Weather for August 2023. Jet stream suppresses summer. Weather forecast for the second half of the holidays for Poland

“Cold evenings and mornings from Anka” says an old Polish proverb. From July 26, more than a month after the summer solstice, you can feel that the summer day is getting shorter, the night is increasing, and thus the time of radiating the earthly heat is longer. If, on top of that, the temperature and sun during the day don’t really spoil, we start to wonder if it’s already the end of summer?

We are in the phase of mature summer, but the weather in places in Poland is typical of its decline. Will the beginning of August bring warmth to the Baltic beaches and peace to the Tatra mountain pastures? Let’s look more closely at the sky, let’s look at the air circulation over the northern hemisphere, let’s try to answer the questions of those concerned about the holiday weather in Poland. August lasting in our minds as a quiet, high-pressure month, ideal for summer holidays, may turn out to be a great disappointment this year. All because of the jet stream. jet stream), which suppresses the summer and will eventually lead to conflict between the northern and southern air masses.

Poland lies in the zone of air masses moving predominantly from west to east. This idyllic flow is interjected sometimes by air masses from the north, sometimes from the south. And so, in the past, the Polish summer was usually an alternation of a few warmer days and a few cooler ones. Only the high stabilized in August carried the sun and warmth for longer. However, this harmony of Nature is increasingly disturbed. And so in recent years, heat and drought coming from the south more and more often last for weeks, and then give way to cold for the next few weeks. Instead of gentle waves in the flow of air masses, we have a sharp ride of masses from the southern sector to the northern one. All thanks to the turbulent movement of the jet stream in the atmosphere at an altitude of about 10-12 kilometers above our heads. For thousands of years, this current has kept cool air masses over the Arctic and surrounding regions in check, creating a cold cap over the pole. It used to be generally a regular compact dome, but in recent decades the cap has stretched a bit, frayed, often disrupting air circulation in temperate latitudes. So fragments of the current penetrate at times far south, then move far north again.

On the first day of August this year, a fragment of the cold cap in our part of the globe, hemmed by the ribbon of the jet stream (blue-green torn belt of strong wind in the atmosphere) is still quite regularly held. But on Saturday, August 5, the forecast shows a great wave of the jet stream over Europe. Then, over Poland, hot tropical air masses will collide with cool polar ones. A fragment of the wave is to lie exactly over Poland, which means that a thick wall of rain clouds will develop over our heads, which will result in downpours, storms and flooding.

In the light of the latest forecasting materials, in the first half of August, Poland is to be in the arms of the jet stream, the current of which is to flow over the country or slightly south of us. This usually means the influx of cold air masses, the movement of successive fronts across Poland and the jostling of hot and cold. This, of course, happens from time to time, but the effects of this fight are worrying. Because the amount of water that can hold air masses from southern Europe is huge. Year after year, the warmer air, absorbing water from the evaporating warmer Mediterranean Sea, is able to carry water hundreds of kilometers north to dump it in a frenzy over the mountains and highlands of central Europe. These are situations typical for June and July, but not for August, when the weather was going for a siesta.

This year there is no sign of calm, because by the middle of the month there will be waves of rain with breaks for clearing up. After August 5 and 6, heavy rains are to come (around August 9, 12 and 16). Rainfall shortages in June and July will be compensated. And although rain is needed, in August – the traditional harvest season – it is not necessarily desirable, and in quantities of 50-100 liters per square meter in 24 hours is a real misfortune. Meanwhile, according to the calculations of the American global GFS meteorological model, by August 11, an average of 50-70 l/sqm is expected to fall. in the north and west up to 100 l/sq m on the south. And as the models underestimate storm downpours, it gets interesting…

The conclusion is that at least until August 11 we will remain in the bay of cold, under the influence of air masses from the Atlantic clashing with hot masses from Africa and the Middle East. Thus, the temperature will be below 30 degrees Celsius, in the range of 20-28 degrees C. Of course, 20 degrees will be more likely on the coast, and 28 degrees at times in Podkarpacie and Lesser Poland.

In the middle of the month, the GFS model predicts the development of a great heat wedge stretching from Africa to the Baltic, which means a hot flash and an increase in temperature in Poland even to 33-34 degrees C. Only for a moment, because around August 16, the heat is to be pushed out through the bay of cold from the Atlantic, which carries the threat of further downpours and storms rolling over Poland from west to east. In the mountains, such weather is particularly dangerous, requiring tourists to be vigilant. Low-pressure vortices that are to develop over Italy, in the Gulf of Genoa, will roll towards Poland and Germany, which means the possibility of flooding and flash flooding.

Another important weather modeling center – ECMWF (European Center for Medium-Range Forecasts) – leaves no illusions. Until the middle of the month, the average air temperature is expected to remain below the long-term standard, which means capricious weather and many cold days. A particularly large temperature deviation to minus is forecast for the western and southern parts of the country. Meanwhile, heavy rainfall until August 6, clearly visible in the forecast as a belt of downpours over southern and eastern Poland, is conducive to cooling. For the second half of the month, ECMWF is more merciful in calculations and assumes an increase in temperature, closer to what the aura has accustomed us to. The end of August is supposed to be normal, with warm weather. Precipitation forecast also in the norm allows us to conclude that peace will finally come and the end of torrential rainfall. The undulating jet stream will be pushed north by air masses pressing in from the south, and we may experience weather closer to that of Italy or Spain. But summer will be coming to an end.

The first half of August is cool and with downpours, as well as calming rainfall and mild aura in the second half of the month, make up the image of the whole of August as a month with normal temperatures. At least that’s how another model from NOAA (the US National Oceanic and Atmospheric Administration) sees it. This is the paradox of the mathematical average, which will be perfectly understood by those resting on holiday in Poland in the first half of the month. However, the upcoming downpours are well visible in the forecast. Because according to NOAA, August this year is expected to be exceptionally wet, with precipitation above the long-term average, especially in the south and east. The barrels of water that will be poured on mountain trails, Masurian campsites and Baltic beaches are to be numerous, which strongly affects the picture of rainfall deviation from the average.

Difficult weather is ahead of those going on holiday, which is a challenge especially for families with children. We know this, because in many Polish families there are legends about memorable holidays in a wooden house by the Baltic Sea or in a tent on Masuriawhen nothing was drying, mosquitoes bit furiously, and the sun was only a looming patch behind a thick layer of clouds. It’s just that these stories are generally from July, not August. Ahead of us “August” – everything turns upside down.