WKU Meteorology

After an anomalously warm start to the winter for the mid-south, seasonable temperatures (30s/40s) have returned since 1/16. So why have we remained snowless? The primary reason for that has been the pattern in the upper levels of the atmosphere. Since the El Nino sharply weakened mid-month, the overall synoptic pattern across the U.S. has yielded a sharp ridge over the western U.S. with a broad u-shaped trough over the east. This pattern does two things…1) Cold air masses from the arctic easily move southeastward across the U.S. every few days resulting in a temperature pattern of cold, warmer, warmer, cold, warmer, warmer… and 2) any storm energy coming across the northern Rockies or from the sub-tropics is quickly pushed eastward by the fast-moving jet stream before a large storm can develop. The arctic air is able to push all the way into the Gulf of Mexico which prevents any warm, moist tropical air from getting involved with the storm. For a winter storm to intensify, a few things have to happen… Continue reading →