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Annual U.S. Drought Highlights and the Seasonal Drought Outlooks: How are We Doing?

Annual U.S. Drought Highlights and the Seasonal Drought Outlooks: How are We Doing?. 34 th Annual Climate Diagnostics and Prediction Workshop Monterey, CA, October 26-30, 2009 Douglas Le Comte, CPC Douglas.lecomte@noaa.gov. Lake Travis, Texas, July 2009.

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Annual U.S. Drought Highlights and the Seasonal Drought Outlooks: How are We Doing?

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  1. Annual U.S. Drought Highlights and the Seasonal Drought Outlooks: How are We Doing? 34th Annual Climate Diagnostics and Prediction Workshop Monterey, CA, October 26-30, 2009 Douglas Le Comte, CPC Douglas.lecomte@noaa.gov

  2. 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).

  3. Now an I-Phone App for the Drought Monitor!

  4. Outline • Drought coverage in 2009 drops to its lowest level since 2001 • Drought intensity peaked in August 2009 in southern Texas and (arguably) in January 2009 in California • We take a closer look at the Drought Outlooks for Texas • We look at some of the forecast tools (then and now) • Overall U.S. skill trend continues up • We plan to work with our partners to improve forecasts

  5. USDM Coverage: The Past YearLate October 2008 22% D1 Coverage

  6. Late January 2009 Drought in CA and TX intensifies; Southeast drought shrinks Texas: Driest Dec-Feb in 114 years! 21% D1 coverage

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

  8. August ‘08 to March ’09 Change DM change maps courtesy Rich Tinker, CPC

  9. Sep ’08 – Feb ’09: Driest on record for SC/S Texas Deficits in southern Texas date back to the fall of 2007

  10. Late April 2009 Southern Texas further intensifies; CA improves; most of Southeast drought over (exc FL!) 18% D1 Coverage

  11. March ’09 to Sep ’09 Change

  12. Late July 2009 Relief northern TX, worse in southern Texas; Wisconsin drought continues 14% D1 Coverage

  13. Late October 2009 Major relief mid-October D1 coverage = 13%

  14. Calendar Year 2009 Change

  15. Water Year 2008-09 Change

  16. South Central Texas: 24-month Precipitation to August 2009 August PMDI = -6.42 in SC TX, lowest since Oct. 1956 (also -6.42). Median = 71.43 in. Lowest (38.54 in) since 1918 (38.01 in)

  17. Drought Impacts Texas Ag damage in the $billions; Widespread water restrictions “Bexar County (San Antonio) has lost 10,000 live oak trees this year.”

  18. 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. October 20, 2009 August 18, 2009

  19. Increasing Optimism Since August for Relief Sep 3, 2009 Outlook Oct 1, 2009 Outlook Aug 6, 2009 Outlook ASO SON OND El Nino onset significantly increases the odds for relief

  20. El Nino Rainfall vs All Years Curtesy Robert Blaha

  21. Putting Together the U.S. Seasonal Drought Outlook • A CPC product • Operational since March 2000 • Released 2/month • Subjectively blends temp/prcp/soil moisture forecasts from short term to seasonal as well as climatological considerations • Verification based on category changes in the USDM • Current format O.K . for general trends, but too vague for use by water managers and ag community

  22. The Texas Drought: How Good Were the Forecasts?

  23. Drought Outlook Skill—All of USA Heavy spring rains in 2009 hurt scores in Texas and Florida

  24. Progression of DO Forecasts for TX(Verification Below) Jan 15 2009 (FMA) Nov 20 2008 (for DJF) Dec 18 2008 (JFM)

  25. Progression of DO for Texas Feb. 19 2009 (MAM) Mar. 19 (AMJ) Apr. 16 2009 (MJJ)

  26. Odds for Palmer Drought Improvement April to July When March in Drought A 77% chance that the PMDI would decline during the period (1951-2006 data) Southern Texas

  27. Summer Drought Outlooks: How Good?

  28. Drought Outlook Verification May to August Not so good for S TX Good for rest of USA

  29. Drought Outlook Verification June to August

  30. Summer CPC Precipitation Outlook Forecast Missed dryness in 3 areas potentially affected drought forecast Verification

  31. Summer 2009 Percent of Normal Rainfall Southern TX: one of hottest and driest summers on record Hottest summer on record at: McAllen, Austin, Del Rio, San Antonio, Corpus Christi, etc. Driest summer (1.38 in) in San Antonio since 1871

  32. Finding accurate seasonal forecasts for JJA 2009 is like looking for an honest politician in Washington… nearly futile!

  33. SWCast Rocks for the Southwest!

  34. 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!

  35. JJA 2009 Sintex Precip Anomsfrom May 1

  36. Hint of Dryness from the CFS

  37. Coastal Dryness from the EuroSIP

  38. CFS Downscaled Soil Moisture Probabilities

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

  40. Selected Experimental Products for Improved Monitoring and Forecasting

  41. University of Washington 3-month Soil Moisture Forecast All Years Forecast Soil Moisture El NinoYears El Nino reduces drought odds

  42. Innovative Use of Historical PDI Data Created by Rich Tinker, CPC

  43. The Next Generation Forecasts Goal: Forecast drought probabilities to better manage drought risk

  44. Concept: Milk More Information from Forecasts and Past Weather to Provide Drought Outlook Information in Probabilistic FormatsPiggyback on existing Work of hydrologists at EMC, Princeton, Univ. of Washington, etc.

  45. Sample Soil Moisture Anomaly Forecasts Princeton-EMC Downscaling of the CFS Downscaling of CPC fcst Downscaling of ESP NLDAS forecasts are a good start. The various forecast techniques must be verified.

  46. Major Players: Development Stage Climate Test Bed Research CPC Research (KM, HV, etc)

  47. Proposed Suite of Probabilistic Seasonal Drought Forecasts Change in soil moisture percentiles Total Column 2-m Soil Moisture Probability of Drought Change Map Total Drought Top 40 cm or root zone soil moisture Change in soil moisture percentiles Probability of Ag. Drought Change Map Agricultural (Short-term) Drought Probability of Runoff or Streamflows Change in runoff or streamflow percentiles Probability of Hydro Drought Change Map Hydro (Long-term) Drought

  48. Questions?

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