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Government of India Earth System Science Organisation
Ministry of Earth Sciences India Meteorological Department
REGIONAL REPORT ON SOUTHWEST MONSOON – 2017 OVER THE SOUTHERN PENINSULAR INDIA
(Prepared by: S.Balachandran, B.Geetha, D.Maragathavel, S.B.Thampi
Y.K.Reddy, S.Sudevan and S.M.Metri)
Regional Meteorological Centre
6, College Road, Chennai 600 006.
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HIGHLIGHTS
During 2017, southwest monsoon (SWM) reached parts of southeast Bay of Bengal,
south Andaman Sea and Nicobar islands on 14th
May. It advanced over Kerala on
30th
May, 2 days prior the normal date of 1st June and covered the entire southern
peninsular India by 14th
June.
Rainfall during the SWM season of June-September, 2017 over the southern Indian
peninsular region comprising of the five states of Andhra Pradesh, Telangana, Karnataka,
Kerala and Tamil Nadu and two union territories of Puducherry and Lakshadweep was
717.6 mm which is 100% of its long period average (LPA) of 716.1 mm even though the
SWM seasonal rainfall over the country as a whole was 95% of its LPA.
Seasonal rainfall over the nine meteorological subdivisions covering the five states and
two union territories in the region, viz., Coastal Andhra Pradesh (CAP), Telangana
(TEL), Rayalaseema (RYS), Tamil Nadu &Puducherry (TN&PDC), Coastal Karnataka
(CK), North Interior Karnataka (NIK), South Interior Karnataka (SIK), Kerala
(KER),Lakshadweep(LAK) was normal to excess.
The seasonal rainfall figures over the nine subdivisions were15%,-13%, 27%, 29%, -
16%, 3%, 2%, -9%, and11% respectively. As such, seven meteorological subdivisions in
the region received normal rainfall (-19% to +19%) and twosubdivisions,RYS and
TN,received excess rainfall (≥+20%)of +27% and +29% of their respective LPAs (40 cm
and 32 cm respectively) during the season.
On the monthly scale, sub-divisional rainfall distribution was (i) normal to excess over 8
subdivisions and deficient over 1 subdivision in June (ii) deficient over 1 subdivision and
normal over one subdivisionin July (iii) 3 subdivisions recorded excess rainfall and the
other five came under normal category in August and (iv) 6 subdivisions received excess
rainfall, 2-normal, and 1-deficient in September.
Excess rainfall of about 60% or more were realised over TN and RYS in August (+82%
and +66% respectively) and over SIK (+81%) during September.
The SWM 2017 withdrew from the region on 26th
October 2017.
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1. Onset and Advance
During the year 2017, the Bay of Bengal (BOB) branch of southwest monsoon (SWM)
current advanced into the BOB on 14th
May. The Arabian Sea branch of the SWM current, which
leads to the onset of SWM over Kerala, advanced over Kerala on 30th
May 2017, 2 days prior to
the normal date of onset over Kerala on 1st June. Subsequently, it advanced gradually into other
parts of India. It covered the entire southern peninsular India (SP) comprising of five states
(Andhra Pradesh, Telangana, Kerala, Karnataka and Tamil Nadu) and two union territories
(Puducherry and Lakshadweep) and divided into nine meteorological subdivisions of Coastal
Andhra Pradesh (CAP), Telangana (TEL), Rayalaseema (RYS), Tamil Nadu &Puducherry (TN),
Coastal Karnataka (CK),North Interior Karnataka (NIK), South Interior Karnataka (SIK), Kerala
(KER) and Lakshadweep (LAK) by 14th
June against the normal date of 10th
June. It covered the
states of Kerala and Tamil Nadu by 7th
June, RYS by 10th
, Karnataka and Telengana by 12th
and
Andhra Pradesh by 14th
June. As such, it took 16 days for the monsoon to cover the entire SP
region. Fig.1a depicts the progression of the northern limit of monsoon (NLM: A line
delineating the regions where the monsoon has advanced from the regions where the monsoon is
yet to set in) over the region and Fig.1b presents the INSAT-3D satellite imageries depicting the
onset of SWM over Kerala on 30th
May and its further advance into the SP region by 14th
June
2017. Fig.1c presents GPM satellite+ gauge merged rainfall depicting the advance of SWM
2017 over the SP region.
Fig.1a Advance of southwest monsoon 2017 over southern peninsular India depicted by
lines of northern limit of monsoon on various dates
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Fig.1b INSAT-3D infra-red imageries as on 14th
, 26th
, 30th
&31th
/ 0300 UTC of May 2017
and 07th
/0300 UTC and 13th
/1200 UTC of Jun 2017 depicting the advance of SWM 2017
over the SP region
14-MAY-2017/0300 UTC
26-MAY-2017/0300 UTC
30-MAY-2017/0300 UTC
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Fig.1b (contd….)
31-MAY-2017/0300 UTC
07-JUN-2017/0300 UTC
13-JUN-2017/1200 UTC
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Fig.1c GPM satellite-Gauge merged 24-hr rainfall in cm as on 0300 UTC (0830 IST) of
02nd
, 07th
, 12th
and 13th
June 2017 depicting the advance of monsoon rains over the SP
region during SWM 2017
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2. Rainfall distribution
2.1 Seasonal subdivisional rainfall
The SWM seasonal rainfall (June-September) during 2017 over the country as a whole
was 95% of its long period average (LPA) and that over the SP region was 100% of LPA.As per
IMD’s classification of monsoon performance over a meteorological subdivision, if the amount
of rainfall received over a region [expressed as percentage departure from normal (PDN)] is
between -19% and +19%, the monsoon performance is termedasnormal. If the PDN is between -
20% and -59%, the region comes under deficient category, if PDN is less than or equal to -60%,
the region falls under scanty category, PDN of +20% to +59% indicates excess rainfall category
and if the PDN is greater than or equal to +60%, it is termed as large excess. During SWM
2017, all the nine subdivisions in the SP region received normal to excess rainfall. Cumulative
seasonal (01st June to 30
th Sep) rainfall figures over the nine meteorological subdivisions of the
SP region are furnished in Table-1 and Fig.2.All the nine subdivisions in the region received
normal to excess rainfall during the season. Whereas TN and RYS received excess rainfall of
+29% and +27% respectively, the other seven subdivisions, viz., CAP, TEL, CK, SIK, NIK,
KER and LAK received normal rainfall during the season.
