On 21 November, a cyclone watch was raised for coastal and nearby inland areas of Western Australia between Wyndham and Beagle Bay.
This watch was soon expanded to encompass areas east to the Western Australia–Northern Territory border and west to the Mitchell Plateau.
Additionally, areas from Mitchell Plateau to Cockatoo Island were placed under a cyclone warning.
The following day, watches extended to Cape Hotham Light in the Northern Territory, including the city of Darwin and the Tiwi Islands.
As the cyclone intensified, warnings gradually spread eastward.
Warnings reached as far east as Point Stuart prior to Alessia's landfall.
All watches and warnings were dropped on 24 November as Alessia moved inland and degraded to a tropical low.

Though impact from the storm was expected to be fairly minimal, residents were still advised to stock up on emergency supplies and be prepared.
Northern Territory Police Commissioner, John McRoberts, urged residents to heed warnings despite the generally non-threatening nature of the storm, "complacency can often be your worst enemy in these types of events."
Many stores across Darwin reported a sharp increase in the sales of bottled water due to the storm.
Despite the approaching storm, regional airports, schools, and businesses remained open.
Ferry service to the Tiwi Islands, however, was suspended for 24 November.

On 23 November, Cyclone Alessia brushed the Kimberley coastline of Western Australia as a low-end Category 1.
The strongest winds were measured on Troughton Island at 69 km/h (43 mph) with gusts to 94 km/h (58 mph).
The storm's brisk forward motion limited rainfall, however, with only 24.8 mm (0.98 in) falling on the island.
Farther west, Kalumburu received 37.8 mm (1.49 in) of rain.
Effects across the Top End region were similar to Kimberly, some reports of gale-force winds with generally light to moderate rain, peaking at 126 mm (5.0 in) along the Upper Wickham River.
Owing to previously dry conditions, the rains proved mostly beneficial to the region.
Flash flooding along the Goomadeer River in Arnhem Land caught at least seven people off-guard, including one infant, as their two vehicles were overcome with water.
Six people safely made it out while another was swept downstream.
He was rescued two days later by local police.
In Darwin, strong winds downed a few trees in the Northern Suburbs and Howard Springs while localised flooding occurred in Palmerston.
Additionally, one power line was downed in the city.
Local authorities reported no serious traffic accidents in relation to the storm nor injuries.
In Milne, a few residents seeking shelter at a local fire station found themselves locked out despite officials advising people to seek shelter if necessary.
On 21 November, a cyclone watch was raised for coastal and nearby inland areas of Western Australia between Wyndham and Beagle Bay. This watch was soon expanded to encompass areas east to the Western Australia–Northern Territory border and west to the Mitchell Plateau. Additionally, areas from Mitchell Plateau to Cockatoo Island were placed under a cyclone warning. The following day, watches extended to Cape Hotham Light in the Northern Territory, including the city of Darwin and the Tiwi Islands. As the cyclone intensified, warnings gradually spread eastward. Warnings reached as far east as Point Stuart prior to Alessia's landfall. All watches and warnings were dropped on 24 November as Alessia moved inland and degraded to a tropical low.
Though impact from the storm was expected to be fairly minimal, residents were still advised to stock up on emergency supplies and be prepared. Northern Territory Police Commissioner, John McRoberts, urged residents to heed warnings despite the generally non-threatening nature of the storm, "complacency can often be your worst enemy in these types of events." Many stores across Darwin reported a sharp increase in the sales of bottled water due to the storm. Despite the approaching storm, regional airports, schools, and businesses remained open. Ferry service to the Tiwi Islands, however, was suspended for 24 November.
On 23 November, Cyclone Alessia brushed the Kimberley coastline of Western Australia as a low-end Category 1. The strongest winds were measured on Troughton Island at 69 km/h (43 mph) with gusts to 94 km/h (58 mph). The storm's brisk forward motion limited rainfall, however, with only 24.8 mm (0.98 in) falling on the island. Farther west, Kalumburu received 37.8 mm (1.49 in) of rain. Effects across the Top End region were similar to Kimberly, some reports of gale-force winds with generally light to moderate rain, peaking at 126 mm (5.0 in) along the Upper Wickham River. Owing to previously dry conditions, the rains proved mostly beneficial to the region. Flash flooding along the Goomadeer River in Arnhem Land caught at least seven people off-guard, including one infant, as their two vehicles were overcome with water. Six people safely made it out while another was swept downstream. He was rescued two days later by local police. In Darwin, strong winds downed a few trees in the Northern Suburbs and Howard Springs while localised flooding occurred in Palmerston. Additionally, one power line was downed in the city. Local authorities reported no serious traffic accidents in relation to the storm nor injuries. In Milne, a few residents seeking shelter at a local fire station found themselves locked out despite officials advising people to seek shelter if necessary.
Cyclone Alessia