What is CoCoRaHS?

There are many thousands of CoCoRaHS observers across the United States.

Plot of CoCoRaHS observations on Oct 27 2017

Active CoCoRaHS observers in Wyoming

What is CoCoRaHS?

CoCoRaHS is an acronym for the Community Collaborative Rain, Hail and Snow Network.  CoCoRaHS is a unique, non-profit, community-based network of volunteers of all ages and backgrounds working together to measure and map precipitation (rain, hail and snow).   By using low-cost measurement tools, stressing training and education, and utilizing an interactive Web-site, our aim is to provide the highest quality data for natural resource, education and research applications. We are now in all fifty states.

Download the updated "CoCoRaHS Brochure" as a PDF (12.4 MB)
CoCoRaHS Wanted Flyer PDF (164 KB)

In northern Lincoln County there are currently about 6 observers that report their precipitation and snow depths every day.  They include

Two in Star Valley Ranch, one each near Thayne, Etna, Afton and Smoot..  While these reports help give some idea of distribution of precipitation across Star Valley, more observations are needed throughout the area to provide a better analysis of rain/snow in the Valley.  Anyone familiar with Star Valley's weather knows there can be big differences over short distances when storms cross the area.

Where did the CoCoRaHS Network originate?

The network originated in the Colorado Climate Center at Colorado State University in 1998, thanks in part to the Fort Collins flood a year prior. In the years since, CoCoRaHS now includes thousands of volunteers nationwide.

Who can participate?

This is a community project.  Everyone can help, young, old, and in-between.  The only requirements are an enthusiasm for watching and reporting weather conditions and a desire to learn more about how weather can affect and impact our lives.

What will our volunteer observers be doing?

Each time a rain, hail or snow storm crosses your area, volunteers take measurements of precipitation from as many locations as possible.  These precipitation reports are then recorded on our Web site www.cocorahs.org. The data are then displayed and organized for many of our end users to analyze and apply to daily situations ranging from water resource analysis and severe storm warnings to neighbors comparing how much rain fell in their backyards.

Water Year 2017 CoCoRaHS plot of Observations at Star Valley Ranch

Who uses CoCoRaHS?

CoCoRaHS is used by a wide variety of organizations and individuals.  The National Weather Service, other meteorologists, hydrologists, emergency managers, city utilities (water supply, water conservation, storm water), insurance adjusters, USDA, engineers, mosquito control, ranchers and farmers, outdoor & recreation interests, teachers, students, and neighbors in the community are just some examples of those who visit our Web site and use our data.

What do we hope to accomplish?

CoCoRaHS has several goals (as stated in our mission statement). 1) provide accurate high-quality precipitation data for our many end users on a timely basis; 2) increasing the density of precipitation data available throughout the country by encouraging volunteer weather observing; 3) encouraging citizens to have fun participating in meteorological science and heightening their awareness about weather; 4) providing enrichment activities in water and weather resources for teachers, educators and the community at large to name a few. 

Who is sponsoring this network?

The National Oceanic and Atmospheric Administration (NOAA) and the National Science Foundation (NSF) are major sponsors of CoCoRaHS. Other organizations have contributed either financially, and/or with supplies and equipment.

What benefits are there in volunteering?

One of the neat things about participating in this network is coming away with the feeling that you have made an important contribution that helps others.  By providing your daily observation, you help to fill in a piece of the weather puzzle that affects many across your area in one way or another. You also will have the chance to make some new friends as you do something important and learn some new things along the way. In some areas, activities are organized for network participants including training sessions, field trips, special speakers, picnics, pot-luck dinners, and photography contests just to name a few.

How can I sign up?

Just click here to sign up as a CoCoRaHS Volunteer Observer or download a .pdf version of our application and return it as soon as possible.

Reservoir Storage Going into the Winter Snow Season

Wyoming will be entering the 2017-2018 snow season with a very healthy carry over water supply in the reservoir systems thanks to last seasons big runoff.  Following is the status of Wyoming reservoirs as of late October showing the percentage of the capacity of each.

