Thousands of members of the National Baptist Convention, U.S.A., will flock to Washington beginning tomorrow for their 104th annual meeting. And some 3,000 local members have been getting ready for it for two years.

"When the convention accepted our invitation two years ago to come to D.C., we began preparing for it," said the Rev. Frank Tucker, coordinator of the Local Entertainment Committee, which has spent $170,/000 and devoted countless hours of work in its effort to be remembered as the best hosts in the convention's history.

The D.C. Convention Center is laying in provisions by the ton and nearby churches are preparing to serve additional meals, rooms are reserved in 36 hotels as well as in many private homes, 200 ushers have been rehearsing all year and a 1,000-voice choir started organizing last September.

"This convention has grown tremendously in the past 20 years," explained Tucker. "It represents over 30,000 churches and some seven million members."

He said there are 175- to 200-local-member churches in metropolitan Washington.

Convention officials say more than 37,000 people from throughout the country are expected to attend the week-long series of meetings, banquets, concerts and religious services.

"It ranks right up there with the biggest conventions we've ever done, if their numbers hold up . . . and we believe they will," said Alan Grip, assistant manager of the D.C. Convention Center, where at least 18,000 Baptists are anticipated. "It's certainly the largest religious gathering we've ever had here."

The National Baptist Convention will occupy the entire center which includes four exhibition halls and 37 meeting rooms. "We'll have to hire extra part-time help to handle it," said Grip.

Among the jobs are setting up 10,000 folding chairs.

One of the week's highlights is a musical extravaganza, scheduled for Tuesday night, by a 1,000-member choir made up of singers from some 130 local Baptist churches.

Tucker said it is hoped the revenue from the concert's $5 admission will cover much of the host committee's expenses.

The singers, who have rehearsed weekly since December at Shiloh Baptist Church, will be directed by Charles Fleming, music director at Shiloh.

Volunteerism has been essential to the 3,000-strong local planning effort which has no paid staff. "There's no reimbursement because that's part of the hosting process," explained Tucker.

For the 145,000 meals they plan to serve next week, the convention center's caterers, Waters/Sportservice, is stocking up: three tons of lettuce, 60,000 dinner rolls and 4,500 gallons of punch. Other banquets will be served at hotels.

"For one dinner we're serving 6,000 pounds of barbequed spare ribs," said John Fear, the caterers' executive assistant chef. "For a group this large we'll have to hire about 10 extra cooks, bringing the total to around 25 cooks, and 40 dishwashers and stewards."

Howard University Hospital is providing materials and doctors and nurses for three comfort stations -- one at the convention center and two at hotels on Capitol Hill, where volunteer nurses also will help out.

Nearly 40 volunteers with walkie-talkies and beepers will be stationed along the route from National Airport to hotels in the District to make sure the arrival of convention members goes smoothly.

Tucker said a fleet of 70 cars and vans have been donated for use throughout the week as a free taxi service for visiting Baptists.

Planners also chartered 26 Metro buses to shuttle visitors to and from the convention center and hotels.

About 200 people have volunteered to be ushers, and have met weekly since January, for training including a special language of gestures so they can communicate without disrupting convention proceedings. And about 10,000 souvenir booklets were printed this week to be sold for $5 each during the convention.

Entertainment committee members predict the Baptists will spend about $15 million at D.C. restaurants and stores. And local businesses have been helpful to the convention planners. For example, Tucker said, Garfinckel's will entertain convention members with a fashion show and complimentary luncheon.

Tucker has been spending long hours at Shiloh, 9th and P streets NW, which has become like "convention central" for the local organization effort, and where last-minute preparations continued in late night meetings all this week.