Saturday, March 30, 2013

Easter Sunday and Spring Break

All indications are that timing is excellent for both Easter Sunday and those who have next week off for Spring Break.  Riverton WFO's weekly video weather briefing covers expected conditions for the next several days.

Riverton WFO Weekly Weather Briefing

Thursday, March 28, 2013

Western States Snow Water Equivalent Map

The map of the SWE for the western states SNOTEL sites paints a rather dismal runoff potential for this Spring.

Only the Washington and Oregon Cascades along with the Canadian border sections of the Montana Rockies can look forward to an above normal runoff.  In Western Wyoming including Star Valley only  around 90% of normal SWE are observed.


Wednesday, March 27, 2013

Update on Star Valley Snowpack

This time of year when much of the snow for the winter season has already occurred, the question arises how did we do?   While snows of significance could still occur in April and even into May in the mountains, chances are the current totals for the winter are indicative of the runoff this Spring.

On Star Valley Ranch the snow amounts from Oct. 1 2012 to March 27 2013  are probably not much below the normal amount.  So far while 14 inches remain on the ground at the observation site  located just north of the Round Barn on the Ranch, the total for the season is 157 inches.  In comparison to the same date last year the total was 162 inches. While the greatest snow depth last winter was almost double this year, 43 inches on 3/3/2012 vs 22 inches on 1/20/2013, the unusually warm March in 2012 had reduced the actual snow pack to just 13 inches vs the 14 inches on 3/27/2013.  The actual Snow Water Equivalent on Star Valley Ranch is 4 inches as of 3/27/13

What really matters in the Spring runoff is the snowpack conditions in the higher elevations.   The Willow Creek SNOTEL site in the Salt Range above Turnerville is at 8450 feet.

Following are the stats for Willow Creek

Snow Water Equivalent  as of 3/27
2010 18.80 inches
2011 35.40 inches
2012 24.40 inches
2013 23.90 inches snow depth 74 inches

2010/2011 was a big snow year, with the greatest snow water equivalent continuing to increase into May reaching 48.80 inches.

Last year by 3/27/2011 the snow water equivalent had about peaked and quickly melted under an unusually warm Spring sun.

This years value of 23.90 inches is 84% of the normal amount.

The long range forecast does not support a wet Spring as occurred in 2011, but hopefully an improvement over last year.

Here is the long range forecasts for both the coming month of April and the 3 month period of April/May/June.







One or two big Spring storms could quickly prove these forecasts wrong in Wyoming, but predictability of any particular storm more than a week or two out is still not possible.

Sunday, March 24, 2013

Cold Sabbath

Temperatures dropped over much of Wyoming and adjacent states Sunday morning to unseasonably cold levels.  In Star Valley there was sufficient moisture and thin clouds to keep readings generally above zero.  The coldest noted was at the Thayne ES station with 2 above.  Even the typically warmer Star Valley Ranch station dipped to 9 above.

Other areas of western Wyoming did not fare as well. The coldest noted was -21 at Bondurant with unofficially as cold as -27 below on the west side of Yellowstone Lake.

Below is a map of the lows around the region this Sunday morning.



Not too far away from Star Valley the remote site on top of Logan Pass to the west of Bear Lake, ended up with the coldest for the U.S. excluding Alaska.  The graph from the Peter Sink site illustrates the low of -35F this morning.




There was a colder reading in Alaska at a remote location in the western portion of the state. Following is a meteograph from that station.  It was down to -39F,  which actually was higher than the -43F on Saturday morning.


 The 500mb analysis from this Sunday morning  shows the deep upper low that is dominating the weather conditions and promise at least one more cold night, prior to a gradual warming trend.


The air mass has been sufficiently unstable during the afternoon for convective snow showers developing over the mountains and then spreading to lower elevations.  Following is a link to an animation taken from the Star Valley Ranch cam looking west across the valley Saturday. 

http://www.youtube.com/watch?v=nIWU6gRE3uU

Thursday, March 21, 2013

Tuesday, March 19, 2013

March Going Out Like a Lion?

The first half of March 2013 with a couple of exceptions has been abnormally mild across much of western Wyoming.  The graph of the daily highs/lows at Jackson show this well




The weather station at Star Valley Ranch also has experienced, with a couple exceptions, rather pleasant late Winter conditions.

Star Valley Ranch Daily Conditions March 2013

While Tuesday is a Chamber of Commerce day in Star Valley, there are significant changes on the horizon to the west.  This can best be observed from the satellite imagery over the Eastern Pacific.


The model forecast for the movement of the trough eastward across the United States, show that Star Valley will be going into a colder and unsettled weather pattern through the weekend.

