LAST JANUARY, while San Antonio was digging out from under an almost unprecedented blizzard, about 1,000 minority students and their parents braved the weather to attend a college planning forum sponsored by the Ivy League schools, Stanford and other top colleges in the country.

The students, most of them still in junior high school, could have waited for sunnier skies to think about college. But the colleges, which are trying to increase the number of minority students on their campuses, say that waiting any longer may hinder their chances of going to college.

"No one is paying attention to the fact that the time to tell kids about college is not in their junior year (of high school), but as theyre leaving junior high," said Katherine Hanson, director of the Consortium on Financing Higher Education, which sponsored the forum. Once students are put on an academic or vocational track at the beginning of high school, Hanson said, it's difficult to stop the momentum which pushes one group toward college and the others into the working world -- or on to the unemployment lines.

Carmen Escamilla, head counselor at Memorial Junior High School in San Diego, which has a minority enrollment of almost 70 percent, notices first-hand the benefits of early counseling.

Two students she particularly encouraged were from families which had never sent anyone to college and who felt they couldn't afford to go. Now, one has a full scholarship at the University of California at Irvine and the other is at San Diego State.

San Diego, Atlanta and San Antonio, all cities with sizable minority populations, were host to the college forums in the past year. The financing consortium, which is based in Cambridge, Mass., represents 30 private, selective and expensive institutions which are concerned over the fact that the pool of qualified minority students is shrinking and that the colleges are competing against one another for these students.

Harvard now enrolls the most minority students it ever has: about 20 percent of its 6,500 undergraduates. But Evans said half of those students are Asian Americans, and that the number of applications from black students has remained about the same for the past 15 years. "However we cut it," said David Evans, senior admissions officer for Harvard and Radcliffe colleges, "they don't exist in the numbers we need."

On their own, Evans and other black admissions and financial aid counselors at Ivy League and Seven Sisters schools are distributing pamphlets around the country to tell junior high minority students what they ought to take in high school if they are considering college.

The advice is "to what a middle-class person may seem common-sensical," said Evans, but for low-income students whose parents have not gone to college, it may be their first exposure to preparing for college. While this traditionally has been the job of the guidance counselor, Evans said, they are "grossly overworked and underpaid."

While the focus now is on reaching students in junior high, it can never be too early to prepare for college. Jerome Tarver, now a sophomore at Brown University, says the turning point came for him in the fourth grade when he was put in a class for talented students.

Although Tarver was a troublemaker who had been suspended from school several times, "One of my teachers thought I could do the work and really needed to be separated from my friends." He said most of those friends from his hometown of Albany are "out of school, in jail, or are fathers right now."

Once placed in the talented class, Tarver got support from teachers, counselors, church members and family. High school counselors told him about financial aid and how to apply for fee waivers. And when Tarver didn't have the money to take the American history advanced placement exam, his high school principal "took the money out of his own pocket," according to Tarver.

The second youngest of eight children, raised by their mother, Tarver is the first in his family to go to a four-year college. He remembers thinking about the possibility of applying to Brown. Its cost, then $11,000, was "half of what my mother made," although he was reassured that the school would provide financial aid.

In addition to the group efforts, individual colleges are taking steps to enroll more minority students. Smith College in Massachusetts has a two-year grant from the Cigna Corp. in Hartford, Conn., for minority recruitment, said Kim Wilson, assistant admissions director for minority concerns. Fewer Blacks Apply

AT SMITH minorities make up about 12 percent of the total enrollment, down from a high of 15 percent in the mid-1970s, Wilson said.

The University of Pennsylvania, meanwhile, is planning to go into Philadelphia's junior high schools this spring to talk to minority students about career development, and how it relates to academic planning and performance, said Willis Stetson Jr., dean of admissions.

The number of minority students at Penn has grown from 292 in 1980 to 400 this year, Stetson said. But the number of minority applications is down, he said, and part of Penn's strategy is to entice more minority students who are accepted into actually enrolling.