2.2 Monthly subdivisional rainfall
The monthly subdivisional rainfall scenario is presented in Table-2 and Fig.3. By and
large, rainfall over the subdivisions of the SP region has been normal to excess during the
months of June, August and September. But for SIK in June and TEL in September, all the
subdivisions received normal to excess rainfall during these months. In fact, largely excess
rainfall ( ≥+60%) was realized over TN (+82%) and RYS (+66%) in August and over SIK
(+81%) and KER (+78%) in September. But the July rainfall was deficient over eight out of nine
subdivisions in the region. Only CAP received normal rainfall during the month. The good
rainfall performance during August and September over the SP region is in contrast to the All
India monsoon scenario wherein only 87% and 88% of the respective monthly LPA was realized
during these months.
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Table-1: Seasonal subdivisional rainfall distribution over the SP region during the SWM
season, 2017 (01st June-30 Sep 2017)
Largely
Deficient
Deficient Normal Excess Large
Excess
≤ -60% -20% to -59% -19% to +19% +20% to +59% ≥+60%
Fig.2 Subdivisionalseasonal rainfall (percentage departures from normal) during Jun-Sep
2017 over the SP region
SUB-DIVISION
Actual
rainfall
(mm)
Normal
rainfall
(mm)
Percentage
departure from
normal (%)
COASTAL ANDHRA PRADESH 669.6 581.1 15 TELANGANA 657.4 755.2 -13 RAYALASEEMA 506.1 398.3 27 TAMIL NADU & PUDUCHERRY 414.2 321.4 29 COASTAL KARNATAKA 2596.3 3083.8 -16 NORTH INTERIOR KARNATAKA 522.9 506 3 SOUTH INTERIOR KARNATAKA 670.5 660 2 KERALA 1855.9 2039.7 -9 LAKSHADWEEP 1108.3 998.5 11
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Table-2: Monthly subdivisional rainfall performance during SWM 2017
ACL: Actual; NOR: Normal; PDN: Percentage Departures from Normal
Largely
Deficient
Deficient Normal Excess Large
Excess
≤ -60% -20% to -59% -19% to +19% +20% to +59% ≥+60%
Sub-division June July Aug Sep ACL
(mm)
NOR
(mm)
PDN
(%)
ACL
(mm)
NOR
(mm)
PDN
(%)
ACL
(mm)
NOR
(mm)
PDN
(%)
ACL
(mm)
NOR
(mm)
PDN
(%)
COASTAL
ANDHRA
PRADESH
152.3 103.9 47 154.6 160.4 -4 223.8 157.7 42 138.9 159.1 -13
TELANGANA
202.2 135.9 49 141.4 238.2 -41 200.7 218.8 -8 113.0 162.3 -30
RAYALASEEMA
88.9 67.7 31 52.2 94.2 -45 171.7 103.3 66 193.4 133.1 45
TAMIL NADU &
PUDUCHERRY 47.9 46.5 3 42.2 69.1 -39 161.6 88.7 82 162.5 117.0 39
COASTAL
KARNATAKA 831.4 867.3 -4 820.1 1159.7 -29 625.3 755.5 -17 319.6 300.9 6
NORTH
INTERIOR
KARNATAKA
131.1 104.7 25 76.8 135.0 -43 105.8 120.4 -12 209.3 146.0 43
SOUTH
INTERIOR
KARNATAKA
107.7 141.7 -24 125.6 216.1 -42 181.4 161.4 12 255.7 141.0 81
KERALA
579.8 649.8 -11 378.5 726.2 -48 462.6 419.3 10 435.0 244.3 78
LAKSHADWEEP
521.9 330.2 58 164.2 287.7 -43 206.2 217.5 -5 216.0 163.1 32
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Largely
Deficient
Deficient Normal Excess Large
Excess
≤ -60% -20% to -59% -19% to +19% +20% to +59% ≥+60%
Fig.3 Monthly subdivisional rainfall distribution during Jun-Sep 2017
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2.3 Weekly subdivisional rainfall progress
Week by week and cumulative weekly performance of SWM 2017 over the SP region are
presented in Table-3a and Table 3b respectively.
Table-3a: Week by week subdivisional rainfall during June-Sep 2017 over the SP region
Table-3a: Weekly cumulative subdivisional rainfall during Jun-Sep 2017
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During the first four weeks of the season (1st-28
th June), rainfall activity was normal to large
excess over 5-7 subdivisions in the region. In the subsequent five weeks (29th
Jun-2nd
Aug), 5-8
subdivisions in the region, came under deficient to largely deficient categories. The week 17th
–
23rd
August, saw significant rainfall activity over the entire SP region with all the subdivisions in
the region recording normal to excess rainfall. During the following week (24th
-30th
Aug), except
TN and LAK all the other 7 subdivisions received excess to large excess rainfall (CAP, RYS,
CK, NIK, SIK& KER: large excess and TEL - excess). These two weeks rainfall activity brought
the subdivisions of Karnataka from deficient to normal category during the following week. The
subdivision of SIK recorded excess to large excess rainfall for about 7 weeks from 10th
August to
30th
September and RYS recorded excess to large excess rainfall continuously for 6 weeks from
10th
August to 20th
September.
2.4 Daily subdivisional rainfall and monsoon activity
Table-4a presents subdivision-wise daily spatial rainfall distribution over the SP region
during the SWM 2016 and Table-4b, the percentage frequency of various categories of spatial
rainfall distribution over each subdivision during the season. Widespread rainfall has been
realized on 76% of the days during the season over CK, on 62% of the days over KER and 50%
of the days over LAK. Fairly widespread to widespread rainfall activity has been realized over
SIK on 51% of the days. Scattered to widespread rainfall was realised for more than 60% of the
days over NIK, CAP and TEL. RYS and TN experienced scattered to widespread rainfall
activity on about 40% of the days during the season. Fig.4 presents daily cumulative rainfall over
the entire SP region during the SWM season, 2017 (01st June-30
th Sep).
