Monday, May 02, 2016

Monsoon Watch - 3.. 2016 ....Part 1....2nd May 2016..
Arrival of South West Monsoon:

1. ENSO:
Subsequent to writing the MW-2, we are keeping a careful watch on the ENSO developments. El Niño is present and is weakening. During the last four weeks, equatorial SSTs were above average across most of the Pacific,except near S. America.However, Below-average subsurface anomalies are evident across most of the equatorial Pacific. Since mid-April, below-average SSTs are apparent near S. America.
But, (SOI) has become negative over the past two weeks, with values returning to neutral bounds. The latest 30-day SOI value to 26 April is - 20 ( Falling from -7.5 in 15 days).

The latest weekly SST
departures are:
Niño 4          0.8ºC
Niño 3.4       1.1ºC
Niño 3          0.6ºC
Niño 1+2    -0.6ºC
The most recent ONI value is 2.0c...(El Nino is characterised by ONI values of 0.5 or above, La Nina is characterised by -0.5 or below).

Indicator: Neutral Chances of ENSO in Early SWM Months..

2. Sub-Continent Seasonal Low: 
We have a Heat Wave..Starting with the  Eastern Region and Peninsula India. Heating trend started in mid-April though....The Heat Waves in NW Sub Continent has now started. Places in Sindh has recorded 47.5c, and Rajasthan with heat wave now records 46c. But things are taking shape slowly. The seasonal trough (eastern wing) could start forming in Northern Thailand in first week of May

The seasonal low in the Thar region is now very weak.The pressure around the Thar desert region is now 1002 mb (994mb required by June beginning). Proper central core is forming now. And ,as per the required scheduled development, a proper gradient should be in the making.

Day temperatures have been normal to above normal in the MW-2/MW-3 inter period ! 
Above normal day temperatures by as much as 6/7c had been recorded in West Bengal, Odisha and Telengana. The Heat now required is in Sindh Region (and Rajasthan). The highest on date in the Sindh areas is 47.5c. In India, it has reached 48.5c, in Odisha. Currently, last 2 days, the Rajasthan region is managing 45/46c. 

An exception this year is the Vidharbh region. The temperatures in Vidharbha are just about managing 42/45c ( Highest recorded on 1st May), and in some cities just hovering around the low 40s. 
Normally Vidharbh is a hotbed.
Nagpur trend in April....

2016: We may feel the heat in the day temperatures, but the minimums are not even near 30c, only on one night Delhi  touched 29.5c, but since then its around 22/23c in Delhi. No 30c recorded yet in Sub Continent. The minimum anomaly is seen here. Most of the Sub Continent in the "Normal" range and North in below normal. In south and East we see above normal.

The max and min temperatures have to rise now in Sindh, Balochistan and North India. Trends of rising temperatures may be seen again  in Vidharbh, Gujarat and adjoining regions of Sindh.
In 2015, the minimum temperatures touched 33c in Sibbi on 26th April, 31c in Rohri Pakistan on 30th. In India, a minimum of 30c or above was yet to be achieved.
In 2011, the minimum temperatures in the region  were higher comparatively at this time. Minimum temperature touched 30c for the first time in 2011on 29th April at Kota (Rajasthan). 
In 2010, 30c as minimum was recorded on 17th April.

True, the entire sub-continent region has to suffer a heat wave, but the gains are much more.  

The line of dis-continuity, currently is located, as a weak trough, in the centre of Southern Peninsula, South from East MP thru Vidharbh and interior Karnataka into Telengana.
For a proper moisture incursion into the Peninsula, and for an ultimate strong Monsoon, LWD should strengthen, in the centre of the Southern Peninsula region. ( Will strengthen in the next 2 days).

Out breaks of pre- monsoon thunder showers are expected normally in the southern states and South Maharashtra.  Though the showers in the South are scanty as on today. We need the thunder showers to commence and precipitate in Maharashtra and Interior Karnataka, indicating a proper flow of moisture into the peninsula region. This is seen developing from 1st week of May when we will see moisture from Arabian Sea and Bay converging in the Interior Peninsula.

A LWD in the central peninsula region "looks after" the moisture content in the interior areas, and prepares the atmosphere with the humidity required fro a proper and good rainfall in the Lee ward regions.

Indicator: -ve.

3.  Bay Low:
Continuing from MW-2, "Bay of Bengal" low pressure parameter is a worrying factor. Normally, the Bay should host a pre-Monsoon low any time after 15th.April. 
Like I mentioned in the previous MW, in 2011 we had a cyclone in the Bay by the third week, and in 2009 a cyclone crossed the Bay on 12th April.2012 hosted a low around 25th April (BB-1).

As on today, this region still maintains a luke warm response to the formation of a quick low. The pressure is anything but low, and the winds indicate a weak "high" trying to stabilise itself. 

