Another Temporary Warmup, and Wet-at-Times WeekApril 12th, 2013 at 9:49 pm by Don Paul under 4 Warn Weather
After this past week’s soaking rain, I wouldn’t say there’s “no rest for the weary”, but there may not be enough rest. A strong warmup on Monday from a downslope wind will boost temperatures by close to 20 degrees from Sunday’s high. The proximity of a nearby cold front will increase the chance for some showers by Tuesday, but the amount of rainfall we can expect from the passage of that front seems uncertain. Later in the week, the European model brings a deep low pressure system toward the northern Great Lakes. That might warm us up again sharply around Thursday, but the Gulf inflow ahead of its cold front and the dynamics of that storm–if realized–could bring convective rains and the potential for larger amounts. A backslide will arrive by or during Friday to below average temperatures into the weekend. The ensemble means are not showing much in the way of a rebuilding of a warmer pattern afterward, into the following week.
The indices seem to support that cooler pattern again as well, with the AO ensemble trending downward later in the month. The NAO has a lot of spread, but there appears to be a slightly negative mean to the ensemble members. And, there is an upward tick in the PNA members at the very end of the 14 day period.
The anomalous snow cover over the upper plains/upper midwest and Canadian prairies is also serving as an anomalous cold air reservoir for the north central US, and that reservoir can also deliver chilly outbreaks to us–as we already know.