SWM 2014 Rainfall-முதல் பருவ மழை

 These two imagery are from METOSAT 7 satellite.
It is indicative of active cross equatorial flow around equator [Northern Hemisphere] and along 70 Deg to 80 Deg longitude. This gives thrust to BAY winds and SWM may set in Andaman Islands today or tomorrow [15 or 16 May 2014]
Mascarene High is just SE-ESE of Kanyakumari and located just close to 85 DEG East longitude and 30 DEG South Latitude [Say,about 3300 km]

தென் மேற்கு பருவக்காற்றிற்கு ஆதாரமாய் இருப்பது இந்திய பெருங்கடலில் உள்ள 'மேச்கரின் ஹை" எனப்படும் உயர் காற்றழுத்த மண்டலமே ஆகும். இவ்வாண்டு இந்த காற்றழுத்த மண்டலம் [இன்றைய நிலையில்] குமரி முனைக்கு கிழக்கு தென்கிழக்கு பகுதியில் சுமார் 3300 கிலோ மீட்டர் தொலைவில் அமைந்து உள்ளது. இதனால், பூமத்திய ரேகையை தாண்டி,வங்க கடல் பகுதியில் நுழையும் தென் மேற்கு பருவக்காற்று அந்தமான் பகுதியில் முதல் பருவ மழையை இன்றோ அன்றி நாளையோ தரவிருக்கிறது.

7pm, Chennai - heavy T shower seen over S-W from city at around 80km

Monsoon Watch -4 ....14th May 2014

Synoptic Situation: 
(1) Season's first well marked low pressure area formed over Comorin area and neighbourhood on 6th  

(2) Northwestern India and North-Central Pakistan  received precipitation due to consistent passage of systems in westerlies. 

(3) Pre-monsoon convective activity increased over central and peninsular India due to presence of wind discontinuity. 

(4) Heat wave conditions prevailed in some parts of west Rajastan during initial part of the week. But, subsided later. 

(5) MJO gained amplitude over the Atlantic & African regions and propagated eastwards approaching Indian Ocean. This is seen to be manifested in the form of a low pressure area over southwest Bay of Bengal. Also, the lower tropospheric wind anomalies  indicate stronger than normal easterlies over south Peninsular region which caused moisture incursion leads to increase in rainfall activity over peninsular and northeast India. 

1. Seasonal Low: Indicator: -ve
The NW plains heating picked up initially, and laxes again, as WDs starting streaming in.

 
Heat should  to pick up in the Rajasthan/Sindh regions soon,  so good chance for the seasonal low to form and establish itself, at least by the 20th. Today the pressure at MSL is 1004 mb, with the core at 1002 mb.
The Sub Continent hot spots have just about touched the 45/46c mark (it is already Late. Refer MW-1) and should head for the 50c mark by around 20th May.

2. ITCZ: Indicator: +ve
As it is by the 10th, that we should have the ITCZ nearing the Equator. Only then would the Bay branch of the SWM could commence in the Southern Bay by the 15th of May. But, it has crossed Equator and is around the 5N latitude.

3. Jet Streams: Indicator:-ve
These are streaming away in a Westerly direction above the 25N line. But the trough looping down is not a very healthy trend.They are just about getting Easterly around 10N. Needs a rapid change now.

4. Cross Equatorial Winds: -ve in Arabian Branch...+ve in Bay Branch
Somewhat getting  established in the Bay region. SW winds, with sufficient speed hitting the S.Myanmar coasts, covering the Bay Islands with 20-30 knts, and could herald the arrival of the SWM in a week's time there.
Arabian Sea winds are dis organised, and in fact winds are heading South in the Central Sea. Sufficient speed in getting the "Somali Current" established is still lacking. The SST off the Somali Coast is 22/24c, While the required SST in First week June is 17/18c. (Required to form masses of Monsoon clouds in the warm central Arabian Sea).

5. ENSO: The sea surface temperature anomaly across the NINO3.4 region (located in the central Pacific) has recently risen to +0.5 °C, warming by 0.1 °C from last week. El- Nino is firming up slowly. 
Since March, Nino 3.4 has warmed up by 0.3c (See Diagram). 

The Southern Oscillation Index (SOI) currently remains neutral. The latest approximate 30-day SOI value to 4 May 2014 is +5.2.

As indicated in earlier MWs, it is gradual in developing. We would expect full El-Nino conditions by August.

Complete on vagaries

#Chennai - 2pm, #HOT at 37 C (but feels like 46 C) ... now Sea breeze has set in, temp will go down.

