Warnings

Nowcast

Descriptive term	Specification
Weak monsoon	Rainfall less than half the normal.
Normal monsoon	Rainfall half to less than 1½ times the normal (Mention of "normal" monsoon may not be necessary in general).
Active monsoon	Rainfall 1 ½ to 4 times the normal. The rainfall in at least two stations should be 5 cm, if that sub-division is along the west coast and 3 cm, if it is elsewhere. Rainfall in that sub-division should be fairly widespread to widespread.
Vigorous monsoon	Rainfall more than 4 times the normal. The rainfall in at least two stations should be 8 cm if the sub-division is along the west coast and 5 cm if it is elsewhere. Rainfall in that sub-division should be fairly widespread or widespread.
Subdued Monsoon	Spatial distribution of rainfall remains dry, isolated or scattered for two consecutive days. Mean actual rainfall of that particular sub-division remains less than the normal for the consecutive two days. The Forecast issued for the next 48 hrs on the particular day for the sub-division is also dry, isolated or scattered. Upon satisfying all the above criteria simultaneously, monsoon activity be described as subdued on the second day.

Notes:

⟩ While describing the activity of the monsoon,
- The normals of stations, whenever available should be used.
- Till normals for all the stations are available the following procedure should be adopted:
Number of stations in a sub-division with normals - a
Normal for these stations - b
Average normal for the sub-division - b/a
Total number of stations reporting rainfall - c
Actual total rainfall reported by these stations - d
Therefore, the average rainfall for the sub-division - d/c
Compare d/c with b/a and describe the activity of the monsoon accordingly, other conditions being fulfilled.
⟩ In the sub-divisions, where the percentage of hill stations is high, the hill stations must be also taken into account for describing the activity of the monsoon. In other sub-divisions, the hill stations will be excluded.
⟩ The monsoon activity will be described in all the sub-divisions of northeast India as is done for sub-divisions of other regions.
⟩ The monsoon activity need not be described over the Bay Islands and the Arabian Sea Islands.

Descriptive term	Specification
Weak monsoon	Rainfall less than half the normal.
Normal monsoon	Rainfall half to less than one and a half (1½) times the normal
Active monsoon	i) Rainfall 1½ to 4 times the normal. ii) Rainfall 1 ½ to 4 times the normal.
Vigorous monsoon	Rainfall exceeding 4 times the normal Rainfall in at least two stations should be 5 cm in coastal Tamil Nadu and south coastal Andhra Pradesh and 3 cm elsewhere. Rainfall in that sub-division should be fairly widespread or widespread.