Sunday, May 29, 2011

SWM remains weak in Sri Lanka:

SWM entered Southern Sri Lanka as a weak current (Vagaries' report) on the 26th, and still remains weak. There was little rainfall in the Southern regions today (Sunday), with Kurunegala measuring 14 mms and Ratnapura getting 11 mms.
The attached sat. image from wundermap (Sunday evening 6.30 pm) shows the SWM still restricted to the Southern half. Anticipitated by Vagaries to cover the Island by the 29th, but seeing the conditions, the advance is not possible today.

Another sat image shows the Kerala region as on Sunday evening, 6.30 pm IST. I feel, (with ref. to IMD statement), the SWM is still 24/36 hrs away. The region
had 2 days of pre-monsoon rain, as mentioned in our blog.

With regards to the Bay sector, the trough off the eastern coast is also weakening, and stationary, again, not allowing the SWM to advance further to cover the Bay Islands.

Vagaries' northern limit map of SWM remains unchanged.

For Your Information:
-Thunderstorms reported on Sunday evening from interior Goa and Dandeli regions.
-Hailstorm with thunder in Dehradun on Sunday evening, continuing till last report at 6 p.m. Rainfall measured 22 mms.
-Belgaum also is also witnessing a thunderstorm this evening. Rainfall 27 mms.


Anonymous said...

there was also heavy rain at HP today

Ron said...

i have a small question...
"Vagaries is following and adopting the norms set by IMD for Monsoon Advance. All monsoon advances announced by Vagaries is as per the norms followed by IMD, but are strictly the veiws of the blogger, and for further commercial uses IMD may be referred to.

Giving below the IMD norms for SWM advance for readers' fast and ready reference.


The guidelines are followed for declaring the onset of monsoon over Kerala.


CRITERIA:- If after 10th May, 60% of the available 14 stations enlisted, viz. Minicoy, Amini, Thiruvananthapuram, Punalur, Kollam, Allapuzha, Kottayam, Kochi, Thrissur, Kozhikode, Thalassery, Kannur, Kasargode and Mangalore report rainfall of 2.5 mm or more for two consecutive days, the onset over Kerala be declared on the 2nd day, provided the following criteria are also in concurrence.


CRITERIA:- Depth of westerlies should be maintained upto 600 hPa, in the box equator to Lat. 10ºN and Long. 55 ºE to 80ºE. The zonal wind speed over the area bounded by Lat. 5-10ºN, Long. 70-80ºE should be of the order of 15 ? 20 Kts. at 925 hPa. The source of data can be RSMC wind analysis/satellite derived winds.


CRITERIA:- INSAT derived OLR value should be below 200 wm-2 in the box confined by Lat. 5-10ºN and Long. 70- 75ºE.

Northern Limit of Monsoon (NLM)

Southwest monsoon normally sets in over Kerala around 1st June. It advances northwards, usually in surges, and covers the entire country around 15th July. The NLM is the northern most limit of monsoon upto which it has advanced on any given day."

if this is the criteria followed by imd in declaring monsoon over kerala or any part of the country..which u also used to declare monsoon over some regions..which criteria acc to you did not meet to conclude monsoon over kerala??

Rajesh said...

@ron:I see the OLR still a little on the negative side as on yesterday. That is a bit short of the parameter required.For ur ref. i have put up the day's OLR on the Mumbai page (only for u).and, the winds as on 29th were still NW over kerala,seen on IMD analysis as on 29th evening chart. one more parameter, which i refer to in Mw, the 200 jet steram. Still not easterly as on 29th.

Rajesh said...

@ron. also rains were weak on 29th as shown in vagaries.

Ron said...

Thanks for the clarification...

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