These reports are the views, study and observations of Vagaries. Estimates and forecasts are also the calculation of Vagaries, and may/may not tally with any other estimates/nodels. This may not be used for commercial purposes. Vagaries of Weather is not responsible for any commercial loss from this article, or these series of articles.
The Monsoon developments, as they unfold, will be analysed , discussed and explained in Vagaries.
Vagaries follows the developments(parameters) that emerge during the summer (Apr/May) which lead to the monsoon.
Vagaries believes the expertise to predict the monsoon in it's entirety during the summer itself is not feasable. The parameters themselves are developing in April and May. Quantum of rain forecasting in April for June right through September is an impossible task.
😎Otherwise the charm of chasing the monsoon parameters as they unfold during the summer , is lost.
➤Further Analysis of the parameters as discussed in MW-1 ,MW-2...
1. Cross Equatorial Winds from Southern Hemisphere and Mascarene high.
2. Pre monsoon showers / LWD.
3. Seasonal low over Indian subcontinent.
Additional parameters from MW-3 :
5. Bay low.
6. Jet Streams (the winds at altitudes above 10 kms ).
1. Cross Equatorial Winds and Mascarene high :
The winds on crossing the equator break into 2 branches. i) gushing into the Arabian Sea, and ii) moving into the Bay of Bengal.
ii) In the Eastern sector, in the Bay Branch, some Westward wind flow is observed towards the Sumatra Coast.This is an improvement over MW-2. Thunder clouds(Cb) developments are seen near the equator in eastern Indian ocean.
We prefer the Bay Branch to be better organised, as the SW Monsoon is normally expected there first (normal date 15 May at southernmost Nicobar island).
ITCZ (Inter Tropical Convergence Zone): This Seasonal trough passes from the South Arabian Sea to Andaman sea after the withdrawal of SWM in Oct. Shifts further south in Dec. Moves North during South West Monsoon.
Now south of the equator (5S) over western Indian ocean and near the equator over the eastern Indian ocean as it was during MW-2.
This is an improvement compared to the high reading of 1023 mb observed during MW-2. The power house of monsoon is almost on schedule as of now.
The sea surface temps in the region of Mascarene High formation are lower than normal .This should help in strengthening the High.
East India (Bengal,Odisha) is experiencing one of it's coolest summers.
iv) The 30 day Southern Oscillation Index (SOI) is calculated using the pressure differences between Tahiti and Darwin.It is in neutral range currently.
(sustained values below -7 indicates El Nino and above +7 indicates La Nina)
|SOI values for|
|Average SOI for last 30 days||0.79|
|Average SOI for last 90 days||-2.70|
|Tahiti hpa - Darwin hpa (5 May 2020)||1013.75 hpa - 1012.45 hpa|
v) IOD (Indian Ocean Dipole) is in neutral range currently.
Latest weekly value is 0.08.
6.Indicator as on 5 May 2020 : Negative