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The Snow Booklet

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A Guide to the Science, Climatology, and Measurement of Snow in the United States

Nolan J. Doesken
Arthur Judson

ISBN #0-9651056-2-8 (2nd Edition)

Colorado Climate Center
Department of Atmospheric Science
Colorado State University
Fort Collins, CO 80523-1371

This booklet was made possible with support from:
What is "The Snow Booklet"
Cover
Authors
Table of Contents
A Few Facts About Snow
U.S. Snowfall Patterns
Problems and Challenges in Measuring Snow
Instructions for Measuring Snow
Other Interesting Links
How to Order Copies of "The Snow Booklet"

What is "The Snow Booklet"

"The Snow Booklet," as its name implies, is a short book (88 pages) about a fascinating subject. Anyone who has ever seen and touched snow, and watched it as it falls from the sky, cannot help but be amazed by its beauty and complexity. "The Snow Booklet" describes, in simplified terms, many facets of snow -- how it forms, how it falls, how it changes, how it melts and how it affects us on the ground including the hazards it presents. Detailed maps, tables and graphs are used to show the patterns and variations in snowfall experienced across the country. Photographs and cartoons help describe this remarkable substance. Special emphasis is given to the measurement of snow -- why it seems so simple and yet can be one of the most difficult meteorological measurements. Detailed instructions on how to measure snow accurately and consistently under a wide range of weather conditions are presented.


Cover

The Snow Booklet
Photo by Daniel B. Glanz

Authors

Nolan Doesken:
Nolan Doesken's love for snow developed at an early age. As a child, he could not sleep at night if snow was falling or predicted. Much of Doesken's appreciation for snow came from his years as a paperboy in a small town in central Illinois. "I particularly remember a Sunday morning in March or April when I awoke to an unexpected four inches of snow. The temperature was close to 32 degrees Fahrenheit, so I figured the snow would be heavy and wet. But, to my amazement, it was like goose down. As I loaded my papers, a car drove past the house at a low speed. A cloud of fluff lifted into the air and when the car was gone, the street had been blown clear. That's when I learned that the ten to one 'rule' didn't always apply." Since 1977, Doesken has been the Assistant State Climatologist at the Colorado Climate Center at Colorado State University. He also is a National Weather Service cooperative observer. Doesken closely works with National Weather Service personnel to improve the quality of weather data for climatic applications.

Arthur Judson:
Snowbursts that frequented his father's logging camps on Tug Hill, New York, fascinated Art Judson. As a young Marine, he chased snowstorms in California's San Bernadino mountains, then found deeper snows in the Rockies and Cascades. After obtaining a B.S. in Forestry from Oregon State University in 1960, he started chasing avalanches as a Forest Service snow ranger in Colorado. He later became a career avalanche forecaster and snow scientist with the Forest Service Avalanche Project. "Jud," as he is known to his friends, organized a special network to provide weather, snow, and avalanche data for avalanche forecasting and warning across the mountainous West. He founded Colorado's Avalanche Warning Program, developed an avalanche forecasting model, and worked to establish a warning service in Alaska. Currently, Jud lives in Steamboat Springs, Colorado (average annual snowfall 171 inches with 300-600 inches falling on the nearby mountains), where he continues to enjoy snow greatly.

Table of Contents

  • Preface
  • The Power and Beauty of Snow
  • The Science of Snow
    • What is snow?
    • Characteristics of fresh snow
    • Snow on the ground
    • Melting snow
    • Brief primer on avalanches
  • Climatology of Snow in the United States
    • Storm tracks
    • Snow frequency
    • Snowiest U.S. weather stations
    • Snowfall duration and intensity
    • Snowfall seasonality
    • National snowfall patterns
    • Snowfall variability
    • Snow hydrology and snowloads
    • Record snowstorms
  • Measuring Snow
    • Historical perspective
    • Elements of snow observations
    • Instruments for measuring snow
  • Problems and Challenges in Measuring Snow
    • Impact of inconsistent data collection
  • Procedures for Measuring Snow
    • Basic preparations
    • Taking observations
    • Snowfall
    • Depth of snow on the ground
    • Precipitation
    • Water content of freshly fallen snow
    • Water content of snow on the ground
  • Dealing With Adversity
    • The big blizzard
    • The day the snow wouldn't stick
  • Common Questions About Snow
  • Bibliography
    • Other suggested readings
  • Data Sources
  • Snow Glossary
  • Credits and Acknowledgements
  • Snow Memories

A Few Facts About Snow

  • Based on 1961-1990 National Weather Service records, Rochester, New York, is the snowiest large city in the United States (population greater than 200,000) averaging 94 inches of snowfall annually. Buffalo, New York, is a very close second.

