US Weather Pattern Becoming More Active (H. Michael Mogil, CCM, CBM, NWA-DS*)
After an almost two weak period in which the upper-level wind pattern could best be described as “zonal,” a more active weather pattern is getting ready to kick in. A zonal wind pattern is typified by west-to-east wind flow. This is being replaced by a high amplitude (more northwest and southwest wind flow) pattern. Linked to the latter is much
more in the way of storminess (low-pressure systems with interspersed high-pressure systems). Look at Figures 1 to 3 to see the forecast transition and differences between these three upper-level wind flow patterns during a two-day period at the end of November. Figures 4 and 5 show the transition in the surface
weather pattern during an overlapping four-day period.
As this high-amplitude upper-level weather pattern establishes itself, we can look for a continual back and forth pattern transition for the next two weeks. There will be a few days of storminess, followed by a few days of tranquility, followed by the next storm system. Overall, storminess will be most pronounced across the eastern half of the U.S. Most places across the U.S. will see significantly chillier weather, with some places, particularly from the Great Lakes into New England, receiving significant snowfall. Fig. 6, shows the next storm system slated for the East Coast into New England by December 7.
With seasonally warm Great Lakes, the more-or-less persistent west to northwest to wind flow across the lakes will bring associated “lake effect” snows along eastern and southern shores. Some areas may see snowfall measured in feet (not uncommon for these locations, I might add).
Meanwhile, California and much of the Desert Southwest will see limited, if any, precipitation.
© 2020 H. Michael Mogil
Originally posted 11/30/20
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