Presentation on theme: "Annual U.S. Drought Highlights and the Seasonal Drought Outlooks: How are We Doing? 34 th Annual Climate Diagnostics and Prediction Workshop Monterey,"— Presentation transcript:
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.firstname.lastname@example.org
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).
Outline 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 (arguably) in January 2009 in CaliforniaDrought 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 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 Year Late 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!)
South Central Texas: 24-month Precipitation to August 2009 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, 2009 October 20, 2009
Increasing Optimism Since August for Relief Oct 1, 2009 OutlookSep 3, 2009 Outlook Aug 6, 2009 Outlook El Nino onset significantly increases the odds for relief ASOSONOND
El Nino Rainfall vs All Years Curtesy Robert Blaha
Putting Together the U.S. Seasonal Drought Outlook A CPC productA CPC product Operational since March 2000Operational since March 2000 Released 2/monthReleased 2/month Subjectively blends temp/prcp/soil moisture forecasts from short term to seasonal as well as climatological considerationsSubjectively blends temp/prcp/soil moisture forecasts from short term to seasonal as well as climatological considerations Verification based on category changes in the USDMVerification based on category changes in the USDM Current format O.K. for general trends, but too vague for use by water managers and ag communityCurrent format O.K. for general trends, but too vague for use by water managers and 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
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 Southern Texas A 77% chance that the PMDI would decline during the period (1951-2006 data)
Summer CPC Precipitation Outlook Forecast 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!
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!
An ENSO Transition Year Composite: JJA Precipitation (Standardized Anomalies)
Selected Experimental Products for Improved Monitoring and Forecasting
University of Washington 3-month Soil Moisture Forecast All Years Forecast Soil Moisture El Nino Years El Nino reduces drought odds
Innovative Use of Historical PDI Data Created by Rich Tinker, CPC
The Next Generation Forecasts Goal: Forecast drought probabilities to better manage drought 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 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.
Major Players: Development Stage EMC Land- Hydrology Team (Produce prototype forecasts) forecasts) CPC Drought Outlook Team Outlook Team (provides guidance on operational products) o Princeton Land Sfc Hydro Grp o NWS Office of Hydro Develop. o U. of WA Land Sfc Hydro Res. o RFCs (contribute methodology) o RFCs (contribute methodology) CPC Research (KM, HV, etc) Climate Test Bed Research
Proposed Suite of Probabilistic Seasonal 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
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