David P. Brown, Ph.D. Regional Climate Services Director NOAA Southern Region March 9, 2012 Presented at the Texas Water Conservation Association annual conference.

1. U N ITE D STATE S D E PARTM E NT O F C OM M E R C E
NATI O NAL O C EAN I C AN D
ATM O S PH E R I C AD M I N I STRATI O N
The 2011-2012 Texas Drought:
Short-Term Extremes and
Long-Term Context
David P. Brown, Ph.D.
Regional Climate Services Director
NOAA Southern Region
March 9, 2012
1

2. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Overview
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news

3. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Overview
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news

19. In addition to record dryness,
there was also record heat

23. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
What has the drought looked like?
• Driest 12-month period ever
– October 1, 2010 thru September 30, 2011
– 2011 was driest calendar year ever (in 117 years)
• Hottest summer ever (in 117 years)
– June-July-August all hottest ever (in 117 years)
• Agricultural losses ~ $6 billion
• Acres burned due to wildfire ~ 4 million
• Mandatory/voluntary water restrictions ~ 1000

24. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Overview
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news

25. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Why did the drought happen?
1. Winter season La Niña

26. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Why did the drought happen?
1. Winter season La Niña
As John Nielsen-Gammon likes to say:
El Nino = EL = Extra Liquid
La Nina = LA = Less Agua
for the Southern U.S.

29. Strong
El Nino
Weak or
Neutral
Strong
La Nina
Figure courtesy of NOAA/ESRL

30. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Why did the drought happen?
1. Winter season La Niña
2. “Missed” spring storms

33. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Why did the drought happen?
1. Winter season La Niña
2. “Missed” spring rainfall
3. Summer heat

34. Figure courtesy of Texas A&M

35. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Why did the drought happen?
• How 2011 summer heat affected the drought
– Dry soil due to low winter/spring precipitation
– Very little evaporation
– Fewer thunderstorms
– Drier soil
• And
– Very little evaporation  less atmospheric cooling 
hotter temperatures  more evaporation of what
little water is left  greater water stress/demand
• Dryness added ± 4-6 degrees F to summer heat

36. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Why did the drought happen?
1. Winter season La Niña
2. “Missed” spring rainfall
3. Summer heat
4. Lack of tropical activity

37. Figure courtesy of Weather Underground

38. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Overview
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news

39. Figure courtesy of SCIPP

40. Figure courtesy of Texas A&M

41. Figure courtesy of SCIPP

42. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Was it a climate change event?
• Temperatures going up (since mid-1970s)
• Precipitation changes uncertain
• Easier to “cross the threshold” into drought
– Higher temperatures  more evaporation
• Future droughts likely hotter and drier

43. NATI O NAL O CEAN I C AN D ATM O S PH ER I C ADM I NI STRATI O N
Overview
• What has the 2011-2012 drought looked like?
• Why did the drought happen?
• Was it a climate change event?
• (Some) recent good news

50. Some improvement, but much
more relief still needed

53. U N ITE D STATE S D E PARTM E NT O F C OM M E R C E
NATI O NAL O C EAN I C AN D
ATM O S PH E R I C AD M I N I STRATI O N
Acknowledgements:
John Nielsen-Gammon (Texas A&M)
Victor Murphy (NOAA NWS)
David P. Brown
david.p.brown@noaa.gov
53