May 14th: Run of glorious autumn days, then rain on the horizon.

The atmosphere flicked a switch as May began, and some parts of Victoria and southern NSW are doing quite well with rain:

may rain so far.png

A cold front only clips us Tuesday into Wednesday, so its limited rain with this one.

Then a high sits just to the east to end the week and for the weekend. Expect glorious autumn days: cold mornings and sunny days with light winds.

This “pause” in the rain may be due to a positive phase of the Southern Annular Mode.

The SAM can control our low pressure, ‘negative’ letting them cross southern Australia, ‘positive’ keeping them well to our south.

The forecast has the SAM heading negative again (see Seasonal Forecasts for more), so we should head back into a stretch of rain producing lows.

Its early days, but the different weather models are starting to show a similar path - a low over South Australia, falling southwards as it passes the eastern states, early next week. And it has a great feed of moisture - out of season Cyclone Ann…

Current outlooks

From Tuesday morning’s run:

ec model.png
us model.png
aus model.png
can model.png

If you squint, there is a similar pattern to all of them now. Generally good falls over SA and far southwest VIC. The potential for something north of the divide (in the first ‘northerly’ part of the system, before the low falls south), but not for Melbourne or Gippsland (blocked by the ranges in the northerly part, then the low is too far away in the southerly part).

Then there may be another “pulse”, producing further rain mid next week.

Stay tuned, I’ll update later this week.

Jane Bunn