Tamil Nadu Weatherman Special: Mettur Dam is opened on the customary date of June 12 for 2nd year in a row

TWM Special – May month Climatology of Chennai, with rare supporting data.
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This post is specially for Chennai audience and took very long time to compile. We are heading into May month, lets understand what happens in May month in Chennai with last 15 years of data, i often hear that its getting hotter and hotter. But data does not show any such trend, maybe we are getting older and getting used to A/C and spending lot of time inside our house than outside these days than during 1990s.

With respect to rains, we have to have clouds coming from Sea. Else we have not got any rains. So next rains eppo Chennaiku kekkarathu munnadi, u should understand how city gets significant rainfall in may month from Cyclones or Depressions. Its very rare for coastal area to rock in May. Because most of the convergence happens in interiors and being the transition month, the west and east winds meets in the interiors.

Some times the western part of city which are little interiors always gets some overhead popups on some hot days, even some days the Northern suburbs close to nagalapuram or Tada gets sudden popups. But for City most heavy rains have been from clouds moving in from sea side eg. 2004, 2010, 2016 in recent years.

Chennai Highest rainfall during May month in last 140 years
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113 mm in 1879 (Madras Severe Cyclone)
147 mm in 1886 (Delta Depression)
135 mm in 1903 (West Coast Severe Cyclone)
241 mm in 1909 (Delta Depression)
147 mm in 1918
103 mm in 1925 (Andhra Severe Cyclone)
207 mm in 1930 (Delta Cyclone)
135 mm in 1940 (Madras Severe Cyclone)
374 mm in 1943 (Madras Severe Cyclone)
230 mm in 1949 (Madras Depression)
471 mm in 1952 (Andhra Severe Cyclone)
181 mm in 1955 (Cuddalore Depression)
112 mm in 1962 (Madras Cyclone)
136 mm in 1979 (Andhra Very Severe Cyclone)
409 mm in 1990 (Andhra SUPER Cyclone)
280 mm in 1995 (Multiple Depressions)
211 mm in 2004 (West Coast Cyclone)
204 mm in 2010 (Severe Cyclone Laila)
208 mm in 2016 (Cyclone Roanu)

Each of the time Chennai City crossed 100 mm for the May month, there was cyclone or a Depression in the Bay, except for 1918, without support from sea side, Chennai May month has always been mostly dry. So lets hope there is atleast UAC or LPA or a Depression or if lucky a Cyclone moving close to us to get over 100 mm rains for the month. May month is always a crucial month for TN interiors, they will rock this may 2020 with thunderstorms irrespective of cyclone or not…So overall a good may for TN and Kerala expected. 2004 was one historic year for Tamil Nadu massive rains across TN coastal, interiors and in ghats with pull effect rains.

All time Chennai Hottest days ever in May month
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45 C in May 2003 (Cyclone curved to Burma)
44.1 C in May 1998 (Cyclone curved to Burma)
43.6 C in May 1980
43.4 C in May 2002 (Depression to Burma)
43.2 C in May 1976 (Depression to Burma)

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What an end to the April Rains current spell, Virudhnagar got semma rains. TN rainfall on 01.05.2020. Some district data are missing due to lockdown.
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in mm

Virudhunagar
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Sivakasi – 120
Srivilliputhur – 89
Sattur – 51
Vembakottai – 28
Watrap – 24
Pilavakkal – 10

Thanjavur
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Madukkur – 74
Thiruvidaimarudur – 36
Manjalaru – 28

Tiruvarur
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Nannilam – 69
Muthupet – 36
Thiruthuraipoondi – 27

Thoothukudi
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Kadambur – 61
Kovilpatti Agro – 28
Kovilpatti – 24
Maniyachi – 12
Ottapidaram – 10
Sathankulam – 10

Kanyakumari
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Suralacode – 57
Chittar II – 50
Perunchani – 48
Puthen Dam – 47
Chittar I – 42
Lower Kothayar – 40
Lower Kothayar AWS – 35
Kuzhithurai – 22
Pechiparai – 20
Kaliel – 10
Upper Kodayar – 10

Coimbatore
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Valparai PTO – 51
Cincona – 43
Chinnakallar – 18
Sholayar Dam – 17
Pollachi – 15

Pudukottai
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Ayinkudi – 34
Kilanilai – 32
Nagudi – 29
Mimisal – 13
Avadaiyarkoil – 12
Aranthangi – 11

Theni
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Manjalar – 20
Periyar Dam – 16
Manalar Dam – 10
Aranmananipudur – 10

Nilgiris
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Ooty – 13
Kundah Bridge – 11
Kotagiri – 11

Others
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Madurai ISRO, Madurai – 14
Tiruvadanai, Ramanathapuram – 46
Sankarankovil, Thenkasi – 13
Nagapattinam, Nagapattinam – 10