New Delhi, May 16 (PTI) Partly cloudy sky led to a marginal dip in the maximum temperature in Delhi on Monday though it was still two to four notches above normal.At the Safdarjung Observatory, Delhi"s base station, the maximum temperature settled at 42.4 degrees Celsius, two notches above normal. It was 45.6 degrees Celsius, the highest this year so far, on Sunday.The automatic weather stations at Najafgarh, Mungeshpur, Sports Complex, Jafarpur, Ayanagar, Pitampura and Ridge recorded a maximum temperature of 44.7 degrees Celsius, 44.4 degrees Celsius, 44 degrees Celsius, 43.9 degrees Celsius, 43.4 degrees Celsius, 43.3 degrees Celsius and 43.1 degrees Celsius, respectively.   The India Meteorological Department (IMD) said a thunderstorm or a dust storm may bring the mercury down by a few notches on Tuesday.  On Sunday, Delhi saw a tormenting heatwave pushing the mercury to 49.2 degrees Celsius at Mungeshpur in northwest Delhi and 49.1 degrees Celsius at Najafgarh in the southwest parts of the city.Maximum temperatures had reached unbearable highs of 48.4 degrees Celsius at Sports Complex, 47.5 degrees Celsius at Jafarpur, 47.3 degrees Celsius at Pitampura and 47.2 degrees Celsius at Ridge.The temperature will start rising again on Wednesday and may hit the 45-degree mark on Friday, the IMD said.  The Met office has issued a "yellow" alert warning of a heatwave in parts of the city on Friday.The capital may witness light rain, thunderstorm and gusty winds under the influence of a fresh western disturbance on Sunday. PTI GVS TDS TDS