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Table-4a: Daily subdivisional rainfall distribution over the SP region during SWM 2017
Date
(ending
0830 IST) CAP TEL RYS TN CK NIK SIK KER LAK
1-Jun ISOL ISOL ISOL ISOL WD ISOL ISOL WD WD
2-Jun ISOL DRY DRY ISOL FWD ISOL ISOL WD WD
3-Jun ISOL ISOL SCT ISOL WD ISOL SCT WD WD
4-Jun ISOL FWD ISOL ISOL WD ISOL SCT WD WD
5-Jun ISOL ISOL ISOL ISOL FWD ISOL ISOL WD WD
6-Jun FWD ISOL ISOL SCT WD SCT SCT WD WD
7-Jun SCT FWD WD SCT WD WD FWD WD WD
8-Jun WD FWD ISOL ISOL WD ISOL SCT FWD SCT
9-Jun SCT SCT ISOL ISOL WD SCT SCT FWD FWD
10-Jun SCT SCT ISOL ISOL WD SCT FWD WD WD
11-Jun SCT SCT ISOL ISOL WD SCT FWD WD WD
12-Jun SCT FWD ISOL ISOL WD WD WD WD FWD
13-Jun SCT WD ISOL ISOL WD FWD WD WD WD
14-Jun SCT FWD ISOL ISOL WD ISOL FWD WD WD
15-Jun FWD ISOL SCT SCT WD SCT SCT FWD FWD
16-Jun WD FWD FWD ISOL WD WD SCT FWD FWD
17-Jun SCT ISOL FWD SCT WD SCT WD FWD SCT
18-Jun ISOL ISOL SCT ISOL WD FWD SCT SCT FWD
19-Jun FWD WD FWD ISOL WD FWD SCT FWD WD
20-Jun ISOL SCT SCT SCT FWD SCT SCT FWD WD
21-Jun SCT SCT ISOL ISOL WD ISOL FWD WD FWD
22-Jun SCT ISOL ISOL ISOL WD ISOL SCT WD SCT
23-Jun ISOL FWD ISOL ISOL WD ISOL SCT WD FWD
24-Jun SCT FWD FWD SCT WD SCT SCT WD WD
25-Jun WD SCT ISOL ISOL WD SCT SCT WD WD
26-Jun WD FWD ISOL ISOL WD SCT SCT WD WD
27-Jun FWD WD ISOL ISOL WD FWD SCT WD WD
28-Jun SCT FWD ISOL SCT WD SCT FWD WD WD
29-Jun SCT ISOL ISOL ISOL WD FWD FWD WD WD
30-Jun SCT SCT DRY ISOL WD SCT SCT WD FWD
1-Jul SCT FWD ISOL ISOL WD SCT SCT WD WD
2-Jul SCT ISOL ISOL ISOL WD SCT SCT WD WD
3-Jul SCT SCT ISOL ISOL WD ISOL SCT WD WD
4-Jul SCT ISOL ISOL ISOL WD SCT FWD WD WD
5-Jul ISOL ISOL DRY ISOL WD SCT FWD FWD WD
6-Jul ISOL SCT ISOL ISOL WD SCT SCT WD WD
7-Jul SCT SCT SCT SCT WD SCT SCT WD SCT
8-Jul SCT SCT SCT ISOL WD ISOL SCT WD FWD
9-Jul SCT ISOL ISOL ISOL WD SCT SCT WD WD
10-Jul ISOL SCT SCT ISOL FWD SCT ISOL WD WD
11-Jul SCT FWD ISOL ISOL WD SCT SCT WD WD
12-Jul FWD FWD FWD SCT WD FWD FWD FWD WD
13-Jul SCT FWD ISOL ISOL WD SCT FWD SCT FWD
14-Jul WD WD SCT ISOL WD FWD FWD WD FWD
15-Jul FWD FWD ISOL ISOL WD FWD FWD WD SCT
16-Jul FWD FWD SCT ISOL WD SCT FWD FWD FWD
17-Jul FWD WD ISOL ISOL WD SCT FWD WD DRY
18-Jul WD WD ISOL ISOL WD FWD FWD FWD FWD
19-Jul WD WD FWD ISOL WD WD WD WD WD
20-Jul SCT FWD ISOL ISOL WD WD WD WD DRY
21-Jul ISOL ISOL ISOL ISOL WD FWD FWD WD WD
22-Jul ISOL ISOL ISOL ISOL WD FWD FWD WD FWD
23-Jul DRY ISOL ISOL ISOL WD SCT SCT WD SCT
24-Jul SCT ISOL ISOL ISOL WD SCT SCT FWD SCT
25-Jul ISOL ISOL ISOL ISOL WD SCT FWD FWD FWD
26-Jul ISOL ISOL ISOL ISOL WD SCT SCT SCT DRY
27-Jul ISOL ISOL ISOL ISOL WD ISOL SCT FWD WD
28-Jul SCT SCT ISOL ISOL WD ISOL FWD WD WD
29-Jul SCT SCT ISOL SCT WD SCT SCT WD SCT
30-Jul ISOL ISOL ISOL ISOL WD SCT SCT ISOL FWD
31-Jul FWD ISOL FWD SCT WD ISOL SCT ISOL WD
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Date
(ending
0830 IST) CAP TEL RYS TN CK NIK SIK KER LAK
1-Aug ISOL SCT ISOL SCT WD ISOL SCT FWD SCT
2-Aug SCT SCT ISOL FWD FWD ISOL ISOL SCT DRY
3-Aug SCT ISOL ISOL ISOL WD ISOL SCT FWD FWD
4-Aug SCT SCT ISOL ISOL WD FWD FWD WD WD
5-Aug SCT ISOL SCT ISOL WD SCT FWD WD WD
6-Aug SCT ISOL ISOL ISOL WD ISOL FWD WD FWD
7-Aug SCT ISOL SCT ISOL WD ISOL FWD WD WD
8-Aug SCT FWD ISOL SCT WD SCT SCT WD WD
9-Aug SCT FWD SCT FWD WD SCT SCT FWD FWD
10-Aug FWD FWD FWD FWD WD FWD FWD SCT WD
11-Aug ISOL SCT SCT SCT SCT SCT SCT FWD WD
12-Aug FWD SCT FWD SCT SCT SCT WD WD WD
13-Aug SCT SCT ISOL FWD ISOL SCT ISOL ISOL WD
14-Aug FWD WD ISOL SCT SCT ISOL ISOL ISOL DRY
15-Aug ISOL ISOL ISOL FWD ISOL ISOL SCT ISOL SCT
16-Aug SCT ISOL SCT SCT FWD FWD FWD WD FWD
17-Aug SCT ISOL SCT SCT WD SCT FWD FWD FWD
18-Aug WD SCT FWD SCT WD SCT WD WD WD
19-Aug WD WD SCT FWD WD FWD FWD WD WD
20-Aug WD WD FWD SCT WD WD WD WD FWD
21-Aug SCT SCT SCT SCT WD SCT WD WD WD
22-Aug SCT SCT FWD ISOL WD FWD FWD WD WD
23-Aug SCT SCT ISOL ISOL WD SCT FWD WD WD
24-Aug FWD ISOL WD SCT WD SCT FWD SCT SCT
25-Aug WD FWD WD SCT WD FWD WD SCT SCT
26-Aug FWD WD FWD ISOL WD WD FWD ISOL DRY
27-Aug SCT FWD FWD SCT WD WD WD WD WD
28-Aug FWD FWD SCT SCT WD WD WD WD WD
29-Aug WD WD SCT ISOL WD WD WD WD WD
30-Aug FWD FWD ISOL ISOL WD FWD FWD WD FWD
31-Aug SCT ISOL ISOL SCT FWD SCT SCT FWD SCT
1-Sep ISOL ISOL SCT SCT FWD SCT SCT SCT DRY
2-Sep SCT ISOL ISOL FWD ISOL ISOL SCT FWD DRY
3-Sep ISOL ISOL ISOL SCT ISOL ISOL SCT WD FWD
4-Sep ISOL SCT SCT ISOL ISOL ISOL ISOL SCT FWD
5-Sep SCT SCT FWD SCT ISOL SCT SCT WD DRY
