High-Impact and Far-Reaching Winter Storm Continues; Cold Expands and Persists

A major winter storm will shift its impacts into the Northeast U.S. with heavy snow through tonight while over the Mid-Atlantic, sleet and freezing rain will diminish. Extremely cold air behind the storm will prolong dangerous travel and infrastructure impacts. Sub-zero low temperatures are expected nearly every morning from the Northern Plains through the Ohio Valley and into the Northeast. Read More >

Florida Keys Cloud Chart

By Jim W. Lee

One of the many functions of the National Weather Service is to collect weather data and observations. One type of observation is a description of "sky condition", the amount and character of clouds visible in the sky. This is coded according to established categories, detailed on the three pages linked below.

Clouds need two major ingredients to form - rising air and moisture. These ingredients are usually only required at the altitude at which the clouds are forming or developing. For example, a cloud deck based at 10,000 feet above the ground indicates sufficient rising air and moisture at that level, but does not necessarily reflect the state of the atmosphere below 10,000 feet (or above the top of the cloud deck). On the following pages I will provide photographic examples and brief descriptions of the various cloud types that are identified for the purposes of sky condition observations. Low level clouds are generally based at or below 6,500 feet above ground, mid-level clouds are generally based between 6,500 feet and 15,000 feet above ground, and high level clouds are generally based more than 15,000 feet above ground.

All of the pictures on these pages were taken in the Lower Keys, unless otherwise noted.

On the following pages, click on any image for a larger version!

Low Clouds

Middle Clouds

High Clouds

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