Gordon wrote: ↑Wed Jan 27, 2021 8:41 am
Hmmm - I don't dare guess. For the last event, Ballarat was down for 'possible heavy falls' in the BOM forecast a day out, and ended up with 8mm (we got 4mm).
I do despair of model accuracy over the last month - for example, EC has gone from 11mm for Ballarat on Friday, to 51mm, in one run! And it's only 2 days out.
Any thoughts anyone on reasons for the consistently poor performance?
Models alway have more difficultly in summer as rainfall is more convective with short time a space scales. Basically the bigger and longer lived an event is, the more straight forward to predict. I doubt the models have been any worse, but they definitely show a wide spread on recent convection dominated events. That tells you that the situation is complex and very small changes in details can make a big difference. Looking at this event, the progs range from 20mm (GFS) to about 80mm (UK and EC) here. That tells me that I’m mostly likely to see something in about the middle (so perhaps 40 to 60mm) but should not be surprised if it end up around 20mm, or I get lucky and get close to 100mm.
I’ve also found we tend to remember the exciting model runs the best. With Tuesday’s low I was expecting about an inch, and got 31mm. That’s pretty good imho.
Appreciate all a bit anecdotal
There are hard numbers published, and I’ll see what I can find.
Progs continue to hold. GFS is the least keen. EC, UK, ACCESS and the EC ensemble are going off. Should see the first action develop for areas mostly west of Melbourne tomorrow. I suspect the stiff southeasterly breeze will keep storms out of the Melbourne metro but hope to be surprised
very widespread rain and storms for Friday.
Btw check out the gradient in rainfall fractions for January. Suspect this explains a bit about how the season and models feel. It’s so patchy, and this is a really smoothed rendering.