Several inches of snow are possible west of Interstate 95 on Wednesday, but more of a wintry mix of rain and snow is expected for Thanksgiving travelers along the busy corridor, according to the National Weather Service.
A winter storm watch is in effect for Wednesday in Carroll, Harford and northern Baltimore counties, with 6 inches or more of snow possible.
The weather service is calling for 1-3 inches closer to I-95 and less than an inch of slushy accumulation to the southeast, closer to the relatively warm waters of the Chesapeake Bay.
Forecasting models are suggesting that a low-pressure system will form over the Carolinas and sweep up the coast. But, as is often the case with these early-season coastal storms, it's difficult to pin down a precise track -- and thus, precise precipitation forecasts. How closely the storm hugs the coast helps to dictate both how much precipitation falls and whether it falls as rain or snow.
Regardless, it is likely to be a messy travel day up and down the East Coast, with the weather service predicting "heavy snow" from the mid-Atlantic into New England.
Here's what forecasters are saying:
- The weather service is predicting that moisture will meet cold air over the region Wednesday morning, with temperatures likely falling throughout the day. Forecasters expect rain mixing in with snow closer to the I-95 corridor for part of the day, transitioning to all snow first in the higher elevations north and west of Baltimore, and eventually across the region. The snow is expected to taper off Wednesday night.
- The weather service's Hydrometeorological Prediction Center is calling for 70 percent chances of at least 4 inches of snow in areas north and west of Baltimore, and a 40 percent chance of that much snow for the rest of Central Maryland.
- AccuWeather.com predicts 3-6 inches of snow for most of Central Maryland, with the line between all snow and a mix of snow and rain running right through the middle of the region. Even in areas where more rain falls, travel could be treacherous, as precipitation is forecast to be heavy and could limit visibility.
- Foot's Forecast cautions, "Get ready for BOOM!" Its forecasters highlight models that suggest half an inch worth of liquid precipitation falling within 6 hours at BWI, likening it to a "snow monsoon" in January 2011 that left thousands stranded in their cars as a rainy mix turned into heavy snow across the region. "This is the real deal, again," they wrote.
With nearly 1 million Marylanders expected to travel for Thanksgiving this year, the most since 2007, AAA Mid-Atlantic is urging drivers to delay their trips if road conditions become dangerous.
“Wednesday can turn into a chaotic and frightening scene of events on the roadways along the East Coast,” AAA Mid-Atlantic spokeswoman Christine Sarames Delise said in a statement.
Regardless of what happens Wednesday, weather service forecasters say the system will move quickly, allowing for quiet but cold weather Thanksgiving and through the holiday weekend.