The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said the intense heat that Metro Manila felt last Wednesday helped bring about the long-awaited rains in the metropolis and the hailstone shower in Imus, Cavite.

According to PAGASA weather forecaster Gener Quitlong, the rains in some parts of Metro Manila, Bulacan, and Cavite were caused by the intense heat evaporation last Wednesday when the metropolis registered the “hottest day of the year” at 37.3 degrees Celsius.

“Due to the intense heat evaporation, heavy rain clouds and localized thunderstorms were formed, resulting in a downpour,” Quitlong said in an interview.

The PAGASA satellite showed that there are still some cloud formations over the National Capital Region (NCR) that are expected to bring isolated rainshowers and thunderstorms until Friday afternoon, he said.

Meanwhile, PAGASA senior weather forecaster Robert Sawi said the occurrence of hail, as what happened in Imus, is not unusual in summer.

Hail is often associated with thunderstorms and is formed during the summer months, particularly in the afternoon and evening hours.

“It is common that when there is a thunderstorm, the rain falls down faster, thus the raindrops are unable to condense to water, hitting the ground in large chunks,” Sawi told the Manila Bulletin.

“Hail is possible with most thunderstorms, produced by cumulonimbus clouds (thunderclouds). The main composition of rain drops is ice crystals. That is why when the rains fell rapidly, they did not liquefy,” Sawi said.

Quitlong said the rains in Metro Manila and nearby provinces were not brought about by the low pressure area (LPA) in Palawan.

He said the LPA spotted in Puerto Princesa City in Palawan is expected to dissipate within 24 to 48 hours.

PAGASA’s 5 a.m. weather bulletin last Thursday said a cold front is affecting extreme Northern Luzon, which will bring to Northern and Central Luzon mostly cloudy skies with scattered light rains.

Meanwhile, the rest of the country will be partly cloudy to cloudy with isolated rainshowers or thunderstorms, mostly in the afternoon or evening.