08/17/2022, 5:24 pm EDT

Australia Month 1-3 Outlook: A cool spring ahead; wet climate North and East.

Executive Summary: The Climate Impact Company month 1-3 ahead climate forecast for Australia is updated. The forecast is based on moderate-to-strong La Nina climate coupled with a moderate-strength -IOD pattern plus influence of the South Pacific semi-permanent ridge associated with the New Zealand “warm blob”. The result is an exceptionally cool spring for much of Australia. Northern and eastern continent is wetter than normal. Elsewhere precipitation is mostly seasonably dry. Climate discussion: Since May 1st, heavy to excessive rainfall has dominated the East Coast of Australia (Fig. 1). Almost as impressive is the developing dryness along the Australia South Coast. Daily soil moisture anomalies provided by NOAA/CPC certainly identify the developing drought along the Australia South Coast (Fig. 2). However, given the long-term wet pattern on the East Coast, the soil moisture regime is likely wetter than indicated. According to the Australia Bureau of Meteorology parts of the central northern coast of Australia have slipped into drought. The more widespread dry soil analysis by NOAA/CPC is likely overstated. Tropical Pacific Ocean SSTA analysis reveals two regimes usually producing major (mostly wet) impacts on Australia climate: La Nina and negative Indian Ocean dipole (-IOD). However, some disruption to that climate pattern is caused by a sprawling semi-permanent high-pressure ridge across the vast warm SSTA pattern associated with the New Zealand “warm blob”. To compensate for this upper ridge, a wet trough has occupied Eastern Australia to enhance the La Nina rains. This feature has prevented most of the remainder of Australia from receiving significant rainfall. The IMME global SSTA forecast maintains the SSTA pattern described through meteorological spring (Fig. 4). Implications are more wet weather for East Australia while West/South Australia wet weather typically associated with -IOD under-perform. La Nina is forecast to fade late summer 2022-23 (Fig. 5) while -IOD ends by late December (Fig. 6).          Fig. 1-2: Australia rainfall anomalies for the past 3 months and daily soil moisture anomalies. Fig. 3-4: Tropical Pacific SSTA observations and the IMME November 2022 global SSTA forecast. Fig. 5-6: Climate Impact Company ENSO forecast using Nino34 SSTA and the Australia Bureau of Meteorology forecast of the IOD pattern. September 2022: The early spring upper air projection features persistence of an amplified ridge east of Australia while a weak upper trough evolves over West-central Australia. The result is wet weather across the eastern continent. Heaviest rainfall is to the north across Indonesia. Western Continent observes lack of significant rainfall which is unusual given the -IOD pattern. Much of the continent is cooler than normal except northern sections which are warmer than normal. Drought across Southwest and South Australia continues and may strengthen. Fig. 7-8: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for September 2022. October 2022: A broad upper trough stretches along the south coast of Australia. An upper ridge extends from New Zealand to Northeast Australia. The upper trough sustains a cool regime across the southern half of Australia. The ridge pattern inspires anomalous warmth for far northern portions of the continent. In-between the cool/warm regimes above normal rainfall is forecast for northwest continent and with patchy character into eastern continent. Excessive rainfall is not indicated. Southwest/South Australia drought continues but does not worsen due to the cooler than normal climate. Fig. 9-10: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for October 2022. November 2022: The tendency for an upper trough to dominate the Australian climate pattern continues during November. Late meteorological spring is wet and possibly excessive wet in parts of northeast Queensland and southeaster New South Wales. Wet weather also eases drought trend in Southwest Australia. Most of the continent is somewhat cooler than normal in November. Fig. 11-12: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for November 2022.