Snow Melt Runoff on the Increase much of Western Wyoming Mountains

Hydrologic Outlook

National Weather Service Riverton WY
1055 AM MDT Wed May 31 2017

..Warm mountain temperatures Wednesday through Saturday
will accelerate snowmelt runoff...

...Flooding expected on smaller creeks and streams by the end of the
week with minor flooding along main stem rivers by the weekend...

Decreases of up to an inch of snow water equivalents (SWEs) occurred
at the 9,000 foot elevation in the last 24 hours at several SNOTEL
locations along the Green and Wind River Basin. There is still around 30
inches of SWEs at several SNOTEL locations at the 9,000 to 10,000
foot elevation across the Wind, Green, Shoshone, and Upper Yellowstone
Basins.

Afternoon temperatures at the 9,000 foot elevation are expected to
warm into the lower to middle 60s Wednesday through Saturday.
Morning low temperatures will also be above the frost
temperature of 37 degrees Wednesday through Saturday.
Windy conditions over the mountains are expected Thursday afternoon
through Friday morning. Mountain rain showers will be more widespread
Thursday afternoon through Friday morning.

Accelerated snowmelt runoff will cause sharp increases in stream and
river levels Thursday morning through Saturday morning. The greateat
increase in stream and creek levels will be Thursday evening through
Friday morning. Flooding of low lying areas is expected on smaller creeks
and streams by Friday; with minor flooding expected along main stem rivers
like the Green, Little Wind, Big Wind, Sweetwater, and Shoshone by
Saturday and Sunday.

People living near flood prone areas along creeks and rivers should make
final preparations for high water later this week through this weekend.
Mountain streams run the highest in the late afternoon through early evening
hours. Do not attempt to cross streams at that time as the swift water will
easily carry you downstream.

Look for flood watches and/or advisories to be issued Thursday and Friday

for the upcoming flooding event.

Graphical forecasts are available at:
http://water.weather.gov/ahps2/index.php?wfo=riw
Visit weather.gov/riverton and select the rivers & lakes tab for
graphical forecasts and additional information.

Northern Lights Seen From Star Valley

Northern Lights were captured on the Bedford Web Cam overnight May 27/28 2017

Snowfall Amounts 3pm Thursday

Public Information Statement
National Weather Service Riverton WY
310 PM MST Thu May 18 2017


...Preliminary Snowfall Amounts...

Below are snowfall amounts ending at 3 pm Thursday. Observations are
collected from a variety of sources with varying equipment and
exposures. We thank all volunteer weather observers for their
dedication. Not all data listed are considered official.

Snotel data are through 2 pm Thursday afternoon. SnoTELs (Snow
Telemetry) are remote sensing sites in high mountain watersheds.
Snowfall data from SNOTELS are estimated based on snow water
equivalent


Location                              Snowfall
Lincoln County...
 Willow Creek Snotel...              10 inches.
 Indian Creek Snotel...               7 inches.
 Spring Creek Divide Snotel...        5 inches.
 Blind Bull Summit Snotel...          5 inches.
 Star Valley Ranch...                 4 inches.
 Salt River Summit Snotel...          4 inches.
 Kelley Ranger Station Snotel...      4 inches.
 Cottonwood Creek Snotel...           3 inches.
 2 SE Thayne...                     2.5 inches.
 3 SE Bedford...                      2 inches.
 Hams Fork Snotel...                  2 inches.
 5 SSE Smoot...                       1 inch.
 3 N Etna...                          1 inch.
 Afton...                           0.5 inches.
Big Horn County...
 Bald Mountain Snotel...              6 inches.
 Shell Creek Snotel...                2 inches.
 Bone Springs Divide Snotel...        1 inch.

