Annual U.S. Drought Highlights and Annual U.S. Drought Highlights and thethe

Seasonal Drought Outlooks: How Seasonal Drought Outlooks: How are We Doing?are We Doing?

3434thth Annual Climate Diagnostics and Prediction Workshop Annual Climate Diagnostics and Prediction Workshop

Monterey, CA, October 26-30, 2009Monterey, CA, October 26-30, 2009

Douglas Le Comte, CPCDouglas Le Comte, CPC

Douglas.lecomte@noaa.govDouglas.lecomte@noaa.gov

Lake Travis, Texas, July 2009

As of Oct 21, Lake Travis 34.4 feet below its historic September average (only lower in 1963 and 1951).

Now an I-Phone App for the Drought Monitor!

OutlineOutline

• Drought coverage in 2009 drops to its lowest level since 2001Drought coverage in 2009 drops to its lowest level since 2001

• Drought intensity peaked in August 2009 in southern Texas and Drought intensity peaked in August 2009 in southern Texas and (arguably) in January 2009 in California(arguably) in January 2009 in California

• We take a closer look at the Drought Outlooks for TexasWe take a closer look at the Drought Outlooks for Texas

• We look at some of the forecast tools (then and now)We look at some of the forecast tools (then and now)

• Overall U.S. skill trend continues upOverall U.S. skill trend continues up

• We plan to work with our partners to improve forecastsWe plan to work with our partners to improve forecasts

USDM Coverage: The Past YearLate October 2008

22% D1 Coverage

Late January 2009

21% D1 coverage

Drought in CA and TX intensifies; Southeast drought shrinks

Texas: Driest Dec-Feb in 114 years!

“I’ve Seen Fire and I’ve [not] Seen Rain”James Taylor

August ‘08 to March ’09 Change

DM change maps courtesy Rich Tinker, CPC

Sep ’08 – Feb ’09: Driest on record for SC/S Texas

Deficits in southern Texas date back to the fall of 2007

Late April 2009

18% D1 Coverage

Southern Texas further intensifies; CA improves; most of Southeast drought over (exc FL!)

March ’09 to Sep ’09 Change

Late July 2009Relief northern TX, worse in southern Texas; Wisconsin drought continues

14% D1 Coverage

Late October 2009

D1 coverage = 13%

Major relief mid-October

Calendar Year 2009 Change

Water Year 2008-09 Change

South Central Texas: 24-month Precipitation to August 2009

24-Month Running Precipitation (in.)

SC Texas

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Lowest (38.54 in) since 1918 (38.01 in)Median = 71.43 in.

August PMDI = -6.42 in SC TX, lowest since Oct. 1956 (also -6.42).

Drought Impacts Texas

“Bexar County (San Antonio) has lost 10,000 live oak trees this year.”

Ag damage in the $billions;

Widespread water restrictions

We Have Seen Major Recent Improvement

• According to the US Drought Monitor, 27% of Texas was in Extreme Drought (D3-D4) on August 18, 2009. With recent rainfall, this number was down to 7% on October 13, 2009.

August 18, 2009October 20, 2009

Increasing Optimism Since August for Relief

Oct 1, 2009 OutlookSep 3, 2009 OutlookAug 6, 2009 Outlook

El Nino onset significantly increases the odds for relief

ASO SON OND

El Nino Rainfall vs All Years

Curtesy Robert Blaha

Putting Together the U.S. Putting Together the U.S. Seasonal Drought OutlookSeasonal Drought Outlook

• A CPC productA CPC product

• Operational since Operational since March 2000March 2000

• Released 2/monthReleased 2/month

• Subjectively blends Subjectively blends temp/prcp/soil temp/prcp/soil moisture forecasts moisture forecasts from short term to from short term to seasonal as well as seasonal as well as climatological climatological considerationsconsiderations

• Verification based on Verification based on category changes in category changes in the USDMthe USDM

• Current format O.K . Current format O.K . for general trends, for general trends, but too vague for use but too vague for use by water managers by water managers and ag communityand ag community

The Texas Drought: How Good Were the Forecasts?

