Friday, April 16, 2010
Monsoon Watch - 2
The Monsoon Rains performance this year is very very critical for India. Its economic growth hangs on the agriculture output this Kharif Season, and the water table needs a boost after the extermely poor Monsoon last year. (Mumbai has very limited water reseves now). IMD has optimistically stated that " 2 sucessive Monsoon failures are very rare."
Lets really hope so.
1. 4. El-Nino factor, is fast turning +ve,change from last week :
Nino 3 +0.8 +1.0 0.2°C warmer
Nino 3.4 +1.0 +0.8 0.2°C cooler
Nino 4 +1.0 +0.9 0.1°C cooler
The decline in the current El Niño event is consistent with which suggest Pacific Ocean temperatures will cool steadily over the coming months, and climate model predictions suggest returning to neutral levels by summer 2010.
The SOI also became positive on 8th April, first time after Sept last year. The latest Soi reading is a healthy +3. A +ve SOI means weakening of the EL-Nino. Lastyear we had a _ve SOI from June thru December.
2. The only +ve factor from the previous MW discussion, the quick formation of the Seasonal Low due to the intwnse heat wave in Central and Northern regions of the Sub-Continent, continues to be favourable. Into the 3rd. week of April now, the heat is relentless. Highs of 46.4c (Ganganagar) today (16th.April), and 46c in Akola and Hissar, has mercilessly baked the North/Central and Eastern region, and Vidharbh, in Central India was scorching at over 45c, at Chandrapur and Nagpur. Across the border, Nawabshah overtakes at 47c on Wednessday last week.
3. But, last week , the Monsoon winds, which originate from the Southern Indian ocean, cross the equator to become south -west , were still weak, and not developed . Now, we find, the South-east winds (below the equator they are SE), have organised themselves in the region south of the Andaman Sea. Currents are seen off the Sunmatra coast. And that is exactly where the start should be. Also, strong SE winds are seen along the Kenyan Coast.
The 3 high pressure zones in the South Indian Ocean, between Madagascar and Australia, have been observed, and the "Power House" of the Monsoon winds is on stream. Almost on time, as per schedule.
But the pre Monsoon Low in the Bay is still elusive. As discussed, we should see a low sometime after the 15th. of April. But as on today , a high pressure region prevails over the Bay.
5. The ITCZ, is in its "normal" position. Its movement northwards, to bring the existing SE winds above the equator should be observed around 1st. of May. At least not till cyclones are active in the Southern Hemisphere.
6. The 200hpa Jet Streams, required to be Easterlies during the Monsoon are not yet organised. Starting their Northward movement from 8N, they should be moving "up North" by the end of April, to facillitate the lower Monsoon winds.
Summary: 1.Getting +ve. 2. +ve. 3.Getting +ve. 4.Normal. 5.Normal.
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There are around 500 number of Rain Gauge stations available in Tamil Nadu which are maintained by WRO, TNEB and mostly by Revenue Departm...