How much snow is on the way?

Two low pressure systems are expected to combine today to produce steady snow by nightfall, with an Arctic cold front sweeping in behind.

The systems were moving in this morning from the west and south and were expected to merge tonight before intensifying into early Friday.

The combined systems will drop from three to seven inches of snow in the Philadelphia region, followed by a blast of frigid temperatures. The National Weather Service has issued a Winter Storm Warning from 3 p.m. tonight through 1 p.m. Friday.

A light snow is expected to start sometime during the day north and west of the I-95 corridor, but with only minor accumulations. Then, snow will likely become heavier as the evening rush hour. Temperatures will reach into the upper 20s or low 30s. But they could reach into the 40s south of Philadelphia into Delaware.

You can read a detailed explanation of expected events by meteorologist John Bolaris here.

Meanwhile, here's the forecast from the National Weather Service out of Mount Holly, N.J.:

For today, there's a chance of rain or snow before 4 p.m., with rain likely between 4 and 5 and a high of 37. Then, it will become blustery as the real snow starts to fall.

The snow will continue into the start of Friday and lows will drop to a frigid 15 and wind gusts up to 24 mph.

Snow will fall through 7 a.m. with a clearing by mid-morning.

But temperatures will remain bitter cold with a high of only 16 forecast for Friday and wind chills dipping into negative single-digits.

The cold will hunker down through Saturday with a high of 30.  Temperatures will drop during the Eagles-Saints game at night.

Gradually, however, it will warm on Sunday with temperatures expected to reach the low 40s, and it's possible we'll see rain.