A few snow showers aren’t out of the question through Thursday morning, but after a moderate warming into the weekend, it looks like a very cold blast of air will come our way starting next week. Isolated snow showers Thursday morning will clear out by the afternoon, and Friday should bring mostly sunny skies back to the region. A dry Saturday will be followed by a weak storm system Sunday, followed by a very cold and unsettled Monday and Tuesday. Highs will go from 40 on Thursday to the low 50s over the weekend, before falling back to the 30s Monday through Wednesday.

Yesterday I mentioned that nearly all the atmosphere mass-wise is crammed into the lowest 5% of the atmospheric column. So just where is the “mass mid-point”? Out of an air column of about 105 miles high, half of all the air molecules are in the lower 3 ½ miles. The 500 millibar (half a bar) surface is located at about 18,000 feet, and is an important layer to watch when forecasting the weather.