Monsoon Advances into
The Southern and Central Andamans are receiving sporadic rains for the last 3 days. Port Blair has measured 71 mms, 57 mms rainfall for the last 2 days, i.e. 25th/26th May. Port Blair got 114 mms in the 24 hrs ended 5.30 pm on Thursday.
As on 26th May, Vagaries advances the SWM as a weak current into the regions of
Heavy rains lashed Colombo on Thursday morning.
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.
MONSOON ONSET NORMS OVER KERALA:
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.
2. WIND FIELD
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.
3. OUTGOING LONGWAVE RADIATION (OLR)
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.