evaluation of winter weather in wyoming based on numerical...

Evaluation of Winter Weather in Wyoming based on Numerical Weather Modeling for Snow Fence System Design

Noriaki Ohara University of Wyoming

Low visibility due to blowing snow amplified the scale of the car crash on April 16, 2015, at 342 mile post on Interstate 80 [Photo: obtained from http://www.wyomingnews.com/articles/2015/04/17/news/01top_04-17-15.txt#.Vaf6q_l3mUM]

Snow fence is known effective for the hazardous high wind and blowing snow conditions in Wyoming.

Very little blowing snow behind fences at Mile 263.0, I-80 (Tabler 1973) From “Tabler’s book” (Tabler, 2003) Photo by Robert L. Jairell

Snow fence design basics

The wind and precipitation tables that are currently used were manually measured by Dr. Ron Tabler in the early 1990's.

Objectives • To reconstruct the continuous long-term wind data

in Wyoming for snow fence design using a numerical weather prediction model.

• To evaluate the evolving climate effect on the wind field last 30 years.

Image: http://bioearth.wsu.edu/wrf_model.html

Model name: Weather Research & Forecasting (WRF) model Input: North American Regional Reanalysis (NARR) data

Numerical Weather Prediction Model Application

Image: https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/north-american-regional-reanalysis-narr

The initial and boundary conditions of the WRF model were prepared from the NARR data.

The NARR model assimilates a great amount of observational data to produce a long-term picture of weather over North America at 32 km resolution.

Weather Research & Forecasting (WRF) model

Computational grid sizes: 12 km

Reconstructed 10m wind field (movie) during the large event in Laramie Valley

(June 1965)

© 2012 N.Ohara

SCRAM Surface Meteorological Archived Data (1984-1992)

WY24018 Cheyenne/Municipal Airport WY24021 Lander/Hunt Field WY24027 Rock Springs/FAA Airport WY24029 Sheridan/County Airport WY24089 Casper/Natrona Co Int'l Airport

SCRAM = Support Center for Regulatory Atmospheric Modeling

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 1.28%

WY24018 Cheyenne/Municipal Airport

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 0.49%

1/1/1992- 12/31/1992 Simulated Observed

Model validation at WY24021 Lander/Hunt Field

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 2.64%

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 19.19%


Model validation at WY24027 Rock Springs/FAA Airport

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 17.18%

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 0.82%

1/1/1992- 12/31/1992

Simulated Observed

Model validation at WY24029 Sheridan/County Airport

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 4.65%

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 12.95%


NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 0.67%

Model validation at WY24089 Casper/Natrona Co Int'l Airport

1301

NORTH

SOUTH

WEST EAST5.2%

10.4%

15.6%

20.8%

26%

WIND SPEED (m/s)

>= 11.1 8.8 - 11.1 5.7 - 8.8 3.6 - 5.7 2.1 - 3.6 0.5 - 2.1

Calms: 0.99%


NORTH

SOUTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

NORTH

SOUTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

NORTH

SOUTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

NORTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

NORTH

SOUTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

NORTH

SOUTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

WYOMING

So, we can extract the continuous wind information at

anywhere in Wyoming.

NORTH

SOUTH

WEST EAS 5.2%

10.4%

15.6%

20.8%

26%

NORTH

SOUTH

WEST EAST 5.2%

10.4%

15.6%

20.8%

26%

Modeled Wyoming-average wind speed

Blue line = Wyoming-average wind speed (m/s) Yellow line = Moving average (n = 255) Black thick line = fitted linear trend line

Wyoming has slightly gotten windier over the last three decades. rate = 0.138 m/s per decade

Wind speed classification Conditions Conditions

knots km/h mi/h at Sea on Land0 < 1 < 2 < 1 Calm Sea like a mirror. Smoke rises vertically.1 1-3 1-5 1-4 Light air Ripples only. Smoke drifts and leaves rustle.

2 4-6 6-11 5-7 Light breeze

Small wavelets (0.2 m). Crests have a glassy appearance.

Wind felt on face.

3 7-10 12-19 8-11 Gentle breeze

Large wavelets (0.6 m), crests begin to break.

Flags extended, leaves move.

4 11-16 20-29 12-18 Moderate breeze

Small waves (1 m), some whitecaps.

Dust and small branches move.

5 17-21 30-39 19-24 Fresh breeze

Moderate waves (1.8 m), many whitecaps.

Small trees begin to sway.

6 22-27 40-50 25-31Strong breeze

Large waves (3 m), probably some spray.

Large branches move, wires whistle, umbrellas are difficult to control.

7 28-33 51-61 32-38 Near gale Mounting sea (4 m) with foam blown in streaks downwind.

Whole trees in motion, inconvenience in walking.

8 34-40 62-74 39-46 GaleModerately high waves (5.5 m), crests break into spindrift.

Difficult to walk against wind. Twigs and small branches blown off trees.

9 41-47 76-87 47-54 Strong gale High waves (7 m), dense foam, visibility affected.

Minor structural damage may occur (shingles blown off roofs).

10 48-55 88-102 55-63 StormVery high waves (9 m), heavy sea roll, visibility impaired. Surface generally white.

Trees uprooted, structural damage likely.

11 56-63 103-118 64-73 Violent storm

Exceptionally high waves (11 m), visibility poor.

Widespread damage to structures.

12 64+ 119+ 74+ Hurricane 14 m waves, air filled with foam and spray, visibility bad.

Severe structural damage to buildings, wide spread devastation.

ForceSpeed

Name

Definition: windy day = wind speed > 12mph (5.4 m/s)

Frequency of windy days last three+ decades based on the reconstructed Wyoming-average wind

speed for 1980 - present

Wyoming has more than 20 more windy days recently.


Modeled wind speed at Arlington

Blue line = Wyoming-average wind speed (m/s) Yellow line = Moving average (n = 255) Black thick line = fitted linear trend line

Arlington, WY, slightly has gotten windier over the last three+ decades. rate = 0.119 m/s per decade

Arlington, Wyoming

Frequency of windy days last three+ decades at Arlington, Wyoming

Arlington has gotten about 20 more windy days recently.


Arlington, Wyoming

Conclusions • Numerical weather model can provide the historical long-

term and seamless wind field data, which can be used for winter weather hazard protection planning.

• Wyoming has gotten windier over the last three+ decades.

• Combine the wind information with the snow condition.

• Analyze the blowing snow events using a finer resolution model.

Next steps

Acknowledgement This study is funded by Wyoming Department of Transportation.

Noriaki Ohara, Ph.D. Assistant Professor Civil and Architectural Engineering University of Wyoming [email protected]

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