What is needed now is a pulse from the Far East, to start with, and break up the existing high pressure area. Currently no Storm or Low pressure in the Phillipines Seas.

MJO has entered a weak phase in our seas. MJO wave gets slightly positive in Bay around 18th May...seems suitable for the Monsoon there ! MJO may turn Neutral after 8th May in the Arabian Sea sector.
The shading indicates outgoing longwave radiation (OLR; W/m²).

Only +ve sign of a quick formation is that the SST is conducive. Map shows around 30c in the Bay and 31c near the Andaman Islands. Getting favourable temperature for  low formation.

Indicator: -ve

4. Cross Equatorial Winds : 

The Southern  high pressure region, the Power House of our Summer Monsoon,shows the development of a proper High at 1035 mb. Subsidiary Highs will soon form.
The Mascrene Highs have maintained their strength, and i would say gained to some extent... at 1035 mb.

The cross equatorial wind flow, has just about picked up in the Western sector Southern Hemisphere. Winds, have not yet achieved the required speeds, but just  hitting the East African coast.To get a defined Somali Current, we need a proper re-curving Northwards/North-East of the winds, on the Kenyan coast. In fact, we see the SST off Somalia coast warmer than the surrounding Seas.(See SST map above)
The winds get organised as soon as the trough in the South Arabian Sea becomes weak. 

However, The region below the equator in the Bay sector is almost in the same situation as MW-2.  In the Bay Branch, the Cross equatorial winds are still haphazard and disorganised. But, in the Bay along India coast, , the winds turn Southerly, due to a weak High Pressure in the Bay.
The winds hitting Sumatra coast are not Westerly (as  required), and also needs to gather strength soon.
Remember, the normal date for SWM to hit the South Andaman Sea is 15th. May.

ITCZ is now close to the Equator. If no further systems form, we see ITCZ moving North, the High in the Southern Indian Ocean has a fair chance of getting stronger and anchoring well.

5. The 200 Jet Streams too, show some awkward anomaly, in the last week. 
The 200 hpa Jet Streams:  core was located between Lat.19°N & Lat. 34°N with the wind speed varying between 65 kts & 128 kts around 200 hPa. The highest wind speed of 128 kts was recorded over Patiala on 21st April at 203 hPa

Conclusion: Indicators:  1) ENSO +ve     2) Seasonal Low -ve     3)  Bay Low -ve  4)  Cross equatorial  -ve   

I would put a slight delay in the South West Monsoon arrival dates for Andaman and Kerala as of now. 
But would like to wait for another 4 days to see any changes in parameters, so will put up MW-3 Part 2 (Brief write up) on 5th May with proper dates of SWM arrival.

Then, we go into analysing the quantum of rainfall expected, in the subsequent MW-5 (which as usual will be in 2 parts), and will be ready for publication in Mid May.

Sunday, May 01, 2016

Rains may provide relief to Interior Maharahtra from Wednesday 4th may:

As the Line of Wind Discontinuity starts forming along the Central Peninsula , we may see much needed thunder showers. Initially, South Interior Karnataka and Kerala will get thunder showers from Monday 2nd May. As showers intensity increase and spread (On Tuesday) in throughout Interior Karnataka and adjoining Telengana and Interior TN, we see the thunder showers pushing into Interior Maharashtra from Wednesday 4th May. Kerala has showers coming after a record heat wave !

It is possible that almost all of Madhya Maharashtra and Vidharbh will get thunder showers on 4th, 5th and 6th May.

Moisture incursion into the Peninsula region is from both Seas, the Arabian Sea and the Bay. Arabian Sea moisture incursion is due to the WD which is likely to bring showers to North and NW India and Pakistan from 2nd May for a couple of days.

Kolkata: Showers to commence from Monday, and heavy thunder showers later on Tuesday and Wednesday.

Bangalore: Much needed showers on Monday and more on Tuesday.
We see a much needed relief in the Sub Continent heat. How will this effect the seasonal be seen !

MW-3 will be put up on Monday 2nd May !

Thursday, April 28, 2016

Scorching heat wave in Thailand is longest in 65 years ...National Record broken !

April in Thailand is typically hot and sweaty, but this year's scorching weather has set a record for the longest heat wave in at least 65 years.

The average peak temperature each day this month has been above 40c, with the mercury spiking one day to 44.3c— just short of the all-time record.
On this very day, April 27, in 1960, Thailand posted its hottest day ever recorded at 44.4c in the northern province of Uttaradit.

Maximiliano Informs:
Thailand National Record has been broken...The highest ever temperature of 44.6c was recorded at Hong Son on 28th April 2016.
Palakkad on 26th recorded 41.9c...The Hottest temperature ever recorded in Kerala. Kannur breaks it all time record with 39.2c.
Countries across Southeast Asia are feeling the heat. Sri Lanka: Jaffna broke its all time high record by touching 37.0c on 28th April, beating 36.7c recorded in 1983. 

