The weather over the weekend and for at least the next few days of December promises to be truly winter. Much of the country will be covered with a thick layer of snow and freeze everywhere. And what awaits us in the next months? The Institute of Meteorology and Water Management (IMGW) has published a long-term experimental weather forecast for winter and early spring 2023.
Synoptics of the Institute of Meteorology and Water Management forecast that December in Poland will be recorded as a normal month both in terms of temperature and precipitation. This weekend in many regions awaits us winter attack with heavy snowfall. Frost is forecast everywhere. The temperature will not rise above zero for the next few days.
IMGW forecast for January
In the first month of the new year, the average monthly temperature throughout Poland should be within the range of the long-term standard from 1991-2020. In the north of the country, the average monthly rainfall is above normal, and in the south of the country, rainfall will be below normal. In other regions, the sum of precipitation for the whole month should be within the long-term norm.
IMGW forecast for February
Forecasters in February do not predict deviations from the norm. Throughout the country, both the average monthly temperature and the sum of precipitation will fall within the range of the long-term standard from 1991-2020.
IMGW forecast for March
The month in which spring begins is different. The average monthly air temperature throughout Poland is to be above the long-term standard from 1991-2020. As for the average rainfall, it will probably be normal everywhere.
IMGW forecast for April
April promises to be the same. The average monthly air temperature in all regions of the country should be above the long-term standard from 1991-2020. In turn, the sum of precipitation will most likely be within the norm.
What do the terms “above normal”, “below normal” and “normal” mean
In IMGW-PIB, as in other meteorological centers around the world, the average monthly temperature/precipitation sum for a given month is forecast in relation to the so-called long-term standard. Currently, the period 1991-2020 is considered.
The values of the average monthly temperature or monthly precipitation for this period are sorted from lowest to highest. The lowest 10 values indicate the temperature/precipitation in the “below standard” class, the middle 10 “normal” and the highest 10 – “above normal”.
If we are dealing with an “above normal” class, we can assume that the month will be warmer or wetter than at least 20 observed same months from 1991 to 2020. If the forecast describes it as “below normal”, it will be cooler or drier, while “normal” – similar to the 10-month averages of the comparative period.
When average temperature/precipitation is predicted:
– above the normit can be assumed that the forecast month will be warmer/wetter than at least 20 observed, same months in the years 1991-2020;
– below standardit can be assumed that the forecast month will be cooler/dryer than at least 20 observed, same months in the years 1991-2020;
– normalit can be assumed that the forecast month will be similar to the typical 10 observed, same months in 1991-2020.
How to interpret classes
IMGW forecasters warn that the forecast of the average air temperature “above the norm” does not mean that there will be, for example, only days with a maximum temperature above 10 degrees C, and the forecast “below the norm” – that we will only have days with a minimum temperature below 10 degrees C. In fact, a “below normal” average temperature forecast does not exclude days with a maximum temperature above 10 degrees C, and an “above normal” forecast – days with a minimum temperature below 10 degrees C.
Experts remind that the forecast average temperature refers to the average temperature of the entire month, both during the day and at night.
Also, the forecast of the sum of precipitation “above normal” does not mean that there will be intense rainfall and storms, and the “below normal” forecast does not rule out the possibility of such phenomena. The forecast total precipitation refers to the total precipitation for all days of the month. The type of precipitation (snow or rain) is not specified in the forecasts.
Verifiability of long-term forecasts
As emphasized by the IMGW, despite the increasing computing power of supercomputers and extensive knowledge of weather processes, errors and differences in forecasts for such a long period in the future cannot be avoided. The discrepancies result both from the risk of sudden (often local) meteorological phenomena that may disturb the forecasted weather processes, and from the very variety of physical assumptions and mathematical and statistical equations used in the forecasting models.
So far in advance it is not possible to describe the forecasted weather more accurately. It should be remembered that the forecast is indicative and experimental in nature, and that it concerns the average mileage for the entire forecasted region and the given forecasting period.
Main photo source: PAP/EPA/MICHAEL BUHOLZER / IMGW-PIB