Fremont County...
 South Pass Snotel...                14 inches.
 Cold Springs Snotel...              14 inches.
 Deer Park Snotel...                 13 inches.
 Hobbs Park Snotel...                12 inches.
 Townsend Creek Snotel...            12 inches.
 St. Lawrence Alt Snotel...           9 inches.
 Little Warm Snotel...                5 inches.
 Burroughs Creek Snotel...            4 inches.
 Jeffrey City...                      3 inches.
 6 SW Lander...                     2.4 inches.
 9 S Lander...                      2.2 inches.
 Lander...                     1 to 2.2 inches.
 Dubois...                            2 inches.
 Lander...                          1.9 inches.
 Atlantic City...                   1.7 inches.
 Riverton...                          1 inch.
 2 W Riverton...                    0.3 inches.
 4 W Riverton...                    0.3 inches.

Hot Springs County...
 Owl Creek Snotel...                  4 inches.

Johnson County...
 Cloud Peak Reservoir Snotel...      11 inches.
 Soldier Park Snotel...               9 inches.
 Little Goose Snotel...               7 inches.
 Bear Trap Meadow Snotel...           1 inch.



Natrona County...
 Casper Mountain Snotel...            8 inches.
 Reno Hill Snotel...                  6 inches.
 Grave Spring Snotel...               4 inches.
 Powder River...                      2 inches.
 5 SSW Casper...                    0.8 inches.

Park County...
 Marquette Snotel...                 14 inches.
 Pahaska...                          14 inches.
 Evening Star Snotel...              13 inches.
 Beartooth Lake Snotel...            13 inches.
 Blackwater Snotel...                11 inches.
 Timber Creek Snotel...              11 inches.
 Kirwin Snotel...                     8 inches.
 Wolverine Snotel...                  5 inches.
 Younts Peak Snotel...                4 inches.
 26 SW Cody...                      3.5 inches.
 1 ENE Wapiti...                      3 inches.
 3 NE Sunshine...                   1.6 inches.

Sublette County...
 Elkhart Park G.S. Snotel...          7 inches.
 Gunsite Pass Snotel...               7 inches.
 Loomis Park Snotel...                6 inches.
 Triple Peak Snotel...                6 inches.
 Big Sandy Opening Snotel...          4 inches.
 New Fork Lake Snotel...              2 inches.
 Larsen Creek Snotel...               2 inches.
 East Rim Divide Snotel...            2 inches.
 Snider Basin Snotel...               2 inches.
 Pinedale...                          1 inch.
 14 NW Pinedale...                  0.5 inches.

Sweetwater County...
 4 NNW Rock Springs...              0.1 inches.

Teton County...
 Grassy Lake Snotel...                9 inches.
 Togwotee Pass Snotel...              9 inches.
 Base Camp Snotel...                  6 inches.
 Phillips Bench Snotel...             3 inches.
 Jackson Dam...                     2.6 inches.
 1 NNW Alta...                        1 inch.
 12 NE Jackson...                     1 inch.
 Moose...                           0.5 inches.
 5 NW Jackson...                    0.4 inches.

Washakie County...
 Middle Powder Snotel...              3 inches.
 Powder River Pass Snotel...          3 inches.

Yellowstone National Park...
 Parker Peak Snotel...               13 inches.
 Sylvan Lake Snotel...               11 inches.
 Canyon Snotel...                    10 inches.
 Lewis Lake Divide Snotel...          6 inches.
 Thumb Divide Snotel...               5 inches.
 Mammoth...                         2.1 inches.
 Sylvan Road Snotel...                1 inch.
 Snake River Ranger Station...        1 inch.
 Yellowstone East Entrance...         1 inch.
 Tower Falls Ranger Station...        1 inch.

Star Valley Skies in mid May

Not your typical May sky over Star Valley. View from west hill across Afton on Wednesday.

Forecast for Star Valley as of 8AM Wednesday-Hard Drive Issues affect the Web Site for a Couple Days

With the loss of a hard drive the Star Valley Weather Forecast and radar and satellite data is not available on the web site.  This will take a couple days to fix.  Periodically will post the latest forecast on the blog.  As of 8am Wednesday the forecast is as follows:

Today

Snow showers before 11am, then rain and snow showers likely between 11am and 1pm, then scattered rain showers after 1pm. High near 42. West southwest wind around 7 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 1 to 2 inches possible.

