Majority of the Philippines has experienced above rainfall conditions in October due to a moderate-to-strong La Niña event that is now well underway in the tropical Pacific Ocean.
Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) Administrator Vicente Malano said sea surface temperature anomalies strengthened last month.
Citing recent climate models, Malano said moderate to strong La Niña will likely persist through February, March, and April 2021.
The last time there was a strong event was in 2010-2011, followed by a moderate event in 2011-2012.
With the anticipated prevalence of a moderate-to-strong La Niña event, above normal rainfall conditions across most parts of the country may persist in the last quarter of 2020 until the early months of 2021, PAGASA said.
The possibility of floods and landslides that may affect vulnerable sectors is highly likely due to the prevailing La Niña.
In the PAGASA's rainfall assessment in October, "most parts of the country have experienced above normal rainfall conditions, except for Ilocos Norte where below normal rainfall was observed."
Of the five tropical cyclones that affected the country last month, only tropical storm "Nika" (Nangka) did not make landfall but enhanced the southwest monsoon or "habagat."
The other cyclones, tropical depression "Ofel," typhoon "Pepito" (Saudel), typhoon "Quinta" (Molave), and super typhoon "Rolly" (Goni), made multiple landfalls and brought heavy to intense rainfall that caused floods and landslides over several regions.
This month, near to above normal rainfall conditions with some patches of below normal rainfall will likely persist over a huge portion of the country.
Based on the PAGASA's historical data, one to three tropical cyclones may enter or form within the Philippine area of responsibility in November.
Siony is the first cyclone to form and make landfall this month.
The second cyclone this month may develop this weekend, which will be named "Tonyo."