing out the details of a furlough plan with headquarters.

Since Powell has returned to his job as a weather forecaster in Chattanooga, Tenn., he has received "a heck of a lot of telephone calls" from other forecasters confused over procedures involved in the event the federal government institutes furloughs to save money. He said he has spent "an excess amount of time" straightening out managers who have sent furlough notices with incorrect information.

Powell is one small cog in the 2.4 million civilian employee bureaucracy trying to plan for furloughs that will be ordered if Congress and the administration do not agree on a way to reduce the federal budget deficit by Oct. 1, as required by the Gramm-Rudman-Hollings law.

While agencies are unable to put a dollar figure on their efforts, many officials said planning for furloughs has become one of their most time-consuming activities.

As Claire Austin, spokeswoman for the Federal Railroad Administration, said of Congress and the administration: "Little do they know how much this is costing them."

Most offices have sent out intent-to-furlough notices to tens of thousands of employees. They have written and sent out explanatory letters, answered technical questions from regional offices and have negotiated with unions over which days people will be on leave and who is subject to furlough.

The length of the furlough will vary from department to department, depending on how much of an agency's budget is subject to cuts under the deficit reduction law.

At the Department of Health and Human Services, three top personnel managers are spending half of their days planning the furlough. Personnel managers and their staffs in the department's 26 regional offices have been negotiating terms of the furlough with about 65 separate regional labor units.

"A lot of these people are going to the {bargaining} table every day or every other day," said HHS Deputy Assistant Secretary Eugene Kinlow. "There's just no end to it. There's literally thousands of hours being utilized in this department working on furloughs."

The Department of Transportation estimates its personnel staff spends about 15 percent of its time on the furlough issue, a department spokesman said. At the Department of Agriculture, two to six people have been staffing a special furlough hotline established in late August. It has received 1,850 calls.

Looking down the barrel of the deficit-driven furloughs, a number of federal agencies and departments last week tried an end run to keep their employees financially healthier.

They wanted to allow employees to work overtime the last week of fiscal 1990 to enable them to earn enough extra money to offset any they might lose were they furloughed in the first week of fiscal 1991, which begins Oct. 1.

Only agencies and departments with money in this year's budget to cover the overtime were considering it.

But the Office of Management and Budget nixed the idea, and in so doing wiped out the first moment of optimism employees had found since the threat of furloughs surfaced weeks ago.

"The response was very positive," said Charles L. Grizzle, the Environmental Protection Agency's top personnel manager. "Even though it would have been a long week, it would be a way for them not to lose pay."

Office of Personnel Management Director Constance B. Newman, whose office came up with the overtime idea, sent a survey to its employees last week to find out if they favored the scheme: About 75 percent said they did.

In an effort to accommodate employees, Newman said in the memo, agency offices would be open for business Saturday, Sept. 29, so that workers who could not rearrange car pools and baby-sitting to work overtime during the week could come in on that Saturday.

The Federal Railroad Administration, the Environmental Protection Agency and the Merit Systems Protection Board each worked up flexible schedules that included overtime at the end of September.

Under federal work rules, employees can work a flexible work schedule as long as they work 80 hours within a two-week period.

"It is at least gratifying that our employees knew we were scurrying around for them," said Grizzle.