Drought Outlook Skill—All of USA

Heavy spring rains in 2009 hurt scores in Texas and Florida

Drought Outlook Verification ScoreForecasts Made Jul '03 - Mar '09

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Drought Outlook Skill -- Forecast minus PersistenceForecasts Made Jul '03 - Mar '09

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Progression of DO Forecasts for TX(Verification Below)

Nov 20 2008 (for DJF) Dec 18 2008 (JFM) Jan 15 2009 (FMA)

Progression of DO for Texas

Feb. 19 2009 (MAM) Mar. 19 (AMJ) Apr. 16 2009 (MJJ)

Odds for Palmer Drought Improvement April to July When March in Drought

April to July Past Palmer Changes Texas CD 9

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Southern Texas

A 77% chance that the PMDI would decline during the period (1951-2006 data)

Summer Drought Outlooks: How Summer Drought Outlooks: How Good?Good?

Drought Outlook Verification May to August

Not so good for S TX

Good for rest of USA

Drought Outlook Verification June to August

Summer CPC Precipitation OutlookSummer CPC Precipitation OutlookForecast

Verification

Missed dryness in 3 areas potentially affected drought forecast

Summer 2009 Percent of Normal Rainfall

Southern TX: one of hottest and driest summers on record

Driest summer (1.38 in) in San Antonio since 1871

Hottest summer on record at: McAllen, Austin, Del Rio, San Antonio, Corpus Christi, etc.

Finding accurate seasonal forecasts for JJA 2009 is like looking for an honest politician

in Washington… nearly futile!

SWCast Rocks for the Southwest!

Only a Few Summer Forecasts Indicated Dryness in Southern Texas

• EuroSip

• CFS

• CFS Downscaled

• SINTEX (Japan)

• Beijing Climate Center

• El Nino composites

• Selected ENSO transition composites

All forecasts understated the intensity of the heat/dryness in S TX!

JJA 2009 Sintex Precip Anomsfrom May 1

Hint of Dryness from the CFS

Coastal Dryness from the EuroSIP

CFS Downscaled Soil Moisture Probabilities

An ENSO Transition Year Composite: JJA Precipitation (Standardized Anomalies)

Selected Experimental Products for Improved Monitoring and Forecasting

University of WashingtonUniversity of Washington3-month Soil Moisture Forecast All Years

Forecast Soil Moisture El Nino Years

El Nino reduces drought odds

Innovative Use of Historical PDI Innovative Use of Historical PDI DataData

Created by Rich Tinker, CPC

The Next Generation ForecastsThe Next Generation Forecasts

Goal: Forecast drought Goal: Forecast drought probabilities to better manage probabilities to better manage drought riskdrought risk

Concept: Milk More Information from Forecasts and Past Weather to

Provide Drought Outlook Information in Probabilistic Formats

Piggyback on existing Work of hydrologists at EMC, Princeton, Univ.

of Washington, etc.

Sample Soil Moisture Anomaly Sample Soil Moisture Anomaly ForecastsForecasts

Princeton-EMC Downscaling of Princeton-EMC Downscaling of the CFSthe CFS

Downscaling Downscaling of CPC fcstof CPC fcst

Downscaling Downscaling of ESPof ESP

NLDAS forecasts are a NLDAS forecasts are a good start. The good start. The various forecast various forecast techniques must be techniques must be verified.verified.

Major Players: Development StageMajor Players: Development Stage

EMC Land- EMC Land- Hydrology TeamHydrology Team

(Produce prototype(Produce prototype forecasts)forecasts)

CPC DroughtCPC Drought Outlook TeamOutlook Team

(provides guidance on (provides guidance on operational products)operational products)

o Princeton Land Sfc Hydro Grpo Princeton Land Sfc Hydro Grpo NWS Office of Hydro Develop.o NWS Office of Hydro Develop.o U. of WA Land Sfc Hydro Res.o U. of WA Land Sfc Hydro Res.

o RFCs (contribute methodology)o RFCs (contribute methodology)

CPC CPC Research Research (KM, HV, etc)(KM, HV, etc)

Climate Climate Test Bed Test Bed ResearchResearch

Proposed Suite of Probabilistic Seasonal Proposed Suite of Probabilistic Seasonal Drought ForecastsDrought 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

Questions?