Wednesday, August 26, 2015

Experimental Climate Monitoring and Prediction for Maldives – August 2015


Heavy rainfall was observed over the entire Maldives in July/ early-August 2015. This is the highest observed monthly rainfall this year. Due to this heavy rainfall the cumulative deficit of rainfall has come down to about 9% in northern islands and central islands and there is no deficit in southern islands. NOAA CFS models predict heavy rainfall in southern and central islands until the end of August while IRI seasonal predictions say that there shall be above average rainfall in the next 3 months with 80% probability. This is in keeping with what’s typical during an El Nino.

Deficit of rainfall (brown hatch) in southern islands of Maldives. High rainfall in  the first two weeks of August 2015 has diminished the gap between observed rainfall and  average rainfall.

 Printable Version of the Full Report (PDF)

---------------------------Inside this Issue------------------------

  1. Monthly Climatology
  2. Rainfall Monitoring
    1. Daily Satellite derived Rainfall Estimates
    2. Monthly Rainfall derived from Satellite Rainfall Estimate
    3. Monthly and Seasonal Monitoring
  3. Ocean Surface Monitoring
  4. Rainfall Predictions
    1. Weekly Predictions from NOAA/NCEP
    2. Seasonal Predictions from IRI



Monthly Climatology:

In July, August, September and October the rainfall is about 150 mm in northern islands and about 200 mm in central and southern islands. In July, August, September and October the entire country usually do not receive strong wind. The wind direction is usually easterly.



Weekly Monitoring:

During 8th- 22 August relatively high rainfall was observed in Maldives. Up to 60 mm rainfall was observed in Maldives on the 8th August and on the 9th the rainfall decreased down to about 10- 20 mm. Then again on the 10th up to 90 mm rainfall was observed throughout the country. On 11th, 12th and 13th southern and central islands received up to 60 mm rainfall while only light rainfall was observed in northern islands. During 14th – 16th only light rainfall was observed throughout the country. Once again up to 60 mm rainfall was observed on the 17th and 18th and thereafter until 22nd only light rainfall was observed. During 8th- 22nd August period very high rainfall was observed in the sea around the Maldives with magnitudes around 140 mm. This heavy rainfall was mostly observed in the sea south of Maldives but on the 18th the sea close to northernmost islands and well as the eastern sea received up to 140 mm rainfall.

Monthly and Seasonal Monitoring:

In July 2015 the entire country received below average rainfall except in northern islands. In northern island about 100 mm rainfall was observed in mid-July which is the highest observed rainfall in this region this year. It is also the highest amount observed in July in the past 5 years in northern islands. About 160 mm rainfall was observed in the first two weeks of August in central Maldives. This is also the highest observed rainfall this year in this region as well as the entire country. The gap between observed and expected amounts of rainfall in this region has reduced due to this heavy rain. Southern islands too received heavy rainfall reaching up to 120 mm in early-August. The rainfall deficit in this region is no longer visible.

Ocean State Monitoring:

Pacific Seas State August 20, 2015:

During late July through early-August 2015 the SST was at a strong El Niño level. All atmospheric variables support the El Niño pattern, including weakened trade winds and excess rainfall in the east-central tropical Pacific. The consensus of ENSO prediction models indicate continuation of strong El Niño conditions during the August-October 2015 season in progress. Some further strengthening into fall is likely, with the event lasting into spring 2016.

Indian Ocean Monitoring August 20, 2015: 

~1 degree Celcius Warmer than usual Sea surface temperature was observed around Maldives.


Weekly Rainfall Forecast:

According to NOAA CFS models, heavy rainfall is expected in central and south central regions in Sri Lanka which shall be about 75 mm total rainfall for six days (24th- 29th August) Very heavy rainfall is expected in the western sea of Maldives during this period.

Seasonal Rainfall and Temperature Prediction:

As per IRI Multi Model Probability Forecast for August to October, the total 3 month precipitation shall be climatological. The 3 month average temperature has a 50- 60% likelihood for northern islands and about 80% likelihood for southern-most islands to be in the above-normal tercile during this period. El Niño usually is associated with higher rainfall in the central and northern islands from October to December but lower rainfall in the southern islands until November.

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