Effective as of 4:00 PM Tuesday December 21 2021
View the latest severe weather warnings from BOM at http://www.bom.gov.au/wa/warnings/ .
Explanatory notes:
Some elevated convection occurred this morning with further isolated activity in the southeast in the afternoon associated with instability aloft ahead of an upper level trough. This activity has contracted away as the upper level trough moves to the east.
Fine conditions with afternoon sea breezes with the west coast trough inland tomorrow and on Thursday.
An unusually intense heatwave, possibly Perth's worst December heatwave on record is increasingly likely from Christmas Eve as a very hot air mass lies over the region with the west trough deepening and lying offshore for several days and an upper level high leading to subsidence heating of the airmass. Temperatures could even be hotter than currently forecast as the current forecast is a little conservative taking into account uncertainty this far out. Perth's longest December 40+°C spell on record was 3 consecutive days in December 2019. Prior to December 2019, 3 consecutive 40+°C days was underheard of in December