Highlights: South western regions of the country experienced heavy rainfall during the latter part of previous week from 9th–15th November. The highest rainfall of 100 mm for the period was recorded in Imaduwa region on 14th. Minimum temperature of 15 OC was recorded from Nuwara Eliya district while most parts of the island recorded a maximum temperature between 30-35 OC .Up to 20 km/h north easterly winds were recorded in the southern region of the country. For the period after the 16th, November the NOAA NCEP model predicts up to 135 mm of rainfall for Sri Lanka outside the South with highest values in the North, East, North-Central regions.
Weekly Monitoring:On 9th up to 20 mm rainfall was received in Madampe region. On 10th western sea, adjacent to Colombo and Gampaha districts received up to 50 mm rainfall. On 11th Haputale, Bandarawela and Ella areas of Badulla district and Wellawaya, Buttala and Badalkumbura areas of Monaragala district including eastern sea adjacent to Trincomalee received up to 20 mm rainfall. On 12th Gampaha district received up to 50 mm rainfall while Colombo, Galle and Kalutara districts received up to 30 mm rainfall. Up to 20 rainfall was received in Kalutara, Ratnapura, Badulla, Kandy, Nuwara Eliya, Kilinochchi and Jaffna districts including several areas of Mullaitivu, Monaragala and Matara districts. On 13th surrounding areas near the district border of Kurunegala and Kandy received rainfall up to 30 mm. On 14th surrounding areas of Imaduwa of Galle district and Telijjavila of Matara received up to 100 mm rainfall while Hambantota district received up to 50 mm rainfall. Kalutara, Ratnapura, Monaragala and Polonnaruwa districts received up to 20 mm rainfall. On 15th Colombo, Matara and Ratnapura districts received up to 70 mm rainfall while Gampaha, Kegalla, Kalutara districts received up to 50 mm rainfall. Galle and Kandy districts received up to 30 mm rainfall. For the past week, the RFE 2.0 tool shows rainfall up to 100 mm in Colombo, Ratnapura, Kegalla, Galle and Matara districts. Up to 75 mm of rainfall is shown for Gampaha, Kalutara, Kegalla and Hambantota districts. Up to 50 mm rainfall is shown for Puttalam, Kurunegala, Kandy, Matale, Badulla and Nuwara Eliya. Up to 25 mm rainfall is shown for the rest of the country. It also shows an above average rainfall of 25-50 mm in Colombo, Kalutara, Galle and Matara districts. Below average rainfall of 50-100 mm is shown for Monaragala, Batticaloa and Ampara districts, and 25-50 mm for most parts of the island.
Monthly Monitoring: Below average rainfall conditions were experienced in the entire island in the month of October except for coastal regions of Galle district, where monthly average rainfall amount to 450 mm/month. Rainfall did not exceed 210 mm/month for the rest of the island. The CPC Unified Precipitation Analysis tool shows ~100 mm of total rainfall in Gampaha, Colombo, Ratnapura, Galle, Matara, Anuradhapura, Mannar, Vavuniya,, Matale, Kandy and Nuwara Eliya districts ; and ~25 mm of total rainfall in Ampara, Badulla, Monaragala, Kegalla and Jaffna districts.
From 6th–12th November the lowest temperature of 10-15 OC was recorded in Nuwara Eliya. The maximum temperature recorded in Kandy, Badulla, Kegalla and Ratnapura regions was between 25-30 OC. The maximum temperature range in rest of the country was 30-35 OC. During this period an above average temperature of 0-1 OC was recorded by the western, eastern and south eastern regions. Rest of the island experienced an above average temperature of 0-3OC.
AAt 850 mb level up to 20 km/h north easterly wind was experienced by the southern region of the island. The rest of the country experienced wind in the same direction with speed less than 15 km/h. At 700 mb level southern and central regions experienced north easterly winds with a speed of up to 20 km/h while rest of the country experienced winds with a speed less than 15 km/h in the same direction.
