1. 2015 Summer Weather Outlook Temperatures, Precipitation, Drought, and Hurricanes

2. Visit www.ercot.com/about/weather for daily and seasonal www.ercot.com/about/weather weather updates.

3. The past two springs (2013 and 2014) have averaged at slightly cooler than normal. That’s certainly possible for 2015 as well, though I believe there will be enough warmer potential mid-to-late spring that this season may average a bit warmer than the past couple of springs. But not to the very warm levels of 2011 and 2012.

4. Introduction Today’s weather outlook is intended to offer a preliminary look at the summer temperature and precipitation potential. We’ll learn how this may impact the current drought in Texas. And we’ll see if the hurricane season can offer any assistance.

5. Objectives At the completion of this course of instruction you will: Be familiar with the hottest summer on record for the state of Texas Know which ocean the ERCOT meteorologist monitors most for potential influence of the Texas weather pattern Be able to identify the historical year that is being applied as the primary historical match (analog) for the summer of 2015 Know the probability of summer 2015 being hotter than normal Recognize the total combined number of tropical storms and hurricanes (named storms) expected in the Gulf of Mexico in 2015

6. TEMPERATURE OUTLOOK Summer 2015

7. Summer 2011 86.8° Summer 1998 84.2° Repeat of 2011? Same difference as 2 nd to 55 th (1998 to 1929) 2.6 degree difference (Jun-Aug)

8. Past Six Summers 2013: 21 st hottest, 81.2° 2012: 13 th hottest, 81.5° 2010: 11 th hottest, 81.6° 2009: 29 th hottest, 80.8° 2014: 50 th hottest, 80.4° 2011: 1 st hottest, 84.6° (POR 1895-current, Jun-Sep; all of Texas)

9. Warming trend from the West over the past several seasons Positive (warm) phase of the Pacific Decadal Oscillation (PDO) has played a significant role. The Pacific Ocean is the primary driver of Texas weather patterns.

10. Building the Forecast 1.Winter temperature and precipitation patterns 2. Winter upper level steering currents 3. Winter sea surface temperature pattern 4.El Niño Southern Oscillation (ENSO) 5. PDO, AMO, PNA, WPO, EPO 6. Drought

11. Winter of 2014-15 69 th Coldest Winter on Record in Texas (1895-current) 69 th Driest Winter on Record in Texas

12. ENSO

13. 200mb SST All 2/12/15 ENSO/200/ SST 2003, 1994, 2005 1987, 1977 1978, 1959 PDO Building the forecast

14. PDO-AMO (was best for winter 2014-15) Building the forecast

15. Top Historical Matches 2003 1994 1977 200519591988 Summer 2015

16. Summer Temperatures 2003 is being applied as the best historical match Latest set of historical years (as of 3/26/15)

17. Summer Temperatures Last Year (for review) 10yr30yr

18. Summer Temperatures Summer 2015 Preliminary temperatures (2/27/15)

19. Summer 2014 Temperatures Last Year (for review) 10yr

20. Summer 2015 Temperatures Continue to rely on a pattern, which has set up long-term. Hot West, mild East. Probabilities of an overall: Hotter than normal summer: 20% Near normal summer: 35% Cooler than normal summer: 45% Unlikely to rank with the summers of 2010-2013 for heat

21. Summer Temperatures By month Best opportunity to break into a hotter pattern will be in September

22. What Others Are Saying

23. PRECIPITATION OUTLOOK Summer 2014

24. Past Six Summers 2013: 64 th driest, 10.89” 2012: 52 nd driest, 10.35” 2010: 105 th driest, 13.49” 2009: 60 th driest, 10.78” 2014: 65 th driest, 10.93” 2011: 1 st driest, 3.60” (POR 1895-current, Jun-Sep; all of Texas)

