The climatic and agroclimatic characterization of April

on the territory the Republic of Moldova

          In April, as compare to March, the average monthly air temperature has increased significantly (by 6-7ºC) and its average values on the territory if the republic are +9ºC in the Northern part and +11ºC in the Southern. Since the beginning of instrumental measurements the coldest April was recorded in 1955, when the average monthly air temperature between +5,0ºC (Briceni) and +6,5ºC (Cărpineni). The hottest April was recorded in 2000 (in the Northern part of the republic) and in1950 (in the Southern part of the republic). The average monthly air temperature in the mentioned years oscillated between +12,5ºC (Briceni, 2000) and +14,0ºC (Cahul, 1950).

          The stable transition of the average daily temperature through 10 ºC towards its increase is usually registered between 16-23 April, through 8ºC (end of heating period) – 5-13 April.

          The average daily air temperature during the month oscillated between  -1..-6ºC (in 1963) to +20..+22ºC (in 1998). The absolute minimum of the air temperature for the whole observation period on the territory of the country constitutes -14,2ºC (Soroca, 4 April 1963), and the absolute maximum +31,3ºC (Tiraspol, 6 April 1998).

          The air frosts in April are possible in average until 5-21 April, the soil frost until 22-30 April, and in some years they may be recorded even in May.

          The monthly quantity of precipitations in April constitutes 30-50 mm, and the number of days with precipitations is around 8-10 days. According to the long term observations, the highest monthly quantity of precipitations reached 172 mm (Bălăsineşti, 2008), and the highest daily quantity - 98 mm (Bălăsineşti , 2008). The precipitations are mostly in form of rain. The snow may be recorded in average until 10 April,and in some years it may be recorded even in May. The latest term for snow melting on the territory of the country is 15-27 April.

          Fogs (in average 1-4 days) and thunderstorms (1-2 days). Also, there may occur snow storms and hails, but their frequency is much reduced (no more than 1-3 occurrences in 10 years).

          The frosts and the strong winds are the mostdangerous)meteorological phenomenain April. They are registered in average once in 3 and 5 years. The intensive hails are possible in average once in 13 years, and the heavy rains – once in 20 years.

          The beginning of the active vegetation of crops is usually registered between 20-23 April in the Northern part of the republic, and between 15-18 April in the Southern part.

          The transition of the soil average daily temperature through +10°C towards its increase at a 10 cm depth is usually recorded between 9-20 April. This term indicates the optimal dates for sowing the thermophilic crops.

          The usual period for flowering of apricot tree is between 15-23 April. The bud swelling for plums, apples, pears is noticed in the first decade of April. The vineyards bud swelling is noticed between 5-22 April, when the stable average daily air temperature transits through +10°C, towards its increase.

          The sowing dates for the sugar beet are determined by the soil warming up to +7..+8°C and disappearance of frosts that may cause damage to raised plants. During the warmest springs the sugar beet sowing is carried out usually at the end of March – beginning of April, and in the coolest springs – at the end of April – beginning of May. During the sugar beet sowing period in the Northern part of the republic the humidity reserves in the plowed layer of the soil usually constitute 30-40 mm.

          The most appropriate terms for sunflower sowing are between 7-18 April (the soil warms up to +10°C). The productive humidity reserves in the plowed layer of the soil for this period are more than 20 mm everywhere.

          The most optimal dates for maize sowing are in the third decade of April. The productive humidity reserves in the plowed layer of the soil for this period are usually fine and constitute 25-40 mm.

In the last pentad of April – beginning of May the sunflower rises up, the sugar beet rise up in mass, the autumn wheat straw gets longer and the flowering of apples and pears begins.

            Chief MCMC                   T. Bugaeva

             Chief AFC                      T. Mironova