Extreme monsoon break conditions
February 17 2022:
The maritime continent has seen an unusual reversal of the monsoon flow against the climatological mean where the wind flow is from Australia towards continental Asia as opposed to the usual Asia-Australia monsoonal flow. At Darwin Airport on Tuesday, relative humidity had dipped to around 30+% with the dry easterlies.
Whilst the monsoon exhibits natural variability and is characterised by active and break periods where easterlies may penetrate the Top End and the Timor Sea and sometimes also the Java Sea during monsoon break periods, it is unusual to see such a strong reversal of winds against the climatological mean and for such winds to penetrate so far into the Northern Hemisphere.
According to ERA-5 reanalysis, such has not happened in February since the beginning of records from 1950.There were several similar occasions, however, those were far weaker and/or did not penetrate that far north.
This reversal appears to be facilitated by an equatorial Rossby Wave and associated tropical lows over the Indian Ocean coupled with an active MJO over the Indian Ocean.
ECMWF 850 hPa winds showing the wind flow being from Australia towards Continental Asia
The maritime continent has seen an unusual reversal of the monsoon flow against the climatological mean where the wind flow is from Australia towards continental Asia as opposed to the usual Asia-Australia monsoonal flow. At Darwin Airport on Tuesday, relative humidity had dipped to around 30+% with the dry easterlies.
Whilst the monsoon exhibits natural variability and is characterised by active and break periods where easterlies may penetrate the Top End and the Timor Sea and sometimes also the Java Sea during monsoon break periods, it is unusual to see such a strong reversal of winds against the climatological mean and for such winds to penetrate so far into the Northern Hemisphere.
According to ERA-5 reanalysis, such has not happened in February since the beginning of records from 1950.There were several similar occasions, however, those were far weaker and/or did not penetrate that far north.
This reversal appears to be facilitated by an equatorial Rossby Wave and associated tropical lows over the Indian Ocean coupled with an active MJO over the Indian Ocean.
ECMWF 850 hPa winds showing the wind flow being from Australia towards Continental Asia
Climatology mean (1980-2020) February 850 hPa wind showing that typically the monsoon wind flows from Asia to Australia in February:
Image courtesy of Meteologix and Climate Reanalyser.