Long Island Weather: 3 Inches Of Snow An Hour Possible Wednesday

UPDATE: Worst Of Storm Arrives This Evening

A winter storm warning is now in effect as another powerful nor'easter threatens to drop up to a foot and a half of snow on parts of Long Island.

"Snow this morning will become heavy by afternoon and into the evening," the National Weather Service says. "Expect significant reductions in visibility at times. A combination of the heavy snow and occasional wind gusts up to 45 mph could bring down tree limbs and power lines, creating power outages. Travel will be very difficult to impossible, especially during the evening commute."

Here are the latest snow total estimates:

• Nassau County– 12-18 inches
• Western Suffolk County- 10-15 inches
• Eastern Suffolk County- 6-12 inches

Near-whiteout conditions are likely at times on the roadways. The Long Island Rail Road is urging commuters to get home as soon as possible.

"Please travel only if necessary as LIRR may need to reduce or suspend service later today if conditions worsen," the railroad said in a tweet Wednesday morning. "Those who are unable to postpone traveling are advised to leave as early as possible this afternoon, allow extra travel time and anticipate delays."

Many Long Island school districts are either closed today or dismissing early.

RELATED: Long Island School Closings/Early Dismissals For Wednesday

PSEG Long Island says it's ready for the fourth nor'easter of the month.