Weather forecast: After the storms – midsummer in September?

A weak disturbance has reached Germany and is causing severe weather events from Thursday to Saturday, where heavy rain, torrential rain and flooding may also play a role. There is then a high in the direction towards Germany, which can affect the weather well into September.

Hhigh. A weak gradient disturbance drives increased shower and thunderstorm activity Thursday through Friday in an energetic weather environment over Germany in the form of heavy rain, lightning and hail, as well as stormy gusts of wind can cause severe weather conditions.

flash floods and floods

Because the soil above Germany is dry and hard, precipitation on the surface drains quickly into streams and rivers. In addition, the cells hardly move from the site, which can lead to prolonged and heavy rain locally. flash floods and floods cannot be excluded from Thursday to Friday. that Temperatures will rise ahead of the severe weather front +28 to +34 degrees and then go back to +22 to +26 degrees. With continuous rain, up to +15 degrees is possible. More on this in the current weather forecast for August 2022.

that Forecast of the European and American weather model: the height that has so far dominated Germany shows weaknesses ©

The rain forecast: stormy!

The severe weather front will occur in clusters whose demise is difficult to predict at this time. However, it is clear that huge amounts of rain can accumulate within a very short time. In some places, the entire month of August can fall within 24 hours.

The European rain forecast is on the left, the US forecast in the middle and the German forecast on the right: heavy and regional heavy showers and thunderstorms are possible over Germany until 21 August
On the left the rain forecast for the Europeans, in the middle that for the Americans and on the right next to the German one: heavy and regionally severe showers and thunderstorms are possible over Germany until August 21 ©

What is the weather like in September?

Some years autumn is already felt in the first decade of September, but in fact the first meteorological month of autumn is still late summer, when temperatures can typically level out between +18 and +24 degrees and on some days up to +26 degrees. degrees. Values ​​of up to or above +30 degrees are rare.

Heat until September?

Heat with temperatures above +30 degrees is a possibility that should be taken seriously in the form of a tendency to maintain the current weather development and has been so repeatedly in recent days Forecast of the prediction models were calcd. But shot down Bird last night Forecast of the Americans, where the temperatures from August 25 to September 2 ranged from +30 to +35 degrees and locally up to +38 degrees.

True, she belonged Forecast of the Americans are by far the warmest varieties compared to the control runs, but the control runs are anything but cold with their temperature forecast. A midsummer weather situation in September is always plausible and would correspond to a marked tendency to maintain. Incidentally, this extreme variant was in the present day Forecast weakened but essentially confirmed with an extensive high pressure core between Scandinavia and western Russia.

The varying stable high pressure weather conditions that can carry midsummer into September
Forecast according to the US forecast model from last night (left) and selected control runs: the variable stable high pressure weather conditions that could lead midsummer into September ©

End of midsummer – finally rain?

Many inquiries reach us with the same question – when will the heat end and when will it come – continuous – rain?

Lots of rain is possible on Thursday and Friday, but the weather situation is not sustainable in terms of precipitation – a high pressure wedge will follow too quickly, and precipitation activity will return to the slightly increased area after August 20.

Is there any indication of a lasting change in the general weather situation? A first indicator would be a positive NAO index, which – to put it simply – describes the relationship between the Azores high and the Icelandic low. Until September, the NAO index was assessed as weakly positive, which does not indicate a strict meridional weather pattern (north-south, south-north), but instead indicates a mixed form with a north-west or south-west weather pattern. Both weather conditions would bring an increased risk of showers and the south-westerly weather conditions would result in an active tendency for thunderstorms.

Both weather conditions are considered unstable, but they are not known for sufficient and area-wide precipitation. Put another way, with a slightly positive NAO index, the general weather situation must not be expected to tip towards early autumn weather. Why is that so? Almost none of the control runs calculate a general weather situation that in the long term can tip in the too cool direction. Rather, the colder varieties are based more on what is typical for the beginning of September.

The early autumn trough varieties
Forecast after selected control runs: The early autumn trough variants ©

In a nutshell: too hot for the season

Although the calculations of individual control runs are extremely warm, and the main runs repeatedly show high-pressure variants that are clearly too warm, the gist of the statement has been – for days – a clearly too high temperature trend until September.

High pressure dominated the weather

And another trend has been confirmed in the last 72 hours compared to the last September forecast. According to the control runs in the period after the storms from 20 August to 2 September, the rainfall performance is weak and shows almost no significant rainfall signals.

This still speaks for the southwest weather conditions. But with a difference: the number of control runs calculating a self-sufficient high-pressure variant has increased significantly in the last 72 hours. The high pressure bubbles are striking, a omega formation assume, which is among the most stable varieties of high pressure weather conditions.

If you sum it up, I am September not to be expected so soon with a striking and lasting change in the weather in early autumn. Warm to warm late summer is more appropriate, and the average of all control runs also calculates a temperature spectrum that can be +2 to +5 degrees warmer than the long-term average and up to +7 degrees over the south and east.

The development in cold and rainy weather looks different
Forecast according to the average of all control runs: the development in cold and rainy weather looks different ©

The long-term model weather trend

The deviation of the temperature forecast is +1.0 to +2.0 degrees compared to the long-term average too hot Range (91/20: +0.5 to +1.5 degrees). The precipitation forecast is unremarkable compared to the long-term target value and in line with the trend a bit too dry judged. There have been no corrections in the last 72 hours.

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