It’s That Time of the Year; A “Blocky” Pattern Will be Evolving…April 21st, 2014 at 2:14 pm by Don Paul under 4 Warn Weather
and that often leads to an unpromising pattern, depending upon what part of a block you find yourself under. In this case, there are signs of a near cutoff low getting closer to us by April 29-early May, and those signs are strongest in the ECMWF mean. If we were to get stuck in the “sweet spot”, a cutoff ridge, that would be a good thing. At this early juncture, that appears less likely than being near a cutoff low moving from the central US to near the Great Lakes. Cutoff systems are those which are cutoff from the higher speed westerlies which keep weather systems moving along. Late April-mid spring is the time when cutoff systems become more climatologically favored. The synoptic weather traffic jams can sometimes impact many parts of the mid-latitudes and northern latitudes.
When we’re stuck under a cutoff low, a lengthier dreary and cool pattern can result, with some showers from time to time. The GFS is also showing signs of this blocky pattern, with the Canadian less so inclined. This is the first time this spring I’ve seen the ECMWF ensembles so strong on a cutoff, so this will need to be watched carefully. For now, I’m not taking this a good sign for the extended range.
In the meantime, cooler weather will arrive Tuesday with mostly AM showers, and then another round of lighter showers Tuesday night which could be mixed with a few wet snowflakes toward Wednesday AM at the highest elevations. Wednesday will be chilly, with some sun returning by afternoon, and Thursday will be dry and sunnier with seasonable temps. Friday will be milder but wetter with some rounds of showers, followed by a damp, cool Saturday with falling temps in the afternoon–though not much accumulating rainfall. Sunday looks chilly (upper 40s) with limited sun and mostly dry conditions, though a few light showers or mixed showers can’t be ruled out. There should be some moderation early next week before the approach of any cutoff low later in the week.