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Summer or Dry season starts end of March; El Nino has 50-60 percent chance, says PAGASA

By Christopher Lloyd Caliwan & Antonette B. Tagnipez

MANILA, Feb. 22 (PNA) – The Philippine Atmospheric, Geophysical and Astronomical Service Administration (PAGASA) said that the country is expected to experience the dry or summer season starting end of March of this year.

“As of now, we are in the neutral season when we experience the average temperature. By end of March until May of this year, we will be experiencing the dry or summer season,” PAGASA weather forecaster Alvin Pura told the Philippines News Agency (PNA) in an interview.

He added that Filipinos will expect warmer days as the state weather bureau will officially declare the onset of the dry or summer season if the “cold” northeast monsoon has ended and the easterlies or warm winds from the Pacific Ocean are in effect.

Pura said the termination of the northeast monsoon was the agency’s primary indicator on the onset of summer.

The northeast monsoon or “hanging amihan” is the cold wind from Siberia that blows into the country, usually from mid-October until March.

According to Pura, the criteria on the onset of summer seasons were gradual increase of the daily air temperature expected over most parts of the country in the coming days, and weather conditions will be mostly hot and sunny associated with warm and humid air.

During summer months, Pura said the easterlies and the high-pressure area (HPA), which is the opposite of a low pressure area (LPA), will be the dominant weather systems in the country.

He noted that once the northeast monsoon stops blowing, the easterlies will start to come in, signaling the start of the dry season.

He added that the North Pacific HPA, which is a weather system consisting of warm air circulating over the Pacific Ocean, is the one that blocks the entry of the northeast monsoon towards the country.

He said this North Pacific system would become more active during these times of the year.

With the presence of a ridge of the North Pacific HPA that extended north of the country, he noted that wind pattern shifted its direction from northeasterly to easterly.

“And this shift in wind pattern signifies the start of warmer days,” he explained.

Pura added that both the HPA and the easterlies will bring high temperatures and good weather conditions to the country.

During summer months, he said, temperatures in the country could climb up.

However, he noted that passing rains, especially in the afternoon or evening, is still possible due to localized thunderstorms or convections.

Citing climatological record, Pura said the dry or summer season in the country usually lasts until middle of June.

Last year, 2014, PAGASA reported the start of dry season last March 26 as the cool northeast monsoon, known as Amihan, has receded.

Meanwhile, Pura said there is a 50 to 60 percent chance of El Niño to happen in the country.

According to Pura, PAGASA has been continuously monitoring the possible development of an El Nino event since May 2014. El Niño is characterized by unusually warm sea surface temperatures (SSTs) at the central and eastern equatorial Pacific (CEEP).

The established threshold of SST anomaly for an El Niño condition is +0.5°C or higher persisting for five consecutive overlapping three months.

Based on the PAGASA advisory, the current status of El Niño Southern Oscillation (ENSO) is still at neutral state. However, since August-September-October Season, PAGASA has noted the occurrence of dry condition in some areas of the country as a result of anomalous atmospheric conditions associated with the continuous warming of the SST over the CEEP.

During the month of October and up to the remaining days of November, some parts of the country will experience drier than normal rainfall conditions particularly over northern Luzon.

With these developments, and considering indications obtained from climate forecast generated from computer models, a general increase in the number of dry days is expected in the coming months. This may lead to possible occurrence of dry spell in some areas affecting irrigation and household water supplies. Dry spell is described as three (3) consecutive months of below normal (41%-80%) rainfall condition.

PAGASA will continue to closely monitor this event and will issue climate outlook in areas where dry spell will likely develop and/or intensify, as appropriate.

Pura said that there is still no projection suggesting that the country will be experiencing the El Nino phenomenon but the weather analyst gave the public some instructions to do during the dry season.

“Please conserve water. Do not go outside your house from 10 a.m. to 4 p.m. if there are no necessary things to be done outside. But basically, it is advisable to stay inside to avoid implications in skin because of heat,” Pura advise the public.

Skin diseases were one of the six common summer diseases listed by the Department of Health (DOH) along with sunburn, flu, sore eyes, stomach ailments and rabies.

He said the El Niño affects the normal rainfall pattern in the country, generally resulting in reduced rainfall.

He added El Nino brings lesser rains but heavier rainfall, with the phenomenon usually occurring every two to nine years.

Pura noted the country could still experience normal number of tropical cyclones and the occurrence of El Niño would cause the behavior of tropical cyclones to become erratic, affecting its tracks and intensity. The tropical cyclone tracks are expected to shift northward and its intensity could become stronger.

El Niño was in effect when Typhoons Ondoy and Pepeng ravaged parts of the country in 2009 and 2010. The El Niño started roughly in July 2009, but the drought was only felt in the last quarter of 2009 until the first quarter of 2010.

El Niño is the abnormal warming of the Pacific Ocean associated with below normal rainfall.

The government is closely monitoring the phenomenon as it could adversely affect the volume of rainfall and reduce water supply in dams for power and irrigation. (PNA) By CTB/CLTC//Antonette B. Tagnipez (OJT)

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