Valentine's Day was expected to arrive with a gift of snow. An "Alberta Clipper," a fast-moving storm packing 1 to 3 inches of snow for Central Maryland was due in time for the morning rush hour.
"This is not going to be a major system," said Dick Diener, a National Weather Service forecaster at Baltimore-Washington International Airport. "It's one of those pesky-type things we've had in the past. We're just sort of sensitive now because of everything we've gone through in the last couple of months."
BWI has recorded 44.1 inches of snow this winter, about twice the average for an entire season. Most of that -- 32.1 inches -- fell during the Jan. 7 blizzard and the two storms that followed it that week.
It also has been cold. November and December were 2.8 and 4.2 degrees below average, respectively. January was about average, but February has been 5.3 degrees below average.
The cold, snowy winter follows a record summer drought and the hottest summer on record at BWI. It may help to remember today that there were 43 days of 90-plus heat from June through August.
"Everything balances out," Mr. Diener said.
Alberta Clippers are named for the western Canadian province. They are small, rapidly moving low pressure systems that drop out of central Canada, swing across the upper Midwest and across the Eastern seaboard. Typically, they do not carry a great deal of moisture, and they move so fast that they don't leave behind major accumulations of snow.
Maryland's biggest snowstorms, like the Jan. 7 blizzard, come from the south, drawing moisture from the Gulf of Mexico and the Atlantic and pumping it into a system of entrenched cold air from Canada.
But the Clippers can be troublesome.
"People should be careful when they drive," Mr. Diener said. "It will be slippery in the morning, and they're going to have to put down salt because the temperatures will be in the upper 20s during the snowfall."
The snow was expected to stop between 7 a.m. to 8 a.m. But strong winds will continue to blow it around, forecasters said. Temperatures south of Baltimore should rise to the mid-30s or 40, allowing some afternoon melting.
The really cold air is due Sunday, Mr. Diener said. "We're looking at [low] temperatures in the single digits. High temperatures will probably be in the upper teens to low 20s."