Season in review

BOM14_06_24

Our snow season is far from over, but the big melt will soon start. Now’s a good time to reflect on what we’ve seen so far, with archive charts from the Australian Bureau of Meteorology:

. . . → Read More: Season in review

Understanding evaporation #4: climate change

Annual_pan_evaporation-Australia

One of a series; also see editions: #1, #2, #3

A warmer climate must mean more evaporation, a drier continent and more drought? Well, yes, that’s pretty much the prediction, but unfortunately the observed response of evaporation to climate change has long been a bit of hole in the story — a real one, unlike . . . → Read More: Understanding evaporation #4: climate change

2-4 September

Spag14_09_02

Updated #2…

After a very long hiatus, it looks like there may be a “real” snow event early in September. By that I don’t mean a big one, just one deriving from the typical winter meanders in the polar circulation.

Update (27 August): This is now up on BOM ACCESS-G and ECMWF (they don’t yet . . . → Read More: 2-4 September

August 17-18 event ... dip

How did I miss this? Like many others I expected a rain event, but as with the 15-16 June system earlier this year, this one delivered marginal wet snow to Perisher Valley and Thredbo (but little to Victoria). These upper atmosphere driven systems can be tough to pick. It’s interesting that the NSW office of . . . → Read More: August 17-18 event … dip

Understanding evaporation #3: potential rate

Australian_point_potential_evapotranspiration

One of a series; also see editions: #1, #2, #4

Talk to a meteorologist about how to measure evaporation and you’ll probably be told not to bother because it can be reliably estimated from other parameters. Therein lies a simplification, an overstatement and perhaps a cop-out.

. . . → Read More: Understanding evaporation #3: potential rate

Trans-Tasman seesaw?

Mt Hutt peak snow depth vs Spencers Creek

You can’t watch snow weather in our part of the world for long without noticing that when things are good in Australia, they’re often not so good in New Zealand, and when they’re bad here, they usually look much better over there. Take this season — in late June and early July we had a . . . → Read More: Trans-Tasman seesaw?

Understanding evaporation #2: evapotranspiration

Stomata on tomato leaf

One of a series; also see editions: #1, #3, #4

Evapotranspiration is one of those ugly made-up words, intended to convey the combination of transpiration from plants and evaporation from the ground under and around them. It’s the relevant meteorological and hydrological parameter at the catchment and landscape scale¹ — the average flux of moisture . . . → Read More: Understanding evaporation #2: Evapotranspiration

10 August - placeholder

Updated…

This season I’ve decided not to blog about inconsequential snow weather systems. The little front arriving around 10 August will be one of those. The next chance of a decent snow event now seems to be out to 20 August at least … hope I’m wrong.

Update (7 August): I should add, inconsequential for . . . → Read More: 10 August – placeholder

Understanding evaporation #1

hare

One of a series; also see editions: #2, #3, #4

Evaporation is that weird cousin in meteorology. The Australian Bureau of Meteorology lists over 18,000 present and past rainfall recording stations in its huge database, but only about 600 stations that have ever measured evaporation, and just 180 of those still operate. But wait, measure . . . → Read More: Understanding evaporation #1

Peak timing

Spencers Creek snow depths by decade

As our world warms, our snowpack thins and our snow season grows shorter, but is that all simple and uniform or is there more to it? Those who have done the work¹² to study and model the physical processes of snow accumulation, consolidation and melt have an answer; perhaps a surprising one:

. . . → Read More: Peak timing