Further Analysis of the parameters as discussed in MW-1.
1. Seasonal Low:
As the average day/night temperatures in the Sub-Continent areas show a distinct heating up, the -ve indicator from the previous MW-1 discussion shows some improvement.
Heat waves are seen in the Northern, Central and Eastern regions now. Regions from Pakistan thru Rajasthan and Central India Southwards thru Maharashtra and Telengana have heated up to above normal temperatures.
The current temperature anomaly. Most of India in the 2-4c above normal range and pockets shooting to 4-6c above normal. ...
The night temperatures have also crossed the 30c mark ! Wardha in Vidharbh was 31.8c as minimum and Chandrapur saw a low of 31.6c on 20th morning.
However, comparison with previous years shows the difference this year. In 2010, the first 45c touched on 10th. April, and on the same day Nagpur was 44c, Delhi 42.8c. Soon on 15 th April 2010, Nawabshah (Pakistan) soared to 47c, Simla to 28.2c on 16th, Ganganagar, Akola and Hissar to to 46c.
But, in 2011, 2012, 2013 and 2014, till date, temperatures were yet to reach 45c anywhere in the Sub-Continent .
2015...Into the 3rd. week of April , we had seen 48c in Pakistan on 19th April in Larkana,and 46.5c in Moen Jo Daro. In India had just topped 44.6c in Barmer on 19th April.
2016....touched 46c in Bankura on 16th April...and is constatntly hot in Eastern region with almost daily a place touching 46c.. Bhunbaneshwar and Titlagarh in India and Dadu in Pakistan have touched 46c. Several large regions in Vidharbh, Telengana and MP are in the 44/43c range.The 16th April day maximum map..see the numerous places in the mid 40s...
The seasonal Low, as a result of good heating, is shaping up fast.
Last 2 days, the lowest pressure, in the Thar Desert region was at 1000/1002 mb. (though 2011/2014 was 1006 mb, 2010/2012 was at 1002 mb this time. 2015 it was at 1002 mb).
Overall, even the 1002 mb Low is within the NW region of the India/Pakistan region.
Currently on 20th, the core pressure has increased to 1004 mb.
Lows over MP, Central India, should become less conspicuous because of the strengthening of the seasonal low over NW india.
As mentioned, it normally should reach a low nadir of 994 mb in June in the Thar Desert, and with 1008mb in the South Arabian Sea, a perfect gradient is created to attract the south -west winds towards the coast.
Seasonal Low should speed up now with extreme heat in the region.
Thunderstorm activity in Southern Tibet is also seen to be picking up.
The Line of Wind Discontinuity should normally stabilise around Central India perpendicular down into the Southern Peninsula by mid April.
This enhances the speed of the Seasonal Low formation. Normally is required to start taking shape for the monsoon by the second week of April.
Currently, LWD through Central Maharashtra down to Tamil Nadu is forming due to UAC is established over Marathwada.
In reality, this LWD remains till June, in variable phases, and finally merges with the Monsoon trough (axis)/ITCZ when the ICTZ moves towards the Sub Continent.
2. ENSO: During January-mid March 2015, near to-above average SSTs were observed in the eastern Pacific. At the sea surface, temperatures have cooled by over 1 °C since their peak, but remain warmer than average and still at El Niño levels.
March values show the NINO3 region in the eastern Pacific cooled by 0.1 °C and the NINO3.4 region cooled by 0.4 °C over the past month.
to 20/3/2016 to 27/3/2016 to 3/4/2016 to 10/4/2016
NINO3 +1.5 °C +1.4 °C +1.5 °C +1.3 °C
NINO3.4 +1.4 °C +1.4 °C +1.2 °C +1.2 °C
NINO4 +1.2 °C +1.2 °C +1.0 °C +0.8 °C
NINO 3.4 is the predominant Region to see ..For our region.
The SOI is at a lowering level at but remains within values indicative of neutral ENSO conditions. The latest 30-day SOI value is -7. This is the threshold of El Nino levels, below -7 is considered El Nino.
The most recent ONI value
(January– March 2016) is 2.0c.
La Niña: characterized by a negative ONI less than or equal to -0.5ºC.
By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping
Weak El Niño conditions are present.
3. Cross Equatorial Winds:
Let me explain, that the winds on crossing the equator break into 2 branches. 1) gushing into the Arabian Sea, and 2) moving into the Bay of Bengal.
Last week, the Monsoon winds, which originate from the Southern Indian Ocean as SE winds, and cross the equator to become South-West, were weak.
In the Western sector, now, we see the dis-organisation of the Southern Hemisphere SE winds, with Cyclone Fantala and a Low South of Sri Lanka. The regular SE flow towards East Africa is disturbed.Tropical cyclone Fantala, which reached category 5 intensity, is the strongest cyclone on record to form this late in the tropical cyclone season in the southwest Indian Ocean.
In the Western Sector, the Arabian Sea branch is still struggling to get organised. Here, sufficient wind speed off the Kenyan coast has yet to form the SE flow required. But should re-organise fast. The Northwards movement of the ITCZ will surely hasten and strengthen the winds.
In the eastern sector, and the Westerly flow in the Bay sector is also gone haywire.
And that is exactly where the start should be for the SWM to arrive at the Andamans. Upper winds at 100-400 hpa are vigorously aiding the lower winds to attain the required strength.
We prefer the Bay Branch to be better organised, as the S W Monsoon is expected there in 22-25 days…
Mascarene high pressure zones in the South Indian Ocean. Main High reading now 1023mb, and 2 more Highs (in the forming) have been observed, one at 1023mb and another at 1017 mb. between Madagascar and Australia.
The "Power House" of the Monsoon winds is slightly behind schedule, for this time of the season. Last year in MW2 we had highs of 1031 mb already formed. A bit this year...(Cyclone effect).
4. But the pre Monsoon Low in the Bay is still elusive.
As discussed, we should normally see a low sometime after the 15th. of April. The high pressure region in the Bay, at sea level, no longer prevails.
I do not see much happening soon, as the region does not have the support of a strong MJO. An strong MJO would hasten the favourable formations and lows, with enhanced precipitation. We see the MJO wave gradually approaching till 28th April. Might bring some rains in the Bay. But will a sort of "false alarm"...As the MJO, it Seems will remain weak another 10 days thence.
Another factor, which helps the winds gain strength, and bring more moisture into the Indian landmass, is the sea temperatures on both sides of the Peninsula. Optimum (warm) temperatures will hasten and create more clouds, and help in faster forming of the lows from the Bay.
5. To bring the existing SE winds above the equator, the ITCZ should move northwards. Around 1st. of May, this should cross the equator. The ITCZ should now come back to its Northward position, as the effective "Lows" created by the Rossby Wave are reducing.
ITCZ around 5S currently.
So, overall, we can summarise as:
Parameter: 1): +ve 2): El Nino (Weak). 3) -ve 4) -ve 5) Normal.
Two parameters are -ve as of today ( weak El Nino Taken as negative as yet). In today's situation, Monsoon arrival in Kerala could be a bit delayed in Kerala and the Bay Islands, and the NE states.
We will put up the estimated date of arrival in the MW-3.
But, situations can change fast, and by the time we discuss the next MW, some factors can suddenly become +ve or -ve. So, MW discusses and follows the developments as they emerge, and discuss the parameters as is where is.
No model can commit today when the Monsoon can arrive.
Quantum of rain forecasting in April for June right through September is an impossible task. Things get clearer by last week of April. Vagaries' (in MW) normally remains true to estimates around early May.
Next MW up on 2nd May with Dates of Monsoon Arrival.