Mallacoota snaps

 Having heard a report of Striated Heron at Coulls Inlet I took my self off there of 30 March.  I didn't find the Heron, but get a few images of an obliging Azure Kingfisher.

The next shot was from a good bit further away and used digital zoom as well as the full 400m.

Late in the day I thought the cloud visible from our front door offered the chance of a fancy sunset.  It didn't, but I think this is nice!

The next morning produced fog over the Lake.

And eventually a good sunrise (phone photo as we started out on our walk.

Couthness at Merumbula

 We went to Merimbula for a little retail therapy on 25 March.  After visiting a few temples of commerce we adjourned to the Red Rocks fishing jetty to look at the red rocks, eat our lunch, check for birds and see what was going on.

The red rocks were as usual very attractive.

Eating lunch was done, involving some pepperoni mini-pizza in my case.  There were few birds around apart from an immature Australasian Gannet which landed (?? not quite the best word) came down and sat on the water.

While looking at the Gannet a young fisherperson - who had been catching baitfish - got very excited , yelling "Dad, dad.  Gget the net.  I've got a Kingie."  He had indeed hooked a lovely big kingfish, rated by another member of the (small) crowd as above 65cm, and thus a keeper.  The net arrived and was lowered into the water.  Unfortunately the Kingie got under the jetty and broke off the line.

The young fisherperson must have then spotted some waterfowl which I didn't see, proclaiming "Duck, duck" rather loudly.

Sundry bird images

 This is a collection of more or less random bird photos I have taken recently.

A Restless Flycatcher turned up at home - in fact I think there were 3 in the area, judging by the churring calls I could hear.

Great Egret and Royal Spoonbill on the Broome St Lagoon.

A trip to the Airstrip fence was fairly quiet  but a pair of Scarlet Robins was pleasant.  Possibly indicating that Summer is finished.

A close-up on the male.

And the female.

Another member of the 'Robin' family: a Jacky Winter.

2 more Royal Spoonbills from the Lagoon.

A Little Egret from Coulls Inlet, beside the Shady Gully boardwalk.

An Azure Kingfisher at the small fishing jetty at the mouth of Coulls Inlet.

Recent heat

You may have noticed it has been somewhat hot recently.  That had led to the BoM issuing a heat wave warning over various days for most of Victoria with the warning lingering in the Mallacoota area.  

I have compiled a blogpost defining various terms that can be used as shorthand for periods of extreme weather.

Here are the temperature readings from my weather station so far in March 2023 (note this is a screengrab image not a table).

The period 2 - 4 March is close to a cool spell, but fails as it is only 3 consecutive days, with an above average maximum on the 5th (after a significantly cold morning)!

From 6 to 11 March is a hot spell, as all readings for 6 consecutive days are above the daily average, albeit 3 readings are less than 1SD above the monthly average.  Embedded in that period is a heat wave from 9 to 11 March, with three consecutive days with both readings more than 1SD above the monthly average (bold red numbers).  (Looking at BoM forecasts I am confident that the hot spell will extend over 12 March with a fair possibility that the heat wave may also extend since Meteye implies a temperature <17.3C is possible up to midnight.) 

Indeed the minimum on the 12th was above the 1SD criterion, and the maximum above the +2SD limit so the heat wave continued for a 4th day (and the hot spell for a seventh  day).  I suspect the 13th will be a warm day, so will extend the hot spell but not the heat wave.

I have used a yellow fill with orange dots to indicate the readings that are >2SD above the monthly average.  The boundary value for that criterion for minimum is 20.3C so the 11th missed out on that by 0.4C.  Had we ended with 3 days with both readings >2SD above average I think I would have added a term of "extreme heat wave".

It should be stressed that my Weather Station compiles data on calendar days and as a result can give different results to BoM which is based on a reset at 0900 hours.  Thus my WS is currently showing a minimum for 12 March of 19.4C but that may change as a change comes through later in the day.  For BoM the current low temperature (18.5C) is likely to be preserved by the 0900 reset. 

I really wish the BoM would change to a calendar day, but appreciate this would cause much turmoil where stations are still based on manual readings, some of which have very very long series (eg Timbillica has a rainfall series starting in 1909!)  While only 2 of the 96 stations shown in Latest Weather Observations for Victoria are manual, the equivalent report for Queensland lists 14 manual stations. 