6-Sep FWD SCT FWD FWD ISOL FWD FWD FWD WD
7-Sep SCT SCT WD SCT SCT FWD FWD SCT WD
8-Sep SCT SCT FWD SCT WD WD WD WD WD
9-Sep SCT ISOL ISOL FWD FWD SCT WD WD FWD
10-Sep ISOL ISOL ISOL SCT FWD SCT WD SCT WD
11-Sep SCT ISOL ISOL SCT FWD SCT FWD FWD WD
12-Sep ISOL ISOL ISOL ISOL FWD ISOL ISOL FWD WD
13-Sep SCT ISOL ISOL SCT WD SCT ISOL SCT FWD
14-Sep SCT FWD ISOL SCT FWD WD ISOL WD FWD
15-Sep FWD SCT WD ISOL FWD FWD FWD WD SCT
16-Sep ISOL SCT FWD ISOL WD WD SCT WD SCT
17-Sep FWD SCT WD FWD WD WD WD WD WD
18-Sep SCT FWD FWD FWD WD FWD WD WD WD
19-Sep ISOL ISOL ISOL ISOL WD SCT FWD WD FWD
20-Sep ISOL ISOL DRY ISOL WD FWD SCT WD WD
21-Sep ISOL ISOL DRY ISOL WD SCT ISOL WD WD
22-Sep ISOL ISOL ISOL ISOL WD ISOL SCT WD DRY
23-Sep ISOL ISOL DRY ISOL ISOL ISOL ISOL ISOL DRY
24-Sep SCT ISOL ISOL ISOL ISOL SCT ISOL ISOL FWD
25-Sep SCT ISOL FWD FWD SCT FWD WD ISOL FWD
26-Sep FWD SCT FWD SCT WD FWD WD SCT FWD
27-Sep FWD ISOL FWD SCT WD WD WD WD FWD
28-Sep WD FWD FWD SCT WD FWD WD WD WD
29-Sep SCT SCT FWD SCT WD WD WD WD FWD
30-Sep SCT SCT SCT ISOL FWD WD WD WD SCT
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Table-4b: Percentage frequency of various categories of daily spatial rainfall distribution
over the subdivisions of the SP region during SWM 2017
Category
Frequency (%)
CAP TEL RYS TN CK NIK SIK KER LAK
WD 11 10 5 0 76 14 20 62 50
FWD 17 22 20 10 12 21 31 20 28
SCT 46 29 18 32 4 42 37 11 13
ISOL 25 39 52 58 7 23 11 7 0
DRY 1 1 5 0 0 0 1 0 9
WD: Widespread; FWD: Fairly Widespread; SCT: Scattered; ISOL: Isolated; DRY: No rain (Note:Kindly refer Appendix(i) for explanations on categorization of spatial rainfall distribution)
Fig.4 Daily cumulative rainfall over southern peninsular region during SWM season, 2017
Table-5 presents the seasonal frequency of active and vigorous monsoon conditions over
the various subdivisions of the SP region during SWM 2017. KER and RYS experienced more
than 25 days (27 and 26 days respectively) of active to vigorous monsoon activity during the
season. 20-25 days of active to vigorous monsoon conditions prevailed over CAP, TEL, NIK and
SIK and CK experienced 18 days of active to vigorous monsoon conditions during the season.
Whereas LAK experienced 3 days of active to vigorous monsoon conditions during June, TN
experienced 10 days of active to vigorous monsoon conditions during August-September.
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Table-5: Subdivision-wise frequency of Vigorousand Active monsoon conditions over the
SP region during SWM 2017
Subdivision
JUN JUL AUG SEP Jun-Sep
VIG ACT VIG ACT VIG ACT VIG ACT VIG ACT
COASTAL ANDHRA PRADESH 5 1 3 2 7 0 4 3 19
TELANGANA 4 7 4 1 5 0 2 5 18
RAYALASEEMA 3 2 3 3 4 2 9 8 18
TAMIL NADU & PUDUCHERRY 5 1 2 2 7 3
COASTAL KARNATAKA 0 5 0 2 1 6 1 3 2 16
NORTH INTERIOR KARNATAKA 0 5 0 2 0 6 2 5 2 18
SOUTH INTERIOR KARNATAKA 2 1 0 2 0 7 4 6 6 16
KERALA 0 5 0 0 1 10 3 8 4 23
LAKSHADWEEP 1 2 0 0 0 0 0 0 1 2 VIG: Vigorous monsoon conditions (FWD to WD rainfall over the subdivision with rainfall amount more than 4
times the normal and at least 2 stations reporting 8 cm or more along the west coast or 5 cm or more else where).
ACT: Active monsoon conditions (FWD to WD rainfall over the subdivision with rainfall amount 1½ to 4 times the
normal and at least 2 stations reporting 5 cm or more along the west coast or 3 cm or more else where)
2.6 District-wise seasonal and monthly rainfall distribution
Fig.5a presents the district-wise seasonal rainfall as percentage departures from normal over the
various states and UTs over the SP region. Of the 102 districts in the SP region [Andhra Pradesh:
13 (CAP-9 & RYS-4), Telangana: 10, TamilNadu and Puducherry: 34 (34 and 2 respectively),
Karnataka: 30 (CK-3, NIK-11 & SIK-16), Kerala and Lakshadweep: 15 (14 and 1 respectively)],
95 districts received normal to above normal rainfall during the season. Five districts in Tamil
Nadu [Coimbatore (+169%), Theni (+131%), Tiruppur (+100%), Perambalur (+90%) and
Sivaganga (+75%)] and one in Karnataka (Mandya: +86%) came under large excess category at
the end of the season. Whereas all the districts in Andhra Pradesh, Tamil Nadu and Puducherry
received normal to above normal rainfall, 3 districts in Telangana (Adilabad, Nizamabad and
Karimnagar), 3 in Karnataka [Dakshina Kannada (CK), Chikkamagaluru (SIK) and Dharwad
(NIK] and one in Kerala (Wayanad) ended up deficient.