With the exception of the southeast, Wyoming Reservoirs are going into the winter snow season with very healthy levels.  It is interesting to note that both Lake Powell and Lake Mead still reflect the long term drought with (60% and 38%) respectively.

However the Snake River Reservoir System which includes much of northwestern Wyoming is holding very high amounts of water.

For Water Year 2018 which we are now beginning as of Oct 1st, the reservoir system is holding nearly 3 times the amount of water as last year at the same time and almost double normal.

Specfically, Palisades Reservoir noted in the figure below, still is over 90%  full. This is 10 times what it was a year

ago and close to double  the amount normally being stored..

It will be interesting to monitor what effects this coming Winter snows  and Spring runoff will have on water levels, particularly in Palisades which is still nearly full.

Riverton Weather Forecast Office History

Forecaster Work Station

The Forecast for Star Valley is produced at the Riverton Forecast Office.  A new forecast is displayed on the Starvalleyweather.com site whenever changes occur.  Riverton is one of some 122 Weather Forecast Offices in the United States. The Pocatello Forecast Office provides for the Idaho Counties and this will sometime account for the differences in forecast for the Idaho vs Wyoming Counties.

Riverton Weather Forecast Office

Riverton Weather Office History

In 1986 the NWS announced a modernization and restructuring program designed to revamp the organizational and staffing structure of the agency. In April of that year Riverton was selected as the site for a proposed NEXRAD (Next Generation Radar) Doppler radar and forecast office. 

Construction of the office facility was completed in March 1995. The installation of the radar soon followed in June and July.  WFO operations began in Riverton on August 28, 1995 with a staff of 18. The radar was formally accepted on April 10, 1996. 

Beginning in 1996 the Riverton WFO took warning responsibility for eleven counties in western and central Wyoming comprising over 56,000 square miles. These counties remain the same today and include Big Horn, Fremont, Hot Springs, Johnson, Lincoln, Natrona, Park, Sublette, Sweetwater, Teton, and Washakie.  The arrival of the Advanced Weather Interactive Processing System (AWIPS) in April 1999 dramatically altered the computer capabilities of the WFO.  AWIPS remains the main computer interface for WFO meteorologists, but upgrades to the operating system and accompanying software occur frequently to keep up with changing technologies. The arrival of the AWIPS also ushered in five new lead forecasters to serve at the WFO. This brought the level of staffing to 23, where it remains today.

The era of typed forecasts came to an end in October, 2002 with the first issuance of a digital database of weather information. Today, the Graphical Forecast Editor (GFE) is used to create a suite of digital weather elements which in turn generate various types of forecasts for users across western and central Wyoming, most commonly the seven-day public forecast and fire weather forecast. 

Today, the 23 professionals at the Riverton WFO remain dedicated to providing the best possible weather forecasts, warnings, hydrologic, and climate information available to the citizens of western and central Wyoming. In addition to the day-to-day weather forecasting, the employees maintain and repair weather observing systems across the service area, create and install new computer software, conduct scientific research, and routinely interface with customers and the public. All are encouraged  to stop by and visit the forecast office on U.S. Highway 26 about five miles west of Riverton.

U.S Winter Outlook Issued

While the New Winter Outlook is calling for somewhat above normal precipitation for Star Valley along with a little warmer than average temperatures we know it will snow. The statement at the end of the article is worth repeating.

NOAA’s seasonal outlooks give the likelihood that temperature and precipitation will be above-, near, or below-average, and also how drought is expected to change, but do not project seasonal snowfall accumulations. While the last two winters featured above-average temperatures over much of the nation, significant snowstorms still impacted different parts of the country.

Snow forecasts are generally not predictable more than a week in advance because they depend upon the strength and track of winter storms.

The U.S. Winter Outlook will be updated on November 16.

