Outlook for 21st, 22nd and 23rd:

Highlights:

1.Tuesday 21st, heavy thunder showers continue in Bangalore. Rainfall reducing elsewhere  in S.I. Karnataka on Tuesday and Wednesday. Some scattered thunder showers in N.I. Karnataka.

2.Tuesday, 21st onwards, Rainfall reduces from Maharashtra, from Tuesday itself.  Thunder showers reduce and almost decrease in South Konkan, Southern Mah. On Tuesday, isolated Thunder heads will be seen in the Eastern Skies of Pune.

Wednesday, 22nd, concentration of thunder showers in Tamil Nadu regions of Salem, Dharmapuri and West of Chennai. Some heavy thunder showers expected west of Chennai.

3.Nor'wester thunder squalls also retreat from Southern and Central W.Bengal. They will seem to have now concentrated in Southern Bangladesh.

4.From Wednesday, rainfall on the increase in Western Nepal.

5.On Thursday 23rd, rainfall from the regions of interior Karnataka and TN will see a major reduction.

6. Severe heat Waves with temperature in the 46-48c range in Rajasthan, UP, Parts of MP and Vidarbha Region of Mah. 48/50c likely in Parts of Balochistan and Sindh on Tuesday/Wednesday.

Vidarbha region will see a reduction in day temperatures from Wednesday by about 2c.

7.Monsoon Advancing in Maldives Regions and North of Andaman Islands in NE Bay.

May Weather of Mumbai Weather and Outlook for the Month..and Lake levels..on Mumbai Page

UAC in Arabian Sea (mentioned in article below), descends as expected , to sea level, and moved West. At 60.5E and 13N, it is at 1006 mb on Sunday...

A new Page on the Blog has been added: "Monsoon Advance Position"..it will be updated as the SWM pregressess, and can be used to see current Monsoon Status...

Post of 16th May (Thursday)

Heat Wave to Grip NW India ans Pakistan Regions: 

Hottest in Pakistan on Thursday, 16th May: Larkana 48c., Jacobabad 47c.

Hottest in India on Thursday: Barmer and Jaisalmer at  46.0c, Nagpur 45.6c Ramagundam 45.0c.

Weather for the weekend, 17th,18th and 19th May.

North India remains dry and hot.

We see the day temperatures rising in Balochistan  and Sindh in Pakistan thru Rajasthan , Punjab, Haryana and Delhi into India. 

Hot conditions likely in Gujarat, UP and Northern MP.

Day temperatures likely to reach 49/50c in Balochistan/Sindh regions of Pakistan.

Rajasthan, adjoining MP and Haryana will see 45/46c, with the odd 47c.

Depression BB-1, erstwhile Cyclone Mahasen will move away, and precipitate rains in Meghalaya and NE states as a depression .

The Line of Wind discontinuity, runs perfectly in the peninsula, from North Mah down South till Kerala.

Weekend will see moderate thundershowers in N.I.Karnataka.

S.I. Kanataka will get heavy thunder showers on all the forecasted days.

Particularly heavy rains are possible in the districts of Dakshin Karnataka, Hasan, Kodagu, Mandya, Tumkur and Bangalore.

Bangalore can expect heavy thunder showers and squall on the weekend.

On Sunday, a vortex may form in the trough, around S.I. Karnataka, hence I would expect heavy showers for Bangalore on Saturday, Sunday and Monday.

AN UAC is likely to form off the Kerala coast on Sunday, 19th. Could be located to the SW off the coast of Kerala.

Would sink to a sea level low (1006mb) on Monday.

As of today (Thursday), expected movement of Low is Westerly. Strengthening may be slow due to resisting High pressure to the North.

NE states would get heavy showers. Eastern Nepal will get weekend thunder showers  Kathmandu which got showers today, will heat by a couple of degrees on the weekend to reach 31/32c. But evening thunder showers are possible.

City Forecasts for the Weekend:

Mumbai (Scruz): Partly cloudy. Hot humid days and stuffy nights, Days will be around 33/34c and nights rising to 25/26c.

Outer townships getting hotter again, after a respite, days expected to touch 37/38c, but more humidity.

Pune: Partly cloudy, but very hot in the sun. Days expected to rise to 39/40c.

New Delhi: Very hot and dry. Surrounding hot dry winds will bring in heat on weekend, with the day touching  44c. Nights warming up to 28/29c.

Nagpur: Sunny day, partly cloudy in the evening. Days will be 46/47c, and nights will be an unbearable 30/31c.

Surat: Sunny and warm, humid at 34 -27/28c.