500 MB forecast from Friday 3/22-Tuesday 3/26
The forecast from the NWS indicate that much of Western Wyoming will experience substantial precipitation through the weekend. 

Precipitation totals for the period Wednesday 3/20-Sunday 3/24.

This amount of liquid would result in 1-2 feet of snow in the mountains of northwestern Wyoming and 6-12 inches in valley locations such as Star  Valley.

The following two  hourly weather graphics produced by the NWS Riverton for Star Valley  suggests snow should begin by Wednesday afternoon, perhaps mixing with rain and then continue periodically through the weekend,


Monday, March 18, 2013

Sunday Snow Total

Riverton Forecast Office has compiled a list of snowfall amounts from Sundays quick hitting storm. 

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
329 PM MDT SUN MAR 17 2013

A POWERFUL...FAST-MOVING WINTER STORM HAS MOVED 
THROUGH THE COWBOY STATE TODAY...BRINGING SNOW
AND STRONG WINDS ACROSS THE AREA.
WEAK LIGHT SNOW SHOWERS WILL CONTINUE THIS AFTERNOON
ACROSS WESTERN PORTIONS...WHILE BRIEF HEAVIER SNOW
SHOWERS WILL BEPOSSIBLE OVER THE BIGHORN MOUNTAINS.
BELOW ARE SNOWFALL TOTALS FROM OVERNIGHT THROUGH 12PM.

SNOTELS (SNOW TELEMETRY) ARE REMOTE SENSING SITES IN HIGH
MOUNTAIN WATERSHEDS. SNOWFALL DATA FROM SNOTELS ARE
ESTIMATED BASED ON SNOW WATER EQUIVALENT.

LOCATION                             SNOWFALL

BIG HORN COUNTY...
 26 E LOVELL...                       5 INCHES.
 BONE SPRINGS DIVIDE SNOTEL...        5 INCHES.
 BALD MOUNTAIN SNOTEL...              4 INCHES.
 SHELL CREEK SNOTEL...                1 INCH.

FREMONT COUNTY...
 HOBBS PARK SNOTEL...                 4 INCHES.
 BROOKS LAKE LODGE...                 2 INCHES.
 SOUTH PASS SNOTEL...                 2 INCHES.
 LITTLE WARM SNOTEL...                1 INCH.
 BURROUGHS CREEK SNOTEL...            1 INCH.
 ST. LAWRENCE ALT SNOTEL...           1 INCH.
 COLD SPRINGS SNOTEL...               1 INCH.
 TOWNSEND CREEK SNOTEL...             1 INCH.

LINCOLN COUNTY...
 SPRING CREEK DIVIDE SNOTEL...        4 INCHES.
 COTTONWOOD CREEK SNOTEL...           4 INCHES.
 WILLOW CREEK SNOTEL...               4 INCHES.
 BLIND BULL SUMMIT SNOTEL...          4 INCHES.
 BLIND BULL SUMMIT...                 4 INCHES.
 KELLEY RANGER STATION SNOTEL...      3 INCHES.
 5 SSE SMOOT...                       2 INCHES.
 INDIAN CREEK SNOTEL...               2 INCHES.
 HAMS FORK SNOTEL...                  2 INCHES.
 BOX Y RANCH...                       2 INCHES.
 5 NNE THAYNE...                    1.5 INCHES.
 2 SE THAYNE...                     1.5 INCHES.
 SALT RIVER SUMMIT SNOTEL...          1 INCH.

PARK COUNTY...
 PAHASKA...                           9 INCHES.
 BEARTOOTH LAKE SNOTEL...             9 INCHES.
 WOLVERINE SNOTEL...                  6 INCHES.
 EVENING STAR SNOTEL...               5 INCHES.
 YOUNTS PEAK SNOTEL...                4 INCHES.
 BLACKWATER SNOTEL...                 4 INCHES.

SUBLETTE COUNTY...
 TRIPLE PEAK SNOTEL...                6 INCHES.
 LOOMIS PARK SNOTEL...                3 INCHES.
 GUNSITE PASS SNOTEL...               3 INCHES.
 SNIDER BASIN SNOTEL...               3 INCHES.
 LARSEN CREEK SNOTEL...               2 INCHES.
 NEW FORK LAKE SNOTEL...              2 INCHES.
 BOULDER REARING STATION...           1 INCH.
 14 NW PINEDALE...                  0.3 INCHES.

