Highlight: Support for a dry climate increasing.

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1 Scott A. Yuknis High impact weather forecasts, climate assessment and prediction. 14 Boatwright s Loop Plymouth, MA Phone/Fax Cell: Climate Impact Company Season 1-3 Ahead Outlook for Australia Issued: Thursday, May 17, 2018 Highlight: Support for a dry climate increasing. Executive Summary: The Climate Impact Company season 1-3 ahead climate forecast valid winter 2018 to summer is updated. The controversial issue governing Australian climate for the remainder of 2018 is whether the current trend toward +IOD develops which would support a dry climate worsening drought and whether weak El Nino evolves also promoting dry climate. The outlooks favor the drier scenario for upcoming winter and especially next spring. Climate discussion: Of considerable interest is a projected shift in the Indian Ocean Dipole (IOD) out of neutral phase. The Bureau of Meteorology/Australia forecasts evolution of the negative phase of IOD (Fig. 1). However, synoptic trends indicate warming of the western tropical Indian Ocean while both the surface and subsurface are cooling in the eastern Indian Ocean tropics (Fig. 2-3). The synoptic trend indicates the positive phase of IOD is developing. Given the cool subsurface of the eastern equatorial Indian Ocean Climate Impact Company forecasts +IOD for upcoming winter which is likely to enhance Australian drought (Fig. 4). ENSO is now in neutral phase. However, subsurface warming of the equatorial Pacific Ocean shifting eastward increases the risk of El Nino developing later in Forecast models are in disagreement on whether El Nino develops later this year. The Climate Impact Company forecast (based on multivariate ENSO index) favors El Nino (Fig. 5). El Nino also favors a drier Australian climate. Given the +IOD and El Nino risk ahead over the next 3-6 months the Australian climate forecast indicates a drier scenario causing drought conditions to worsen. 1

2: Latest Indian Ocean SSTA analysis indicates warm phase of

2 Fig. 1: The Bureau of Meteorology/Australia Indian Ocean Dipole forecast indicates negative phase for winter Fig. 2: Latest Indian Ocean SSTA analysis indicates warm phase of the Indian Ocean Dipole developing as the western IO tropics have warmer. 2

3 Fig. 3: The equatorial subsurface ocean temperature anomalies during April 2018 indicate cooling in the eastern Indian Ocean suggesting a trend toward +IOD (cooler eastern IO) ahead. Fig. 4: If +IOD forms (as trends indicate) instead of IOD (as forecast by BOMA) a much drier winter occurs across Australia enhancing drought. 3

Fig. 5: The Climate Impact Company ENSO analogs point toward El Nino ahead for 2018. El Nino also promotes a dry Australian climate.

4 Fig. 5: The Climate Impact Company ENSO analogs point toward El Nino ahead for El Nino also promotes a dry Australian climate. Forecast: The Australian climate is based on evolution of +IOD combined with a trend toward El Nino. These conditions are forecast with below average confidence and require close monitoring. The analog years include 2006, 2009 and 2012 for ENSO and 2006 and 2012 for +IOD. JUN/JUL/AUG 2018: A potential ENSO transition toward El Nino and evolution of a +IOD regime support a dry national climate during winter The upper air projection based on analogs indicates an upper ridge pattern across southwestern Australia while and upper trough is well east of Australia. The upper air pattern supports a drier than normal climate for both Southwest and Southeast Australia crop areas. Needed rainfall to reverse drought is not indicated. Only the east/southeast coast of Queensland is wetter than normal. The temperature outlook is marginally cooler than normal across northwest and north-central Australia. South and east portions of the continent are forecast warmer than normal. 4

Fig. 6-8: The Climate Impact Company constructed analog temperature and precipitation anomaly forecast for JUN/JUL/AUG 2018 across Australia. The projected 500 MB anomaly pattern is below.

The upper air pattern features a persistent upper ridge stretched across Southern Australia. The influence on precipitation is quite dry across Eastern Australia extending westward to mid-continent.

5 Fig. 6-8: The Climate Impact Company constructed analog temperature and precipitation anomaly forecast for JUN/JUL/AUG 2018 across Australia. The projected 500 MB anomaly pattern is below. SEP/OCT/NOV 2018: The potential full-tilt dry effect on the Australian climate caused by +IOD/weak El Nino projection on Australian precipitation evolves during meteorological spring The upper air pattern features a persistent upper ridge stretched across Southern Australia. The influence on precipitation is quite dry across Eastern Australia extending westward to mid-continent. Near normal precipitation (except wet interior northern Western Australia) is indicated. The temperature outlook is warmer than normal for the entire continent except cooler than normal northeast portion of Queensland. 5

Indicated is beneficial wet climate into Queensland. Northwest Australia is the dry zone for next summer.

6 Fig. 9-11: The Climate Impact Company constructed analog temperature and precipitation anomaly forecast for SEP/OCT/NOV 2018 across Australia. The projected 500 MB anomaly pattern is below. DEC/JAN/FEB : Forecast confidence is below average. Indicated is beneficial wet climate into Queensland. Northwest Australia is the dry zone for next summer. West and south portions of Australia are the hot zones while Queensland is less hot than normal. The prevailing upper air pattern is a strong ridge southeast of Australia. The ridge position implies a wet tropical/subtropical flow into northeast Australia. 6

Fig. 12-14: The Climate Impact Company constructed

forecast for DEC/JAN/FEB 2018-19 across North

7 Fig : The Climate Impact Company constructed analog temperature and precipitation anomaly forecast for DEC/JAN/FEB across North Australia. The projected 500 MB anomaly pattern is below. 7

Summer 2018 Southern Company Temperature/Precipitation Forecast

Summer 2018 Southern Company Temperature/Precipitation Forecast Scott A. Yuknis High impact weather forecasts, climate assessment and prediction. 14 Boatwright s Loop Plymouth, MA 02360 Phone/Fax 508.927.4610 Cell: 508.813.3499 ClimateImpact@comcast.net Climate Impact