Highlights: The entire country received low rainfall
during the previous week except the sea adjacent to North Eastern side of the
island. During the previous week maximum temperature
of 35-40 0C was seen along the eastern coastal belt while the
minimum temperature of 200 C was recorded in Nuwara Eliya. NOAA NCEP
models predict up to 55mm total rainfall in the Ratnapura town in the next week
while Colombo may experience up to 45mm rainfall. NOAA CPC GFS model predicts 35-
40 0C maximum temperature along the coastal region in the eastern
side of the island. Wind speed is expected to remain at 15m/s throughout the
country and the surrounding sea. MJO shall enhance rainfall conditions up to 5
days ahead and thereafter shall suppress.
Monitoring
Rainfall
Weekly Monitoring:No rainfall received by the island from 22nd
to 25th but a considerable amount of rainfall was seen in the North
Eastern Sea close to Kilinochchi and Mulativu as up to 80 mm. The intensity of
the rain was seen to have reduced on the 24th and a rainfall of 20 mm
was recorded in the north eastern sea in general. Only slight rains were
recorded in that region on the 25th. On the 26th, no
significant rainfall was seen in the entire country. Up to 20mm rainfall was
recorded in Balangoda, Kahawatta and surrounding areas as well as on the
central part of the Galle- Matara border on the 27th. On the 28th,
up to 20 mm of rainfall was recorded in the north eastern ocean adjacent to
Kilinochchi and Mulativu and slight rainfall was recorded in the Central
Province and in Kegalle, Badulla and Balangoda. On the same day up to 30 mm of
rainfall was recorded in the south eastern ocean as up to 30 mm. Based on the
CPC Unified Precipitation Analysis, a total precipitation of up to 25 mm was
recorded in the Central and Sabaragamuwa provinces as well as in Matara and
Galle districts. According to the RFE 2.0 model a total precipitation of 25mm
was recorded in Ratnapura and Galle districts as well as in some areas of the
Central Province. The model shows 25mm below average rainfall in the Western Province
and sea adjacent to Matara and the western province.
Monthly Monitoring: Entire country received more rainfall than the
historical average during May 2016. The districts in western, north western and
north central provinces received up to ~450 mm monthly excess rainfall than the
historical average. CPC Unified Precipitation Analysis (during 20th May- 28thth
June) recorded up to 500 mm total rainfall in Kalutara and Colombo Districts.
The model along with the RFE 2.0 model records 150-200 mm total rainfall in the
rest of the Western province, Kegalle district and major part of the Ratnapura
district. A total precipitation of 75-100 mm was recorded in the Central
province and the Central belt of the North western province. Within the period
Kalutara, Kegalle, Ratnapura and Matara received 1.5 times more rainfall than
the normal and Northern Province, Batticaloa and Moneragala received only 25%
of the normal rainfall. During 1st-27th June highest
precipitation was recorded on 7th and 12th and up to 70
mm below normal average precipitation was recorded in the entire country during
the period.
During the week from 19th
to 25th highest maximum temperature was seen as 35-40 0C along
the eastern and north eastern coastal band of the island. Nuwara Eliya region
experienced lowest maximum temperature of 20-250C.The minimum temperature
of 15-20 0 C was recorded in Nuwara Eliya. The mean temperature
during this week was 1- 3 0C above average in the southern region as
well as in Jaffna and Kilinochchi.
The southern half of the
country received 15-20 m/s total north westerly wind at the 850 mb level during
the previous week while northern region received up to 15 m/s wind in the same direction.
At the 700 mb level, Nothern province received wind speed up to 15 m/s while the rest of the country
received wind speed up to 20m/s.
Ocean State
Pacific seas state: May 19, 2016
During mid-June 2016
the tropical Pacific SST anomaly was near zero, indicating ENSO-neutral conditions.
The key atmospheric variables also indicate neutral ENSO condition. This
includes near-average upper and lower level tropical Pacific winds, as well as
near-normal cloudiness and rainfall patterns in the central and eastern
equatorial Pacific. Most ENSO prediction models indicate neutral ENSO
conditions during June, with likely development of La Niña (of unknown
strength, but likely weak) by late July or August, lasting through fall and
into winter. (Text Courtesy IRI)
Indian Ocean State
Neutral sea surface temperature anomaly was observed around Sri Lanka.
14-day prediction: NOAA NCEP models predict up to 45mm total rainfall in Ratnapura
and surrounding areas and up to 35mm rainfall in Colombo district during the
week from 29th June to 05th July. In the same week the
rest of the Sabaragamuwa province, Kurunegala and Gampaha districts may
experience up to 25mm of rain. During the week from 6th-12th
July, Colombo and the western side of Ratnapura will receive up to 55mm of
rainfall. The adjacent areas including Gampaha and Kegalle may experience a
rainfall of up to 45mm. The central province, North Western province, Ratnapura
and the central region of Ratnapaura may experience rainfall of between
15-35mm.
Weekly prediction: IMD GFS model predicts up to 20 mm rainfall in the western
region of the country on 1st July and there shall not be any rain
during 2nd – 4th July in the entire country. On 5th,
up to 20 mm rainfall is expected in Kalutara and Galle coastal region. On 6th
the western Region of the Galle district including Galle town and the adjacent
sea may receive up to 20 mm of rain. Up to 40 mm of rain is expected in the sea
adjacent to Colombo and Kalutara on the 7th while up to 20 mm of
rainfall is expected in rest of the Western province.
IMD WRF Model Forecast & IRI forecast:According
to the IMD WRF model, on 2nd July there will up to 35 mm
of rainfall in the western and Sabaragamuwa provinces while there shall not be a
substantial amount of rainfall in the rest of the island. Up to 35 mm of rain
is expected in the same region along with the North western region on the 3rd
July. No extreme rainfall is expected in the island for the period of 29th
June-04th July and for the period the total expected precipitation
remains at 25mm.
Seasonal Prediction:As per IRI Multi Model Probability Forecast for July
to September, the total 3-month precipitation shall be climatological. The
3-month temperature has more than 70-80% likelihood in the entire country of
being in the above-normal tercile during this period.
Temperature
NOAA CPC GFS model predicts 35- 40 0C
maximum temperature along the coastal belt in the Eastern side of the country,
the Northern Province as well as in Monaragala and Polonnaruwa Districts. The north
western side of the country, Matale and Gampaha districts will experience a
maximum temperature of between 30- 35 0C. Maximum temperature in the hill country and
the Western province shall be between 25- 30 0C. During the same
week, minimum temperature is expected around Nuwara Eliya and Badulla to be 15-
20 0C while in the northern region and Hambantota it shall be 25-30 0C.
The minimum temperature in the rest of the country shall be 20-25 0C.
Wind
The wind speed shall remain at 15 m/s
in the entire country as well as the surrounding sea during 22nd – 29th
June in at 850 mb and 700 mb levels.
MJO based OLR predictions
MJO shall be in the Indian Ocean in
the next 5 days. Thereafter the MJO shall move to the Maritime Continent. There
shall be some enhancement of rainfall
conditions due to the MJO in the next 5 days and the enhancement shall be less
during day 6- 10 in the future. After that there shall be a slight suppression
in rainfall conditions.
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