Seasonally Low Arctic Oscillation
If you listened to my weekly briefing you might remember that I mentioned that the Artic Oscillation was forecast to dip to a seasonal low level this week. Well, take a look! As most of you know, temperatures have dipped well below normal over most of the nation as the AO is the lowest of the season. Welcome to Spring!
The rapid transition to this latest low level produced a wide varity of precipitation, including severe storms. The system that moved through this past weekend brought additional snow to parts of the northern U.S. and severe weather to the Southeast U.S. The variety of weather is an early sign of the transition from winter to spring — although it seems to be put on hold by the recent dip in the AO.
Here are accumulations of precipitation for the past 3 days. It is quite interesting to see the more widespread precipitation (snow) over Minnesota and Wisconsin, the heavy synoptic rainfall over Kentucky and nearby states, and the tracks of severe storms over the Southeast U.S., especially Georgia. Note the linear alignment in tracks over Georgia from west to east. These are tracks of individual thunderstorm cells.
New Storm On The Way
You might remember that the AO tends to tighten up the thermal gradient (on the southern edge of cold air). There are signs that a significant snow event could development this weekend in Kansas, spreading into Missouri, Illinois, Indiana, and Ohio. This will be along the southern edge of the colder air (with snow in the colder air). It looks like this snow could be heavy, replenishing soil moisture across portions of the Midwest into the Ohio Valley.
Additional heavy rain could fall over areas south – including the Southeast U.S.