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A summary for Sri Lanka of last weeks weather and climate, a review of the rainfall, temperature over land and sea, and a suite of predictions from 3 days, 7-14 days, monthly and seasonal for rainfall and temperature. Our summary is below and the links direct you to details.

Note, while we provide a synthesis from reputed outlets and conduct validation, this is a research product developed and ope rationalized over the last decade for water management by the MASL years and it is experimental. Please add this email address and fectsl@gmail.com to your contact list. Background on this report is available (Click Here). If you wish to subscribe Click Here
 
 
Maldives

Highlights

Up to 40 mm rainfall was observed in northern, north eastern, western, south western and southern regions of the country during the time period 29th September- 5th October. Southern region of Anuradhapura received heavy rainfall up to 110 mm on 25th September and rainfall up to 70 mm was observed in Badulla on 1st October and in Moneragala on 2nd October. Every prediction model predict increase of rainfall during the next week.
 

Contents and Links to Sections

1.Monitoring

Weekly Monitoring During 29th September – 5th October, few regions of the country received heavy rainfall. On 29th September heavy rainfall up to 110 mm was observed in southern region of Anuradhapura and in the ocean near Jaffna while rainfall up to 40 mm was observed in Hambantota. On 30th September Trincomalee, Galle and ocean near Colombo received rainfall up to 40 mm. On 1st October only Badulla received rainfall up to 70 mm and northern region of Moneragala received rainfall up to 70 mm on 2nd October. No rainfall was observed in any part of the country on 3rd October. Rainfall up to 90 mm was observed in Jaffna on 4th October while Ratnapura received rainfall up to 60 mm and Galle and Kalutara received rainfall up to 40 mm. No rainfall was observed in any part of the country on 5th October.

Weekly Monitoring
Image caption:- observed satellite rainfall of 3rd and 4thClick Here - for  maps in pdf.

Monthly Monitoring: : In September 2015 the entire country received above average rainfall while the ocean near northern and eastern provinces received below average rainfall.

Monthly Rainfall MonitoringImage caption:- The figure in the left shows the average observed rainfall in the previous month. The rainfall anomaly in the previous month is shown in the figure to the right. The  brown color in the anomaly figure shows places which received less rainfall than the historical average while the green color  shows places with above average rainfall. Darker shades show higher magnitudes in rainfall Click Here for  maps in pdf.

Satellite Derived RainfallImage caption:- Dekadal (10 Day) Satellite Derived Rainfall Estimates
Click Here for  maps in pdf.


Weekly Average SST Anomalies

Image caption:-Weekly Average SST Anomalies
Click Here for  maps in pdf.


2.Predictions
14 day predictions: NOAA NCEP models predict relatively high rainfall in south western region of the country compared to the rest of the country during 7th - 13th October. Total rainfall up to 85 mm is expected during the week in the south western region and total rainfall up to 55 mm is expected in the north eastern region. Rest of the country shall receive total rainfall up to 45 mm. These models predict the rainfall shall be increased significantly during 14th- 20th October and total rainfall up to 135 mm is expected in western region, total rainfall up to 125 mm is expected in north western, eastern and southern regions and the rest of the country shall receive total rainfall up to 95 mm.

NCEP GFS 1-14 Days Prediction
Image caption: NCEP GFS 1- 14 Day prediction
Click Here for  maps in pdf.

IMD WRF &IRI Model Forecast: WRF Model Forecast(From IMD Chennai)

According to the IMD WRF model rainfall up to 35 mm is expected in Trincomalee on 9th October and any significant amount of rainfall is not expected for the rest of the country. Any part of the country shall not receive significant amount of rainfall on 10th October as well. IRI CFS models predict total rainfall up to 100 mm in south eastern region of the country during 7th - 12th October.
 

Image caption:-WRF Model Forecast (from IMD Chennai)
Click Here for  maps in pdf.

Weekly Rainfall Forecast
Weekly Rainfall ForecastImage caption:Total rainfall forecast from the IRI for next  six days is provided in figures below. The figure to the left  shows  the  expectancy  of  heavy  rainfall  events  during these six days  while  the  figure  to  the right is the prediction of total rainfall amount during this period.
 

Click Here for  maps in pdf.
Seasonal Prediction: As per IRI Multi Model Probability Forecast for October to December, the total 3 month precipitation has 50% likelihood of being above average. The 3 month temperature has more than 70-80% likelihood in the entire country of being in the above-normal tercile during this period.

Seasonal Rainfall and Tempreature
Image caption: Following is the latest seasonal precipitation and temperature prediction for the next 3 months by the IRI. The color shading indicates the probability of the most dominant tercile -- that is, the tercile having the highest forecast probability. The color bar alongside the map defines these dominant tercile probability levels. The upper side of the color bar shows the colors used for increasingly strong probabilities when the dominant tercile is the above-normal tercile, while the lower side shows likewise for the below-normal tercile. The gray  color indicates an enhanced probability for the near-normal tercile (nearly always limited to 40%)
Click Here for  maps in pdf.

PACIFIC SEAS STATE(Text Courtesy IRI)
During late August through early September 2015 the tropical Pacific 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 September-November 2015 season in progress. Some further strengthening into later fall is possible, with the event lasting well into spring 2016.

INDIAN OCEAN STATE
Neutral sea surface temperature was observed around Sri Lanka.

MJO STATE
MJO is weak and therefore significant impact on rainfall is not expected.

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