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PAGASA-DOST Presscon - 04 October 2010 Amihan Conference Room

PAGASA-DOST Presscon - 04 October 2010 Amihan Conference Room. SST Evolution in the Tropical Pacific. Period: 07 July – 22 Sep 2010. SST: Oceanic Indicator:.

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PAGASA-DOST Presscon - 04 October 2010 Amihan Conference Room

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  1. PAGASA-DOST Presscon - 04 October 2010 Amihan Conference Room

  2. SST Evolution in the Tropical Pacific Period: 07 July – 22 Sep 2010 SST: Oceanic Indicator: Weekly averaged sea surface temperatures (left, °C) and anomalies (right, °C) for the past twelve weeks.  SST analysis is the optimum interpolation (OI) analysis, while anomalies are departures from the adjusted OI climatology (Reynolds and Smith 1995, J. Climate, 8, 1571-1583).

  3. SOI: Atmospheric Indicator: SOI is above La Niña thresholds The SOI has remained firmly positive and fairly steady in value for the past two weeks. The latest (27 September) 30-day SOI value was +25; the monthly value for August was +19. The SOI has been consistently positive since early April. Source: BOM, Australia

  4. NOAA Operational Definitions forEl Niño and La Niña El Niño: characterized by a positive ONI greater than or equal to +0.5°C. La Niña: characterized by a negative ONI less than or equal to -0.5°C. By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons. CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 SST departures meet or exceed +/- 0.5°C along with consistent atmospheric features. These anomalies must also be forecasted to persist for 3 consecutive months.

  5. ONI (Oceanic Niño Index) Red – El Niño Blue – La Niña Black - Neutral

  6. Global Advisories

  7. Recent ENSO Conditions: (Sept. 2010) • All key indicators of ENSO (cooler than average sea surface temperatures and the persistently stronger than average low-level winds, coupled with above average values of the Southern Oscillation Index (SOI), are at levels typical of La Niña. Expected Conditions: • Based on recent trends and model forecasts, La Niña is likely to persist up to the early part of 2011.

  8. Actual Rainfall

  9. Actual Seasonal Rainfall July-August-September (JAS) 2010 Normal (mm)(1971-2000) Actual (mm) % Normal

  10. Actual Rainfall for September 2010 September 2010 Normal (mm)(1971-2000) Actual (mm) % Normal

  11. Monthly Rainfall (June - September 2010)

  12. Forecast Rainfall

  13. Rainfall Forecast Range in % of Normal per Province (Oct – Dec 2010)

  14. TC Forecast

  15. Average TC Tracks (4th Quarter) November The period covers the first half of the NE monsoon season. Tracks of tropical cyclone during this period are likely across central and southern parts of Luzon, and Visayas with secondary tracks over Northern Mindanao. October December

  16. Summary: • La Niña is expected to bring more than average (above normal) rainfall in most parts of the country during the OND season, based on the forecast. • Expected number of tropical cyclones (TCs) on the remaining months (Oct-Dec) are about 5-8. Average tracks during OND season - likely across Central and Southern Luzon and Visayas.

  17. Summary: • Precautionary measures should be done by all concerned agencies against possible flooding, flashfloods and landslides in preparation for the expected La Niña to affect the country in the coming months. ***PAGASA will continue to monitor the development of the La Niña and the day-to-day associated rainfall/weather conditions that will affect the country. Updates will be issued as necessary.

  18. THANK YOU… http://www.pagasa.dost.gov.ph “tracking the sky . . . helping the country”

  19. IMPACTS OF ENSO ON PHILIPPINE RAINFALL Legend: Severe drought impacts Drought impacts with major losses Moderate drought impacts Near normal to above normal condition Way above normal condition Potential for flood damage Severe flood damage REDcolored years areEL NINOyears, BLUE colored years are LA NINA years and BLACK colored years are NON_ENSO years

  20. Historical El Niño and La Niña Episodes Based on the ONI computed using ERSST.v3b NOTE: After updating the ocean analysis to ERSST.v3b, a new La Niña episode was classified (ASO 1962- DJF 1962/63) and two previous La Niña episodes were combined into one single episode (AMJ 1973- MAM 1976).

  21. Rainfall Forecast Range in mm. per Province (Oct – Dec 2010)

  22. Reanalysis of Vector Wind Composite Anomaly (Jun - Aug) Source: ESRL (Earth System Research Laboratory)

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