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Aviation Weather Report (METAR/SPECI)
METAR is an aviation routine weather report issued at hourly or half-hourly intervals. It is a description of the meteorological elements observed at an airport at a specific time.
SPECI is an aviation special weather report issued when there is significant deterioration or improvement in airport weather conditions, such as significant changes of surface winds, visibility, cloud base height and occurrence of severe weather. The format of the SPECI report is similar to that of the METAR and the elements used have the same meaning. The identifier METAR or SPECI at the beginning of the weather report differentiates them.
The aviation weather report also includes a section containing the trend forecast, which indicates the forecast change in meteorological conditions in the next two hours.
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The latest aviation weather report at the Hong Kong International Airport issued by the Hong Kong Observatory at 03:31 HKT on 26 Jul 08
METAR
VHHH 1930 22004KT 180V250 9999 FEW030 29/24 Q1005 NOSIG=
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Decoded METAR/SPECI in plain language:- Aviation weather report (METAR) at 1930 UTC on 25 Jul 2008 issued by the Hong Kong Observatory :
| Wind |
Visibility |
Weather |
Cloud Amount |
Cloud Base |
Temperature |
Dew Point |
Pressure (QNH) |
| 4 knots from 220 degrees (SW), variability: 180-250 degrees
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10 km or above |
No significant weather |
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29 oC |
24 oC |
1005 hPa |
| Next Two Hours Change |
| No Significant Change |
| Visibility: |
As a result of an amendment by the International Civil Aviation Organization starting from 1 November 2001, the night-time visibility for aviation purpose represents the greatest distance at which light in the vicinity of 1 000 candelas can be seen and identified against an unlit background. As it is made specifically for aviation purpose, it may occasionally differ from the night-time visibility for general purpose which represents the degree of atmospheric transparency and is independent of the intensity of lights being observed. |
| okta(s): |
the international unit for reporting cloud amount. Cloud amount is assessed in total which is the estimated total apparent area of the sky covered with cloud. |
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1 okta is one-eighth of sky covered with cloud. 0 okta = sky clear, 1-2 oktas = few, 3-4 oktas = scattered, 5-7 oktas = broken and 8 oktas = overcast. |
| QNH: |
the pressure value measured at airport with adjustment made to suit aeronautical use. |
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Aviation Weather 
