The analysis of measurement data from synoptic stations shows that this year’s April can, for now, be considered an extremely thermally warm month, with an average area air temperature anomaly compared to long-term conditions of +3.4°C (as of April 21, 2024). Positive anomalies are recorded throughout the country. The lowest temperatures occur in the north in Hel (+2.6°C), the highest in Lesko (+4.3°C), and in the rest of Poland they exceed +3.0°C.
As part of the test work aimed at launching a climatological service at IMWM-PIB, aimed at providing the public with information on climatic threats, an attempt was made to relate the thermal conditions forecast for April 23 (minimum temperature) at selected synoptic stations to the characteristics (average value, quantiles 5 % and 95%) from the period 1991-2020. This type of analysis allows you to easily determine the degree of uniqueness of the forecast conditions, including the probability of their occurrence.
Forecast of the minimum air temperature on April 23, 2024 against the background of long-term conditions (1991-2020)
If we look at average (1991-2020) thermal conditions at the beginning of the third decade of April (April 23), then in this period (excluding mountain and foothill stations: Kasprowy Wierch, Śnieżka, Zakopane) we should expect a minimum temperature of 1.8° C (Białystok) to 7.2°C (Zielona Góra). Meanwhile, the forecasts (from April 22, 2024) for April 23 indicate that the minimum temperature values (TMIN) will be much lower than average. At 40 stations, minimum temperatures lower than or equal to 0°C can be expected. The lowest TMIN value (-6°C) will occur in Jelenia Góra and Kłodzko. At 28 stations (65%), TMIN anomaly values will fall below -5°C. The highest negative anomaly is expected in Zielona Góra (-10.2°C). At 23 stations (53%), the TMIN values will not exceed the multiannual value of the 5% TMIN quantile. With some simplification, it can be stated that such low TMIN values are recorded at these stations on average once every 20 years (the probability of exceedance is 95%).
On April 23, temperatures throughout the country were much lower than expected
Comparison of the predicted TMIN values from the ALARO model (forecast of April 23, 2024) with long-term characteristics allows us to conclude that throughout the country we will experience values that are much lower than expected values. We expect negative anomalies exceeding 4°C in most parts of the country. It should be emphasized that in the west the anomaly values will fall below -8°C. The analysis of the TMIN forecast in relation to the value of the 5% TMIN quantile over a multi-year period indicates that in the western, southern, north-western and locally north-eastern parts of the country we can expect TMIN values to occur less frequently than once every 20 years.
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