Bangalore: Thunder showers, very heavy in some parts. Squall and thunder showers heavy on Sunday.

Kolkata: Partly cloudy days, and stuffy at night, as minimum temperature will be around 26/27c. Days will remain in the 36/37c range this weekend.

SWM advances into Andamans Today:

Monsoon Watch 5-Arrival Dates.

As always explained, the MW parameters are to represent the progress of the developments in the Monsoon build up. On "as-is-where-is-today" basis, Vagaries calculates and forecasts the arrival date of the Monsoon. Again, these parameters are not referred in this MW for the quantum of rainfall. 

The, normally expected and much talked about (in our MW series) low from the Bay came and became a Cyclone, adding much vigour and momentum to the SWM.

Current Status:
Bay factor: In the Bay sector, the SWM has moved into the South Andaman Seas on the 14th of May, and into the rest of Andaman on 16th. This pull was aided by the Cyclonic storm "Mahasen". In the Bay sector,the attached UTH map shows the advancing of a SWM current in the Southern regions

The cross-equatorial wind is re-building and reorganising again across the East Indian Ocean. SW winds are clocking 30 knts South and SW of Sri Lanka. 

Onward Monsoon progress Northwards towards the NE States will have to be monitored, but the approximate dates are shown in the map.

The latest winds in the Bay continues to show strong winds rushing Northwards along the East coast of India, and re-curving into a Westerly flow of winds at the South Myanmar coast.

A lone pre-Monsoon low (B-1) had appeared in the region (early May) this year. 
Indicator : +ve

The cross equatorial flow: This flow off the African Coast, in the Western Indian Ocean, this was a bit "disrupted" previously, but has now re-formed itself fast, and is strong off the African Coast South of the Equator. 
The Somali Current, is getting defined, and blowing strong, with winds at >35 knts off the coast! We will wait for the Somali coastal SST to drop further.

 In the map, observe the difference in SST along Somali Coast and Central Arabian Sea.The SST off theSomali coast is 23/24c.
The previously weak factor, the equatorial cross flow South of the Arabian Sea, is steady. 

With a Low forming in the SE Arabian Sea by the 19th of May, the winds will gather speed, and enhance clouding in the mid- Arabian Sea.

The Mascarene highs are established at 1030 mb, are are now "pushing" the South-Easterlies from below the Equator.  

However, I feel, a real good booster is required for the Arabian Sea branch of the Monsoon. 
Indicator: Improved since MW4

Seasonal Low: With the heat factor still lacking absolute "full strength", in the Northern regions, the Seasonal Low core in the Thar Desert is now somewhat "unsteady", with a core pressure at 1000 mb, and requires to spread more westwards, rather than east. This (pulling Eastwards) is happening due to recent  WDs (M-1).

The heat waves are just about to revive. However, the minimums still showing vast regions in the below normal range. By this time each year, vagaries normally charts the "above 30c" minimums. But this year as yet, forget 30s, we are still barely reaching 26s in the night, with the odd one out in the NW plummeting to below 20c recently.
And the days ? Good, and 47/48 is just about getting its foothold!

To refresh, reproducing a clipping from Vagaries of 10th May 2011: "Readings of 10th May:
Hottest in Asia: Larkana (Pakistan) 48c, Nawabshah and Jacobabad  47c.
Hottest in India: 45.2c at Khajuraho, Agra  44.7c,  44.5c at Brahmapuri. 
Lows above 30c in India: Khajuraho 31c, Gwalior  30.7c, Gondia  30.4c, Kota  30.3c, Satna  30.2c. No lows above 30c noticed in Pakistan".

The Heat wave expected now, in the Western Sector of the Sub-Continent in next few days, will deepen the seasonal low and its core.

A North-South trough indicates the line of wind dis-continuity is unfavourably tilted towards the east in the Peninsula region. Normally, a perpendicular N-S trough is an ideal pre monsoon formation, and is a fore-runner for the seasonal low to stretch its presence over central India. 

As mentioned in my MW prevoiusly, the creation of a good gradiant between Kerala pressure and Rajasthan/Sindh pressure is an absolute requirment. And that is a must for creating a pull Northwards for the Monsoon. Overall position in this parameter is improved slightly since MW 4. 
Indicator: Neutral

The ITCZ now runs along the Equator from the African coast to Andaman  Island. Normal,for it to touch the equator around the 10th. (For more read previous MW).
Indicator: +ve

The 200 hpa jet stream: Normally, they should be Easterlies right upto 20N by May end. This would facilitate the Northward movement of the Monsoon Current. Today, the Easterly jet stream is developing  upto 10N. These 200 hpa jets winds normally need to come upto 10N by 15th.of May, so would consider this parameter as doing well. 
Then move upto 10-15N before 20th.May, to be in time for the Maldives Monsoon arrival.

