METEOROLOGISCHE DIENST SURINAME

NATIONAAL METEOROLOGISCH CENTRUM

J.A. PENGEL AIRPORT, ZANDERIJ (TEL:035206/0325190)

Short report on the weather pattern of May 2021

Primarily the Inter Tropical Convergence Zone, now and then enhanced by westward moving low level wave was responsible for rainfall during the month May.

May can frequently be considered as the wettest month of the great rainy season. Abounded of moisture within the atmosphere and slow northward migration of the Inter Tropical Convergence Zone across the interior contributes to heavy rainfall over a large area.

May 2021 completely support the above statement.

A weak to neutral La Nina episode also contribute to an enhance precipation pattern in Suriname this year.

The Figure below illustrates the impact of La Nina on the weather world wide, but in this case emphasis should be placed on the northeast of Brazil, Suriname and French Guiana.

Extract of the daily monitoring on the weather in May 2021

Atmospheric dynamics On May 4 th 2021

Upper/mid level trough approaching Suriname from the west resulting in blocking pattern, as an induced low level wave starts to develop across the far Atlantic.

Low level moisture from Leading edge of approaching wave now entering French Guaiana and Suriname. Convection within the southeast quadrant of WBS area is behind the wave axis.

Wind pattern indicate trough and wave influence Atmospheric dynamics

On May 28 th 2021 at 0600lt

Wind field suppots a wave system with axis running across Suriname.

Conclusion

The weather in May 2021 was dominanted by the Inter Tropical Convergence Zone, low level waves or TUTT. Rainfall amount from rain guages measurements are attach to support evidence.

There is a relatively small devitation in rainfall amount when compare results
between the coastal area and the interior.

Since rainfall amount is not the only factor causing local flooding within the interior, it is wise to consider other factor by closely study the area near the southern border. It is also possible that heavy rainfall occur outside the rain gauges.

Figure below is an analysis of rainfall amount perform by INPE INMET Brazil. which prove significant rainfall across the northern part of Brazil, especially along the border between Brazil, Suriname and French Guiana.

In general local flooding across Suriname are also enhanced by the large mass of ocean water which is moved by the northeast trade towards the coastal area of Suriname. This phenomenon prevents water levels in the rivers to drop significantly, resulting in accumulation of surface water on land.

The Text of this short report was compiled by R.Oehlers