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Fig.5a District-wise seasonal rainfall (percentage departure from normal) over various
states and union territories in the SP region
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Fig.5a contd.
Fig.5b District rainfall performance over the entire SP region
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Fig.5c (i) District-wise, monthly rainfall distribution over Andhra Pradesh (CAP & RYS)
during Jun-Sep 2017
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Fig.5c (ii) District-wise, monthly rainfall distribution over Telangana during Jun-Sep 2017
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Fig.5c (iii) District-wise, monthly rainfall distribution over Karnataka (CK, NIK & SIK)
during Jun-Sep 2017
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Fig.5c (iv) District-wise, monthly rainfall distribution over Kerala and Lakshadweep
during Jun-Sep 2017
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Fig.5c (v) District-wise, monthly rainfall distribution over Tamil Nadu and Puducherry
during Jun-Sep 2017
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In the monthly scale, the following salient features are noted:
Andhra Pradesh (CAP & RYS): During June, except Vizianagaram which came under
deficient category (-22%), all other districts in CAP and RYS received normal to excess rainfall.
Large excess rainfall was realised over the districts of East Godavari (+89%), Guntur (+88%)
and Nellore (+71%). In July, Srikakulam and East Godavari districts received excess rainfall of
47% and 20% respectively. While West Godavari, Krishna, Guntur and Chittoor districts
received normal rainfall, all other districts ended up deficient with Kadapa recording largely
deficient rainfall of -61%. In August, excepting East Godavari, West Godavari and Krishna
which received normal rainfall, all other districts reported excess to large excess rainfall with
Nellore and Kadapa recording (+107% each) and Chittoor, Prakasam, Vizianagaram and
Srikakulam recording +70 to +90% during the month. In September, all districts in RYS received
excess rainfall with Chittoor coming under large excess category. In CAP, while Krishna, West
Godavari, Visakhapatnam and Srikakulam ended up deficient, all other districts received normal
to excess rainfall during the month.
Telangana: During June, all the ten districts in Telangana received excess to large excess
rainfall with Khammam, Mahabubnagar and Rangareddy districts reportinglarge excess rainfall
of +72%, +70% and +64% respectively. In July, excepting Khammam which came under normal
category (-19%), all other districts received deficient rainfall with Adilabad recording large
deficiency of -63%. In August, while Hyderabad recorded excess rainfall of +29%,Rangareddy,
Mahabubnagar and Karimnagar came under deficient category. Other districts received normal
rainfall during the month. In September, excepting Hyderabad, Mahabubnagar, Nalgonda and
Warangal which received normal rainfall, all otherdistricts ended up deficient with Nizamabad
recording large deficiency of -61%.
Karnataka: In June, 6 districts (Bidar, Kalaburgi, Vijayapura, Yadgir and Koppal in NIK and
Kolar in SIK) received excess to large excess rainfall. All three districts in CK (Uttar Kannada,
Udupi and Dakshina Kannada), Belagavi, Bagalkote and Raichur districts in NIK and
Shivamogga district in SIK received normal rainfall. All other districts came under deficient
category with Gadag, Bangalore-Rural and Chamrajnagar recordinglargely deficient rainfall. In
July, excepting Udupi (CK), Belagavi (NIK) and Chitradurga (SIK) which received normal
rainfall, all other districts ended up deficient with 5 districts in NIK and 4 districts in SIK
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reporting largely deficient rainfall. In August, excepting Uttar Kannada (CK), Belagavi,
Dharwad, Haveri and Yadgir (NIK) and Shivamogga (SIK) which came under deficient category,
all other districts received normal to largeexcess rainfall [Large excess rainfall was realised over
Mandya (+174%), Mysuru (+140%), Ramanagara (+90%), Bangalore-Urban (+80%) and
Bangalore-Rural (+69%)]. In September all districts in SIK received excess to large excess
rainfall. While Shivamogga and Chikkamagaluru received excess rainfall, all other districts in
SIK received large excess rainfall. Mysuru (+166%), Mandya (+146%), Ramanagara (+119%),
Bangalore-Urban (+118%), Bangalore-Rural (+115%) and Davangere (+103%) received large
excess rainfall of more than +100%. In NIK, excepting Bidar which received deficient rainfall
and Kalaburgi&Vijayapura which received normal rainfall, all districts received excess to large
excess rainfall during the month. Haveri (+124%) and Belagavi (+109%) received large excess
rainfall of more than +100%. All three districts in the CK region received normal rainfall during
the month.
Kerala: In June, all districts in Kerala recorded normal rainfall excepting Idukki and Wayanad
districts which recorded deficient rainfall. July was a deficient month for all the districts in
Kerala with Wayanad, Idukki, Pathanamthitta, Kollam and Thiruvananthapuram recording
largely deficient rainfall. In August, all districts received normal to excess rainfall excepting
Wayanad which came under deficient category. September saw very good rainfall activity over
Kerala with all districts receiving excess rainfall. In fact 11 out of 14 districts recorded large
excess rainfall during the month.
Tamil Nadu & Puducherry: In June, most of the eastern coastal districts and adjoining areas
and the western districts of Coimbatore, Theni, Tirunelveli and Kanyakumari received normal to
large excess rainfall, but, the other interior districts ended up deficient to largely deficient. In
July, but for the extremely northern coastal districts and one or two interior districts (Coimbatore
and Sivaganga) all other districts (26 out of 34) came under deficient to largely deficient
category. However, August rainfall was beneficial to most of the districts. 30 out of 34 districts
recorded excess to large excess rainfall during the month. In September, the southern parts of
Tamil Nadu and the western districts of north Tamil Nadu received excess to large excess
rainfall, but, the northern coastal districts and some adjoining areas came under deficient to
normal category.
