Clouds_Codes - Clouds/WX Codes B.1 Introduction This...

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1 Clouds/WX Codes B.1 Introduction This appendix provides the necessary tables and specific instructions to enter Clouds/Wx at the Surface Data screen. This guidance assumes no previous knowledge of synoptic code procedures. However, a basic understanding of clouds and weather is necessary. For those already familiar with synoptic code, you will notice some departure from conventional WMO coding procedures. If you simply observe the elements requested and report them according to tables provided in this text, the intent of the Clouds/Wx entry will be fully met. B.2 Getting Started The Cloud/WX entry is a nine-digit, mandatory group. All nine digits must be entered, regardless of the presence or absence of clouds or significant weather conditions. Operational Suggestion: If time before release is critical to where a proper Clouds/Wx coding cannot be made, simply enter any nine digits to complete the Surface Data screen. After release, properly code the clouds and weather. Edit the surface observation by clicking on “Tools” and selecting “Change Surface Data” enter the Clouds/Wx block with new data. The WMO format for entry of clouds and weather has been modified in the RRS software to meet NCDC requirements. All stations using RRS software will follow this modified format, regardless of location; i.e., stations in either WMO Region IV or WMO Region V. A description of the nine digit format follows: 1. Clouds/Wx group format: N h C L hC M C H WWWW a. N h = Amount (in oktas) of the sky covered by all low clouds ( C L ) observed or the amount of sky covered by all the middle clouds ( C M ) observed. In no case will the amounts of the low and middle clouds be combined to report N h . Use Table B-1 to report the amount of low or middle cloud coverage. b. C L = Type of low cloud, based on the priority given in Table B-2 . A solidus (/) is reported if C L clouds are not visible owing to fog or similar obscuring phenomena. Note: Clouds are divided into three families, classified as low, middle, or high. The general height ranges for these are: surface to 6500 feet for low; 6500 feet to 20000 feet for middle; and above 20000 feet for high. Remember, these ranges are not absolute, but given as a guide only. More consideration may be given to the cloud form than the height in many cases. Each cloud family is coded with a single digit, 0 through 9. The code figure 0 is used to indicate that clouds are not present for a given family. c. h = Height of the base of the lowest cloud observed. The height reported is with respect to the surface. The height is coded as a solidus (/)
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2 if there is a total surface-based obscuration that prevents an observation of the clouds. Use Table B-3 for the cloud base height. d.
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This note was uploaded on 01/08/2012 for the course MPO 551 taught by Professor Zhang,c during the Summer '08 term at University of Miami.

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Clouds_Codes - Clouds/WX Codes B.1 Introduction This...

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