The 200 hpa jet streams did get a bit dis- organised in the Bay recently. 
Indicator: Normal.

Arrival Time Conclusion: 
Vagaries  advance map for easy reading.

SWM has feebly moved into the Andaman Region. 

SWM will start covering the complete Bay Islands to reach the NE states by the 1st of June. 

SWM could be expected over the Maldives by the 20th of May.(Normal date 20th). Over Sri Lanka around the 27th of May.

I would estimate the SWM to advance into Kerala around June 1st/2nd could be the date for Kerala, but remain weakish till the middle of June in coastal Karnataka and Kerala.

Initially, as a result of a weak MJO wave, the SWM would be weak in Kerala in June. The further current into Kerala would be "reluctant" to move ahead in a weak MJO, as International forecasters predict the MJO phase in our seas to become weak up to the 10th of June. 

Nevertheless, the SWM could progressively advance into Goa/coastal Karnataka from 5th June, and Mumbai by the 9th/10th. of June. . 
SWM could delay advance into interior Karnataka and interior Maharashtra by a week from the 10th.

Around 18th of June, I would include entire Mah and South Gujarat as covered by the SWM. I would put the SWM in a weakish phase till the 15th.  

Mumbai can get pre-monsoon thunder showers from 28th/29th May.
Pre-Monsoon thunder showers can be expected in the outer townships from the 28th/29th May.

(This Monsoon chase is my personal view, and my personal analysis and deciphering is done as per my assumptions. Should not be used for commercial purposes). 

Next MW-6 will be published on 24th May evening.

Post of 16th May (Thursday)

Heat Wave to Grip NW India ans Pakistan Regions: 

Hottest in Pakistan on Thursday, 16th May: Larkana 48c., Jacobabad 47c.

Hottest in India on Thursday: Barmer and Jaisalmer at  46.0c, Nagpur 45.6c Ramagundam 45.0c.

Weather for the weekend, 17th,18th and 19th May.

North India remains dry and hot.

We see the day temperatures rising in Balochistan  and Sindh in Pakistan thru Rajasthan , Punjab, Haryana and Delhi into India. 

Hot conditions likely in Gujarat, UP and Northern MP.

Day temperatures likely to reach 49/50c in Balochistan/Sindh regions of Pakistan.

Rajasthan, adjoining MP and Haryana will see 45/46c, with the odd 47c.

Depression BB-1, erstwhile Cyclone Mahasen will move away, and precipitate rains in Meghalaya and NE states as a depression .

The Line of Wind discontinuity, runs perfectly in the peninsula, from North Mah down South till Kerala.

Weekend will see moderate thundershowers in N.I.Karnataka.

S.I. Kanataka will get heavy thunder showers on all the forecasted days.

Particularly heavy rains are possible in the districts of Dakshin Karnataka, Hasan, Kodagu, Mandya, Tumkur and Bangalore.

Bangalore can expect heavy thunder showers and squall on the weekend.

On Sunday, a vortex may form in the trough, around S.I. Karnataka, hence I would expect heavy showers for Bangalore on Saturday, Sunday and Monday.

AN UAC is likely to form off the Kerala coast on Sunday, 19th. Could be located to the SW off the coast of Kerala.

Would sink to a sea level low (1006mb) on Monday.

As of today (Thursday), expected movement of Low is Westerly. Strengthening may be slow due to resisting High pressure to the North.

NE states would get heavy showers. Eastern Nepal will get weekend thunder showers  Kathmandu which got showers today, will heat by a couple of degrees on the weekend to reach 31/32c. But evening thunder showers are possible.

City Forecasts for the Weekend:

Mumbai (Scruz): Partly cloudy. Hot humid days and stuffy nights, Days will be around 33/34c and nights rising to 25/26c.

Outer townships getting hotter again, after a respite, days expected to touch 37/38c, but more humidity.

Pune: Partly cloudy, but very hot in the sun. Days expected to rise to 39/40c.

New Delhi: Very hot and dry. Surrounding hot dry winds will bring in heat on weekend, with the day touching  44c. Nights warming up to 28/29c.

Nagpur: Sunny day, partly cloudy in the evening. Days will be 46/47c, and nights will be an unbearable 30/31c.

Surat: Sunny and warm, humid at 34 -27/28c.

Bangalore: Thunder showers, very heavy in some parts. Squall and thunder showers heavy on Sunday.