TETON COUNTY...
 SNAKE RIVER STN SNOTEL...            9 INCHES.
 GRASSY LAKE SNOTEL...                7 INCHES.
 BASE CAMP SNOTEL...                  6 INCHES.
 JACKSON HOLE-RAYMER...               5 INCHES.
 PHILLIPS BENCH SNOTEL...             5 INCHES.
 JACKSON HOLE-RENDEZVOUS BOWL...      5 INCHES.
 GROS VENTRE SUMMIT SNOTEL...         5 INCHES.
 3 SSW WILSON...                      4 INCHES.
 GRAND TARGHEE SNOTEL...              4 INCHES.
 SNOW KING SKI AREA...                3 INCHES.
 TOGWOTEE PASS SNOTEL...              3 INCHES.
 JACKSON HOLE-MID...                  3 INCHES.
 GRAND TARGHEE-CHIEF JOSEPH...        3 INCHES.
 2 NE TETON VILLAGE...              2.5 INCHES.
 GRANITE CREEK SNOTEL...              2 INCHES.
 MOOSE...                           1.5 INCHES.
 JACKSON HOLE-BASE...                 1 INCH.
 12 NE JACKSON...                     1 INCH.
 TOGWOTEE MOUNTAIN LODGE...           1 INCH.

YELLOWSTONE NATIONAL PARK...
 LEWIS LAKE DIVIDE SNOTEL...          9 INCHES.
 TWO OCEAN PLATEAU SNOTEL...          7 INCHES.
 THUMB DIVIDE SNOTEL...               5 INCHES.
 SYLVAN LAKE SNOTEL...                5 INCHES.
 PARKER PEAK SNOTEL...                4 INCHES.
 SYLVAN ROAD SNOTEL...                4 INCHES.
 CANYON SNOTEL...                     3 INCHES.
 TOWER FALLS RANGER STATION...        1 INCH.
 LAMAR RANGER STATION...              1 INCH.

Thursday, March 14, 2013

Warm weather to be replaced by Storm Sunday

Temperatures warmed Thursday across all of Western Wyoming, with even 60F being reached at a few locations such as Star Valley Ranch and the Box Y Ranch.  It was cooler along the Salt River where the inversion persisted and highs were substantially lower in the 40s.  Following is a map of maximum temperatures on Thursday afternoon across the area:

There will be one more day of very pleasant temperatures prior to the approach of the storm system expected by Sunday.

The following sequence of 500 mb charts depict the storms system currently over the Gulf of Alaska  and its movement into Wyoming by later Sunday.

Thursday evening 
Friday evening
Saturday evening
Sunday evening
  Precipitation which should spread across the region on Sunday will be snow at all elevations, with potentially heavy snow in the nearby mountains.  It does appear that several inches could fall in Star Valley during the day on Sunday along with gusty winds and falling temperatures.

The following in a link to the weekly video briefing from Riverton Forecast Office  for the coming weekend storm.

http://www.crh.noaa.gov/riw/?n=weatherbriefing

Monday, March 11, 2013

Latest Water Supply Outlook

The Riverton Forecast Office has issued the latest update for this Springs runoff and water supply.  Hopefully this will be a wet Spring!

 

Wyoming Water Supply Outlook---issued March 11

...February basin precipitation was 85 to 90 percent of average across Wyoming…
…Mountain snowpack across Wyoming continues to be around 80 to 85 percent of average... 
Below normal streamflow volumes expected across a majority of Wyoming’s watersheds...
…Wyoming reservoir storages continue to be near average for early March…
February precipitation across Wyoming was 85 to 90 percent of average. Precipitation numbers varied between 153 percent of normal over the Tongue Basin to 49 percent of normal over the Upper Green Drainage.
Mountain snowpack across Wyoming continued to be around 80 to 85 percent of normal by early March.  Snowpack "water" numbers and/or SWEs were the highest across northern Wyoming—varying between 85 to 95 percent of normal.  SWEs were the lowest across southern Wyoming---varying from 65 to 80 percent of normal.
Streamflow snowmelt volumes are expected to be below normal across a majority of basins across Wyoming.  Near normal (91 to 99 percent) streamflow volumes are expected across portions of the Powder, Big Horn, and Shoshone Watersheds
Well below normal (50 to 75 percent) spring and early summer snowmelt volumes are expected for a majority of watersheds across southern Wyoming.
Reservoirs storages across Wyoming are near average for early March.
The latest Wyoming water supply outlook graphic:

Thursday, March 7, 2013

Spring Like Temperatures Coming Next Week?

