Overnight lows dropped into the low teens across much of Maryland early today, with single digits recorded again out in the far western counties.

We had a low of 12 degrees out on the WeatherDeck in Cockeysville. It was 19 here at The Sun in downtown Baltimore. The airport reported 14 degrees - not quite tying for the second-coldest night of the year.  

But it could be worse, as residents of many northern states could testify this morning. (That's this morning's snow- and ice-cover map below.)

The high-pressure system that delivered this arctic chill is headed out to sea tonight, and in its wake we will warm into the 50s tomorrow.

The rub in this is that the departure of the high opens us up for the arrival of another low-pressure system now forming in the central Plains states. That low will help to draw warmer, wetter air up into the region from the South. And that will mean rain on Wednesday. Rain, that is, as soon as the incoming warm air is able to drive out the lingering surface cold air we're enjoying this morning. Until it does, some of us could see a period of freezing rain early Wednesday before everything turns to plain rain.

Forecasters say the most likely geography for freezing precip is across the northern tier of counties. Ice accumulations, if any, will be light, they say - less than a tenth of an inch. Once it turns to rain during the day Wednesday, rain amounts will become more generous, with up to a quarter-inch possible Wednesday night.

The weather service has issued a Hazardous Weather Outlook for the area. All things considered, a miserable night for flying a sleigh. The only prospect for flakes in the air on Christmas Eve will be in the mountains of western Maryland, where the arrival of colder air behind the storm may touch off some snow showers late in the evening.

Christmas Day looks quite pleasant - partly sunny with daytime highs a few degrees above the long-term averages. We should see the upper 40s as the storm moves off, another cold front moves by and high pressure returns. Briefly.

By Friday night, the next low will be moving in, with more rain scheduled overnight Friday and Saturday.