Tonight

Scattered rain showers before 9pm, then scattered snow showers. Mostly cloudy, with a low around 26. West wind around 5 mph becoming calm in the evening. Chance of precipitation is 40%. New snow accumulation of less than a half inch possible.

Thursday

A slight chance of rain and snow showers before noon, then a slight chance of snow showers. Mostly cloudy, with a high near 50. Calm wind becoming north 5 to 8 mph in the afternoon. Chance of precipitation is 20%.

Thursday Night

A 20 percent chance of showers before midnight. Partly cloudy, with a low around 32. North northwest wind 5 to 7 mph becoming calm in the evening.

Friday

Mostly sunny, with a high near 57. Calm wind becoming northwest 5 to 7 mph in the afternoon.

Friday Night

Partly cloudy, with a low around 32. Northwest wind around 6 mph becoming calm in the evening.

Saturday

A 20 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 61. Light and variable wind.

Saturday Night

A 20 percent chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 34.

Sunday

A 40 percent chance of showers and thunderstorms after noon. Partly sunny, with a high near 65.

Sunday Night

A chance of rain showers before midnight, then a slight chance of rain and snow showers. Some thunder is also possible. Mostly cloudy, with a low around 34. Chance of precipitation is 40%.

Monday

A slight chance of showers and thunderstorms. Partly sunny, with a high near 65.

Monday Night

A slight chance of showers and thunderstorms. Mostly cloudy, with a low around 34.

Tuesday

Mostly sunny, with a high near 66.

Snow Returns to Western Wyoming

Salt River and Wyoming Ranges-
1005 PM MDT Tue May 16 2017

...WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 PM MDT WEDNESDAY...

The National Weather Service in Riverton has issued a Winter
Weather Advisory for Snow, which is in effect until 6 PM MDT
Wednesday.

* TIMING...Moderate to occasionally heavy snowfall will increase
  across much of the Salt and Wyoming Mountains later tonight...
  continuing through Wednesday.

* TOTAL SNOW...4 to 12 inches.

* MAIN IMPACT...Highways may become slick, slushy and snow
  covered, including the Salt River Pass. Visibility could be
  reduced to under one quarter mile at times in heavy snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A winter weather advisory for snow means periods of snow will
cause primarily travel difficulties. Be prepared for snow covered
and slick roads with limited visibilities. Slow down, and allow
extra time to reach your destination. Check the latest road
conditions at wyoroad.info or by dialing 5 1 1.

Model Snow Forecast through Thursday Morning

WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 6 PM THIS EVENING TO 6 PM MDT WEDNESDAY

URGENT - WINTER WEATHER MESSAGE
National Weather Service Pocatello ID
312 AM MDT Tue May 16 2017

Upper Snake Highlands-South Central Highlands-Caribou Highlands-
Wasatch Mountains/Idaho Portion-
Including the cities of St. Anthony, Ashton, Island Park, Driggs,
Victor, Malad City, Oakley, Rockland, Henry, Soda Springs,
Downey, Lava Hot Springs, and Montpelier
312 AM MDT Tue May 16 2017

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 6 PM THIS
EVENING TO 6 PM MDT WEDNESDAY...

* IMPACTS...Accumulating snow may create difficult travel
  conditions especially over mountain passes. Backcountry travel
  and recreation may become dangerous.

* TIMING...Accumulating snow will begin this evening and continue
  through Wednesday, becoming heavy at times late tonight.

* SNOW ACCUMULATIONS...Storm total through Wednesday afternoon
  of 5 to 10 inches above 6000 feet and 1 to 4 inches in the
  mountain valleys.

* CONFIDENCE...High confidence in timing. Low confidence in
  accumulations due to dramatically fluctuating snow levels.

* LOCATIONS...Elevations primarily above 6000 feet, including
  Pine Creek Pass, Fish Creek Summit, Georgetown Summit, and the
  Island Park area.