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2.5 Heavy rainfall activity and extreme rainfall events
Table-6a presents the number of days of heavy rainfall occurrences (≥ 7 cm/day) over the
various subdivisions of the SP region during SWM 2017 and the month-wise frequencies are
presented in Table 6b.In the seasonal scale, SIK recorded 57 days of heavy rainfall events which
included 17 days of isolated very heavy rainfall occurrences with 3 days of extremely heavy
rainfall events (11th
June, 19th
July and 20th
July). CK and TN also recorded 2 days (11th
June
and 2nd
July) and one day (5th
Sep) of extremely heavy rainfall events respectively. In general,
CAP, TN, KER and CK recorded 50 or more days of heavy rainfall events. List of very heavy to
extremely heavy rainfall events is presented in Table 6c.
Highest rainfall of 29 cm/day has been recorded on 20th
July in Baghamandala in Kodagu
district of SIK followed by 27 cm/day at Ponnampet in the same district on the same day and at
Shirali in Uttara Kanada district of Coastal Karnataka on 11th
June.
Spatial distribution of very heavy to extremely heavy 24-hr rainfall that occurred on
11th
&19th
June, 5th
and 17th
Sep as depicted by IMD-NCMRWF GPM satellite-Gauge merged
rainfall is presented in Fig.6.
Table-6a: Subdivision-wise frequency of heavy rainfall days over the SP region during
1stJune-30
thSep 2017
Subdivision
No. of days of Heavy rainfall
(Rainfall ≥ 7 cm in 24 hrs)
Extremely
Heavy
(≥21 cm)
Very
Heavy
(≥12 cm)
Heavy
(≥7 cm) COASTAL ANDHRA PRADESH 0 7 56
TELANGANA 0 5 45
RAYALASEEMA 0 5 27
TAMIL NADU & PUDUCHERRY 1 15 54
COASTAL KARNATAKA 2 19 50
NORTH INTERIOR KARNATAKA 0 2 29
SOUTH INTERIOR KARNATAKA 3 17 57
KERALA 1 16 51
LAKSHADWEEP 0 1 7 Note: Kindly refer Appendix-(ii) for explanations on various terminologies used for description of rainfall intensity.
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Table-6b: Month-wise frequency of heavy rainfall days during June-Sep 2017
ExH: Extremely Heavy (≥21 cm); VH: Very Heavy (≥12 cm); H: Heavy (≥7 cm)
Table-6c District-wise list of stations & dates of very heavy -extremely heavy rainfall
occurrences with rainfall amount during Jun-Sep 2017
District Date, Station and 24-hr accumulated rainfall (in cm) (ending 0830 IST of the specified date)
COASTAL ANDHRA PRADESH
Guntur Jun: 19th
: Atchampet-15
Krishna Aug: 10th
: Tiruvuru-13
Vizianagaram Jul: 11th
: Pusapatirega- 12
Aug: 12th
: Pusapatirega- 12; 28th
: Kurupam-16
West Godavari Sep: 17th
: Polavaram-13
Visakhapatnam Sep: 30th
: Narsipatnam-14
Srikakulam Aug: 28th
: Palasa- 12;
TELANGANA
Adilabad Jun: 11th
: Luxettipet-15, Boath-14;
Aug: 20th
: Mudhole-18
Mehabubnagar Jun: 19th
: Kundurg-18;
Khammam Jun: 19th
: Burgampadu-14, Mulakalapalle-12
Medak Aug: 20th
: Narayankhed-13
Nizamabad Jun: 16th
: Jukkal-12, Madnur-12
Aug: 20th
: Ranjal-19, Navipet-18, Nizamsagar& Kotgiri-17 each,
Varni& Yellareddy-16 each, Bodhan-15, Rudrur-13, Pitlam, Jukkal, Banswada &
Gandhari -12; 26th
: Machareddy & Sadasivanagar – 12 each;
Warangal Aug: 20th
: Nallabelly-19, Venkatapur-18, Shayampet-16, Atmakur-15,
Mulug&Govindaraopet – 14 each
Karimnagar Aug: 20th
: Sarangapur-17
Sub-division No. of days of Heavy rainfall(Rainfall ≥ 7 cm in 24 hrs)
June July Aug Sep ExH VH H ExH VH H ExH VH H ExH VH H
COASTAL ANDHRA
PRADESH 0 1 11 0 1 11 0 3 21 0 2 13
TELANGANA
0 3 15 0 0 6 0 2 11 0 0 13
RAYALASEEMA
0 0 4 0 0 2 0 2 8 0 3 13
TAMIL NADU &
PUDUCHERRY 0 4 9 0 2 8 0 5 18 1 4 19
COASTAL
KARNATAKA 1 6 16 1 6 12 0 5 13 0 2 9
NORTH INTERIOR
KARNATAKA 0 1 7 0 0 5 0 0 5 0 1 12
SOUTH INTERIOR
KARNATAKA 1 4 14 2 3 13 0 7 13 0 3 17
KERALA
0 6 15 0 2 7 0 3 14 1 5 15
LAKSHADWEEP
0 1 4 0 0 0 0 0 1 0 0 2
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27
RAYALASEEMA
Chittoor Aug: 10th
: Chittoor- 13;
Sep: 09th
: Chittoor- 13.
Anantapur Sep: 10th
: Rolla- 12; 15th
: Setur- 13.
Kadapa Aug: 10th
: Royachoti-12; 25th
: Duvvur-15, Chapad-13
Kurnool Aug: 25th
: Owk- 20.
TAMIL NADU & PUDUCHERRY
Thanjavur Jun: 06th
: Papanasam-14;
Aug: 09th
: Pattukottai & Adirampatnam- 13 each; 10th
: Thanjavur-13;
Sep: 09th
: Kumbakonam-16
Sivaganga Jun: 15th
: Sivaganga-14
Coimbatore Jun: 27th
: Valparai(PTO) -17, Chinnakalar-14; 28th
: Chinnakalar-13;
Sep: 18th
: Chinnakalar & Valparai (PTO)- 17 each.
Nilgiris Jul: 20th
: Devala- 20, G.Bazar & Naduvattam – 19 each;
Sep: 11th
: Coonoor PTO – 12
Vilupuram Jul: 30th
: Tindivanam-12
Kancheepuram Aug: 2nd
: Madranthagam-15
Thiruchirappalli Aug: 2nd
: Pullambadi-14
Thiruvannamalai Aug: 2nd
: Chengam -13; 13th
: Polur-14
Madurai Aug: 2nd
: Vadipatti -12;
Sep: 2nd
: Peraiyur-12
Thiruvallur Aug: 19th
: Redhills-13
Dindigul Sep: 2nd
: Natham-17
Karur Sep: 2nd
: Karur-16, Aravakurichi-14
Vellore Sep: 2nd
: Alangayam-12
Theni Sep: 5th
: Uthamapalayam-24
Tiruppur Sep: 5th
: Kangeyam-12
COASTAL KARNATAKA
Dakshina Kannada June:11th
: Mangaluru AP- 15, Panambur, Mudubidre- 14;
12th
: Mulki&Mudubidre- 15 each; 26th
: Mani- 15, Mudubidre- 13, Puttur -12;
July:14th
: Mulki- 15;
Aug: 4th
: Bantwal- 16; 29th
: Sulya- 12;
Sep: 17th
: Mulki- 12.
