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APPENDIX I.4

DEFINITIONS OF METEOROLOGICAL FORECASTING RANGES

1.

Nowcasting

A description of current weather parameters and 0 -2 hours description of forecasted weather parameters

2.

Very short-range weather forecasting

Up to 12 hours description of weather parameters

3.

Short-range weather forecasting

Beyond 12 hours and up to 72 hours description of weather parameters

4.

Medium-range weather forecasting

Beyond 72 hours and up to 240 hours description of weather parameters

5.

Extended-range weather forecasting

Beyond 10 days and up to 30 days description of weather parameters, usually averaged and expressed as a departure from climate values for that period.

6.

Long-range forecasting

From 30 days up to two years

6.1

Monthly outlook

Description of averaged weather parameters expressed as a departure (deviation, variation, anomaly) from climate values for that month (not necessarily the coming month).

6.2

Three month or 90 day outlook

Description of averaged weather parameters expressed as a departure from climate values for that 90 day period (not necessarily the coming 90 day period).

6.3

Seasonal outlook

Description of averaged weather parameters expressed as a departure from climate values for that season.

Notes:

(1)

In some countries, long-range forecasts are considered to be climate products

(2)

Season has been loosely defined as Dec/Jan/Feb = Winter; Mar/Apr/May = Spring; etc...in the northern hemisphere. In the tropical areas seasons may have different durations. Outlooks spanning several months such as multi-seasonal outlooks or tropical rainy season outlooks may be provided.

7.

Climate forecasting

Beyond two years

7.1

Climate variability prediction

Description of the expected climate parameters associated with the variation of inter-annual, decadal and multi-decadal climate anomalies.

7.2

Climate prediction

Description of expected future climate including the effects of both natural and human influences.


 

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