AMOSSG/5-SN No. 16

4/4/05

Revised

AERODROME METEOROLOGICAL OBSERVING SYSTEMS STUDY GROUP (AMOSSG)

FIFTH MEETING

Montreal, 11 to 14 April 2005

Agenda Item	7:	Guidance material

TS IDENTIFIED AS A PRESENT WEATHER PHENOMENA

(Presented by D. Hart)

SUMMARY
Edition 15 of ICAO Annex 3 introduced a difference between the described reporting practice for thunder/lightning and the supportive templates. This paper suggest changes to the templates to overcome the issue.

1.	INTRODUCTION

1.1	With the introduction of edition 15 of ICAO Annex 3 changes where incorporated in the templates for reporting local routine and special reports, METAR and SPECI. In case of the inclusion of characteristics of recent weather phenomena, the abbreviation RETS was deleted out of the templates, compared with edition 14 of the annex.

1.2	While the templates do allow the coding of the weather phenomena "thunder heard or lightning detected at the aerodrome but no observed precipitation", it is not included as a recommended practice to report as recent weather. Appendix 3, paragraph 4.4.8.1 states this requirement in contradiction with the deletion out of the associated templates. This contradictions leads to misunderstanding.

2.	DISCUSSION

2.1	It's proposed to harmonize the templates for local routine and special report, METAR and SPECI with the requirement stated in Appendix 3, paragraph 4.4.8.12.4; RETS shall be reintroduced in the relevant templates.

3.	ACTION BY THE GROUP

3.1	The AMOSSG is invited to:

a)	note the content of this paper;

b)	agree on the proposal stated in paragraph 2.1; and

c)	undertake any further action, if necessary.

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