At least one cyclonic storm may develop from the depressions in the Bay of Bengal this month, the met office said yesterday in its long-range forecast for May.

It also said that the northern and central regions of the country may experience five to six moderate to severe nor'westers or thunderstorms. Elsewhere, four to five mild to moderate nor'westers and thunderstorms are likely, it added.

The forecast was issued after a meeting of experts at the met office.

The cyclone in the Bay, if formed, would be named abc, from a panel of code names selected for the Bay of Bengal cyclones of this year, senior meteorologist and cyclone expert Sujit Kumar Dev Sharma told BSS.

Two to three moderate to severe heatwaves (38-42 degrees Celsius) may rage over the northern and central regions, the monthly weather forecast said adding that some other parts of the country may experience mild to moderate heat waves (36-40 degrees Celsius).

This month's rainfall is likely to be 10 to 20 percent in excess of average rainfall.

Although the forecast for April had said the rainfall would be 10 percent higher than average, it was actually 78 percent less than the normal average precipitations.

The reason behind this was the absence of mating of westerly and easterly pressures over Bangladesh, experts said.