It’s been a positive end of the month since the anomalous ridge on the eastern two-thirds emerged in mid-April and we should still see a pattern of activity kick in when we flip the calendar to May.
Below, we have elevation anomalies over a 5-day period which averages the elevations that form over different regions. What is finally starting to be seen is the break of the Greenland mass that has allowed the polar jet stream to descend into the US and cooler air to filter in. We see a correction to the general 500mb pattern as that band now shifts westward into central Canada and through the middle of CONUS into the 2nd week of May. Below-average elevation shifts eastward into the Atlantic Ocean with a hovering slope off the West Coast.
How this plays out in terms of the temperature anomaly is below-average thermoregulation across the Great Lakes, the Ohio Valley, and the Northeast. We see the focus of mean to above average temperatures shift across the Intermountain West and northern Plains before flowing slowly east as we near mid-May.
This pattern development allowed a remarkably dry pattern to form across the Plains and across the East as the upper air pattern formed an extended high pressure moving down the United States.
We see this nicely reflected in CFS weekly rainfall that differs from the average over the 10-day period. As we see that the upper gully moving slowly over the Lake/Northeast shifts outward (notice the relatively wet east side), it is then replaced by a drier pattern in mid-May. The latter is very important as we are in the middle of the corn Belt growing and planting season, so there is a possibility of a window. In the Southwest and Deep South, a trough shifts out of California with what appears to be an active southern branch of the jet stream bringing moisture waves and overall patterns of activity in areas. This.
Again, this is supported by the evolution of the MJO signal that will propagate across the Maritime Continent and into the Pacific as we enter May and especially into week 2. For the most part, May 5 now looks to be a fleeting month without many stagnation patterns and no noticeable heatwave on the horizon yet.
About the author
Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands