I tried to match up some years so that we can get a better idea of what april will look like. Here is what march looked like in my analog years which is pretty close to what we have seen so far. Notice the warmer then normal anomalies across the bering sea with the tongue of cold extending from NW to SE.
I will break down each year in my analog set.
1965 had a very cold march with strong blocking west of greenland. The core of the cold was focused towards the northern plains, prairies and western great lakes. We also saw a transition to neutral ENSO conditions in the spring. In april of 1965 we saw cold shots focused across quebec, ontario and the great lakes with warmth building up across the southern tier of the CONUS.
In 2002 we saw very similar temperature anomalies in march with a slow transition out of cold bias la nada conditions. In april cold shots were common across the north as the PV drops south at times.
In spring 2011 a moderate to strong la nina began to weaken into a la nada state. It had a warm AMO and -PDO as well which matched nicely.
2009 is one of the top analogs in my set with a cold start and a warm finish. The ENSO signal was also very similar with a +AMO and -PDO. The first half of april is on the left and second half on the right.
In 1996 we had a very cold march with a similar tongue of cold showing up. Notice the strong blocking over greenland. ENSO trend also coming out of a weak/moderate la nina.
Based on analogs, modelling and indices it looks like the first half of april will start off cool across the prairies, great lakes and quebec as pieces of the PV drop south. A weak -NAO and ridge along the west coast will allow cold shots to move down with warmer temperatures across the southern u.s. Towards the end of the month the weak -NAO/AO couplet should begin to relax and the -PNA trough begin to re-establish itself along the west coast. This will allow the heat from the south to begin to move northwards towards the ohio valley, great lakes and northeast. I still think that moisture stays above normal in and around the GL's with northern branch features dropping down, especially in the first half of the month. I do see a drier trend in the great lakes towards the end of the month with the SE ridge strengthening and less blocking across greenland. With features moving into the ridge expect some severe weather to break out, mostly south of the canadian border but a shift northwards is likely in may. Once we get out of this cold pattern, it looks like a quick snap to above normal conditions is likely.