Forecasters Guide - (IMD), Pune

CHAPTER 5
IMPORTANT PROCEDURES DURING THE MONSOON SEASON
The agrarian economy of India depends mainly on the southwest monsoon rainfall
and hence this is a period of crucial importance to w eather forecasters. In order to avoid
mistakes and omissions in our duties, a certain set of procedures and regulations, evolved in
time are enclosed in the appendix.
5.1 Onset/ Withdraw al of Monsoon
The arrival of monsoon current over the Andaman Seas, its onset over the mainland
and further advance need to be monitored closely.
During the onset/ w ithdrawal phase, bulletins are issued by Weather Central, Pune,
RCs and MCs w hich w ill be posted on their respective websites as well as disseminated by
the media. To avoid contradictory bulletins to the public from various met. offices, Weather
Central, Pune, w ill issue an advisory bulletin at about 1130 hrs IST by Fax/ AMSS to
RCs/MCs regarding the advance/ withdraw al of monsoon from different met-subdivisions as
and w hen occasion arise. This will be prefixed by the wordings, ‘tentative bulletin dated -
………….’ and w ill be based on the 0000 UTC and 0300 UTC charts as w ell as telephonic
discussions among Director, Weather Central, Director-in-Charge of the concerned RCs and
NHAC New Delhi. (Appendix 5.1.1)
Onset Phase : The monitoring commences from 10 th May onw ards.
MC Thiruvananthapuram, DGM SATMET (New Delhi) and DGM (NHA C) New Delhi are
required to send the specified data, as given in the forecasting circular No. 1/2006 (Appendix
5.1.2) to the O/o DDGM(WF) via e-mail/Fax on a regular basis, till the onset is declared over
Kerala.
5.2 Strength and performance of monsoon
The procedures for describing the activity of monsoon, mentioning the temperature
conditions w hen the situation arises and the criteria follow ed in declaring the w ithdraw al etc.
are provided in the respective forecasting circulars. (Appendices 5.2.1 to 5.2.6)
Each forecasting office shall prepare a checklist on all these procedures to be
follow ed along w ith a list of w arnees (and phone numbers of disaster mitigation agencies)
and keep it handy prior to the starting of the season.
5.3 Commencement / cessation criteria for NE monsoon
Almost similar procedures need be follow ed during the NE monsoon period over the
southern peninsula. The respective instructions are added in Appendix 5.3.
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