Pacific seas state: November 10, 2016
During early November 2016 the tropical Pacific SST anomaly was slightly cooler than -0.5C, the threshold for weak La Niña. Also, most of the atmospheric variables across the tropical Pacific have been consistent with weak La Niña conditions. The upper and lower atmospheric winds have been suggestive of a strengthened Walker circulation, and the cloudiness and rainfall have also been consistent with weak La Niña conditions. The collection of ENSO prediction models indicates SSTs near or slightly cooler than the threshold of La Niña during the remainder of fall, persisting through mid-winter, then weakening to cool-neutral by later winter. .(Text Courtesy IRI)
Indian Ocean State
0.5 O below average sea surface temperature was observed in the southern sea of Sri Lanka.
14-day prediction: 14-day prediction: From 16th-22nd November, the NOAA NCEP models predicts total rainfall, more than 135 mm for Northern, North Central and Eastern provinces including Kurunegala, Matale, Badulla, Colombo and Monaragala districts; 125-135 mm in Puttalam and Kandy districts; 115-125 mm in Gampaha, Nuwara Eliya, Ratnapura, Galle and Kegalla districts; and total rainfall between 115-105 mm is expected in Matara and Hambantota districts. For the period 23rd-29th November total rainfall more than 135 mm is expected in Colombo, Kegalla, Ratnapura , Kurunegala, Matale, Polonnaruwa, Trincomalee and Galle regions. Total rainfall more than 95 mm is expected in rest of the country.
Weekly prediction: : IMD GFS model predicts rainfall between 20-40 mm in Batticaloa and adjacent sea regions on 17th. Rainfall between 1-10 mm is expected for the rest of the island. On 18th rainfall between 1-10 mm is expected for the entire country except for surrounding regions of Yala. On 19th and 20th Ratnapura region expected to receive40-70 mm rainfall while north western, eastern and south eastern coastal regions expected to receive 20-40 mm rainfall. Rest of the country expected to receive 1-10 mm rainfall. Adjacent western and eastern sea regions are expected to receive rainfall between 70-130 mm on 20th. On 21st rainfall is expected to be increased with northern coastal regions also receiving rainfall between 40-70 mm and adjacent western sea receiving rainfall between 130-200 rainfall. On 22nd surrounding areas of Ratnapura is expected to receive rainfall between 70-130 rainfall while eastern and western coastal regions expected to receive 20-40 mm rainfall. Rest of the island is expected to receive rainfall between 1-10 mm. On 23rd rainfall between 40-70 mm is expected in Kandy and Nuwara Eliya including western, eastern and southern sea regions. Rainfall between 20-40 mm is expected for rest of the central and northern regions of the country while rest of the island expected to receive 1-10 mm rainfall.
IMD WRF Model Forecast & IRI forecast:According to the IMD WRF model up to 124 mm of rainfall is expected in Trincomalee and Polonnaruwa districts on the 18th. Matale, Batticaloa and Anuradhapura regions are expected to receive up to 64 mm rainfall with rest of the central and northern regions of the island expected to receive up to 35 mm rainfall. On 19th rainfall is expected to be increased with Ampara district also receiving rainfall up to 124 mm and, Ratnapura and Mullaitivu regions experiencing rainfall up to 64 mm. Matara and Galle districts are also expected to receive up to 35 mm rainfall.
Seasonal Prediction:As per IRI Multi Model Probability Forecast for November to January 2017, the total 3-month precipitation shall be climatological for the whole island. The 3-month temperature has more than 70-80% likelihood in the entire country of being in the above-normal tercile during this period.
NOAA CPC GFS model predicts 35-40 OC maximum temperature in Hambegamuwa area of Monaragala district. The maximum temperature for the rest of the island will range between 30-35 OC.For the same period minimum temperature is expected in Nuwara Eliya, Kandy, Ratnapura and Badulla to be between 15-20 OC.
The 850 mb level and 700 mb predict up to 30 km/h north easterly wind for northern and central regions of the country. Up to 20 km/h wind in the same direction is expected for the rest of the country.
MJO based OLR predictions
MJO shall not have a significant impact on the rainfall in Sri Lanka for the next 5 days and shall enhance the rainfall during the following 10 days.