 NOAA’s Climate Prediction Center released the U.S. Winter Outlook,  with La Nina potentially emerging for the second year in a row as the biggest wildcard in how this year’s winter will shape up. La Nina has a 55- to 65-percent chance of developing before winter sets in.

NOAA produces seasonal outlooks to help communities prepare for what's likely to come in the next few months and minimize weather's impacts on lives and livelihoods. Empowering people with actionable forecasts and winter weather tips is key to NOAA’s effort to build a Weather-Ready Nation.

“If La Nina conditions develop, we predict it will be weak and potentially short-lived, but it could still shape the character of the upcoming winter,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “Typical La Nina patterns during winter include above average precipitation and colder than average temperatures along the Northern Tier of the U.S. and below normal precipitation and drier conditions across the South.”

Other factors that influence winter weather include the Arctic Oscillation, which influences the number of arctic air masses that penetrate into the South and is difficult to predict more than one to two weeks in advance, and the Madden-Julian Oscillation, which can affect the number of heavy rain events along the West Coast.

The 2017 U.S. Winter Outlook (December through February):

Precipitation

• Wetter-than-average conditions are favored across most of the northern United States, extending from the northern Rockies, to the eastern Great Lakes, the Ohio Valley, in Hawaii and in western and northern Alaska.

• Drier-than-normal conditions are most likely across the entire southern U.S.

Temperature

• Warmer-than-normal conditions are most likely across the southern two-thirds of the continental U.S., along the East Coast, across Hawaii and in western and northern Alaska.
• Below-average temperatures are favored along the Northern Tier of the country from Minnesota to the Pacific Northwest and in southeastern Alaska.
• The rest of the country falls into the equal chance category, which means they have an equal chance for above-, near-, or below-normal temperatures and/or precipitation because there is not a strong enough climate signal in these areas to shift the odds.

• NOAA’s seasonal outlooks give the likelihood that temperature and precipitation will be above-, near, or below-average, and also how drought is expected to change, but do not project seasonal snowfall accumulations. While the last two winters featured above-average temperatures over much of the nation, significant snowstorms still impacted different parts of the country. Snow forecasts are generally not predictable more than a week in advance because they depend upon the strength and track of winter storms. The U.S. Winter Outlook will be updated on November 16.

Preliminary Snowfall Totals Through Noon Saturday

3 Inches at Star Valley Ranch  Friday Night

Public Information Statement
National Weather Service Riverton WY
200 PM MST Sat Oct 14 2017

...Preliminary Snowfall Totals Through Noon Saturday..

Snowfall began in western Wyoming late Friday night and began to
spread east of the Divide during the predawn hours Saturday. The
snow is tapering off now and will soon end across the state. A
relatively narrow band of persistent heavy snow passed over Teton
Pass to Teton Village area where and estimated 4 to 10 inches of
snow accumulated.

Snotels (Snow Telemetry) are remote sensing sites in the mountain
watersheds.  Snowfall data from SNOTELS are estimated based on snow
water equivalent.
Location                              Snowfall

Lincoln County...
 Willow Creek Snotel...               4 inches.
 5 NNE Thayne...                    3.5 inches.
 Cottonwood Creek Snotel...           3 inches.
 Commissary Ridge...                  3 inches.
 Star Valley Ranch...                 3 inches.
 Box Y Ranch...                       2 inches.
 Spring Creek Divide Snotel...        2 inches.
 Indian Creek Snotel...               2 inches.
 Blind Bull Summit...                 2 inches.
 Afton...                           1.5 inches.
 5 SSE Smoot...                       1 inch.
 Salt River Summit Snotel...          1 inch.
 Kelley Ranger Station Snotel...      1 inch.
 2 SE Thayne...                       1 inch.



Big Horn County...
 Shell Creek Snotel...                2 inches.
 Bald Mountain Snotel...              1 inch.

