Federal Reserve officials will meet tomorrow and Tuesday to set a course for monetary policy for the next two months and most Fed watchers think they will leave the policy levers about where they are now.

Any action to tighten credit conditions to slow the recent spurt in the money supply could mean higher interest rates and possibly threaten the economic recovery. Any attempt to lower interest rates, perhaps through a cut in the Fed's discount rate from 8.5 percent to 8 percent, would run the risk of making the money supply bulge greater.

Short-term interest rates generally have risen about half a percentage point over the last two weeks. Financial market analysts aren't entirely sure but most believe this has been the result of a "snugging up" by the Fed--that is, the Fed being very slightly less generous in providing reserves to the banking system.

The money markets are apprehensive precisely because participants have not been able to define the future course of Fed policy. "The general tone in the market is that a very modest tightening has taken place," said economist Charles Lieberman of Morgan Stanley & Co.

And that seemed to be confirmed by senior Reagan administration officials who said that Federal Reserve Chairman Paul A. Volcker has said that the central bank has indeed been "snugging up . . . taking in a little of the slack but not really pulling on the rope."

But what happens next? The answer will depend on what the Fed policymakers, the members of the Federal Open Market Committee, decide is the meaning of the money supply bulge. For the moment, that meaning is as obscure as ever.

"I don't think we have the intellectual basis to say what is going on right now," said one Fed official. "We still have no good sense of the strength of the recovery we will see this year" or whether the normal relationship between money and current-dollar gross national product that collapsed in 1982 will be reestablished, the official said.

And as for the bulge in money, Martin S. Feldstein, chairman of the Council of Economic Advisers, says candidly, "M1 is doing strange things. I don't understand why M1 is as high as it is. I wish I had a good theory but I don't."

So far, rapid money growth has left both short-term and long-term interest rates relatively high compared with inflation. Some top administration officials blame market uncertainties over Federal Reserve intentions for that fact. Other analysts say expectations of future inflation are the cause. Other factors, such as banks' desire to bolster profits and very large U.S. Treasury borrowings to finance a record budget deficit, are also mentioned.

Salomon Brothers' influential chief economist, Henry Kaufman, said last week that short-term rates could rise another half or a full percentage point within a month. "Although the nascent recovery's vigor is still questionable, new Fed staff evidence has suggested that recent institutional changes allowing new types of deposit accounts have contributed only moderately to the rapid growth of the monetary aggregates," Kaufman said. "In response to this information, the Fed has moved from accommodation to 'taking in some of the slack.' "

Kaufman went on to note that the Fed's "cautious" response so far is unlikely to restrain the growth of money by much. But even the actions to date could increase the federal funds rate--the interest rate banks charge one another on loans of reserves--by up to a percentage point. "Even this . . . would place upward pressure upon a variety of other interest rates, including the prime, and thus risk undermining the present recovery," he said.

Nor has that recovery really taken off as monetarist theories indicate it should. The Reagan administration last week revised upward from 3.1 percent to 4.7 percent its estimate for real GNP growth between the fourth quarter of 1982 and the fourth quarter of this year. But it also revised downward its figure for inflation, as measured by the GNP deflator, from 5.6 percent to 4.5 percent for the year. As a result, it raised the estimate for current-dollar GNP only from 8.8 percent to 9.3 percent.

Over most of the last two decades, such growth of current-dollar GNP would have been consistent with about a 6 percent increase in the money supply readily available for transactions, the measure known as M1, which includes currency in circulation, checking deposits at financial institutions and travelers checks. As it happens, 6 percent is the midpoint of the 4 percent to 8 percent range for M1 growth that the Fed has said is consistent with its policy goals for 1983.

The difficulty is that M1 in mid-March was already more than 5 percent above its fourth quarter average. To some monetarist economists, that jump in money indicates that current-dollar GNP should be rising very rapidly, and that with current inflation low, so should real GNP. For instance, Jerry Jordan of the University of New Mexico, a former member of the Reagan Council of Economic Advisers, predicts that real output will rise at about a 7 percent annual rate in the first half of this year. And by late next year or early 1985, inflation could be back up to 9 percent if money growth is not slowed, he warns.

