Thursday, May 08, 2008

Monsoon Watch-12

Bay Region: The recent sst anolomy shows a larger area of below normal temperatures in the sea than the last posting. In fact, the cooler area has spread northwards. The unexpected cooling will not allow a low to develop in the south bay at sea level pressures, for the next 5 days, at least, from today (7th. May). Resultantly, the initial rush of south westerly monsoon winds and monsoon rains will resume in the south Andamans around the 13th., but will be restricted to the 8N limit in the bay, and may not advance northwards of 8N immiedietly after the 13th. but may take a few days. However, the IMD forecasts an upper air circulation in the south Andaman region by the 11th.

Sub continent mainland: Again, unexpectedly, yesterday's W.D. has cooled down the entire region north of 20N in both India and Pakistan for more than 2days , and brought a major portion of the in the "below normal" colours of the map. The highest in Pakistan on the 7th. was "only" 43c at Turbat , and most "hot spots"in northern and central India were below 40c, with the highest at 42c (Ramagundam,A.P.). The result is that the seasonal heat low has become distorted, more so with an induced low sitting stagnant over the Sindh/Rajasthan border area and pushing in cooler air in the region. Also with another (sudden) W.D. forming and rushing into the same region tomorrow, 8th. May (some light rain has already commenced in Jacobabad by 7th. night), no major rise in the temperatures in northern regions, could be expected for another 2 days. In fact now from the 8th., the days may remain a little below normal, and no heat wave could be expected for the next 5 days. Re-organising of the seasonal low over Rajasthan can take place only after the 12th.

Southern Hemisphere: The push from the southern hemisphere for the cross equatorial winds is now perfect. The southern MJO has weakened in the exreme east region, and hence with good south -easterly flows in the south Indian Ocean, the ICTZ has advanced northwards and could be said to be at 2S today. However, a cooler Arabian Sea and a ridge over it, prevents a straight flow of south-westerlies over the Arabian Sea. But this is normal for this time of the month, and the pressure should stabilise in the second half of May.



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