  • Approximately 70 percent of the annual snowfall in the United States falls during December, January and February. However, for areas near the eastern slopes of the Rocky Mountains, March and April are often their snowiest months.

  • On average, 105 snow producing storm systems hit the lower 48 United States annually.

  • The old saying that ten inches of fresh snow contains one inch of water is only occasionally true. In reality, ten inches of new snow can contain as little as 0.10 inches of water to nearly four inches.


U.S. Snowfall Patterns


Maps are NOT for publication or redistribution without written permission from Colorado State University, Department of Atmospheric Science.

Problems and Challenges in Measuring Snow

To the uninitiated, measuring snow seems simple. All you need to do is push a measuring stick into the snow, then read the number on the stick and write it down, right? Unfortuately, it's not that easy.

Three properties of snow are responsible for most of the difficulties in making accurate and consistent measurements.

  1. Snow often melts as it lands or as it lies on the ground, both from warm soil below or from warm air, wind, or sunshine above. As a result, the observer may be in a dilemma. The observer may wonder, "It snowed for three hours, but there is nothin g on the ground. Do I report zero or a trace, or do I make something up?"
  2. Snow settles as it lies on the ground. Depending on the initial density of fresh snowfall and on other coincident weather conditions, the snow may settle rapidly or very gradually. This can have profound effects on observations. Observers who me asure more often than once each day may report much more snowfall than a once-daily observer.
  3. Snow is easily blown and redistributed. It tends not to land or lie uniformly on the ground, but instead forms deep drifts in some areas while exposed areas may be blown completely clear. A related problem is precipitation gauge catch. Even at r elatively low wind speeds, snow is easily deflected around the top of precipitation gauges. Most winter precipitation measurements using standard precipitation gauges underestimate the precipitation that actually fell and sometimes by large amounts.

Consistent and comparable snow data are only possible if standard procedures are established and followed. The use of snowboards and snowstakes, for example, is an important first step towards standardizing snowfall measurements.

Two crucial issues in measuring snowfall accurately are:

  1. determining a representative location for measuring snow, and
  2. establishing a consistent time interval between measurements of the depth of freshly fallen snow.

Unless observing locations and the interval of between measurements is standardized, snowfall data will be erratic and inconsistent, and not comparable from one site to another.

For example, an observer who measures new snow accumulation very frequently, and each time clears the snowboard to begin a new accumulation, will report snowfall totals that exceed what has actually accumulated on the ground. Frequent observations (hourly or every few hours) may be very useful for evaluating the intensity of snowfall, but these incremental measurements cannot be added together to give a meaningful snow accumulation.

For purposes of climatological comparison, what is reported as snowfall should be the maximum measured accumulation of new snow since the previous day.


Instructions for Measuring Snow

The following steps result in a complete climatological observations of precipitation and snowfall.

  1. Measure the amount of snowfall for the previous 24 hours from a snowboard in a representative location or from an average of several measurements.
  2. Measure the total combined depth of old and new snow on the ground.
  3. Measure the precipitation that has accumulated during the past 24 hours in a properly exposed precipitation gauge.
  4. Measure the water content of new snow that has accumulated on the snowboard (if representative) during the previous 24 hours.
  5. Measure the total water content of both old and new snow on the ground.
  6. Record all data using consistent and documented units.
Pages 61-76 of "The Snow Booklet" provide detailed instructions for measuring snow under a wide range of weather conditions.

Other Interesting Links

National Snow and Ice Data Center's homepage

National Weather Service Snow Measurement Guidelines


How to Order Copies of "The Snow Booklet"

If you are in the United States, the cost of "The Snow Booklet" is $15.00 plus $2.50 shipping & handling fee. For orders from Mexico or Canada, shipping and handling is $5.00. If you have an International order, please call or e-mail for shipping charges. We only take Visa or MasterCard credit cards. To pay in advance, please send a check or money order to -- Attention: Snow Booklet, Colorado Climate Center, Atmospheric Science Department, Colorado State University, Fort Collins, CO 80523-1371. Our phone number is 970-491-8545 or our fax is 970-491-3314. If you need more information, please email wendy.ryan@colostate.edu.

For your convenience, a copy of the order form can be obtained by clicking here.


Mailing Address:
Colorado Climate Center
Dept. of Atmospheric Science
1371 Campus Delivery
Colorado State University
Fort Collins, CO 80523-1371


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