Editor’s note: This story will be updated as more information becomes available.

Large parts of Arkansas have been upgraded to a winter storm warning for Thursday and Friday as forecasters get a clearer picture of the type and location of winter weather that will occur across much of the state.

All of Arkansas, except three counties, is under a winter storm warning, the weather service said in a post Wednesday afternoon.

The winter storm warning is scheduled to go into effect around noon on Thursday and last until 6 p.m. on Friday.

A winter weather advisory is in effect for Benton, Ashley and Chicot counties.

Joe Goudsward, a forecaster with the National Weather Service office in North Little Rock, said the move to a winter storm warning instead of a warning for most of the state was largely due to timing.

“We’re further along. The idea behind it hasn’t really changed, but the event is in sight,” Goudsward said Wednesday afternoon.

A winter storm warning is issued depending on location and confidence that a winter weather event will occur, said Colby Pope, another meteorologist at the National Weather Service office in North Little Rock.

“For a warning to be issued, we must have an 80% or greater confidence that a winter weather event meets or exceeds a location’s snowfall criteria,” Pope said Wednesday morning. No specific confidence level is required to issue a winter storm warning.

Snowfall amount criteria for issuing a winter storm warning vary across Arkansas.

The criteria now include impact and vulnerability in relation to winter weather, the briefing said. For many northwestern parts of the state, the weather forecast must call for at least 10 cm of snow or more before a warning is issued. Areas in central and eastern Arkansas should see 3 inches of snow forecast, while far southern Arkansas only needs a forecast of 2 inches.

As of Wednesday afternoon, Little Rock is expected to get about 9 inches of snow, Goudsward said.

“About 7 inches of snow is expected to fall over a fairly large area from Murfreesboro through Arkadelphia and Brinkley to Searcy and back to Fort Smith,” he said.

“We’re going to get some good snow for sure,” Goudsward said Wednesday afternoon.

Pope said the high snowfall forecast for the metro area is a “five-year forecast.”

“It’s not unprecedented (but) this will definitely be one of our highest-profile events,” the meteorologist said. “Little Rock averages about 3 inches of snow per season.”

According to the Probabilistic Winter Storm Severity Index included in the weather briefing, there is a likely chance that snow will have moderate and possibly even some major impacts on portions of the state.

“The likelihood of moderate impacts from snow on winter weather has increased across the central third of the state,” the briefing said. Parts of the Ouachita Mountains, as well as Little Rock and Hot Springs, are most likely to experience moderate or higher impacts from snow.

If the impact is moderate, disruption to everyday life is expected and drivers should exercise particular caution while driving.

The severe impacts of winter weather, expected to reach 40% in the Little Rock area due to snow accumulation, include significant disruptions to daily life, such as “dangerous or impossible driving conditions” and widespread closures.

Pope said Little Rock could expect light snow starting around midday Thursday.

“The snow will be light and you might see some people walking around saying, ‘Oh God, is that that dust? It was just a broken forecast.’ But the snowfall rate will increase overnight Thursday into early Friday and then continue into the evening,” he said.

The current forecast and winter storm watches and warnings are expected to be modified and refined.

Goudsward also said southern Arkansas saw about 0.25 inches of ice accumulation during the winter storm.

Freezing rain can cause more problems than snow, Pope said. Ice can build up on power lines and cause damage, as well as cover roads with a sheet of ice, making safe travel difficult.

And because temperatures remain cold even after the winter storm has left the state, ice can remain, causing additional problems.

“You could have a problem where it gets warm enough during the day to melt the snow, but overnight it gets so cold that the water freezes back into ice,” Goudsward said. “It won’t be single-digit arctic cold, but it will still be very cold and we could thaw and freeze again for several nights.”