Recent Summer Wrap-up

[johnno]

Intresting but at the same time I find it a coincident that WA previous Hottest Summer was at the back of the 97/98 El Nino & Darwin has had its wettest Jan/Feb period since that Summer as well.. Conicident David? Or something linked with El Nino?

[Karl Lijnders]

Certainly interesting that we have seen an increase in precipitation through this part of the world in this season than previous, sort of bucks the trend a little. Be interesting to also see how we perform over the next 12 months and compare.

[droughtbreaker]

Well, not wanting to sound controversial but we are getting a double whammy from global warming atm. Just as predicted we are getting more intense (short term within long term) droughts, heat and bushfires, (last summer as prime example), but also intensely severe storms like we haven't seen for a long time, I don't think I ever remember such volatile setups and severe storms, humidity and heat are increasing together and combining as our oceans warm up. We are starting to get Brisbane weather in summer given the right climatic conditions but other years we get the severe droughts and heat remains intense, particularly average temps. Not that long to wait now (probably 10 years or so)I reckon before we start getting ex cyclones on our doorstep causing 200-300mm of rain statewide and 100km/hr sustained winds.

June to Feb rainfall has been average for here and that is a big positive because it is significantly 'bucking the trend' of long term drought that we have seen most of the past 13 years up until then. If this upcoming system ends up a goer then we will be significantly above average for the June-March period. This gives us an excellent chance of having an average 12 month period which is something we would only have dreamed of at the start of last year.

[Karl Lijnders]

Uhuh!!!

See this is what gets me a little offside. If it rains hard and we get flooding, it is global warming, when it is drought conditions, it is global warming. When it is fog for 4 days is that global warming.

I don't mean to sound so rude but try and win the layman person over!!!

[droughtbreaker]

Well, I was only born in 1982 but I never remember a summer as humid as this with so many huge, no sorry not huge, massive storms, temperatures chronically above average and by large margins and ridiculously warm waters around the continent in an El Nino year. Basically Sydney's weather in summer.

The predictions from climate scientist were that we would have more severe droughts, more severe storms and floods from extreme weather events and possibly a generally drier climate. The only one of those three that is still up in the air is the last one as we have had regular cold fronts, lows and troughs with average rain here since June which is bucking the general trend.

I always keep an open mind but the only explanation for this that makes sense to me atm is global warming. Would be fascinated if it was proven to be something else happening to our climate, I am in no way biased on either side of the debate but I try to make objective judgments based on the evidence I have presented to me and how I interpret that evidence.

[Anthony Violi]

I dont think we know...we just dont. Everytime we think we have it sussed, bang, another curveball. We are just guessing, its not easy using a miniscule amount of evidence in time.

One thing i have noticed, my theory anyway, is that the blocking pattern is rare thesedays. Allowing lots of upper troughs through which is enhancing rainfall. This summer has been unbelievable, biblical storms because of the relentless humidity.

[johnno]

In general I believe the planet has warmed up over recent years/decades but for this Summer I can't see everything thats happend how thats global warming? All the moisture/humidity that we have had since Christmas has to do with 3 tropical lows or ex cyclones paying us a visit all the way down to Victoria and having a direct or indirect affect on us on incresing humidity and moisture therefore lifting overnight tempertures as well. Sometimes we go 2 or 3 summers having no effect from a tropical low up North this year we have been blessed with 3 of these systems so no wonder the humidity hasn't had time to leave.. everytime it does the next tropical system would come and pay us a visit. The only time we had the humidity clearing properly was when we had the cold outbreak in the 3rd week of Jan for 10 days or so but as soon as that occured down came Ex Olga to bring it all back again.

This weekends wild weather had nothing to do with extreme heat or anything that was even remotely hot! Had to do with extreme humidity residuley left from all the heavy rains up North from the last Tropical low that passed through Southern Queensland which filtered down here with the NE winds and with Cold Upper air flung in the Uppers from Antartica (which you don't to often see in March) it has created the best set ups for Super storms otherwise known as super cells heat or global warming had nothing to do with whats happend the past 3 days and anyone who trys to say it did are kidding themselves

[droughtbreaker]

Another 20mm by the end of the month and it will be the wettest Jan-March period since at least 1976 here (records going back to then). Incredible turn around from the same period last year which was the driest first three months on record (pretty sure).

[droughtbreaker]

I was going to say the exact same things that you just posted David. Also let's not forget the record minimums this summer, not only here but in places like Sydney as well and most of the SE and east of AUS for that matter.

