CPC’s U.S. Seasonal Drought Outlook & Future Plans

April 20, 2010

Brad Pugh, CPC

(High-Res Soil Models)

+

(Seasonal Forecasts of Temperature and Precipitation) =

(Soil Moisture/Drought Forecasts)

Using Soil Moisture Models to Monitor Drought at the NOAA Climate Prediction Center

“Leaky Bucket” model: a 1-layer hydrological model. Uses observed precip. and temps to calculate soil moisture for a soil column of 1.6 meters.

www.cpc.noaa.gov/soilmst/leaky_glb.htm

NLDAS 1-m and 2-m soil column; 4 separate models and ensemble; versions produced by NOAA EMC and the University of Washington

www.emc.ncep.noaa.gov/mmb/nldas/drought/

The NLDAS uses four land surface models: Noah, Mosaic, SAC and VIC, run in near real-time at the NCEP’s Environmental Modeling Center to support the National Integrated Drought Information System (NIDIS) and US Drought Monitor.

North American Land Data North American Land Data Assimilation System (NLDASAssimilation System (NLDAS)

NLDAS

NOAA/NCEP NASA/GSFC

NOAA/OHDPrinceton and

Univ. of Washington

Sponsored by the ClimatePrediction Program

of the Americas (CPPA)

What Goes Into the Models?What Goes Into the Models?Hourly input: gauge precipitation, air temperature, air specific

humidity, wind speed, etc.

Water F

luxes

En

erg

y F

luxe

s

State Variables: soil moisture, soil temperature, skin temperature, snow cover, snow water equivalent, snow depth

“Land data assimilation systems, with their high quality representations of soil moisture, present an ideal platform for drought monitoring….” Brian Cosgrove, NASA GSFC

Using the NLDAS Ensemble Mean Soil Moisture as a Drought Indicator

Ensemble Mean

NCEP Noah

NASA Mosaic

OHD SAC Princeton VIC

Shallow layers of soil moisture can be used as agricultural drought indicators. Model runoff as hydro indicators.

Percentile soil moisture levels correspond to U.S. Drought Monitor levels D0 to D4

http://www.emc.ncep.noaa.gov/mmb/nldas/drought/

CPC U.S. Drought Outlook: Short and Long-Term Forecast Contributions

Start with latest U.S. Drought Monitor D1 areas

Extended Range (e.g.,2-week

Soil Moisture Forecasts)

3-monthPrecipitation and

Temperature Outlooks

Constructed Analogue Soil Model

Medium-Range Fcst

Palmer 4-moProbabilities

CPC Long-LeadPrecip. Outlook

Selected Drought Outlook Inputs

Challenges

• Blending short-term forecasts with seasonal forecasts

• Improving skill of forecasts at all time ranges

• Providing useful information for both the agricultural and hydrologic community

• Next step –develop an objective & probabilistic outlook

Next Step in Drought Forecasting

• A seasonal forecast of drought probabilities

• Consideration of agriculture and hydrology (short-term and long-term drought)

• Inclusion of short-term forecasts

• Potential of 1-Month Outlook (ag related) and Expansion to include Canada/Mexico

Two-Path Approach to Improving Drought Forecasts

Continue to improve current seasonal forecasts

Continue to improve current seasonal forecasts

Develop probabilistic seasonal

forecasts for agriculture and water

supplies

Develop probabilistic seasonal

forecasts for agriculture and water

supplies

Quantitative forecasts bring improvement

Improved Drought Forecasting and Early Warning

NLDAS land models can be linked to downscaled seasonal forecast models to produce soil moisture and drought probability forecasts NOAA’s Climate

Prediction Center is working with its partners to develop operational numerical drought forecast products.

Forecast Soil Moisture Anomaly for April 2010

Issued March 2010

June 2010

http://www.emc.ncep.noaa.gov/mmb/nldas/forecast/TSM/prob/

NWS River Forecast Centers: New Seasonal Streamflow Forecasts

Candidate for a national hydrological forecast system

Proposed Suite of Probabilistic Proposed Suite of Probabilistic Seasonal Drought ForecastsSeasonal Drought Forecasts

Probability of Ag. Drought

Probability of Hydro Drought

Probability of Drought

Total Column 2-m Soil Moisture

Change Map

Change in soil moisture percentiles

Change Map

Top 40 cm or root zone soil moisture

Change in soil moisture percentiles

Probability of Runoff or Streamflows

Change Map

Change in runoff or streamflow percentiles

Total Drought

Agricultural (Short-term) Drought

Hydro (Long-term) Drought

Future Plans: Developing New and Innovative Forecast Products

• Develop next-generation drought forecast tools that provide probabilistic information on seasonal time scales

• Work with our partners in academia and the government to develop prototype products

• Potential expansion to a North American domain