Wednesday, October 31, 2012

Experimental Climate Monitoring and Prediction for Maldives – October 2012

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After a wet August, rainfall continues to decrease in the first half of October in North and Central islands of Maldives and drought conditions continue to persist. In contrast, the Southern islands received highest recorded rainfall in September for the last 5 years. For the October-December season, wetter conditions are predicted for central Maldives and near-normal conditions are predicted for the southern regions. Warmer than average conditions driven by the warm Arabian Sea surface conditions shall be felt throughout the Maldives.  

Image: Sea Surface Temperature Anomaly, 7-13 of October 2012

 Image: Rainfall in Southern Maldives (Black) compared to the last five years.



Monthly Climatology: 

The climatology refers to the average conditions experienced historically for a given month. Usually the climatology is a good guide to what one may expect in a given month absent other information.  The historical average rainfall for the Northern islands is high in July (200-250 mm), higher in August (250- 300 mm) and drops in September & October (100- 200 mm).  In the Central islands rainfall is usually moderate (150- 200 mm) during the August – October period. Heavy rainfall is typical for the Southern islands during these four months. The winds over the Northern & Central islands are usually westerly (from West to East) and wind speeds are expected to be high. For Southern islands, low wind speeds are expected for July and August but stronger westerly winds in September and October.


Weekly Monitoring: 

During 11th to 16th of October, 0-20 mm rainfall was observed over entire Maldives. Islands in the South received more rainfall than Islands in the North.

Monthly and Seasonal Monitoring:

In North and Central islands of Maldives, the amount of rainfall received continues to drop after experiencing heavy rains in August. The rainfall deficit also continues to increase. But in Southern islands, highest amount of rainfall in this year was observed in October and it has been increasing gradually in past two weeks. This amount of rainfall is in fact the highest reported among other Octobers in last 5 years. The rainfall deficit in this region has also decreased.

Sea Surface Temperatures and ENSO state: 

In the Pacific, the ENSO state has moved towards an El Nino state. The unusually warmer sea surfaces of the Arabian Sea/Central Western Indian Ocean are stronger than normal during El Nino periods. Past work has shown that these conditions lead to lower than average rainfall in Sri Lanka and Northern and Central Maldives upto September followed by be higher than average for October to December.


Weekly Rainfall Forecast: 

Dry conditions are expected for Maldives for the period of 17th -22nd of October 2012.

Seasonal Rainfall and Temperature Prediction: 

As per IRI Multi Model Probability Forecast for October 2012 to February 2013, there is a 40- 60% probability for precipitation to be above normal. Furthermore, there is 40- 70% probability for Temperature to be above-normal.

Pacific Seas State 18th October, 2012

More than 80% of the ENSO prediction models predict El Nino SST conditions during the September- November season, continuing into Northern winter 2012-13. Among those predicting El Nino, very few predict more than a weak event.
(Text Courtesy IRI)

Indian Ocean State 30th October, 2012

The tropical Indian Ocean shows unusually warm anomalies in the Arabian Sea and at the same latitudes to South of the Equator. The Indian Ocean Dipole shows a warm positive phase. These are likely to alter climate drastically.

Inside this Issue

1.       Monthly Climatology
2.       Rainfall Monitoring
a.       Daily Satellite derived Rainfall Estimates
b.      Monthly Rainfall derived from Satellite Rainfall Estimate
c.       Monthly and Seasonal Monitoring
d.      Weekly Average SST Anomalies
3.       Rainfall Predictions
a.       Weekly Predictions from NOAA/NCEP
b.      Seasonal Predictions from IRI




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