Friday, June 28, 2019

Weekly Hydro-meteorological Report, 27, June 2019

Highlights

· The IRI weekly rainfall forecast predicts up to 25 mm of total rainfall in the entire island during 25 – 30 Jun.

· Between 18 – 24 Jun: up to 20 mm of rainfall was recorded in in Kurunegala, Ratnapura and Batticaloa districts on the 24^th.

· From 19 – 25 Jun: CDAS Mean Vector Wind Total Not Available.

· 1 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

Download full report ↓

Monitoring

Weekly Monitoring: On June 18^th, Monaragala and Ampara districts received up to 5 mm of rainfall. No significant rainfalls were recorded in any part of the island on the 19^th. On June 20^th, Ratnapura district received up to 5 mm of rainfall. On the 21^st, Gampaha, Kegalle, Nuwara Eliya, Ratnapura, Matara, Galle, Kalutara and Colombo districts received up to 10 mm of rainfall; and Jaffna and Kilinochchi districts up to 5 mm. On the 22^nd, Ratnapura, Nuwara Eliya, Monaragala and Ampara districts received up to 5 mm of rainfall. On the 23^rd, Kurunegala, Batticaloa, Ratnapura and Kalutara districts received up to 20 mm of rainfall; and Polonnaruwa, Matale, Kandy, Badulla, Ampara, Monaragala, Nuwara Eliya, Kegalle, Gampaha, Colombo, Galle and Matara districts up to 15 mm.

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 10-25 mm in Batticaloa, Ampara, Kegalle, Ratnapura, Nuwara Eliya, Gampaha, Colombo, Kalutara, Galle, Matara and Kurunegala districts; and 5-10 mm in Polonnaruwa, Puttalam, Matale, Kandy, Badulla and Monaragala. Below average rainfall up to 25-50 mm is shown for Puttalam, Kurunegala, Gampaha, Colombo, Kegalle, Ratnapura, Kandy and Nuwara Eliya districts; and up to 10-25 mm in Anuradhapura, Polonnaruwa, Matale, Ampara, Badulla, Monaragala, Galle, Matara and Hambantota districts.

Monthly Monitoring: During May – Below average rainfall conditions up to 240 mm were experienced by Nuwara Eliya, Kegalle, Colombo, Kalutara, Gampaha, Kurunegala and Ratnapura districts; and up to 180 mm in rest of the island. The CPC Unified Precipitation Analysis tool shows up to 150 mm of total rainfall in Colombo, Kalutara and Galle districts; up to 100 mm in Gampaha, Kegalle, Ratnapura, Matara, Badulla, Monaragala and Galle districts; up to 75 mm in Trincomalee, Polonnaruwa, Nuwara Eliya, Ampara and Hambantota districts; and up to 50 mm in Vavuniya, Anuradhapura, Puttalam, Kurunegala, Matale and Kandy districts.

Predictions

Rainfall

14-day prediction:
NOAA NCEP models:

From 26^th Jun -2^nd Jul: Total rainfall up to 35 mm Puttalam, Kurunegala, Gampaha, Kegalle, Colombo and Ratnapura districts; up to 15-25 mm in Galle district; and up to 5-15 mm in Jaffna, Kilinochchi, Mullaitivu, Vavuniya, Mannar, Anuradhapura, Matale, Kandy and Nuwara Eliya districts.

From 3^rd - 9^th Jul: Total rainfall up to 35 mm in Puttalam, Gampaha and Ratnapura districts; and up to 15-25 mm Kurunegala, Kegalle, Galle and Matara districts.

IMD NCMWRF Forecast:

27^st Jun: Not Available.

28th Jun: Not Available.

IRI Model Forecast:

From 26^th Jun 1^st Jul: Total rainfall up to 25 mm is expected in most parts of the island.

MJO based OLR predictions:
For the next 15 days:
MJO shall suppress the rainfall in Sri Lanka.

