Wednesday, September 14, 2011

NOAA has changed its outlook for a La Nina from "watch" to "advisory", basically going from it might happen to they’re quite sure it will.

Right now, temperatures in the Pacific are where they are supposed to be, or what NOAA calls neutral. But, SST anomalies across the tropical Pacific Ocean

have cooled during August, when compared to those for July. First 10 days of september are maintaining the trend, though weakly. This has increased the chance of La Niña returning during the last quarter of 2011.

Current ENSO indicators are approaching values typically associated with La Niña events. NOAA scientists don’t think temperatures will stay there much after the last quarter of 2011. After that, temperatures in the Pacific should drop below normal again, kicking off what forecasters say could be another La Nina.

However, some models predict only modest cooling resulting in a borderline-La Niña event, but others predict stronger cooling. Vagaries presumes there is an expectation that the trend towards La Niña will continue, and if a La Niña does form, it will be weaker than the strong 2010-11 event.

The official monthly SOI for August was +2.1.During September, the SOI, has increased marginally. Further cooling of the central Pacific Ocean

coupled with persistent positive SOI values in the next few months would further increase the chance of a La Niña event at the end of 2011.

Meanwhile, BB-7

has precipitated heavy rains in Orissa, with Balasore receiving 123 mms in 9 hrs on Wednesday. Kolkata too had good rains today with Alipore measuring 33 mms in the day.


received had a severe thunderstorm today, and received 75 mms of rain in a short spell of time in the afternoon.

All these regions were expected to get the benefits of BB-7 as mentioned yesterday. Today the system is very much over the area, at 998 mb in the region of Orissa/W.Bengal.

Indications are of its westward movement into M.P.It seems from the current wind charts, the system will meet with resistance (explained in blog of 13th) on its westward track, and could weaken as a result.

An upper air W.D. is likely to cause medium scale precipitation and snow in the higher reaches of H.P. and Kashmir on Thursday and Friday.

Northern Pakistan

areas will also benefit from this system.

Mumbai forecast for Thursday/Friday published yesterday holds good.
See Mumbai Page for Wednesday sunset pic.

For latest all India Rain toppers upto 11th September see:


junaid said...

@rajesh so glad to see the amboli rainfall figure!!!thank you ,,my native place is sum 30 kms away from amboli on the coast!!!!!

Rajesh said...

junaid:and Amboli is the all India leader. It was a tough job getting these end september figures will also come.

svt:All time high for S'Cruz is 3785 mms, and we are still at 3106 mms.

NT said...

Will there be an increase in rains from Thursday night onwards as mentioned in your Thursday forecast for Mumbai or with the fact that BB7 meeting with Resistence the rains would not be much? The 12z GFS runs for Precipitation seem to suggest reduction of rainfall in and around Mumbai in the coming days.
BTW there were plenty of Thunder clouds around Mumbai today evening.

Also, what will be the effect of the La Nina revival on India?

Pavan said...

Damn sure that castlerock wil have same figures equal to amboli but data may nt be available

Tyrone said...

Hi rajesh, Could you briefly explain the effects of el Nino and la nina on the subcontinent weather pls. Thanks Tyrone

emkay said...

cats and dogs at Panvel from 0530 hrs, seems quite localised as per Radar, but seems this may creep into Mumbai soon

Rajesh said...

Tyrone:Since a La-Nina is predicted to happen,I feel the NE monsoon striking the east coast of India could be strong.
Even,and cyclones could emerge from the Bay.
But, in Northern India, and Pakistan, we should see a colder winter, with regular W.Ds precipitating snow in the North. Colder winters in the central and southern Pakistan could be possible with W.Ds in regular frequency.
BUT, it all depends on the strength of the La-Nina, its predicted to be mild at this stage.

RK said...

very heavy torrential rain storm lashing delhi and nearby regions from last few rained heavily yesterday too....rain amounts should be huge....
Even there are news reports of cloudburst in airport region yesterday...
Whats causing all this Rajesh?

Rajesh said...

RK: its the S-3 W.D. mentioned in this same Wednesday's blog. Check update on Friday.

 26th Day Temperatures..Mumbai cooler than Pune,Nasik and Same as Mahabaleshwar