Although the colleges want to keep up their enrollments of all minority students -- blacks, Asians, Hispanics, American Indians -- the drop in black applicants has them particularly concerned. The number of blacks enrolled in college mushroomed in the early 1970s, following the passage of civil rights laws and the development of federal financial aid programs for low-income students.

But from 1975 to 1980, when the number of black youths graduating from high school jumped almost 20 percent, the number enrolled in college remained about the same, according to the National Center for Education Statistics (NCES).

The overall figures also fail to show that a disproportionate number of minority students end up in two-year colleges, says a report by the American Council on Education. For instance, Hispanics made up 6.2 percent of two-year college enrollments in 1982, but only 3 percent of those enrolled in four-year colleges.

One reason minority students are finding it more difficult to go to college is the decrease in federal student aid available under the Reagan administration, said Reginald Wilson, director of the ACE's office of minority concerns. In addition, he said, the recent push for educational excellence and tougher admissions standards has had the effect of screening out minorities.

But Wilson also charges that colleges today have less commitment to affirmative action. "It's easy to say, 'We'd love to enroll more, but none meet our standards,'" he said. Colleges have a responsibility to seek out not just the top minority students, he said, but also those with lesser credentials and to provide counseling, tutoring and remedial education programs.

Many colleges say they have a "built-in sensitivity" to minority applications, in the words of Gordon Chavis, regional admissions director at Georgetown University. For instance, he said, Georgetown's minority students average about 100 points lower on the SAT than the undergraduates as a whole.

The attitude is a little different at Harvard, where Evans said, "We don't have a side door for admittance" nor separate academic considerations once minority students are on campus. "Students must demonstrate to us as best they can that they can survive here, indeed, make it," Evans said. Getting on the Track

ALTHOUGH THE trend has many educators worried, it means good news for minority students who are academically talented. "The youngsters here are very much in demand," said Marion Flagg, guidance counselor at Benjamin Banneker High School in Northwest Washington, a virtually all- black school that offers only a strict college preparatory curriculum.

Banneker students must take four years of English and social studies, three years each of math, science and a romance language, one year of Latin, introductory computer studies and typing, and put in 270 hours of community service. The school sent 98 percent of its first graduates, the class of 1984, on to college.

Lack of academic preparation is not the only thing keeping many minority students from college. The college forums also stressed the need for families to plan ahead to help pay for college, but told them that "if the kids are academically prepared, it wouldn't matter if the family could pay," because financial aid is available, Hanson said.

Indeed, today's $16,000 annual cost to attend Brown University is enough to scare away minority students before they even apply, agreed Leslie Lane-Epps, associate director of admission at the Rhode Island school. "They say, 'Wow, we can never afford to go there,'" she said, even though Brown provides financial aid to all needy students.

Cost is not as much a factor at state-supported schools, such as the University of Virginia, which is pulling in more minority applications this year both from Virginians and out-of-staters. Despite this year's gains, minority students still account for less than 5 percent of 16,000 applications for admission, said John Blackburn, acting dean for admissions.

Thus, Virginia recruiters for the past three years have been visiting middle schools that enroll large numbers of minority students, including those in Richmond, Roanoke and Arlington. Blackburn is "cautiously optimistic" that talking to students in grades six through eight will help increase the minority pool. But he noted that "more and more colleges are getting into the act of recruiting," while the number of minority students in Virginia is not expected to increase.

Some schools get a boost in minority recruitment by factors having little to do with academics or cost. For instance, it doesn't hurt to have a championship basketball team with a heavy minority membership, acknowledged Georgetown's Chavis.

The Hoyas captured the 1984 NCAA title (and lost it this year in the finals) under the guidance of coach John Thompson, and the university this year is attracting up to 7 percent more minority applicants. While the jump in applications can't be attributed only to winning seasons on the court, Chavis said, "The basketball exposure has done a lot to heighten interest, particularly for black students."