Riverton Forecast Office has issued their weekly Video Weather Briefing indicating the possible arrival of Spring like temperatures by the middle of next week.

http://www.crh.noaa.gov/riw/?n=weatherbriefing

Saturday, March 2, 2013

Wyoming Drought Information

The Riverton Weather Forecast Office has provided comprehensive information on the current drought situation as it pertains to Western Wyoming including Star Valley:


DROUGHT INFORMATION STATEMENT
NATIONAL WEATHER SERVICE RIVERTON WY
808 PM MST THU FEB 28 2013

...SOME EASING OF DROUGHT CONDITIONS ACROSS WESTERN WYOMING DURING FEBRUARY...
...MARCH OUTLOOK - COLDER THAN NORMAL...

SYNOPSIS...

THE LATEST U.S. DROUGHT MONITOR FOR WYOMING RELEASED ON FEBRUARY
28TH SHOWED SOME IMPROVEMENT ACROSS WESTERN WYOMING AND THE BIG
HORN BASIN DURING FEBRUARY. TETON COUNTY WAS LARGELY DROUGHT FREE
WITH ABNORMALLY DRY /D0/ CONDITIONS NOW COVERING YELLOWSTONE
NATIONAL PARK AND MOST OF TETON COUNTY. DROUGHT CONDITIONS ALSO
IMPROVED ACROSS THE REST OF THE FAR WEST WITH MODERATE DROUGHT
/D1/ OVERTAKING SEVERE DROUGHT /D2/ ACROSS THE STAR VALLEY AND
WESTERN UINTA COUNTY. DROUGHT CONDITIONS REMAINED MOSTLY THE SAME
ACROSS CENTRAL AND EASTERN WYOMING DURING FEBRUARY. EXCEPTIONAL
DROUGHT /D4/ COVERED 10.1 PERCENT OF THE STATE...OR MOST OF
GOSHEN...NIOBRARA AND WESTON COUNTIES...CREEPING INTO EASTERN
CONVERSE AND SOUTHEAST CAMPBELL COUNTIES. EXTREME DROUGHT /D3/
COVERED MOST OF CENTRAL WYOMING...WITH EXTREME OR EXCEPTIONAL
DROUGHT COVERING 56.7 PERCENT OF WYOMING. SEVERE /D2/ DROUGHT
REMAINED ACROSS THE NORTHEAST...SOUTHEAST CORNERS OF THE STATE AS
WELL AS PORTIONS OF WEST CENTRAL AND SOUTHWEST WYOMING. SEVERE
DROUGHT OR WORSE COVERED 83.6 PERCENT OF WYOMING.

SUMMARY OF IMPACTS...

RIVER AND STREAMFLOW CONDITIONS.

USGS WYOMING DROUGHT-WATCH 28-DAY MAP OF BELOW AVERAGE STREAMFLOW
SHOWED BELOW NORMAL STREAM FLOW ACROSS THE SNAKE RIVER BASIN...THE
UPPER AND LOWER GREEN RIVER BASINS...THE LITTLE SNAKE RIVER BASIN
AND THE SOUTH PLATTE BASIN. NO RIVER BASINS IN WYOMING WERE IN
HYDROLOGIC DROUGHT CONDITIONS.

FIRE WEATHER IMPACTS.

NO FUELS WERE CLASSIFIED AS CRITICAL IN ANY AREAS ACROSS WEST AND
CENTRAL WYOMING. MOST FUELS RECEIVED ADDITIONAL SNOW DURING
FEBRUARY AND REMAINED UNDER SNOW COVER. CONTACT YOUR LOCAL COUNTY
OFFICIALS FOR THE LATEST BURNING RESTRICTIONS.

CLIMATE SUMMARY...

BELOW ARE THE CUMULATIVE PRECIPITATION AMOUNTS FROM SELECTED
LOCATIONS ACROSS WEST AND CENTRAL WYOMING FOR THE CURRENT WATER
YEAR...OCTOBER 2012 THROUGH JANUARY 2013.

LOCATION                   PRECIPITATION             % AVERAGE
                           OCT 2012-JAN 2013
--------                     -------------           -----------

AIRPORTS

* BIG PINEY                      0.50                      37
* BUFFALO                        2.08                      91
+ CASPER                         1.71                      60
^ EVANSTON                       2.34                      70
+ GREYBULL                       0.68                      48
+ LANDER                         2.27                      72
+ RIVERTON                       1.18                      61
+ ROCK SPRINGS                   0.32                      14
* SHERIDAN                       3.50                     108
+ WORLAND                        1.25                      83

COOPERATIVE OBSERVER STATIONS

^ BEDFORD 3 SE                   9.95                     128
* BILLY CREEK                    2.52                     125
+ BITTER CREEK 4 NE              1.20                      68
* FOSSIL BUTTE
  NATIONAL MONUMENT              4.31                     135
+ GREEN RIVER                    3.12                     156
+ JEFFREY CITY                   1.00                      45
  MOOSE                          9.10                      97
  OLD FAITHFUL                   9.92                     108
* POWELL FIELD STATION           0.77                      71
+ RIVERTON (DOWNTOWN)            1.44                      81
* THERMOPOLIS                    1.58                      55

+ LOCATION IN EXTREME DROUGHT /D3/
* LOCATION IN SEVERE DROUGHT /D2/
^ LOCATION IN MODERATE DROUGHT /D1/

PRECIPITATION/TEMPERATURE OUTLOOKS...

