Friday, September 10, 2010

With the low moving thru Kutch, the desert regions and rest of Gujarat were (again) battered by very heavy rains.
No explanations needed.Here are the 24 hrs rain amounts in cms. for Gujarat:

Gujarat region :- Dholka – 36; Barwala, Umagaon-17
each; Dhandhuka, Ranpur, Daman – 15 each; Kamrej – 12; Navsari – 11; Amod, Hansot – 10 each
Dohad, Petlad, Tarapur, VV Nagar, Dediapada, Nandod, Pardi, Gandevi, Olpad – 9 each; Baroda,
Bodeli, Valsad, Vapi, Jalalpur, Bardoli, Khambhat, Mehmadabad – 8 each; Anand, Matar, Ankleshwar,
Silvassa, Mangrol, Palsana – 7 each; Valod, Rajpipla, Dharam
pur, Vagra – 6 each. 5cm and less
rainfall recorded at a number of places.

Saurashtra–Kutch :- Jamnagar-13; Vallabhipur – 12; Kutch-Mandvi-11; Limbdi, Botad, Porbandar,
Okha – 9 each; Bhavnagar, Gogha, Kutiana, Dhrol, Lalpur, Rajkot – 8 each; Ranavav-7; Keshod,
Dhrangandra, Umrala, Kalawad, Jasdan, Upleta – 6 each; Kodina
r, Veraval, Chotila, Kharaghoda,
Lakhtar, Sihor – 5 each; Babra, Lathi, Sutrapada, Halvad, Palitana, Dwarka, Jodia, Kalyanpur, Gondal,
Abdasa, Naliya – 4 each. 3 cm and less rainfall recorded at a number of places.

Since the low has merged with the seasonal low over Sindh, rains have spread
into the South Rajasthan. (Uni.of Wisconsin map).
In the sindh region of Pakistan, good rains are reported, with North Karachi getting 36 mms of rain yesterday.
On moving into drier areas, I expect the low to fizzle out within next 24 hrs. Hence subsequent decrease in rainfall in Gujarat/Karachi region from tomorrow,

SWM shifts into +ve Zone:
The overall all India statistics for the monsoon rain is now +1%. Shifting into the plus zone is good, but it is very important to see alongwith if there is any r
egion still in the deficit.
The map is clear and self explanatory.
The situation is particularly bad in Jharkhand where rainfall deficit is touching 50%.
It has been very obvious this year that the monsoon’s bounty has been generous to largely dry areas of west Rajasthan and Kutch/Saurashtra getting 54 and 106% more rains this year.
While The monsoon starters of Kerala and coastal Karnataka witnessed lesser rains this season.

Withdrawal signs:
The monsoon usually starts receding from Western Rajasthan from Sept 1. However this year, this region has been receiving rainfall upto 10th. of September. IMD has stated in its latest updates that it might be a bit late in the monsoon witdhrawing. NCEP is of similar opinion and expects a withdrawal from Northwest India only after 15th of September.

Current analysis show the 200 hpa jet streams having moved very marginally south of 30N. But, on the western side, in Pakistan, we see the jet streams westerlies below 30N, as on Friday. And, as discussed yesterday, the seasonal low in Sindh is becoming 1000 mb, and maybe going up to 1002 mb by Monday.
I would back on a witdhdrawal from Pakistan and Western Rajasthan from Monday or Tuesday.
Further witdhrawal, southwards will be monitored stage wise.

A low is forecasted to form in the bay around the 14th. If true, then as per the above developments, the low may just skirt off north/north-eastwards. But ,another factor to estimate the track, is to see and observe is the axis alighnment as on that date.
Too early to discuss these permutations today !

kapadias@gmail.com

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