25. Top Historical Matches 20031994 1977 2005 19591988

26. Summer Precipitation 2003 is preferred

27. Summer Precipitation Summer Precip 2015 (2/27/15)

28. Summer Precipitation 80-120% Near normal Similar to last summer; Possibly a bit wetter

29. DROUGHT OUTLOOK Summer 2014

30. Drought Texas Reservoirs at 70.5% (Apr 14)

31. Drought 35.5% 2014-04-07 36.4%, 2015-04-14 628.5 of 681ft

32. Drought

36. 80-120% Near normal

37. HURRICANE OUTLOOK Summer (and Fall) 2014

38. Hurricane Forecast Historical Averages Named Storms: 12 Hurricanes: 6 Major Hurricanes: 3

39. Hurricane Forecast

40. ENSO is a strong factor in determining the Hurricane season (number and intensities). Will the current weak El Niño continue Into the hurricane season?

41. Hurricane Forecast Factors in Determining Numbers and Intensities ENSO Saharan Dust Dry Air Vertical Wind Shear Ocean Temperatures

42. Hurricane Forecast What happened last year? MDA/EarthSat: 12/6/2 NOAA: 8-13/3-6/1-2 Colorado State University: 9/3/1* WSI/TWC: 11/5/2 ERCOT: 9/5/2 2014 Actual: 8/6/2 Normal: 12/6/3 *increased with a July update

43. Hurricane Forecast 12 6 3

44. Hurricane Forecast Total Named Storms: 11 Total Hurricanes: 6 Major Hurricanes: 2 Named Storms in Gulf : 4-5 Named Storms in Western Gulf: 2-3 Hurricane in Gulf: 1-2 Major Hurricane in Gulf: 0-1 Named Storms with Texas Landfall: 0 or 1 Hurricanes with Texas Landfall: 0 or 1 Near normal but a bit more active than 2014 – Especially in the Gulf of Mexico

45. TRENDS Long-Term Historical

46. 20142011 6 of the hottest 21 summers on record (1895-current) in Texas have occurred since 2000. 2011 (1) 2012 (9) 2009 (13) 2001 (15) 2010 (18) 2006 (21) However … 5 of the hottest 21 (6 of 22, and 5 of the top 12) summers on record in Texas occurred in the 1950s. 19 of the 30 hottest summers on record occurred prior to 1960.

47. 20152011 Of the driest one-third of years since 1895, 15 of them have occurred since 1955. 25 occurred prior to 1955. The 1950s had the most dry years (6) followed by the 1930s, 20s, and 10s. Of the wettest one-third of years since 1895, 23 of them have occurred since 1955. 17 occurred prior to 1955.

48. Between 1998 and 2013 (PDO-), an average of 16/8/3. Between 1976 and 1997 (PDO+), an average of 10/5/2. Between 1943 and 1975 (PDO-), an average of 10/6/3. 2013 and 2014 combined had fewer hurricanes and tropical storms than 2012. Quietest back-to-back years since 1993-1994.

49. Summary 80% likelihood of either normal or below normal temperatures for the summer as a whole, continuing a trend that began in the autumn of 2013 Improvements to the drought may be limited. Likely still an issue for portions of Texas following the summer season, but not expecting deteriorating conditions Hurricane season holds a bit more potential than the previous two years – but should El Niño hold, that could hamper the potential

50. Questions ? ? ? ?

51. 51 1.______ was the hottest summer on record for Texas. a)2009 b)2010 c)2011 d)2012

52. 52 2.Which ocean has shown the best correlation to Texas weather patterns? a)Atlantic b)Indian c)Pacific d)Saturn

53. 53 3.The historical year that is being applied as the primary historical match for the Summer 2015 is______? a)2002 b)2003 c)2004 d)2005

54. 54 4.Percentage probability for the summer of 2015 to be hotter than normal: ____? a)10% b)20% c)35% d)45%

55. 55 5.The number of named storms forecasted in the Gulf of Mexico for 2015 are _______? a)0-1 b)2-3 c)4-5