Kolkata: Partly cloudy days, and stuffy at night, as minimum temperature will be around 26/27c. Days will remain in the 36/37c range this weekend.

SWM advances into Andamans Today:

MW-5 Will be Published on Friday Night...

Cyclone Mahasen:

Cyclone Mahasen to make landfall by 4 pm IST on Thursday at 91E, Southern Delta region of Bangladesh

South West Monsoon Moving into Rest of Andamans on 16th May...posted on 16th May @ 2 pm IST

Cyclone Mahasen:  Tracked NE, and still shy of striking land. Around 290 Kms SE of Kolkata, at 21N and 90.4E, and at 986 mb, with core winds now gushing at 50-55 knts. Very heavy rainfall reported North of centre of system...expected rains in coastal Bangladesh and adjoining W Bengal shores around 7-9 cms or more.

May swerve NE and make landfall today (Thursday) along the Bangladesh Coast. Inundating low areas, with precipitation in excess of 9 cms. 

Radar image from BMD

London Weather Analysis for Jan-May 15th from Rohit... on International Page
Konkan Analysis Jan-May from rohit ...on Mumbai Page.
Cyclone Mahasen Update as on Wednesday 15th Noon and 3 days Track Estimate

South West Monsoon Advances into South Andamans...14th May 2013              

Cyclone Mahasen Latest Status:             >>>>>>>>>>

Cyclone Mahasen (BB-1) Position as on 12.30 am (IST)13th May : Location 10.7N and 86.6 E. Core pressure 996 and winds at 45 Knts. 
Precipitation expected on Sunday along TN coast, South AP coast and interior AP, adjoining Mah.

MW-4 (Part-2) 2013...Seasonal Quantum Performance of SWM.

Very Briefly, explaining the Factors considered for Seasonal Forecast:
Situation assessed after the arrival  of the SWM..and the scenario mentioned below are after the Monsoon sets in.

To take and assess the SWM performance, we refer back to the MW-4 (Part-1). We have to take into consideration most of the 15 parameters (Gowariker Method) before making an assessment, and these have to be analysed one by one. The prominent among the 15 are , ENSO, Mar temperatures of North India and East Coast, Himalayan Snow cover till March and SOI to name a few.
Of-course, I am not going to take each and every one of the 15 here, but, derive at an estimate on these basis and on the new model developed. I hope readers of vagaries trust that I have tried my best to estimate as accurately as possible.

If we take into account, that the ENSO will be Neutral, but "leaning" towards a weakish El-Nino phase by, say, August, then:

a) Till July end, we can see normal rainfall and progress of the SWM in the Sub_continent regions. Normal conditions in the Pacific Oceans will send a few "pulses" to create "in situ" systems in the Bay, and the first 2 months will see around 3/4 noteworthy systems traversing the Sub continent. WDs will be few, hence, we can expect a few systems to track towards Central and Northern India, resultig in good rains in the plains of N.India and Central Pakistan regions..and fairly good above normal rains in Nepal.
During the Northern track of the system, the monsoon trough could be pulled far North into the Himalayas, and possibility of "short "break Monsoon in 3rd week of July or near around thar time period.
Break monsoon situations, and winds bringing in moisture from the Bay (diverted to the NW directions) will result in excessive rainfall this season in Nepal, more so the Eastern regions. NE states of India will get continuous feeding from the Bay. (Cherrapunji seems the likely candidate for the highest SWM rains).

b) In such a scenario, even the Easterly 200 hps jet streams would move further Northwards. Could bring  rainfall to Upper Pakistan regions. Hence, rainfall could be  normal in rest Northern Pakistan and Kashmir.

c) Due to systems reluctant to track southwards, we may see lesser rains in the Southern Peninsula regions. Even the support to the west coast (South of Mumbai)may be lesser than normal. 
Hence, rain shadow regions in TN and interior Karnataka may be slightly deficient. However, normal gradient along the West coast will show rainfall along West Coast of India.
  

Things, if and when they change (drastically) will be posted and Vagaries readers will be kept well informed, of any variation in the forecast.  

These are my personal views, and should be depended upon commercially or otherwise. They may differ from other models.

 Next Update and MW-4 (Part -2)  will be published at 11.30 pm IST on Saturday
BB-1 Update              Cyclone "Mahasen" forms under rapid Intensification             >>>>>>>>>


Posted on 10th May @ 10.15 pm IST..Track and Posiyion of BB-1 Re-Produced on previous Map..

The rainfall during the 4 months of SWM of some important cities of India on Stats and Analysis Page...sent by Arpit