In order to get vicious supercell storms this far south to the extent that it is rivalling the worst storms they get in Queensland and up there with the lower end of storms they get in the plains states of the US, you need two vital ingredients. A significant area of upper cold air associated with a front, low or trough and a tropical or subtropical air mass at the surface, the most severe and organised storms will generally develop where the cold pool and low/front/trough (trigger point) combine with the subtropical air and also convergence into the low if one is present (as it was on Saturday to the west) . This sort of environment is common in SE QLD and northern NSW in late Spring/Summer but quite rare down south in southern VIC, and even northern VIC doesn't usually get smashed like Melbourne did on Saturday all that often. This summer there have been tornado reports left right and centre coming from parts of the state. Why the sudden increase of tornado reports etc.? It's not like people have only just started to chase storms this year. Why are we suddenly seeing storm chasers from QLD coming down to Victoria to chase? This sort of thing is almost unheard of.

Now to get a major upper low at this time of year (or even in summer) is nothing out of the ordinary, to get major storm outbreaks at this time of year associated with upper lows is nothing out of the ordinary in fact it is fairly common for March. To combine the upper cold pool with high teens to low 20s DPs throughout VIC leading to CAPE over 2000 through a huge chunk of VIC and LIs down below -7 over a similarly vast area most certainly is. We are known to get rather nasty squall lines in southern VIC, plenty of pulse storms which can be severe and the odd supercell does occur as well most years but with only a fraction of the intensity of the one on Saturday which was a mammoth supercell.

Now if you look at the SST anomaly chart during this event you will see that the sea surface temps off the SE of Aus are at sub tropical values with huge warm anomalies and have been since around winter but most intense the last couple of months for us. Not normal at all. Clearly, warming oceans have played a very large role in our extremely stormy summer and exceptionally severe storm cells. This warming of the oceans is not normal climate variation, I mean we are still in an El Nino, why would we be getting such huge positive anomalies off the east coast? La Nina you can almost understand it but El Nino?

[Sean Mac]

David

Not questioning the stats that are there to see (hottest day, hottest year, warmer oceans etc etc) but how do you measure the "deadliest weather event"? Or "the worst storm"?

Surely this is more emotive than statistical, and only sensationalises the phenomenon of "global warming" further?

Andrew, fwiw my childhood memories from the mid-late 70s and early 80s are of big summer storms on a regular basis in Melbourne. If anything, this summer has only reminded me of how things used to be - perhaps minus the humidity (can't recall). I also remember blisteringly hot days and have the freckles/sunspots to remind me.

Of course i have no statistical basis for this observation other than my memories and I might be wrong, but I'd need to be convinced. I'm looking forward to seeing if the winters might return too (minus the heavy frosts which won't for reasons of air pollution, heat island effect etc). Oh, and to deal with matters of geography, 30 years on I still live within 5km of where I grew up.

Sean

[johnno]

I'll put money down for this Summer if we hadn't had those 3 ex tropical cyclones or lows come down here and affect us in some way there be no way known the humidity would of been as high as it was therefore less rainfall, storms, intensity of storms and cooler overnight minimums, also if Queensland had of been dry last week in other words if that tropical low hadn't of payed it a visit from the Gulf of Capentaria late Feb there is no way we would of had the thumping thunderstorms that we had last weekend. There is no direct link of whats happend down here this Summer to the East Australia current David the 3 tropical systems that have come down towards us and dumped all the humidity and moisture around have either come from the Indian Ocean or Top End/Gulf of Caperntaria.

Its ironic isnt it.. Last year we had a strong sub tropical ridge or Upper high over Australia right through January and February restricting the Monsoon trough Over Northern Australia and not allowing any moisture coming down to SE Australia and we had record dry cos of it and plenty of heat too & we blamed global warming or climate change I remember yourself saying this DJ as were some others and fair enough too.. This year the Upper high hasn't been there during these 2 months (only time it was was for a brief period around Jan 11th when we had the 43c in Melb) theres been more Upper troughs, Upper lows, more Surface troughs more fronts allowing these tropical systems to come down and produce the heavy rains and we are still blameing Climate change or global warming. I'm not on either side but fairs fair you can't have it both ways can you?

[johnno]

I have only been on this planet for 32 and half years but in my life time I haven't seen to many strong cold pool come up the Bight like that in March let alone early March mabye a few to that degreee and intensity. Of course when your going to get such a super cold pool surge up like that with so much moisture coming down from Queensland due to record rain its going to go off like bananas isn't it?? I can't believe how some people are trying to pinpoint this to climate change or global warming.


Andrew happends all the time those warm ssts off the East coast at the back of any El Nino same thing happend in 2007 and 1998. Usually right on cue Jan, Feb, March or April the rain and storms become more frequent over SE and Eastern Australia at the end of any El Nino and this year is no expecption. Happend in 1972, 1983, 1995, 1998, Feb 2003, Jan 2007.
Big monsoonal low tracked SE from the GOC into Southern Queensland and Northern NSW bringing widespread 150-250mm in Jan 1995 once again the back of an El Nino.

For some reason Tropical lows and ex cyclones like to track inland (South or SE) in El Nino's Summers/ Early Autumn its well known fact alot of history and facts support this hence the heavy rainfall and of course higher humidity and higher overnight temps that comes attributed to that.

