What the fog is going on?
Wonder why you have been waking up most mornings and can’t see your hand in front of your face?
In plain English, it’s been foggy.
In Bureau of Meteorology speak, Echuca, Rochester, and Kyabram have had so much persistent fog because we’re slap, bang under a massive record-breaking high-pressure system
Compounded by – and this won’t come as any great surprise – because we are also surrounded by heavy river valley moisture.
This “rare atmospheric combination” has locked our region into a multi-day cycle of thick winter fog.
The offending high-pressure system has run out of steam parked itself over southeastern Australia, driving down winds to near zero and clearing the night skies.
Which the bureau says creates severe radiational cooling, where the ground rapidly loses heat after sunset, generating a powerful temperature inversion, an atmospheric lid, if you will, trapping cold air and moisture right against the valley floor.
Not good when you consider Echuca, Rochester, and Kyabram are already geographically prone to the heaviest fog because of local geography:
- Their proximity to major river systems such as the Murray, Campaspe, and Goulburn Rivers provides an endless supply of low-level surface moisture.
- Surrounding irrigated agricultural flatlands hold significant soil moisture. When temperatures plunge to the dew point overnight, this abundant moisture instantly condenses into exceptionally thick fog.
Normally, morning sun burns the fog away.
However, because this fog has been so dense it also reflects the winter sunlight back into space. The sun cannot warm the ground enough to break the inversion loop, causing the mist to linger straight into afternoons.