But such predictions assume that the normal ratio of the money stock to current-dollar GNP--known as the velocity of money--will be reestablished this year, with current-dollar GNP growing at least 3 percentage points faster than M1 and perhaps even more rapidly.

However, velocity took a strange turn in 1982 when GNP ran well below what it should have, given the amount of money available. Rather than rising at its long-term average of about 3 percent or 3 1/2 percent, the velocity of M1 fell 4.6 percent between the fourth quarter of 1981 and the fourth quarter of 1982. The result was a prolonged recession when the Fed's goal was a recovery.

The decline in M1 velocity is continuing this quarter, too. So far this quarter, M1 seems to be growing at about a 15 percent annual rate compared with growth of current-dollar GNP at about an 8.3 percent rate, according to initial Commerce Department estimates.

William Poole, a member of the Council of Economic Advisers and a monetarist, said that changes in the money supply usually have been reflected in changes in current-dollar gross national product with a lag of a quarter or so. Introducing such a lag into the calculations still leaves the behavior of velocity in 1982, according to Poole's analysis, with a decline that sticks out like a sore thumb. And on the same basis, velocity is still falling since M1 grew considerably faster in the fourth quarter of last year than GNP is growing this current quarter.

An appropriate monetary policy remains to a significant degree a function of what the policymakers choose to believe about the likely behavior of velocity this year. It also depends heavily on an assessment of why some of the measures of money are growing so fast.

In the analysis to which Kaufman referred, the Federal Reserve staff estimated that about $3.5 billion of the money placed in Super NOW accounts in January, about one-fourth of the average level of the accounts that month, came from accounts and investments not included in M1. Similarly, the staff estimated that about 20 percent to 25 percent of the $140.8 billion that flowed into the new money market deposit accounts (MMDAs), which are part of the broader monetary aggregate M2, came from sources not included in M2.

In fact, the staff report prepared in February indicated that the shift of funds out of M1 into the MMDAs likely was greater than the shift of funds into M1 due to the launching of Super NOWs. Therefore it is possible that the new accounts served to depress rather than increase M1 growth in January, when the aggregate rose at a 9.8 percent annual rate, or at least that the flows offset each other.

No similar estimates are available publicly from the Fed concerning the accounts and their impact on the aggregates in February, when M1 rose at a 21.2 percent rate. But there seems to be little reason to assume that the new accounts had more of a distorting effect last month than in January.

"If M1 is strong, it's strong," said one Fed official. "These accounts are not distorting it."

On the other hand, M2 clearly has been inflated by the MMDAs. Chances are that the impact of the account in February was smaller than in January, since the spread in rates between market instruments, such as large certificates of deposit, and the accounts narrowed substantially. If the shift of about 20 percent of the $88.5 billion increase in MMDAs in February is disregarded, then M2 rose at about a 13 percent annual rate last month. A comparable calculation would put M2 growth at about a 12 percent annual rate in January.

The Fed has set a target for M2 growth of 7 percent to 10 percent from its average level in February and March to its average for the fourth quarter of this year. That range includes a 1 percentage point allowance for continued shifts of funds into the new accounts from sources outside M2.

If all these uncertain adjustments to the money figures are correct, then M2 apparently has been rising at a rate 3 or 4 percentage points higher than the track the Fed intends for later this year.

But should the adjustments be made? No one can tell whether the funds placed in these accounts will be used in the same way as the bulk of the funds in M1 and M2 in the past. In other words, what will the velocity of M1 and M2 be now?

Economist Allen Sinai of Data Resources, Inc., noted, "It will be very difficult for the Federal Reserve to determine the purpose of the new funds in M1 and M2, whether transactions or savings. By deduction, however, it would seem as though the sharp rises in the aggregates do not represent a resurgence in economic growth and inflation beyond what the central bank will tolerate . . . Indeed, the second quarter could produce only a 1 percent or so rise in real GNP."

When the Federal Open Market Committee members gather tomorrow from around the country, they will have before them a variety of economic and monetary scenarios. The Fed's own staff expects an increase in current-dollar GNP in the second quarter similar to the 8 percent or so rise now estimated for the first quarter--neither the boom of the monetarists nor the slower growth of DRI; in short, another reason not to adjust the monetary policy levers very much.