Udupi June:11th
: Kundapur- 19, Siddapura ,Kollur& Kota- 16 each, Karkala- 14;
12th
: Kollur- 17, Kota- 12; 25th
: Kota &Kundapur- 13 each;
26th
: Kollur&Karkala- 15 each;
July:2nd
: Kollur- 25; 3rd
:Kollur- 16; 4th
: Kollur- 15; 14th
: Kota- 13;
19th
: Siddapura- 12.
Aug: 25th
: Siddapura- 13;
Sep: 28th
: Karkala- 15.
Uttara Kannada June: 6th
: Kumta- 14; 10th
: Honnavar- 15,Shirali- 14;
11th
:Shirali- 27, Kumta- 15, Honnavar- 14, Gersoppa- 13;
12th
: Kumta- 16, Gersoppa & Shirali- 15 each, Honnavar- 14;
July: 2nd
:Gersoppa- 13; 3rd
: Gersoppa- 12; 4th
: Honnavar- 13;
14th
: Shirali- 13; 19th
: Gersoppa & Siddapur – 12 each; 20th
: Kadra- 12.
Aug: 20th
: Manki- 12; 27th
: Gersoppa- 12;
NORTH INTERIOR KARNATAKA
Bidar June:13th
: Bidar- 13
Bagalkote Sep: 14th
: Kerur- 12.
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28
SOUTH INTERIOR KARNATAKA
Kodagu June: 26th
: Bhagamandala- 12
July:19th
: Bhagamandala- 20;
20th
:Bhagamandala- 29, Ponnampet- 27, Virajpet- 15, Napoklu- 13, Madikeri- 12.
Aug: 29th
: Bhagamandala- 12.
Sep: 19th
: Bhagamandala- 12.
Shivamogga June:11th
:Agumbe- 23,Hosanagar- 18; 12th
: Hosanagar- 19,Agumbe- 12;
25th
: Agumbe- 13; 26th
: Agumbe- 15;
July:19th
: Agumbe- 15; Linganamakki- 12;
20th
: Agumbe- 20; Hosanagar- 16; 21st :Hosanagar- 21; Linganamakki- 12.
Aug:4th
: Agumbe- 15; 12th
: Agumbe- 16; 21st: Agumbe- 12; 27
th : Agumbe- 14
Chikkamagaluru June: 26th
: Sringeri, Kalasa – 12 each
July:19th
: Kottigehara- 15, Kammaradi-12;
20th
: Kottigehara- 21, Kammaradi- 14, Kalasa- 13.
Mysuru Aug: 10th
: T Narasipura- 12;
Sep: 6th
:Mysuru -12
Mandya Aug:15th
: Mandya -13;
Sep: 6th
: KR Sagara- 12.
Bengaluru U Aug:15th
: Bengaluru HAL AP- 14, Bengaluru City- 13
Davangere Sep:25th
: Davangere- 13
Ramnagara Sep:10th
: Magadi-14
KERALA
Kozhikode Jun:11th
: Vadakara- 18
Jul:2nd
: Vadakara – 12
Aug:5th
: Vadakara – 14
Sep: 17th
: Vadakara - 18
Kasaragod Jun: 12th
: Kudlu- 12
Malappuram Jun: 24th
: Ponnani – 16, 27th
: Perinthalmanna – 12;
Sep: 11th
: Manjeri – 12, 14th
: Nilambur – 17;
17th
: Angadippuram – 19, Perinthalmanna – 16
Palakkad Jun: 27th
: Alathur – 12
Sep: 17th
: Mannarkkad – 23
Thrissur Jun: 26th
: Vadakkancherry – 15, Vellanikkara – 13;
Sep: 17th
: Vellanikkara&Kodungallur – 12 each
Wayanad Jun: 28th
: Vythiri – 15
Jul: 20th
: Vythiri – 13
Kottayam Aug: 11th
: Kottayam – 18
Kannur Aug: 29th
: Irikkur – 13
Alappuzha Sep: 6th
: Mavelikkara - 12; 18th
: Mavelikkara - 12
Idukki Sep: 14th
: Peermade – 17
Ernakulam Sep: 17th
: Piravom – 15, Perumbavur – 12
18th
: Ernakulam (South Railway) – 15
Pathanamthitta Sep: 17th: Konni – 12
LAKSHADWEEP
Lakshadweep Jun: 3rd
: Agathi – 12
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Fig.6 GPMsatellite-Gauge merged rainfall in cm depicting very heavy(12-20 cm/day) to
extremelyheavy(≥ 21cm/day) rainfall at isolated places over CK on 11th
Jun, TEL on 19th
Jun, Tamil Nadu on 5th
Sep and Kerala on 5th
and 17th
Sep 2017.
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2.6 Dry and Wet conditions
Based on Standardized Precipitation Index (SPI), a widely accepted index based on
rainfall used for drought monitoring world-wide, moderately/severely/extremely dry or wet
situations over various districts of the region during June-Sep 2017 are depicted in Fig.7. The
SPI indicates wet conditions over all districts of CAP, RYS and TN and parts of SIK, NIK and
TEL at the end of the season. Most districts of CK and KER ended up mildly-moderately dry.
Fig.7 Standardised Precipitation Index (SPI) over the SP region during Jun-Sep 2017
2.7 Chief synoptic features
Onset phase: Under the influence of an upper air trough from NIK to South TN extending upto
0.9 kma.s.l on 25th
and 26th
May and an off-shore trough from North Maharashtra coast to North
Kerala coast on 30th
May which extended from South Maharashtra coast to North Kerala on 31st
May, onset of SWM 2017 took place on 30th
May.
Monthly features: Fig.8 depicts the 850, 500 and 250 hPa wind anomaly during the months of
June, July August and September 2017.
