Tuesday, May 29, 2012

92B, a low forming in the Bay at 16N and 90E, South of Bangladesh.
Status of low formation in Arabian Sea same as given Below, no additional narration at this stage. Shall update in the evening if required.
Check Current Weather Page for June rainfall estimate (Revised) and SWM progress Map updated.

Low in Arabian Sea ?

A couple of International Forecasting Models estimate a low pressure to form in the Arabian Sea, around 10N and 60E by the 1st of June. There are few other models which do not agree and show NO low formation in the region around that time frame.

With 2 diverse opinions by several International Models, it becomes confusing for the average reader to actually judge or estimate the fact, especially at a critical time when the SWM is advancing along the West Coast of India.

Vagaries' View: 

Citing the "patch" of warmer SST in the Central regions of the Arabian Sea (around 55-60E), it is possible that a low pressure system can form in the region by the 1st/2nd June. A no. will be given when it forms.

But, as it travels North, it can encounter a slightly colder sea, thus limiting its growth. The low, initially could be at 1000 mb, can deepen to 996 mb by the 4th of June, before it starts weakening again from the 5th.

Naturally, even a nominal system near the coast will "suck in" the Monsoon moisture, and weaken the SWM over Kerala. 
As the arrival of SWM coincides with the System, the monsoon will have an initial "resistance" to advance into Kerala, but move in it will
As it moves into Kerala by the 2nd/3rd of June, it could then suddenly weaken temporarily in Kerala, as the Arabian Sea low take away all the moisture, and diverts the winds away. 

If the low, even for 3 days after forming, moves North, it can always pull up a weak SWM along the Karnataka/Goa coast by the 4th of June, as per Vagaries' earlier forecast, and maybe into Mumbai by the 8th of June, earlier than expected.

The SWM can, however, may be restricted to the coast, and interior Mah. and Karnataka could be almost dry

A deepening seasonal low in Sindh/Rajasthan at 994 mb in early June will draw moisture and clouds with strong winds into Saurashtra/Kutch and Coastal Sindh (East) regions.

Mumbai Forecast:

30th May: 33-28c. Partly cloudy with humidity rising. 

31st May/1st June: 34-29c.  Overcast morning with light drizzle in some parts of the city. Clouds getting sparse in the afternoon.

2nd June; 35-29c.  Cloudy morning and hot afternoon. Thunder clouds developing by afternoon/evening n the Eastern sky.

3rd June: 34-28c.  Cloudy and humid. Thunder clouds in the afternoon/evening with some rain in parts of the city.


sset said...

That is not good Rajesh. Earlier u mentioned good rains for Karnataka and now usual drought continous - it is bomb for water starved Bangalore/AP. Again same bells as you mentioned Kutch/Saurashtra for good rain in june and no rain for south including kerala - very strange and holds key for climate change - south drier and towards desertification.

Pavan said...

Sset always hope for good pray for good i am sorry i am commentng here and mr rajesh is not bhagirath or raju guide even though his predictin r upto 80 to 90 percnt true many people ask many thng to him he answer to al ther query, i pray that ur bangalore and AP gets bountyful rains! 'lets think green'

sset said...

Rajesh is weather scientist. We are thankful to Rajesh. Sorry for my prompt blog. Just looking at correlation last year similar Arabian sea low during start of 1st of day rain brought 100mm to Mumbai and rest is history - 3800-4000mm till october and 8000mm at Amboli. Same Karnataka/AP very leass rain. Last 5years Gujarat and Rajisthan are getting rains both from Arabian sea as well as Bay of Bengal - as ananth mentioned earlier place of origin of low do not get rains but travel west and north to form uac and lows. Real change in weather patterns and currents.

Rajesh said...

sset/Pavan: I had earlier put up a map for the June rain forecast. That too was showing deficit for interior regions of Mah and Karnataka. This time i refer to the system, if it forms, will bring almost no rains to interiors of these states till 13th/14th June.
anyway,i am slightly correcting the june rain estimate, ansd shall put up new and old (to compare) tomorrow afternoon on Current weather page.
Thanks guys.

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