Nor'easter precipitation forecast

Maryland, previously expected to get snow in a nor'easter storm Wednesday, is now in an area predicted to get rain. (Hydrometeorological Prediction Center / November 6, 2012)

An unpredictable nor'easter is expected to bring a mix of rain and snow to the Baltimore area overnight Wednesday, with northern and eastern parts potentially waking up to the season's first light snow cover.

But the storm's reach will be limited, forecasters said Tuesday. Depending on its track, snow could reach as far west as the Interstate 83 corridor, with most accumulation expected in Harford and Cecil counties and points northeast. Farther to the west, there could be nothing but breezy winds.

Nor'easters are common in the winter months when the air and ground are much colder, but the rarity of such storms in early November is making it difficult to pin down precise snowfall predictions, forecasters said.

"Normally storms like this aren't as confusing," said Aaron Salter, spokesman for meteorology website Foot's Forecast. "It's hard to figure out whether the snow we do have is going to stick right away and whether the surface temperature is going to be cold enough for it to be snow and not rain."

The National Weather Service's Baltimore-Washington forecast office is predicting a slushy mix of rain and an inch or less of snow in western parts of the region, like Carroll and Howard counties, said forecaster Kevin Witt. In Harford, Cecil and Kent counties, snowfall could reach 1.5 or 2 inches, according to the weather service.

But the Philadelphia weather service forecast office, which covers parts of the Eastern Shore, is being more conservative. Cecil and Kent counties are under a winter weather advisory from 6 a.m. Wednesday through 6 a.m. Thursday, with about an inch of snow expected.

The weather service is expecting a "sharp moisture gradient", with a narrow area receiving rain, snow or nothing at all, according to forecast discussions. On the Eastern Shore, rainfall could total up to 1.5 inches.

Temperatures are expected in the upper 30s to around 40 throughout the day Wednesday, with a light cold rain starting in the afternoon. Overnight, temperatures could reach the mid-30s or below freezing. Any significant snow accumulation would occur before daybreak Thursday, Witt said.

While wind gusts could reach 50 mph in Ocean City, they are expected to top out at 35 mph with sustained winds of 20-30 mph in the Baltimore area late Wednesday and early Thursday.

If the storm were to arrive during colder weather in December or January, it could generate perhaps 2-3 inches of snow, Salter said.

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Nor'easter forecast

Timing: Wednesday afternoon through Thursday morning

Precipitation: Light rain, mixed with snow in northern/eastern suburbs, where it could turn to snow overnight. Totals of a quarter-inch of rain, up to 1-2 inches of snow in Harford County.

Temperatures: Highs in upper 30s to around 40 Wednesday, lows in low- to mid-30s overnight

Source: National Weather Service