Sporadically heavy showers dumped another quarter inch of rain on the already saturated Washington area yesterday, slowing auto traffic in some spots and adding to the general meteorological misery of the month of May so far.

But take heart - the weatherman says clear skies and pleasant temperatures are on the way and should prevail over the coming weekend.

National Weather Service forecaster Charlie Chilton said a southwesterly flow of upper altitude air currents responsible for recent rainstorms seems to be shifting, "and we should get some drier northwesterly steering currents during the weekend."

Temperatures should be seasonably pleasant, he said, with nighttime lows in the upper 50-degree range and daytime highs about 80 degrees.

Yesterday's rains bring the month's total to 5.21 inches so far, well above the normal of 3.68 inches for the entire month. The total for the year now stands at 18.96 inches, also well above normal.

According to Weather Service observers at National Airport, rain has fallen on 12 of the first 24 days of May. This may seem like a lot, but Chilton notes that May can be a month of extremes, "and the pattern this year isn't really all that unusual, either for the number of days or the total accumulation."

Weather service records dating back to 1871 show, for example, that total rainfall for May has ranged from .41 inches in 1939 to 10.69 inches in 1889 and 1953. In May 1953, there were 17 days of rain and 15 thunderstorms.

Despite yesterday's occasionally heavy rain, little or no flooding occurred in the Washington area.

U.S. Park Police reported some traffic congestion in Rock Creek Park because of slippery roads and standing water on road surfaces, but this resulted not from flooding by Rock Creek and its tributaries but from poor road drainage.

National Weather Service river forecaster Leo Harrison reported no flooding by local streams and said none is expected the rest of this week.

The Potomac River, which hit a high flow mark for the month of 73 billion gallons a day at Little Falls on May 17, had in fact subsided to 14.8 billion gallons a day by yesterday, according to U.S. Geological Survey spokesman Frank Forrester. Normal daily flow at this time of year is 8.6 billion gallons, he said.