Ocean State (Text Courtesy IRI)
Pacific sea state: June 19, 2019

SSTs in the tropical Pacific maintained a weak El Niño level during May and early June, and temperature anomalies of subsurface waters were slightly above average. Some patterns in the atmosphere show intermittent El Niño conditions. Collective model forecasts show a continuation of at least weak El Niño-level SSTs lasting through 2019. The official CPC/IRI outlook, with an El Niño advisory, calls for a 66% chance of El Niño continuing during Jun-Aug, decreasing to 50-55% for continuing through fall and winter.

Indian Ocean State

1 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

Friday, June 21, 2019

Weekly Hydro-meteorological Report, 20, June 2019

Highlights

· The IRI weekly rainfall forecast predicts up to 100 mm of total rainfall in Western province during 19 – 24 Jun.

· Between 11 – 17 Jun: up to 50 mm of rainfall was recorded in Colombo district on the 11^th.

· From 11 – 17 Jun: up to 54 km/h, westerly winds were experienced by the entire island.

· 1 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

Download full report ↓

Monitoring

Weekly Monitoring: No significant rainfalls were recorded in any part of the island on June 12^th. On June 13^th, Jaffna and Kilinochchi districts received up to 30 mm of rainfall; and Mullaitivu district up to 20 mm. On the 14^th, Colombo district received up to 30 mm of rainfall; and Puttalam, Gampaha, Kegalle, Ratnapura and Kegalle districts up to 20 mm. No significant rainfalls were recorded in any part of the island on the 15^th. On the 16^th, Kurunegala, Anuradhapura, Matale, Polonnaruwa, Batticaloa, Ratnapura and Matara districts received up to 5 mm of rainfall. On the 17^th, Vavuniya, Batticaloa, Ampara, Monaragala, Badulla, Kegalle, Colombo and Galle districts received up to 5 mm of rainfall.

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 10-25 mm in Jaffna, Kilinochchi, Mullaitivu, Puttalam, Gampaha, Colombo, Kalutara, Ratnapura, Nuwara Eliya and Batticaloa districts; and 5-10 mm in most parts of the island. Below average rainfall up to 25-50 mm is shown for Kurunegala, Kandy, Nuwara Eliya and Badulla districts; and up to 10-25 mm in most parts of the island.

Predictions

Rainfall

14-day prediction:
NOAA NCEP models:

From 19^th – 25^th Jun: Total rainfall up to 55 mm Puttalam, Gampaha, Kegalle, Colombo, Ratnapura and Galle districts; up to 35-45 mm in Kurunegala, Nuwara Eliya and Matara districts; and up to 15-25 mm in most parts of the island.

From 25^th Jun -2^nd Jul: Total rainfall up to 25 mm in Puttalam, Gampaha and Ratnapura districts; and up to 5-15 mm Kurunegala, Kegalle, Galle and Matara districts.

IMD NCMWRF Forecast:

21^st Jun: Not Available

22^nd Jun: Not Available

IRI Model Forecast:
From 22nd – 27th May:

From 19^th – 24^th Jun: Total rainfall up to 100 mm is expected in Gampaha, Colombo and Kalutara districts; up to 75 mm in Puttalam, Kurunegala, Kegalle, Tatnapura and Galle districts; and up to 50 mm in Kandy, Nuwara Eliya, Matara and Hambantota districts.

MJO based OLR predictions:
For the next 15 days:
MJO shall not have an impact on the rainfall in Sri Lanka in the next 10 days and shall suppress in the following 5 days.

Ocean State (Text Courtesy IRI)
Pacific sea state: June 19, 2019

Indian Ocean State

1 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

Tuesday, June 18, 2019

Real-time flood monitoring in Sri Lanka

By Dimithri Wijesinghe and Chenelle Fernando Read Full Article Here

The Centre for Urban Water Sri Lanka of the Metro Colombo Urban Development Project (MCUDP) has a system underway to monitor floods in real time.

According to engineer and Project Director Thushari Andra Hannadige, the real-time warning system has already been implemented through a pilot project. She said: “The project will reach full completion by June, 2020, with the completion of other factorial interventions.” These, according her, include the construction of pumping stations, tunnels, and floodgates.

