1. Ground Deicing Update Scott Landolt, Roy Rasmussen and Jenny Black

2. Snow Machine Testing Current Tasking – Laboratory testing of Heavy rates (> 2.5mm/h) and very light rates (< 0.4 mm/h) – Indoor testing time versus outdoor testing time variations – Snowfall pattern distribution improvement within the machine

3. Frost Detection and Diagnosis Complete testing of various sensing techniques at Marshall – Leaf wetness sensor – Infrared camera – Other methods Integration into LWE system

4. Future Checktime Integrate WSDDM one-hour nowcast or precipitation rate to nowcast holdover/checktime times Integrate high-resolution model output (HRRR) data into Checktime to forecast holdover times beyond one hour

5. Measurement of Liquid Fraction during Wet Snow using a dual Hotplate Roy Rasmussen and Scott Landolt National Center for Atmospheric Research (NCAR)

6. 6 Hotplate at Marshall Test Site, Boulder Colorado

7. Dual Hotplate System Temperature = 30 C Temperature = 80 C Estimates the ice mass in snow over 5 minutes by melting the ice only. Estimates the total precipitation mass (ice +water) over 5 minutes by sublimating ice +water

8. Benefits of the new system Improved holdover time during the most common deicing condition: wet snow The fraction of ice in wet snow will cool the wing by taking heat out of the wing to melt the ice. The performance of the deicing fluid depends on the temperature of the fluid, and therefore the fraction of ice present.

9. Deicing in a Future Climate Roy Rasmussen and Kyoko Ikeda, NCAR

10. High Resolution Simulations of the Colorado Headwaters snowfall, snowpack and runoff 1.Perform past climate simulations using high resolution WRF model  Grid spacing: 4 km.  Continuous eight years: 2000 – 2008 2.Verified results of WRF integrations using NRCS SNOTEL data and showed that grid spacing of at least 6 km needed to faithfully reproduce the spatial pattern and amount of precipitation (Rasmussen et al. 2011, J. Climate). 3. Investigate enhancement of water cycle by adding CCSM 10 year mean temperature and moisture perturbation from 50 year future A1B simulations from AR4 runs to NARR boundary conditions Full Domain Headwaters domain SNOTEL sites

11. Model Verification with SNOTEL data Full model domain Snow pillow Precipitation gauge  Verifications performed using 93-112 Snowpack Telemetry (SNOTEL) sites over the Headwaters domain.  SNOTEL typically located at elevations between 2600 and 3600 m  Global Historical Climatology Network (GHCN) data at lower elevations for rainfall Headwaters Domain 3/14/1211 Orographic Precipitation and Climate Change Workshop, Boulder, CO SNOTEL

12. 7-year average cool-season precipitation : 1 October – 31 May 4/12/12 USBR-USACE meeting 12 36 km4 kmOBSERVATIONS 1000 900 800 700 600 500 400 300 200 100 0 Precipitation (mm)

13. (1360 x 1016 grid points) Four kilometer horizontal resolution climate simulations will be conducted for 13 years in the past and 13 years in the future (centered on 2050) over the domain below using the WRF model using the Thompson et al. microphysics allowing precipitation type and rate to be determined with good accuracy

14. March RUN2 PRISM RUN1 Test 4 km WRF model estimate of precipitation for March, 2001