Fremont County...
 St. Lawrence Alt Snotel...           6 inches.
 Hobbs Park Snotel...                 6 inches.
 Dubois...                            5 inches.
 Hudson...                          3.5 inches.
 Townsend Creek Snotel...             3 inches.
 Lander Airport...                  2.6 inches.
 Brooks Lake...                       2 inches.
 Riverton Airport...                1.9 inches.
 4 W Riverton...                    1.5 inches.
 7 WNW Lander...                    1.1 inches.
 Little Warm Snotel...                1 inch.
 Deer Park Snotel...                  1 inch.
 Castle Creek Snotel...               1 inch.
 Riverton...                        0.2 inches.
 Burris...                          0.1 inches.

Hot Springs County...
 Owl Creek Snotel...                  3 inches.
 Thermopolis...                     0.2 inches.

Johnson County...
 Cloud Peak Reservoir Snotel...       2 inches.
 Bear Trap Meadow Snotel...           1 inch.


Natrona County...
 Grave Springs Snotel...              2 inches.
 Reno Hill Snotel...                  1 inch.
 Casper Airport...                  0.2 inches.

Park County...
 Beartooth Lake Snotel...             7 inches.
 Blackwater Snotel...                 4 inches.
 Evening Star Snotel...               3 inches.
 Kirwin Snotel...                     3 inches.
 Timber Creek Snotel...               2 inches.
 Marquette Snotel...                  2 inches.
 Pahaska...                           1 inch.
 Wolverine Snotel...                  1 inch.
 Younts Peak Snotel...                1 inch.
 3 NE Sunshine...                   0.9 inches.
 26 SW Cody...                      0.5 inches.

Sublette County...
 Pocket Creek Snotel...               6 inches.
 Boulder Rearing Station...           3 inches.
 Snider Basin Snotel...               2 inches.
 Big Sandy Opening Snotel...          1 inch.
 Gunsite Pass Snotel...               1 inch.
 East Rim Divide Snotel...            1 inch.
 14 NW Pinedale...                  0.8 inches.
 Daniel Fish Hatchery...            0.1 inches.

Sweetwater County...

Teton County...
 Jackson Hole - Rendezvous Bowl...   11 inches.
 Jackson Hole - Raymer...             9 inches.
 Jackson Hole - Mid Mountain...       9 inches.
 Grand Targhee - Chief Joseph...      8 inches.
 Togwotee Pass Snotel...              8 inches.
 Jackson Hole - Base...               8 inches.
 2 NE Teton Village...                7 inches.
 5 NW Jackson...                      7 inches.
 Grand Targhee Snotel...              6 inches.
 Snow King...                         5 inches.
 Jackson...                      2 to 4 inches.
 Base Camp Snotel...                  3 inches.
 Jackson Dam...                       3 inches.
 Togwotee Mountain Lodge...           3 inches.
 Grassy Lake Snotel...                2 inches.
 Snake River Stn Snotel...            1 inch.

Washakie County...
 Powder River Pass Snotel...          3 inches.
 16 SSE Ten Sleep...                0.5 inches.

Yellowstone National Park...
 Sylvan Lake Snotel...                6 inches.
 Lewis Lake Divide Snotel...          5 inches.
 Parker Peak Snotel...                5 inches.
 Two Ocean Plateau Snotel...          3 inches.
 Canyon Snotel...                     2 inches.
 Yellowstone East Entrance...         2 inches.
 Sylvan Road Snotel...                1 inch.
 Thumb Divide Snotel...               1 inch.

Summary of a Record or Near Record Water Year For Western Wyoming Including Star Valley

The Riverton Forecast Office has compiled a summary of the Water Year(Oct 1 2016-Sept 30 2017) precipitation for locations in Western Wyoming. For comparison Star Valley Ranch measured 38.05 inches with 252 inches of snow. This is comparable to the amount observed at Old Faithful in YNP where the 38.57 inches was the greatest ever recorded going back to 1905!  Another reliable observer in Star Valley Ranch actually measured around 40 inches for the Water Year.