We spoke to the Team Leader of the MCUDP Prof. Sri Kantha Herath about the real-time monitoring system for floods and other projects underway in order to make Colombo a sustainable city, resistant to flooding.

According to Herath, Colombo city often falls victim to urban flooding caused by excessive rains, resulting in the available drainage systems being insufficient.

“Currently, the system includes four drainage ways, three into the sea, and one to the river (Kelani River). However, in the past 30 years, we’ve had eight major floods and that’s been due to the Kelani River overflowing, thereby being unable to contain the excess being drained from the city.”

Urban flooding is often caused due to a lack of drainage in an urban area, and as there is little open soil that can be used for water storage, nearly all the precipitation needs to be transported to surface water or the sewage system.

High intensity rainfall can cause flooding when the city sewage system and draining canals do not have the necessary capacity to drain away the amounts of rain that are falling. Water may even enter the sewage system in one place and then get deposited somewhere else in the city.

Herath discussed other cities which have undergone severe urban flooding disasters, such as Beijing in China, which is a city that has a high land value and therefore, construction of drainage is near impossible and so the city finds it extremely difficult to drain water.

There’s also Tokyo, which has an underground river; the same has been adopted by Bangkok, Malaysia, and Singapore by building underground tunnels. However, these are very expensive alternatives – expenses that are overwhelming for a country like ours, and we are, thankfully, not at a level where we require such extreme measures; that is if we utilise our available resources.

For this issue, there have been various steps undertaken under the purview of the Ministry of Megapolis and Western Development. One such solution includes the implementation of two strategic micro tunnels, one of which is situated in Torrington and was very recently executed.

The Irrigation department too has a World Bank project in place, looking into alternative options to contain water in the Kelani River to prevent it from overflowing.

There are further steps taken and implemented by the Colombo municipality with regard to building and planning, which requires all establishments coming up to satisfy a certain requirement of water retention. Then, there is the utilising of Colombo’s wetlands, which are a natural resource – an ideal solution to urban flooding; there is a system underway to optimise the utilising of wetlands.

As for the monitoring system, its main job remains to forecast rain level in the city in order to estimate the best operational system. Referring to such a system for the purpose of creating such a database, which is able to forecast accurately, Herath said: “We need a dense network of monitoring systems, and we should be able to couple them with the rain level and other information. We need to read this data quickly, and so we do it in real time via an internet of pings; it is also very cost effective.”

Herath added that currently, additional rain gauges (30 currently) are being installed as a final measure, including other gauges to measure humidity. The data acquired will be transmitted to their computer model which is not inclusive of a human interface and the data collected is an open source and will be available to everyone. He said: “The system is largely done now, and with the installation of output measures, we can calibrate.”

Tuesday, June 11, 2019

Weekly Hydro-meteorological Report, 6, June 2019

Highlights

The IRI weekly rainfall forecast predicts up to 200 mm of total rainfall in Kalutara and Galle districts during 5 – 10 Jun.
The IRI weekly rainfall forecast predicts up to 200 mm of total rainfall in Kalutara and Galle districts during 5 – 10 Jun.
From 28 May – 3 Jun: up to 54 km/h, southwesterly winds were experienced by the entire island.
0.5 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.

Download full report ↓

Monitoring

Weekly Monitoring: On May 28^th, Gampaha, Colombo, Kalutara and Galle districts received up to 10 mm of rainfall. No significant rainfalls were recorded in any part of the island on the 29^th. On the 30^th, Kalutara, Ratnapura, Galle and Matara districts received up to 20 mm of rainfall. On the 31^st, Polonnaruwa and Ampara districts received up to 20 mm of rainfall. On June 1^st, Kilinochchi, Puttalam, Kurunegala, Anuradhapura, Polonnaruwa, Matale, Gampaha, Kegalle, Colombo, Kalutara, Galle and Ratnapura districts received up to 5 mm of rainfall. On the 2^nd, Anuradhapura district received up to 5 mm of rainfall. On the 3^rd, Kalutara and Matara districts received up to 40 mm of rainfall; Puttalam, Kurunegala, Gampaha, Colombo, Ratnapura, Badulla, Hambantota and Monaragala districts up to 30 mm; and Kegalle, Kandy Nuwara Eliya, Kilinochchi and Jaffna districts up to 20 mm. On the 4^th, Badulla, Monaragala, Ampara and Kurunegala districts received up to 50 mm of rainfall; Puttalam, Gampaha, Ratnapura, Kegalle and Kandy districts up to 30 mm; and Vavuniya, Mullaitivu, Polonnaruwa, Colombo, Kalutara, Galle, Matale and Nuwara Eliya districts up to 20 mm.

