A crippling storm bearing the second major snowfall in a week struck the afternoon rush hour here yesterday, smothering the streets with 5 to 6 inches of new snow and immobilizing large parts of the area in one of the worst traffic jams in years.

The unexpectedly severe storm combined with the early release of thousands of employes from their jobs to create an agonizing chaos, a slow-motion ballet of stalled autos and stranded commuters that stretched far into the night.

Hundreds of cars skidded out of control. Drivers ignored traffic signals. Many abandoned their cars. Cars ran out of gas. Car batteries died. Scores of fender-bender accidents tied up traffic for miles.

At midnight, cars were still backed up in massive, immobile pileups on Wisconsin Avenue and M Street in Georgetown and portions of Canal Road as Virginia commuters attempted fruitlessly to get home. A D.C. snow emergency official said he expected much of the jam to remain throughout the night. (Story on A7).

At the peak of the bedlam downtown yesterday evening, D.C. Transportation Department spokesman A1 Perkins described the traffic snarl as "collosal," with city streets "turned into long parking lots" of stationary cars.

Traffic is "at a standstill.... Even the snow plows are stuck in the mess," said Cpl. Phillip B. Caswell of the Montgomery County Police.

Thousands of would-be bus riders stood in packs along downtown street curbs, leaning into the wind-driven snow and waiting sometimes for hours.

Few police were present to untangle traffic. Cars were strewn haphazardly in intersections, as pedestrians picked their way through.

Along K Street downtown and other arteries in the whitened city, cars sat immobile for 15 and 20 minutes at times before moving forward a few inches or feet. Cars blocking intersections drew curses and angry gestures from other motorists.

Metro trains were packed, and police had to restrict crowds attempting to get into the busy Farragut West station downtown.

Compounding the situation was a 250-tractor parade by American Agriculture Movement farmers from their encampment on the Mall to the Lincoln Memorial in the early afternoon. Metro officials said the parade further disrupted bus service along Constitution Avenue and adjacent areas.

Ambulance and other emergency services were taxed to the limit. In addition to hundreds of minor accidents, two fatal accidents were reported, both in Prince George's County. A 32-year-old woman identified as Randi A. Reider of Indian Head was killed when her car apparently skidded and cross the centerline of Piscataway Road in Clinton, striking a van traveling east, according to county police.

In the other fatal accident, a car skidded along 57th Avenue near Landover Road in Hyattsville, killing a 17-year old pedestrian, identified by county police as Beadra W. Longer-beam of Hyattsville.

Several cases of persons suffering heart attacks were also reported. Ambulance dispatchers said emergency vehicles were slowed to a near standstill in many locations delaying help to stricken residents.

One ambulance driver in Montgomery County reported taking an hour to get from Gaithersburg to Suburban Hospital in Bethesda, a trip that normally takes 15 minutes.

At Holy Cross Hospital in Silver Spring last night, all doctors on hand were urged to remain because others were stranded and could not get to the hospital.

Virginia and Maryland-bound commuters reported taking four and five hours to reach home from downtown.

Some abandoned the effort and stopped at nearby restaurants and hotels for the evening.

All in all, the afternoon rush hour stretched from about 3 p.m. to after 10 p.m.

National Airport closed its runways at 4:21 p.m. because of heavy snow, and all flights were cancelled or diverted. As soon as work crews plowed the runways, the snow covered them again, said Federal Aviation Administration spokesman Dave Hess. "It was just coming down too hard."

Dulles and Baltimore-Washington International airports remained open throughout the day.

U.S. Park Police reported traffic at a near standstill for hours on all outbound bridges across the Potomac River to suburban Virginia. Virginia State Police described I-95 as "very hazardous."

Snow emergency plans were imposed in most jurisdictions. In Alexandria, police prohibited parking on several main streets, and, like police in other jurisdictions, warned that drivers without snow tires or chains who became stuck would be liable to prosecution under snow emergency regulations.

In the city, the tunnel under the Mall leading to I-395 was closed for about an hour because fumes from stalled cars were reaching dangerous levels, D.C. police said.

Thousands of government workers, especially those at suburban offices, were released early. Public schools in Montgomery and Prince George's counties also closed early.

But the early release had the effect of hampering snow removal operations in many areas, according to highway and transportation officials.

"With the early rush hour, there was no chance to get our plows and spreaders to a lot of the main roadways," said A1 Perkins at the D.C. snow emergency center.

By 4:15 p.m., he said, the city had 69 salt spreaders and 39 plows on the streets. An additional 260 plows were being mobilized, but Perkins said some probably would not be able to get to crucial areas until the bulk of the rush hour traffic had passed.

The new snow was spawned by a weak low pressure center over eastern West Virginia yesterday that became temporarily stalled, causing the snow to fall for a longer period than National Weather Service forecasters had originally expected.

As a consequence, forecasters kept increasing their snow accumulation estimates during the day from one inch to two inches and finally to five inches. Because of the smaller estimates earlier in the day, snow removal crews were slow getting onto main roadways in some jurisdictions.

The stalling of the low pressure center also caused the snow to come later in the day than originally forecast, adding a further element of surprise to the afternoon rush hour.

By late last night, forecasters had measured 5.6 inches of new snow at National Airport -- the official observation post of the weather service -- and greater amounts were recorded in some suburban areas. This comes on top of 5.6 inches of snow that fell last Wednesday and an inch more last Friday.

And there's a chance of still more -- probably a light fall -- by late tonight or early tomorrow, weather service forecasters said.

Forecasters said sustained cold has been caused by a high pressure ridge over the western United States and Canada forcing cold air to flow from central Canada to the mid-Atlantic states -- the same pattern that occurred during extreme cold spells in January 1977 and again last February.

The high pressure ridge is expected to shift eastward and "flatten" somewhat toward the end of this week, forecasters said, letting warmer air spill over it from the west and bring moderating temperatures to the Washington area. By the end of the week, they said, high temperatures should be near the seasonal norm of mid to upper 40s with nighttime lows in the upper 20s.