Infact similar set up happend in March 1983 to what just happend last weekend & guess what? Back of an El Nino again & 400mm+ in the Otways 110mm in Melbourne heavy rain storms right across the state with a cold pool in the Bight interacting with a tropical low from the North.. But did we blame Climate change and global warming then when it happend in 1983 at the end of the El Nino? 27 years ago? I highly doubt it until the mid 90's global warming or climate change wasn't even mentioned.


Going by history our best rain and storms (for Eastern and SE Australia) come at the back on Any El Nino anywhere from January onwards why do you think the BOM since November have been going for more increased chance of wetter conditions? infact I believe we get it better down here at the end of any El Nino than any Neutral or La Nina years.

I suppose now the High block for the next week or 2 will be blamed on climate change too now

[Anthony Violi]

That's easy DJ...the worst earthquake, definitely coming. Although, of course, that would have nothing to do with climate change.

I agree with Johnno 100%...this set up was rare, in any year put that sort of humidity into that set up and we get the same results. I cam remember plenty of times when the humidity has been just as bad over the last 20 years, but never with an upper cold pool like this.

[johnno]

So basically David your saying if we hadn't of got the tropical lows or ex cyclones travelling inland and affect us in some way and those tropical lows & ex cyclones would of remained in Northern Australia ie Top end of out to sea over the Timor sea etc etc we would of have the same humidity most of the Summer down here in Victoria and Melbourne?? Your not serious are you?

If those systems hadn't of travelled inland our moisture and humidity content would of been at least half of what it was as any Northely component wind that would of come down from Central Australia or Southern Queensland would of been alot drier than what it was.

I don't think the higher Ssts off Eastern Australia would of contributed alone it would of only had a minor affect in increasing the humidity but IMO I think 80% of the reason had to do with those 3 tropical systems coming down from the North and NW I'm suprised your not willing to see this?

[Karl Lijnders]

See this is what gets me a little offside. If it rains hard and we get flooding, it is global warming, when it is drought conditions, it is global warming. When it is fog for 4 days is that global warming.

Karl Australian average dewpoints have risen by a degree since 1950. This is directly as a result of a warming ocean. At the same time we have seen a clear global increase in both extremes of rainfall and extremes of drought. In a hotter world the hydrology speeds up and the absolute humidity rises. We are seeing this.

No one would claim one drought or one storm is global warming or caused by global warming. Nor is it proof - the proof of global warming is that it's getting hotter and we are piling massive quantities of heat into the ocean (about 95% of global warming) and the cryosphere (take almost all the rest fof the heat).

But let's just look in our backyard in the last decade. We've had the hottest year (and the second hottest), the hottest winter (last year), the hottest autumn, the hottest spring (last year), the hottest day (lat year), the wettest day, the longest drought, the deadliest weather event (last year's heatwave, not even including the fires) and now the worst storm. You could not make this up if you tried. We hardly go a season without being walloped by something far outside of our records. We are seeing stuff that seasoned weather experts could not even imagine...

BTW just to add to the list we are also on the longest run of 20C+ days on record

Thanks DJ for getting back on this.

I do have to somewhat agree that the affect from the Heat Island in Melbourne could cause the 20C stretch to be somewhat dubious. Still impressive none the less.

[Karl Lijnders]

Thanks again DJ Interesting read. Now we await our first <20C day. Maybe around Easter I am tipping.

This could also be equated to the bay temp as well in the region I feel which has been fairly high the last few months.

[Sean Mac]

Thanks for the reply David.
Sure "deadliest heatwave" and "worst storm" help build the case, but I'm not still not sure they should be used as a measure of climte change.
Nevertheless appreciate your position and you posting the link to the DHS document.

Sean

[johnno]

Don't totally agree but thanks for your views David

[droughtbreaker]

Humidity was exceptionally high over most of VIC before those cyclones had an impact. Let's not forget the New Year storm outbreak. They were pretty severe storms too and went on for hours here, I think we ended up getting hit with about 10 individual storm cells here that came down in a stream. Not sure I've ever witnesssed anything like that before. This was pretty much just a basic trough I'm pretty sure, the sort that we get heaps of in summer and often cause just the odd storm in relatively dry years. The major factor was the elevated heat/moisture levels thanks to the warmer oceans.

Also humidity and moisture was high right back through Spring, again we had warm oceans surrounding us. A lot of the moisture came down in a NW airstream, the type that usually dry us out in the warmer months.

This cyclone season has seen just 4 cyclones so far (a low number) which is hardly going to cause a massive spike in moisture over the continent by itsef. We might have got lucky with Olga pumping a lot of moisture down here but that was over a month ago.

[Karl Lijnders]

I noticed when I woke up this morning that pressure had risen to 1038hPa overhead!!! Amazing High Pressure System.

Record for Melbourne?