Old Faithful measured 262 inches of snow vs the 252 at Star Valley Ranch.

For more details of this record water year including graphs go to the link
http://www.weather.gov/riw/drought_4

Coldest Morning in 7 Months

Sunrise Over Afton WY October 9 2017 from the West Hills

Temperatures dipped to the lowest levels across much of Western Wyoming including Star Valley in about 7 months.  As an example Thayne Elementary weather station dropped to 19 degrees at sunrise the coldest since it was 17 above zero on March 6th.  The lowest reported reading in the valley this morning as 15 above zero at Double L Ranch located along the Salt River to the northwest of Etna

The following map is a plot of reported minimum temperatures across the region.  There were a few  single digits observed in the high elevations of northwest Wyoming.

Minimum Temperatures October 9 2017

Dry Fall Weather Ahead

With the dissipation of the snow showers Sunday evening across Star Valley it brings to an end a very wet 30 day period.  Star Valley Ranch has measured 5 inches of precipitation since the 8th of September. However it now appears that the jet stream pattern will be adjusting with much of the storm activity tracking mainly to the north of Western Wyoming the next couple of weeks.

There will be fast moving cold fronts crossing the mountain west during much of the remainder of October, for the most part they will be dry but windy.  Unlike the last few weeks, it appears like sunshine will be a frequent visitor to Western Wyoming, particularly this coming work week.

Beyond this week the forecasts are calling for cool and dry conditions.

Temperature Forecasts October 14-18 2017

Precipitation for period October 4-18 2017

Looking ahead toward the latter half  of October continued dry conditions cover much of the area.

Precipitation Probability Oct 21-Nov.  3 2017

Temperature Probability Oct 21- Nov 3 2017

The skill of forecasting, particularly precipitation, degrades  certainly beyond a week, however it is interesting to see the computer model forecast of accumulated precipitation over the next 16 days.

Totals for the next two plus weeks are generally less than an inch except for the high country in Northwest Wyoming.

  

Cloud Videos Across Star Valley on Monday October 2 2017

Monday was a great cloud day across all of Star Valley.  For those who also enjoyed the skies of Star Valley Monday, following are 4 cam videos from the day with different perspectives.

Cam located near Bedford looking north toward Star Valley Ranch

Cam located in the West Hills looking east toward Afton

Cam located near Star Valley Ranch  looking north across Etna

Cam located in Double L Estates viewing north toward Alpine

Star Valley and Wyoming Water Year 2016-2017,

October 1st marks the beginning of a new water year.  Also a time to review the water year just ended.  With the exception of  a rather dry summer, Star Valley and surrounding areas were favored with  beneficial moisture,including both rain and snow.

The first figure displays the total precipitation that was measured from October 1 2016-September 30 2017(Water Year) for much of western Wyoming and surrounding areas.

Total Precipitation Oct. 1 2016 to Sept. 30 2017

Much of Northern and Western Wyoming experienced above to much above normal precipitation for the water year 2016/2017, noted in the following figure.

Daily observations of rain and snow are measured at Star Valley Ranch. Following are the monthly totals in inches of each at the Star Valley Ranch site at an elevation near 6400 feet.

Month          Rain        Snow

Oct 2016      6.05          9.8

Nov              1.63        17.5

Dec              3.90         64.0 

Jan 2017      5.00         69.5

Feb              5.04         41.1

Mar             2.81         17.2

Apr             4.56         23.7

May            1.47          5.0

Jun              2.06             0

Jul                 .22            0

Aug               .62            0

Sep              4.69         4.0

Total          38.05     251.8

The consequence of last winters snows was a very large spring and early summer runoff that filled the Snake River reservoir system by the first of July.  The water levels remain well above normal even as the new water year begins. The graph below compares the current vs last year and average water supply in Palisades reservoir.

       

With the benefical precipitation during the last half of September, the water level in Palisades has actually increased recently. It will be of interest to see how  the coming winter snow impacts the well above normal  current water storage in the Snake River System..