Wednesday, April 27, 2016

We look at the relationship between ENSO 3.4 and actual Monsoon from 1950 onwards...

The BROWN line represents the original 3 month moving average of monthly ENSO 3.4 data and the GREEN bars represent actual rainfall that is above or below normal...

LHS side is the actual ENSO 3.4 temp +/- normal
RHS side is the (1/100) of actual +/- normal rainfall (e.g if rainfall is 920mm in a particular year with normal at 890mm than a reading of 30mm above normal will show as 0.3 on the RHS axis).

(Puneet pointed out the discrepancy in the 1972 data which has been corrected. A column of previous year had transposed by error one year ahead... Thanks Puneet.)

As can be seen there is no one on one relationship between ENSO 3.4  and level of monsoon..but some level of correlation is possible/visible...there are some years when ENSO temps are at LA NINA levels but we had a bad monsoon and vice versa...

ENSO DATA from (1950 to feb2016)

Monsoon data from IMD. (1950 to 2015)

Monday, April 25, 2016

Severe Heat continues in East, with Titlagarh at 46.0c being the hottest....The map shows the Eastern Region heat, and the Western Region with normal to below normal temperatures.

A Bifurcating Red Line is imposed on the Max Anomaly map (B).

From Tuesday, severe heat wave conditions abate from Karnataka, A.P. and Telengana. Day temperatures will drop 2/3c in these states from Tuesday. 

Severe heat wave prevails for a day on Tuesday in Odisha, and abates from Wednesday.
However, heat and hot conditions, with days above normal by 2/3c remain till Friday in Odisha, Gangetic West Bengal and East U.P.

The structural formation of the seasonal trough running through the peninsula was blocked due to a series of upper air WDs, and the formation of an "in shore " trough along the East Coast of India.. The "in shore" trough in the interiors of the East coast of India was the cause of the extreme heat running from West Bengal thru Odisha into A.P. and Telengana down to Karnataka.
The East coast trough becomes weak after Thursday 28th April, when the seasonal peninsula trough will be "allowed" and start to form.

Initially, it forms around Central Maharashtra (with Thunder showers in South Madhya Mah and Marathwada), and extends Southwards after a couple of days ( after Thursday).

Thence, after 1st/2nd May, the much needed and expected thunder showers in South ( Bangalore) and Central (N.I.Kar and South Mah) interior Peninsula, the heat relievers, will commence.

Bangalore: Local thunder showers brought the much needed relief to Bangalore on Monday. 20 mms was recorded in the afternoon/evening, and the city saw the temperature drop from a day's of 37.1c to 23.2c by 8.30 pm IST. Cloudy weather next 2 days, with a thunder shower or dust storm popping up in the vicinity. Days remain around 35c.

Kolkata: Hot conditions, with temperatures around 38-40c till Friday. A thunder shower expected in some parts and vicinity on Friday.

Below Post from Rohit:

Bizzare April 2016 till now  : 

  • Bangalore (Garden city ) records same average max temp for April month as Chennai Airport  !! 
  • Mumbai remains the mildest metro in April 
  • ( Mumbai past ten days .. 33 / 24 ,  Bengaluru .. 37.5 / 25 ) 
  • Hyderabad the hottest metro in April
  • Kolkata hotter than Delhi 
   Avg . max temp in c  (1 April - 25 April 2016)

Bangalore records its highest ever temperature...Hottest day ever for the Garden City, Silicon City of India !
After weeks of relentless heat, Bangalore touched 39.2c on 24th April 2016.The previous record was held on for 85 years, and was 38.9c recorded on 22nd May 1931.

Last 30 days Graph for Bangalore...."Red" all over !

2 more all time records broken in Karnataka...Mysore records 39.9c and breaks its od record of 39.4c last recorded in 1917 !
Mandya with 39.6c, also broke its highest ever record of 39.1c recorded in May 2003.

On 24th April Sunday, Titlagarh shoots up to 48.5c (Hottest ever April Temperature)...4th day running as the Hottest place in the world !
Tirupati was very hot at 45.7c.

All time record broken as highest ever in Tamil Nadu...Dharmapuri which was 42c on 24th beats its all time high of 41.4c in May 1991.
Madurai at 42.3c and Tondi at 38c beat their April records.

Rainfall News from Cherrapunji: Available data indicates that Hailstrom occurred over M.O. Cherrapunji from 1645 to 1652 hrs IST 9 23rd April) with diameter is 50 mm; With 421 mms rain in 24 hrs ended 8.30 24th April, the rainfall from 1st March -24th April = 2211 mms.