Total Rainfall for the Past Week: The RFE 2.0 tool shows total up to 50-75 mm in Kalutara, Ratnapura and Galle districts; up to 25-50 mm in Gampaha, Colombo, Kurunegala, Puttalam, Kegalle, Kandy, Nuwara Eliya, Matara, Hambantota, Ampara, Badulla and Monaragala districts; and 10-25 mm in Mannar, Anuradhapura Polonnaruwa, Matale and Batticaloa districts. Above average rainfall up to 25-50 mm is shown for Ampara and Badulla districts; and up to 10-25 mm in Puttalam, Kurunegala, Anuradhapura, Kegalle, Kalutara, Ratnapura, Galle, Matara and Monaragala districts.

Monthly Monitoring: During May – Below average rainfall conditions up to 240 mm were experienced by Nuwara Eliya, Kegalle, Colombo, Kalutara, Gampaha, Kurunegala and Ratnapura districts; and up to 180 mm in rest of the island. The CPC Unified Precipitation Analysis tool shows up to 150 mm of total rainfall in Colombo, Kalutara and Galle districts; up to 100 mm in Gampaha, Kegalle, Ratnapura, Matara, Badulla, Monaragala and Galle districts; up to 75 mm in Trincomalee, Polonnaruwa, Nuwara Eliya, Ampara and Hambantota districts; and up to 50 mm in Vavuniya, Anuradhapura, Puttalam, Kurunegala, Matale and Kandy districts.

Predictions

Rainfall

14-day prediction:
NOAA NCEP models:

From 5^th – 11^th Jun: Total rainfall up to 75 mm Galle and Matara districts; up to 55-65 mm in Kalutara and Hambantota districts; up to 45-55 mm in Colombo district; and up to 35-45 mm in Gampaha, Kegalle, Nuwara Eliya, Badulla, Monaragala and Ampara districts.

From 12^th – 18^th Jun: Total rainfall up to 55 mm in Ratnapura, Galle and Matara districts; up to 35-45 mm in Gampaha and Hambantota districts; up to 25-35 mm Puttalam, Kurunegala, Nuwara Eliya, Badulla and Monaragala districts.

IMD NCMWRF Forecast:
7th jun: Not Available
8th Jun: Not Available

IRI Model Forecast:

From 5^th – 10^th Jun: Total rainfall up to 200 mm is expected in Kalutara and Galle districts; up to 150 mm in Gampaha, Colombo, Kegalle, Ratnapura and Matara districts; up to 100 mm in Puttalam, Kurunegala, Nuwara Eliya and Hambantota districts; and up to 75 mm in Kandy district.

MJO based OLR predictions:
For the next 15 days: MJO shall enhance the rainfall in Sri Lanka.

Ocean State (Text Courtesy IRI)

Pacific sea state: May 20, 2019

SSTs in the tropical Pacific maintained a weak El Niño level during April and early May, while temperature anomalies of subsurface waters decreased markedly to just slightly above average. Some patterns in the atmosphere show weak El Niño conditions. Collective model forecasts show a continuation of at least weak El Niño-level SSTs lasting through 2019. The official CPC/IRI outlook, with an El Niño advisory, calls for an approximate 70% chance of El Niño continuing during Jun-Aug, decreasing to 55-60% for Sep-Nov.

Indian Ocean State

0.5 ⁰C above average sea surface temperature was observed in the seas around Sri Lanka.