THE OUTLOOK FOR MARCH SHOWED A BETTER THAN EQUAL CHANCE OF BELOW
NORMAL TEMPERATURES ACROSS WYOMING WITH THE GREATEST CHANCE OF
BELOW NORMAL TEMPERATURES NORTH OF A KEMMERER TO CASPER LINE. THIS
WOULD BE QUITE A CHANGE FROM A YEAR AGO...MARCH 2012 WAS THE
WARMEST ON 119 YEARS OF RECORD IN WYOMING.

WYOMING HAS AN EQUAL CHANCE OF ABOVE...BELOW OR NORMAL
PRECIPITATION DURING MARCH.

THE THREE MONTH OUTLOOK FOR MARCH...APRIL AND MAY SHOWS A GREATER
THAN EQUAL CHANCE OF ABOVE NORMAL TEMPERATURES ACROSS THE
SOUTHEAST CORNER OF WYOMING. THE REST OF WYOMING HAS EQUAL
CHANCES OF ABOVE...BELOW...OR NORMAL TEMPERATURES. THE
PRECIPITATION OUTLOOK FOR THIS THREE MONTH PERIOD SHOWS A BETTER
THAN EQUAL CHANCE FOR BELOW NORMAL PRECIPITATION ACROSS THE
SOUTHWEST TWO-THIRDS OF THE STATE. THE NORTHEAST THIRD OF WYOMING
HAS EQUAL CHANCES FOR ABOVE...BELOW OR NORMAL PRECIPITATION OR NO
SIGNIFICANT CLIMATE SIGNAL.

DEVELOPMENT OF EL NINO CONDITIONS STALLED OUT IN SEPTEMBER IN THE
PACIFIC OCEAN. ENSO NEUTRAL CONDITIONS WERE OBSERVED IN JANUARY.
ENSO-NEUTRAL CONDITIONS ARE EXPECTED TO CONTINUE THROUGH SPRING.

THE U.S. SEASONAL DROUGHT OUTLOOK RELEASED ON FEBRUARY 21ST SHOWED
THAT DROUGHT CONDITIONS WERE FORECAST TO PERSIST ACROSS MOST AREAS IN
WYOMING CURRENTLY CLASSIFIED WITH DROUGHT CONDITIONS THROUGH
MAY. HOWEVER...SOME IMPROVEMENT WAS FORECAST OVER THE SHOSHONE AND CLARKS
FORK RIVER BASIN.

HYDROLOGIC SUMMARY AND OUTLOOK...

SNOWPACK DATA FOR FEBRUARY 28TH -

                                  PERCENT OF AVERAGE
DRAINAGE BASIN                    SNOW WATER EQUIVALENT (SWE)
                                  (BASED ON 1981-2010 NORMALS)

SNAKE RIVER                                87
MADISON                                    91
YELLOWSTONE                                93
WIND RIVER                                 86
BIG HORN BASIN                             95
SHOSHONE RIVER                             93
POWDER                                     101
TONGUE                                     93
BELLE FOURCHE                              84
CHEYENNE                                   89
UPPER NORTH PLATTE                         76
SWEETWATER                                 78
LOWER NORTH PLATTE                         68
LARAMIE                                    76
SOUTH PLATTE                               73
LITTLE SNAKE RIVER                         80
UPPER GREEN                                83
LOWER GREEN                                79
UPPER BEAR                                 75
_____________________________________________

RESERVOIR DATA FOR FEBRUARY 27TH -

RESERVOIR                 PERCENT FULL

CENTRAL WYOMING
BOYSEN                      70.0
BUFFALO BILL                66.5
BULL LAKE                   51.4
PATHFINDER                  42.0

UPPER GREEN RIVER BASIN
BIG SANDY                   20.0
FONTENELLE                  41.0
FLAMING GORGE               79.0

UPPER SNAKE RIVER BASIN
GRASSY LAKE                 85.0
JACKSON LAKE                73.0
 
 
 
 Here is a look at what the forecast temperatures and precipitation are for much of the Spring.
 
 Monthly and Seasonal Outlook
 
 Monthly and Seasonal Outlook