National Weather Service United States Department of Commerce

NOAA Cloudwise/Weatherwise Poster

Cloudwise

NOAA Cloudwise Poster

We see clouds almost daily. But clouds are complicated and varied. In fact, the presence of a generic cloud means almost nothing without more details.

Clouds can grow very tall or appear flat as a pancake. They are typically white in color but can also be different shades of grey or brilliant yellow, orange or red. They can weigh tens of millions of tons yet float in the atmosphere.

Clouds can be harbingers of good weather or bad. Their absence can be a good thing after a flooding rain or a bad thing during a drought.

They provide relief from the heat of direct sunlight but also trap warmth, leading to higher temperatures. Precipitation from clouds helps crops to grow, but can make driving more dangerous due to reduced visibility.

They come in infinite shapes and sizes yet we often recognize more familiar objects or animals. Clouds can be carried along by winds of up to 150 mph (240 km/h) or can remain stationary while the wind passes through them.

They can form behind high flying aircraft or can dissipate as a plane flies through them. They are not confined to earth but are found on other planets as well.

What are clouds? They are the visible aggregate of minute particles of water and/or ice which form when water vapor condenses. Learn about clouds and how they form to become "NOAA Cloudwise".

 

Weatherwise

NOAA Weatherwise Poster

The motion of surface weather systems (high- and low-pressures, front, etc.) is driven primarily by the jet stream. The weather we experience depends upon the position and strength of the jet stream(s), as well as the season.

In the hypothetical scenario on the NOAA Weatherwise poster the actual weather at any location would vary by season. The chart provides a broad overview of the weather in each of four major regions on the lower 48 States. The following images show, given the position of the above weather systems, how the weather might change over the course of a year.

Remember, this is a broad generalization of possible weather based on the location of the jet stream, fronts, and relative pressures seen in the image.

Spring / Autumn

Spring and Autumn are the transition times between the extremes of Winter and Summer. As such there can be large contrasts between hot and cold from south to north. Also, as moisture pushes north from the gulf of Mexico, the dry line boundary become sharp. Temperatures west of the dry line can become quite warm in the very dry atmosphere.

Spring and Autumn are the transition times between the extremes of Winter and Summer. The large contrasts between hot and cold from south to north also make the jet streams the most vigorous and, consequently, weather extremes the most intense. This can be especially true of Spring.

It is not uncommon in Spring to have blizzard-like conditions in the Central and Northern Plains and severe thunderstorms and tornadoes in states along the Gulf of Mexico and the same time.

Summer

Summer is when the jet stream is the weakest and temperatures ranges from south to north or the least. Cold front and warm front boundaries are also harder to discern. However, Gulf of Mexico moisture permeates the South and Southeast making for quite muggy and oppressive conditions.

The Desert Southwest and inland valleys of California heat up as well. Also in California, the immediate coastal regions can remain rather cool due to the cold ocean current located just offshore. However, a few short miles inland can experience temperatures 20 to 40 degrees Fahrenheit higher.

With a relatively weak jet stream, large organized weather patterns are also weak. Precipitation across the country almost always includes thunderstorms but these storms are scattered and dotted around. The major risk from summer thunderstorms, besides lightning (which is always a hazard) are damaging winds.

Summer heating also leads to the almost daily formation of thunderstorms over the Rocky Mountains. These storms develop as the lift created by summer sunshine is greater than the downward motion of high pressure. Many wild fires have been started from these daily thunderstorms.

This is the monsoon season in the Desert Southwest; typically the wettest time of the year. While thunderstorms often remain scattered in coverage, their downburst of wind can created large areas of blowing dust. Another hazard from these thunderstorms is flash flooding that occurs many miles form the parent storm as water is channeled into dry creek beds and flows for miles.

Winter

Cold Arctic air rushes south into the Northern Plains and Great Lakes/New England regions. The Southeast can be pleasant temperature-wise but it is the Desert Southwest that experiences the mildest conditions.

A strong jet stream can bring large amount of snow to the northern half of the country. Blizzard conditions can occur in the Central Plains. If strong surface low pressure would to move up the East Coast then blizzard conditions could occue in the New England states, called a Nor-easter.

Thunderstorms will occur along cold fronts in South Central and Southeastern U.S. The Desert Southwest is in their dry season.

 

Download the poster

NOAA Cloudwise and Weatherwise is nearly 26" wide and 11" height (It is the same as three 8½ x 11" pages). Following are links to various PDF versions of the poster.