Halloween night. Window soaping, a few childish pranks.Well, put those visions away. Window soaping and childish pranks are things of the past.

Instead, say area police and civic leaders, the young vandals of today are leaving the soap in the shower and arming themselves with rocks, spray paint and BB guns. And instead of soaping car windows, vandals are smashing or shooting them out.

As Halloween 1980 approaches, community leaders, school administrators and police are holding their breaths and preparing for the worst: The night of ghouls and ghosts is also the night that brings the worst vandalism of the year.

"It's a nightmare," said Shelia Laughlin of the Fairfax County Police Media Relations office, as she recalled Halloween last year. "I was out on the street last year on Halloween and we were just running from one call to another."

Although officials emphasize that vandalism is a year-round problem, police in all three major Northern Virginia jurisdictions are increasing regular patrols for tomorrow night and the rest of the weekend.

In Fairfax County, school security patrols will be out in full force, and many civic associations are planning all-night vigils to see that troublemakers are deterred in their attempts to inflict random property damage.

"We beef up the road patrols and ask people to turn on their porch lights," said Arlington Police Sgt. Frank Hawkins, who calls vandalism one of the most "frustrating" crimes for law enforcement officers.

Already this year, police in Northern Virginia can point to a lengthy list of acts of vandalism: more than 60 slashed tires in Alexandria, cars spray-painted a rainbow of colors, car antennae snapped off and house and car windows smashed with rocks and shot out will small-caliber guns.

Still, says Hawkins, ". . . very few [vandals] every get caught . . ."

Police say two problems plague their efforts to apprehend vandals: There generally are few witnesses, and the vandals strike quickly and run.

Statistics, on vandalism are misleading, police say, because many of the crimes are never reported. But in Fairfax County alone, there have been more than 9,084 reported acts of vandalism since the first of the year.

The most popular targets of vandalism in Northern Virginia appear to be the 164 Fairfax County schools. Last year, the county paid $385,250 in vandalism-related repairs. In the first three months of fiscal year 1981 (whicch began July 1) Fairfax schools suffered more than $57,069 worth of damage because of vandalism, up 6.9 percent from the same period last year.

So far this year, the most costly act of vandalism for Fairfax scchools occurred two weeks ago at Frost Intermediate School on Pickett Lane when 270 windows were smashed. The repair bill is expected to be $3,000 to $6,000. Two 16-year-old youths were detained by school security officers, who were alerted by a silent alarm at the school.

"This one gets the bobby prize," said a bewildered William Shadle, the school system's assistant superintendent for general services.

The most costly and probably the best known act of vandalism, which later was classified as arson, was the fire at Fort Hunt High School in 1979. The fire, set by three youths, caused $4.5 million damage and gutted much of the school.

Vandalism has become so routine that Ed Cox, head of Fairfax County's security system, says he cannot remeber a single day that he has not recorded some sort of vandalism at a county school.

"First thing in the morning I count the buildings and hope they're all there," Cox jokes bitterly.

The incidents range from a few broken windows and graffiti to school buses that have been set on fire.

Ironically, schools are not the hardest hit on Halloween -- homes and other private property are.

"They get us 364 days of the year," says Cox. "[Halloween's] the night they go after the neighborhood grouch."

In an effort to combat vandalism -- which several school officials admit privately has gotten out of control -- schools and other community groups are trying several new programs.

Fairfax, for instance, is trying a "lights-outs" experiment at several schools, which reverses the thinking of several years ago that well-lit buildings are safe-from-vandals buildings. The "light-out" program already has been used in San Antonio schools, were officials reported a dramatic drop in vandalism when no lights were left on at the schools.

"They thought maybe the lights were actually attracting kids," said Cox."After all, what's the fun in throwing bricks through windows if you can't see them break?" he asked facetiously.

Other observers have suggested that teen-age vandals could be deterred if they knew their names would be made public. But Cox gives an unequivocal veto to that plan.

"In 50 percent of the cases," he says, "the kids would become heroes. [I was told recently] that one of those kids [who set the fire at Fort Hunt] was introduced at a disco one night as 'the guy who burned Fort Hunt down,' and he got a standing ovation!"

Earlier this week at a community meeting in Fairfax, where the topic of the evening was how to combat vandalism, one woman described privately an incident in which vandals threw rocks through two of her living room windows last year.

"It was the most frightening thing that's every happened to me," she said with a shiver. "They never caught the kids, and I was scared to death they would come back during the night [when there were gaping holes in her windows]. You can't really explain it -- it was so senseless and so terrifying."

At least five Fairfax County civic associations have organized "neighborhood watch" programs, in which volunteers equipped with CB radios drive along residental streets looking for suspicious activities, which they report to the police.

John Chwat, president of the Ravensworth Farms Civic Association and one of the organizers of a local neighborhood watch, says the 900 homes in his subdivision have fallen victim to fewer and fewer instances of vandalism and burglaries since the neighborhood watch began.

"We are not vigilantes," Chwat says emphatically. "We have 150 people signed up and we are simply the eyes of the police."

Chwat says the volunteers remain in their cars at all times, alterting the police to suspicious activities. On Halloween, Ravensworth Farms and other civic groups with neighborhood watch programs will be operating a dusk-to-dawn surveillance.

While civic leaders and police gear up for Halloween, the discussion of what can be done to reduce vandalism -- and expensive and largely unsolvable crimes -- goes on.

The Fairfax County School Board has approved a proposal which would ask the General Assembly to make parents responsible for damages caused by their delinquent children, and school officials say they are trying to make students aware of the damage and expense of vandalism.

But the police say there is only one deterrent to vandalism.

"You've got to be alert and be aware of what's going on around you," said Arlington's Sgt. Hawkins. "I heard a noise outside my house the other night and I went to the window to watch four drunk boys getting into a car. I just stayed there and waited until they went away -- but a lot of people wouldn't get out of bed to see what's going on if they hear a strange noise."