Last week, several weather maps indicated the passage of cold air masses that swept through. This occurrence is rather unusual, as the cold weather conditions were caused by a so-called "cold drop" from the northeast. A cold drop is an upper low-pressure zone located at high altitudes and cannot be detected on the ground. This particular cold drop initially separated in the polar region, which explains the transport of cold air mass to Europe last week. Therefore, Europe's weather was influenced by the East, which is unusual as European weather phenomena are typically influenced by air masses from the Atlantic Ocean.
The effects of this event encompass a decline in temperature, thunderstorms accompanied by rain, snow in the Alps, and ground frost in many areas.
The synoptic pressure map (first screenshot) serves as a valuable instrument for identifying upper low-pressure zones that cannot be detected with a ground-level barometer. For example, the 500 hPa pressure map displays the geopotential altitude in meters (GPM) where the air pressure is 500 hPa, roughly half the standard atmospheric pressure at sea level.
The blue-shaded areas on the map indicate a low-pressure zone at higher altitudes, while the yellow and red regions mark high-pressure zones at higher altitudes. Further, the map tracks the movement of a cold drop moving from the northeast on Wednesday (April 19th 2023), crossing Germany until Thursday evening (April 20th) and then passing over to France and Great Britain on Friday (April 21st).
In addition, we provide several cloud cover maps, some divided into different tropospheric altitudes. For instance, you can see the cold drop’s path during the last days with the help of the Cloud Cover Total map. A counterclockwise circulation travels from northeast to southwest whilst crossing Germany. Ultimately, the structure disintegrates due to Atlantic air masses pushing into it.
As mentioned above, the passing of the cold drop led to cold temperatures, resulting in frost and snowfall in certain regions. The Freezing Level Height map shows the 0-degree isotherm, and the cold drop is visible in violet, indicating frost for some European areas. Especially locations in higher altitudes, such as the Alps, were affected by a massive amount of fresh snow. To check the actual snow depth and the accumulated daily and hourly snowfall, you can use the various precipitation maps included in our point+ subscription.
Currently, an intermediate high-pressure area over Central Europe brings warmer temperatures, although the weather is currently very unsettled and changeable.
