Yea’s Rainfall Split Phenomenon in Action Yesterday and Why it Occurs

by Jan 16, 20211 comment

Yesterday’s rainfall map clearly showed the rainfall split phenomenon that effects Yea on many occasions throughout the year. It is actually called a Foehn effect.

In March 2019 I contacted the BOM to see if they could explain this strange rainfall pattern. The BOM’s explanation was posted back then. If you have not read it, here it is again.

We often see these kinds of rain effects across eastern Victoria, where the terrain is more complex. Even though Victoria’s ranges aren’t very high in the scheme of things, they’re still high enough to have an impact on the weather, often reducing rainfall in the lee of hills/mountains. This is called the Foehn effect, and even though it usually happens with more significant mountain ranges, it still makes itself felt in lower-lying areas too. 

Weather coming directly from the NW has the best chance of reaching Yea. It would likely be driven down the Goulburn Valley from Seymour to Yea.

However, if prevailing winds are more NNW’ly, the Strathbogie ranges to the north may produce some blocking effects, reducing rainfall near Yea. Likewise, if winds are more WNW’ly, Mt Hickey and the other hills to the WNW may have a similar impact.

Unfortunately, when a cold front or rain band move across the state, winds are rarely direct NW’lies, meaning that more often than not Yea receives less than its fair share of rainfall.

Other local effects may also be in play here, but this orographic forcing is the most likely culprit.”

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