future precipitation and snowpack along the wasatch range

Future precipitation and snowpack along the Wasatch Range

Court Strong

University of Utah

Department of Atmospheric Sciences

Outline

• Study region (Great Basin and Wasatch Range)

• Projected climate change (big picture)

• Climate modeling framework

• Precipitation and snowpack 1950-2100

Study region

Annual mean precipitation (cm)

Great Basin UT

WY

Elevation (m)

“Wasatch Range”

UT

ID

Projected climate change (big picture)

Warming

• Increased moisture content of atmosphere

• Wet years become wetter

Jet stream shifts north

• Wetter north / drier south

• Increased variability

Climate modeling framework • Three greenhouse gas emission

scenarios were considered

High emission (A2) Moderate emission (A1B) Low emission (B1)

Image from IPCC AR4 Report

Climate modeling framework Coarse-scale simulations (100 to 200 km)

dynamical downscaling

statistical downscaling

12-14 km

Precipitation 2000-2049

minus 1950-1999

2050-2099 minus 1950-1999

High emission (A2)

Moderate emission (A1B)

Low emission (B1)

Change in annual precipitation

cm

Moderate emission (A1B) Wasatch Range annual mean precipitation

Precipitation: Wasatch

mean of all simulations

Moderate emission (A1B)

annual precipitation

Moderate emission (A1B) Moderate emission (A1B) Wasatch Range annual mean precipitation

Moderate emission (A1B) Wasatch Range annual mean precipitation

Moderate emission (A1B)

annual precipitation

Precipitation: Wasatch

mean of all simulations

Temperature: Wasatch Moderate emission (A1B)

average maximum air temperature: March-April

mean of all simulations

Moderate emission (A1B) Moderate emission (A1B)

snowpack (SWE) April 1

Snowpack: Wasatch

mean of all simulations

Based on 14-km model projections May not represent highest-elevation changes

Precipitation: Wasatch

Amplified seasonality • Increased

precipitation during high snow months

• Decreased precipitation during May-June

precipitation trend

1950-2099 (% change)

precipitation seasonality

(cm)

Summary • Drier over southern Great Basin and wetter

over northern Great Basin (jet stream wetter and shifted north)

• Wasatch Range trends (to 2100) – Increase in annual mean precipitation (~ 7%)

– Overall increase in precipitation variability

– Snowpack declines due to warming

– Amplified precipitation seasonality (wetter snow season, drier in May and June)

• New data (released last week)

Precipitation and snowpack: historical

Extremely high and very low years just occurred back to back.

Snowbird SNOTEL 1989-2012

Annual precipitation (cm)

Average maximum air temperature

March-April (°C)

Snowpack SWE April 1 (cm)

Wasatch Range

Future projections: Wasatch