#Nagercoil - 10:40am, warm and hazy. T shower possible after 1pm. http://instagram.com/p/n7MGmmuquF/

1:30pm, T showers popping over N-W Tamilnadu, central W-ghats of Kerala ... http://ow.ly/i/5y7sT 

RT @GanpatTeli1: Heavy rain in delhi @weatherofindia (5:18am)

RT @aknarendranath: @weatherofindia Heavy downpour in Delhi just got over. (5:35am)

9am, Heavy rain seen over S,central Kashmir, Himachal, Haryana into Uttarakhand and W Uttarpradesh ... http://ow.ly/i/5y1ga
9am, S,S-central,S-E Bay along Andamans continue to be very active ... #Monsoon is near ... http://ow.ly/i/5y1ga

South West Monsoon 2014 - update #2 - "Monsoon for Andamans on 17-May-2014"

The feared "El Nino" - South West Monsoon killer !!
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As compared to previous El Nino alerts this latest report / alert suggests that this year's El Nino is expected to be a weak one.
Here's the report published by BOM-Australia...

The tropical Pacific Ocean has warmed steadily in recent months, with large warm anomalies in the ocean sub-surface (5-day values up to +6 °C) and increasingly warm sea surface temperatures. Climate models surveyed by the Bureau suggest El Niño development is possible as early as July. These factors indicate that while El Niño in 2014 cannot be guaranteed, the likelihood of an event developing remains at least 70% and we are at El Niño ALERT level.

As far as latest analysis, the Indian Ocean Dipole (IOD) is presently in Neutral state and expects it to be Neutral till Dec-2014.

As per the above report, the El Nino may not haunt this year's Monsoon !

Central, N-E India Heat LOW
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As of today, the LOW pressure generated by HEAT over N-W, Central, East India is around 1002mb and this is slightly high at this time of year. It should be around 1000mb.
Even though the W.D systems traversing N,N-W India has reduced, the consistent heating has not picked up.

North-South inland low-level trough (or) Line of Wind Discontinuity 
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After the LOW pressure crossing the S-central Peninsula, the N-S low-level trough from N Bengal to S Tamilnadu is expected to be back in position on 13-May.

Sea Surface Temperature(SST) over Bay and Arabian sea
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SST over most of Bay is around 30 C, meanwhile there's almost reduction in SST seen along Somali seas, this is sign that less cross equatorial winds are reaching Somali coast. Please note, that around 25-May, the SST along Somali coast should be around 20 C.

Bay LOW
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From 5-May to 10-May, the Bay LOW materialized somewhat in the form 91B, which formed along Gulf Mannar and then moved to S-E Arabian sea and pushed inland thru Coastal Karnataka and then died along S,central Chatisgarh.
Now, GFS predicts a weak low-level circulation on 15 / 16-May over S-central Bay, Which will act as a driving engine for the entry of S-W Monsoon winds into S,S-E Bay into S,central Andaman Islands. On 18/19-May, the circulation may strengthen and slowly drift N-N-E into Bay.
Monsoon is expected to break into S,central Andamans on 17-May-2014.

Mascarene HIGH pressure system and Cross Equatorial Winds
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At present the pressure over the Mascarene high pressure system over South Indian Ocean is around 1020mb, and in fact the system is pushed slightly to East by a LOW (which is located S-W to the High). In coming days, this high pressure system should come near to Madagascar Islands and pressure should be around 1030mb before 20-May. This will help the speedy push of winds towards Somali coast and start to cross into S-W Arabian sea.
Not a good sign at this time ! Arabian sea wing of Monsoon may get delayed !

Present, W.D low-level circulation is expected to push into S-W Rajasthan in next 12hrs and drift E-N-E ... http://ow.ly/i/5xD59 
The mid-level W.D trough and circulation is expected to come close to N,N-W India on 13-May and drift East ... http://ow.ly/i/5xDcA 

On 13-May, W.D, scattered moderate rain expected over S,S-W Kashmir, Himachal, into Uttarakhand, Punjab, N,N-E Rajasthan, Haryana and #Delhi
Some showers also expected over W Uttarpradesh, E,S-W Rajasthan as well on Tuesday.

At very-low-levels (925hpa).. a circulation is expected over N Bengal and its trough is expected down South upto S Tamilnadu thru N-W Andhra
This circulation and South dipping trough is expected to persist during next 2 days ... it'll drift slightly to East along to S-E coast

Tomorrow again T showers expected over S,S-W Tamilnadu and over S, south W-ghats of Kerala... http://ow.ly/i/5xCql 
Morning showers along S Kerala coast and S tip Tamilnadu coast is expected tomorrow (13-May) morning as well !
Tomorrow, isolated T showers also for N,N-E Madhyapradesh, S,central Uttarpradesh and S Bengal.
NO reduction in scattered T showers expected over N,central zones of N-E states on 13,14,15-May.

#Chennai - Temperature Today...
Nungambakkam = 38.6 C
Airport = 39.3 C

#Chennai - Expected to continue with around 39 C and may touch 40 C before 16/17-May.

Tirunelveli - T showers !!

Tirunelveli - 1:55pm, hot and humid. Thunder cell seen over N-E. #weather

Tirunelveli - 3:47pm, thunder shower just started.