In June, at 850 hPa level an anomalous cyclonic circulation over southwest Arabian Sea
and anomalous easterlies were observed. At 500 hPa level, an anomalous anticyclonic circulation
was observed over the northwestern region and adjoining areas. At 250 hPa level an anomalous
anticyclonic circulation was observed over the northern and central parts of the country. Under
the influence of the Arabian Sea and the Bay of Bengal branches of the monsoon current during
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31
the onset phase and its further advancement, good rainfall activity prevailed over the SP region
in June.
In July, at 850 hPa level, an anomalous cyclonic circulation /east west trough was
observed over the central parts of country. This anomalous circulation/trough extended upto 500
hPa level. At 250 hPa level, an anomalous anti-cyclonic circulation was observed over the
northern and northeastern parts of the country. Under active monsoon conditions over the central
and northern parts of India in association with advance of the monsoon current into these
regions, monsoon activity over the southern region was rather weak in July.
During August, at 850 hPa level, an anomalous north-south wind discontinuity over the
peninsular region and anomalous southerlies over the northeast region were observed. At 500
hPa level, anomalous westerlies were observed over the peninsula. At 250 hPa level, anomalous
ridge was observed over the eastern/northeastern region.
In September, at 850 hPa level, an anomalous cyclonic circulation /trough was observed
over the east Arabian Sea and adjoining Kerala coast. Anomalous easterlies /southeasterlies were
also observed over the samelevel. At 500 hPa level, an anomalous anticyclonic circulation was
observed over the peninsula and centralparts of the country. Thus anomalous anticyclonic
circulation was more marked at 250 hPa level.
Under break monsoon conditions on many days in August and September, troughs in the
monsoon westerlies and cyclonic circulations in the lower tropospheric levels over the peninsular
region led to good rainfall activity over the SP region.
In the daily scale, off-shore troughs at mean sea level along the west coast of peninsular
India, upper air cyclonic circulations over the various parts of the SP region and over Bay of
Bengal and neighbourhood, east-west shear zone in the lower-mid troposphere running along the
13-18°N latitudes, low pressure areas that formed over Westcentral and adjoining North Bay of
Bengal off Andhra Pradesh / South Odisha coast with their associated upper air cyclonic
circulation extending upto mid tropospheric levels tilting southwest-wards with height, troughs
on sea level chart that ran from CAP/TEL to Tamil Nadu / Comorin area across Rayalaseema
and interior Tamil Nadu and troughs in the monsoon westerlies in the lower tropospheric levels
were associated with rainfall activity over the SP region. Mean sea level pressure analysis based
on 10-06-2017/0300 UTC depicting an off-shore trough and a low pressure area over the
northern parts of central of Bay of Bengal is shown Fig.9a.
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Fig.8: 850hPa, 500 hPa& 250 hPa wind anomalies over Indian region during SWM
2017(Source: Climate Diagnostic Bulletin of India, IMD Pune)
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33
Fig.8 contd. …
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34
(a)
(b)
Fig.9 (a) Mean sea level pressure analysis chart based on 10-06-2017/0300 UTC and (b)
upper air streamline analysis based on 09-08-2017/0000 UTC
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35
Fairly widespread to widespread rainfall was realized in CK, KER, LAK and SIK on 11-
06-2017 with extremely heavy rainfall of 27 cm/day recorded at Shirali in CK. Upper air
streamline analysis based on 09-08-2017/0000 UTC indicating trough in monsoon westerlies and
cyclonic circulation affecting parts of SP region is shown in Fig.9b. Fairly widespread to
widespread rainfall activity was reported on 10-08-2017 in all the subdivisions in the region
except Kerala where scattered rainfall was realized.
3. Withdrawal of SWM 2017 from the SP region
Withdrawal of SWM 2017 from the SP region commenced on 17th
October over northern
parts of Telangana and gradually proceeded southwards. With the gradual setting in of
northeasterlies along the southeastern coastal areas, SWM withdrew from the entire country on
26th
October 2017. Fig.10 depicts gradual withdrawal of SWM 2017 from various parts of the SP
region.
Fig.10 Isolines of dates of withdrawal of SWM 2017 over the SP region
4. Summary
During 2017, southwest monsoon reached parts of southeast Bay of Bengal, south
Andaman Sea and Nicobar islands on 14th
May. It advanced over Kerala on 30th
May, 2 days
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prior the normal date of 1st June and covered the entire southern peninsular India by 14
th June.
Rainfall during the SWM season of June-September 2017 over the southern Indian peninsular
region comprising of the five states of Andhra Pradesh, Telangana, Karnataka, Kerala and Tamil
Nadu and two union territories of Puducherry and Lakshadweep was 717.6 mm which is 100%
of its long period average (LPA) of 716.1 mm even though the SWM seasonal rainfall over the
country as a whole was 95% of its LPA. Seasonal rainfall over the nine meteorological
subdivisions covering the five states and two union territories in the region, was normal to
excess. The seasonal rainfall figures over the nine subdivisions CAP, RYS, TEL, TN, CK, NIK,
SIK, KER, LAK) were15%, -13%, 27%, 29%, -16%, 3%, 2%, -9%, and 11% respectively. On
the monthly scale, sub-divisional rainfall distribution was (i) normal to excess over 8
subdivisions and deficient over 1 subdivision in June (ii) deficient over 8 subdivisions and
normal over one subdivision in July (iii) 3 subdivisions recorded excess rainfall and the other
five came under normal category in August and (iv) 6 subdivisions received excess rainfall, 2-
normal, and 1-deficient in September. Excess rainfall of about 60% or more were realised over
TN and RYS in August (+82% and +66% respectively) and over SIK (+81%) during September.
The SWM 2017 withdrew from the region on 26th
October 2017.
Acknowledgements
This report is a compilation of real-time observational data and analytical products
generated by various IMD offices including IMD New Delhi, Pune, Hyderabad, Bangalore and
Thirvananthapuram as well as Raingauge networks of various state governments. Contribution
from all officials involved in generation of data and analytical products used for preparation of
this report is duly acknowledged.
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APPENDIX-(i): Terminologies for Spatial rainfall distribution
WD - Widespread (Most places): 75 % or more number of stations of a region (sub-division)
reporting at least 2.5 mm rainfall.
FWD- Fairly widespread (Many places): 51% to 74 % number of stations of a region (sub-
division) reporting at least 2.5 mm rainfall.
SCT- Scattered (at a few places): 26 % to 50% number of stations of a region (sub-division)
reporting at least 2.5 mm rainfall.
ISOL- Isolated (At isolated places): 25% or less number of stations of a region (sub-division)
reporting at least 2.5 mm rainfall.
DRY: No station of a region reported rainfall
APPENDIX-(ii): Terminologies for description of intensity of rainfall