01 June 2022
Cherry and sakura are slow to bloom this spring. Yes, and the lilac, which at the end of May is usually in the last stage of its wonderful decoration, is now just blooming. But we had a rare opportunity almost at the same time to admire the white fog bird-cherry, the bright lilac clusters, the proud candles from blooming chestnuts …
PHOTO Alexander DROZDOV
The weather in St. Petersburg this spring was not a pleasant warmth. But it did not bother with frequent rains.
March, if readers had time to forget, was warmer than average and with a remarkable humidity deficit – the monthly total rainfall in March was only 41% of the norm. April in terms of temperature indicators was close to the norm and maintained the trend of March to a deficit of rainfall, their monthly amount was only half of the norm.
The last month of this spring has proven to be even rarer for heat. For most of May, daytime temperatures did not exceed 17 degrees. The air warmed to 19 degrees only on May 7 and 21 and to 22 degrees on May 30. And those were the hottest days of this spring.
The average temperature for the month was 10 degrees, ie one and a half degrees below the climatic norm. (Let me remind readers that it is calculated taking into account both day and night temperatures.) For the past 22 years, this is the second or third result on the list of coldest. May 2017 was a bit colder, then the average monthly temperature was 9.4 degrees and exactly the same average monthly temperature as this year was in May 2020.
The amount of rainfall for the month was about 70% of the monthly norm. The total duration of sunshine proved to be close to the long-term average.
The beginning of the meteorological summer is calculated from the date of a steady transition of the average daily temperature through 15 degrees upwards and this date does not coincide with the calendar date. That is, today is the first day of summer on the calendar, but in fact in our area it comes on average a week later – June 7-8.
Before we talk about what weather we expect from next June, let’s draw its “climate portrait”, or, in other words, those long-term average values of the meteorological parameters that are typical of the first summer month.
The average monthly air temperature in June in St. Petersburg is 16.1 degrees, the monthly rainfall is 69 mm. (Let me remind you that new climate rules were introduced in April, “focusing” on the period from 1991 to 2020). The average daily air temperature is 20.6 degrees, the average night temperature is 11.9 degrees. The total duration of sunshine is 254 hours.
The last “touches on the portrait” are extreme temperature indicators. According to long-term data, in St. Petersburg, the absolute minimum air temperature was recorded on June 2, 1930 and rose to just 0.1 degrees Celsius and the highest temperature – 35.9 degrees – was recorded on June 23, 2021.
On the threshold of summer, which we all expect, although our ambitions are not always rewarded with favorable weather. Something that is not unusual in our climate. So this June, we will repeatedly witness its sharp whims …
For most of the month, weather will occur under the influence of cyclone regions, which are associated with increased cloudiness, rain and low temperature backgrounds, and in cyclone (or high pressure field) regions, which are affected. with reduced cloud cover, interruption of rainfall and significant daily heating.
Therefore, dry and hot periods will alternate with periodic short-term rainfall and slight cooling.
In the first and second decade of the month, the prevailing temperatures during the day are forecast to range from 15 to 20 degrees, but on some days the heating can reach 21-26 degrees. The prevailing night temperatures are expected to range from 9 to 14 degrees, but in the suburbs some nights the air temperature may drop to 5-8 degrees.
In the third decade the temperature background will rise slightly, but the weather will remain unstable.
The average monthly air temperature is expected to be close to the climatic norm. It is predicted that the anomaly (deviation from the rule) will not exceed plus or minus 1 point. The monthly amount of rainfall is likely to be slightly below normal or close to normal.
And in conclusion, I want to say that the monthly forecasts are justified on average 65 – 75%. At the current level of development of science, these numbers are the limit. Therefore, if readers make some important decisions based on these assumptions (which, of course, are correct and prudent), the risks that in a quarter of cases they may not be justified should also be taken into account.
I must remind you once again, as I read in the media the wishes of some citizens that meteorologists be held criminally liable for unfulfilled forecasts.
I want to emphasize that the term “forecast” itself is a scientifically based probabilistic judgment about the future state of the object of study. Our interest in all kinds of forecasts (and not only in meteorological forecasts) is due to the desire to know the events of the future, and this, taking into account probabilistic, statistical, empirical laws, is in principle 100% impossible. Please think about it.
The material was published in the newspaper “Saint Petersburg Vedomosti” No. 97 (7180) of 01/06/2022 with the title “Summer is not according to the calendar”.