The National Weather Service has issued a winter weather advisory until 7 p.m. tonight as heavy snow and sleet continue to fall across St. Lawrence County creating dangerous road conditions and slippery sidewalks, driveways and parking lots.

The first widespread storm to hit St. Lawrence County this winter dropped a few inches of snow overnight with sleet and rain mixed in creating messy roads of slush with patches of ice.

The slick roads caused all NYSARC and public transportation buses to cancel their routes for the day. All schools in St. Lawrence County are closed due to Christmas vacation.

Motorists are advised to use extreme caution when driving and to be precautions when walking outside.

Snow and sleet are expected to mix through noon today before sleet takes over from 1 until 4 p.m., NWS said.

Snow is expected to return from 4 until 8 p.m. with freezing drizzle likely overnight Tuesday.

Total new snow accumulation throughout the day is 1 to 2 inches. Ice accumulations is expected to be less than .1 of an inch.

There is a 30 percent chance of freezing drizzle before 9 a.m. Wednesday and then a chance of showers after 2 p.m., the service says. The high will be around 36.

Wednesday night could see the return of rain and snow, likely before 10 p.m., with rain likely between 10 p.m. and midnight and snow after midnight. About a half inch of snow is possible. The overnight low will be about 33 degrees.

The forecast through the weekend is as follows:

Wednesday

A chance of freezing drizzle before 9am, then a chance of rain showers after 2pm. Cloudy, with a high near 36. Light and variable wind. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Wednesday Night

A chance of rain and snow before 10pm, then rain likely between 10pm and midnight, then a chance of rain and snow after midnight. Cloudy, with a low around 33. Southwest wind 6 to 8 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.

Thursday

A 40 percent chance of snow showers. Cloudy, with a high near 34. West wind 9 to 11 mph.

Thursday Night

A 30 percent chance of snow showers after 1am. Mostly cloudy, with a low around 25. West wind 8 to 10 mph.

New Year's Day

A 30 percent chance of snow showers before 1pm. Cloudy, with a high near 32. West wind 10 to 14 mph.

Friday Night

A 30 percent chance of snow showers. Mostly cloudy, with a low around 25. West wind 9 to 14 mph.

Saturday

A 30 percent chance of snow showers after 1pm. Partly sunny, with a high near 27. West wind 9 to 11 mph.

Saturday Night

Mostly cloudy, with a low around 15. West wind around 8 mph.

Sunday

Mostly cloudy, with a high near 23. West wind around 6 mph.

Sunday Night

Mostly cloudy, with a low around 9. West wind 3 to 6 mph.

Monday

Mostly sunny, with a high near 25. West wind 5 to 8 mph.