Saturday, June 15, 2019

Posted 15th June:
Data compiled by Vagarian Abhijit and Map made by Vagarian Tejas

Technical Note:
The confusing "Vayu" continued its variable track due to the secondary Low Level convergence Zone. The Low level Divergence was present in the radius of about 400 kms from the centre. But the secondary low level convergence occurred at 1000 kms from the centre.
When the cyclone started moving West, the Secondary Low level convergence occurred over the West coast (Maharashtra Region), causing "outer band " rains.
The diabatic heating associated with the cyclone triggers a Rossby wave, with a ridge on the Peninsula in the lower and middle troposphere.
This will create a trough in the Bay head and activate the SWM in the Bay and west coast, pulling it North. Will create the required gradient also.
When Westerly winds approach the west coast, thry are de celareted due to western ghats. A zone of convergence is created off the coast.
Now, South of Goa, the winds are SW, But along the Maharsatra coast, the winds are Southerly, hence dynamics of off shore trough formation is absent.
An off shore trough today prevails from Goa to Kerala. With the re-curving of Vayu, a proper gradient will be created to help the SWM along the remaining west coast. If no recurving, then Bay activity should help Monsoon progress.
(As discussed with IMD scientists)

Hence Monsoon Limit stationary today at Northern limit of Goa and thence thru coastal Karnatak and TN.

Vayu is currently located at 20.8N and 67.4E, having moved slightly West. 
Heavy rains likely to decrease in Saurashtra and Kutch for the next 2 days. 
Yesterday also S Saurashtra lashed by heavy rain due to outer bands of cyclone Vayu 

Sutrapada (Gir Somnath) 120 
Talala (Gir Somnath) 100
Veraval(Gir Somnath) 90
Kodinar (Gir Somnath) 80 
Kutiana (Porbandar) 60
Malia (Junagadh) 6

Mumbai weekend given below
 in yesterday's post.


Abhijit Modak said...

Thanks for technical note sir.. Was really helpful to gain knowledge regarding it.

And yes Cyclone Vayu is keeping all models, meteorological agencies on its toes. As daily new tiwst were thrown.

Also as per Vagaries, when Kokan region including Mumbai to see Monsoon onset?

Also Vagaries blog is followed by farmer s of Marathawada, Vidarbha region closely. So regarding that also when interior Maharashtra to get cover in Monsoon?

So overall Maharashtra waiting for onset after torrid heat of last 3 months!

It's 15 June. Already half of June passed away. When Maharashtra to see Monsoon onset?

sset said...

difference of opinion + good snaps of Verval

Vayu cyclone neither wants to hit coast nor wants to move deep west into ocean away from Indian coast. This is impacting our SWM. Otherside Tamil Nadu Chennai (south east India) boils at 40+c no rain....

This reminds me of Lord Vishnu incarnation-Narasimha destroys evil - neither animal nor human, neither day nor night, neither in nor out.... Vayu seems to be as intelligent as Vishu!

Rajesh said...

Abhijit: Just a small note to explain the dynamics and technicality of our trough and cyclone zones.
I feel if the cyclone curves into Kutch region, immediately a gradient will be sufficiently created to pull the monsoon Northwards, so around 18th/19th.
If not so, then the resumption of the W.SW winds will create the dynamics for an off shore trough off Maharastra, and Monsoon can gather strength. Also around 19th.
Another factor is the possibility of Low in the Bay. Around 17th, it will form and strengthen the making of the off shore trough.
o, expect between 18th -20th , can we say ?
As per my talks and notes to marathwada farmers, I have told them to hold on sowing till 18th. Expecting the Monsoon in thrust via the Bay low . Which i see the track today due to Monsoon axis location around 20th at Central India levels.

Abhijit Modak said...

Ok Rajesh Sir. So as per Vagaries beyond Goa to Mumbai onset will be on one go like? whole Maharashtra coast to see onset between 18-20 June or South Kokan 18th & North Kokan by 20 June..

Aks said...

Great info Rajesh Sir.

Atul P Naik said...

Hot and humid in Goa today. High 33-34C, Low 27-28C. Rainfall during last 12 hrs negligible. Clear skies and almost 12 hrs of sunshine. Missing the Monsoon feel.

NilaY Wankawala said...

All are reporting the path taken by Vaayu, you being the only one explaining the cause , the real reason behind such path taken by Vaayu.

sset said...

seems vagaries option 1 seems to be in force: Vayu crossing Lucky Gujarat...
As per IMD
The Severe Cyclonic Storm 'VAYU' (pronounced as VAA'YU) over northeast and adjoining eastcentral Arabian Sea moved nearly westwards with a speed of about 12 kmph in last six hours and lay centred at 0830 hours IST of today, the 16th June, 2019 near Lat. 20.8°N and Long. 65.2°E over northeast and adjoining northwest & central Arabian Sea, about 470 km west-southwest of Porbandar (Gujarat), 440 km southwest of Dwarka (Gujarat) and 545 km
southwest of Bhuj (Gujarat). The system is very likely to weaken gradually into a Cyclonic Storm during next 24 hours. The system is very likely to move west-northwestwards during next 06 hours; gradually recurve thereafter northeastwards and cross north Gujarat coast by the midnight of 17th June 2019 as a Depression.

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