May 2021.PNG

Author: Wilfried Küchler

Monthly review May 2021

The month of May was considerably too cold compared to the reference period 1961-1990.
However, with a monthly mean of 11.7 °C it was only the eleventh coldest May in our
country since 1961 (-1.8 degree deviation). May 2010 was even colder in this century with
11.25 °C and May 1991 proved to be the coldest May in Dresden-Klotzsche since 1961 with
even only 9.85 °C.

The flow configuration in the middle troposphere over the Atlantic-European region showed
a very unusual constellation for the month of May. Thus, the frontal zone ran on a very far
southern course, covering the Mediterranean Sea. Such a southerly position of the westerly
wind band is not common even in winter and has not occurred in May in recent years. With
only a few interruptions, "stuck" trough weather conditions with predominantly unstable air masses determined the weather pattern (local showers and thunderstorms) in Central Europe throughout May.

190 hours of sunshine were registered, a slight minus of 8 hours compared to the official
reference period 1961-1990. However, if one compares with the 30-year period 1991-2020,
which is also directly in the past, one obtains a much more significant minus of -32 hours.
Indirectly, this reflects the fact that sunshine duration in May, as in many other months of
the year, has recently increased significantly overall.

The sum of all individual measurements of precipitation reached 63.9 mm in Coswig in Mai.
Thus, the monthly sum corresponded to just 107 % of the normal value for Mai. We thus
registered a slightly above-average third spring month in terms of the total amount of
precipitation that fell. Thus, the spring of 2021 proved to be too dry overall due to the very
dry April. Nevertheless, due to low temperatures in April and May, the topsoil remained
sufficiently moist for the most part.The exceptional drought of the overall soil (due to the deeper soil layers still being very dry) remained unchanged.

Note: Comparisons of May rainfall totals in Saxony (mean Saxony 94.8 mm) and especially
with the region around Meißen (measured value in Garsebach near Meißen 87.8 mm) show
that especially the Coswig-Radebeul area was very disadvantaged in terms of rainfall totals
in May. Coincidence and above all orographic or terrain influences played a role here and
predominantly caused a weakening of the approaching rain areas and thunderstorms. By the
way, on the basis of the echoes of the precipitation radar it is possible to observe these
partly surprising effects in real time.