Heat waves and other extreme temperature phenomena

There seems to be a need for consistent terminology to cover extended periods of extreme temperatures in either directions.  This is most evident (in Australia) with periods of extreme heat leading to BoM issuing heat wave warnings.  However the same can apply to periods of very cold weather (noting that Australia's coldest recorded temperature - I think -22C - wouldn't cause people in Canada, Russia or most of the USA  to get their gloves out of the wardrobe, let alone put them on.)

High temperatures

The BoM definition, in their Glossary, of a heat wave is "A period of abnormally hot weather lasting several days."  I have in the past seen - somewhere - this expressed more precisely as "3 consecutive days of both maximum and minimum temperatures significantly above the long term mean".  The closest I have been able to locate to this definition is in a document by the Climate Council:

"In Australia, a heatwave is defined operationally as a period of at least three days where the combined effect of high temperatures and excess heat is unusual within the local climate (BoM 2012; Nairn and Fawcett 2013). Two aspects of this definition are important. First, a heatwave is defined relative to the local climate. That is, a heatwave for Hobart will occur at lower temperatures than one for Alice Springs. Second, the concept of excess heat is also important. Excess heat occurs when unusually high overnight temperatures do not provide relief from the daytime heat."

 My operational definition of a heat wave has had the following elements":

1. At least three days duration;
2. The days should be consecutive
3. Both minimum and maximum must be high;
4. "significant" means greater than 1 standard deviation above the long-term term mean for the month.

I usually record daily extremes in a spreadsheet, in which I use colour codes to indicate the status of the minima and maxima.  The graphic below shows the situation for the period 0000hrs 14 Sept to 0900hrs on 19 Sept

Blue is below the daily mean for that extreme, orange is above the daily mean for that extreme.  Text in bold red is >1SD above monthly mean (not shown below, but bold yellow is >1SD below monthly mean).  The horizontal hatching means >2 SD above!  A code of 1 is a summarising indicator showing both measures above the daily mean.

So for the 6 day period concerned (and by 0900 on 19/9 the maximum is already 27.7 and thus >2SD above the monthly mean) we have 4 days which satisfy most of the criteria.  However days 3 and 5 only have 1 extreme more than 1SD above the monthly mean, so we do not three consecutive days meeting the other three criteria.  So it hasn't been a heat wave according to my rules.  

This seems a bit 'odd', especially noting that the maximum on 18/9 only missed being 'significantly high' by 0.3C.  It can be overcome by some semantics!  I will define another term "hot spell" to refer to:

• a period of  consecutive days in which both minimum and maximum temperature are above the average temperature for the day, and 
• a majority of the days  are more than 1 SD  above the long term monthly average, which allows for a few readings to be 'warm' rather than 'hot'; and
• the period lasts at least 4 days (chosen to make it a little tougher than a 3 day run).

Going back to mid September 2023 here is another clip, showing final results.  The readings with horizontal black lines indicate reading >2SD above the long term mean.

There is not a heat wave  in this period as a few readings fail the 'significance' criterion.  However the period from 14 to 20 September is 7 days with both readings above the daily averages and 11/14 (79%)  readings more than 1 SD above the monthly average.  This counts as a 7 day hot spell.

I will also define a hot day as a day in which both extremes are more than 1 SD above the long term monthly average (for example 25 September).  This would allow the definition of a heat wave to become "3 or more consecutive hot days" but I am happy to stick with the more wordy definition which spells out the elements.  

I will also for completeness define: 

• a warm day as a day with both readings above the daily average but one or both by less than 1SD;  and 
• a warm spell as a period of at least 4 consecutive days with both readings above the daily averages but less than half more than 1 SD above.

Note that a heat wave can be embedded within a hot spell (or even a warm spell).  For example, in the example above, if the minimum on 16/9 had been 11.4C that would have given a 4 day heat wave within the 7 day hot spell.

Low temperatures

These are the equivalents to the periods above but going low rather than high.  In the second table image above both results for 23 September are filled blue (below daily average) with yellow text indicating >1SD below the monthly average.  As it's both readings, that is a cold day.

• Cool day: both readings < daily average;
• Cold day: both readings more than 1SD below the monthly average.
• Cool spell: at least 4 consecutive days with both readings <daily average, and <50% of readings more than 1SD below the monthly average.
• Cold spell: at least 4 consecutive days with both readings <daily average, and >50% of readings more than 1SD below the monthly average.
• Cold snap: At least 3 consecutive days with both readings more than 1SD below the monthly average

A trip to Eden

 We had to take the Mazda to Kings Smash Repairs in Eden as a result of my efforts.  A pretty pleasant drive although there was lots of smoke haze from Habitat Reduction Burns.

The smoke was evident at the lookout over the Bay so we decided not to do a walk there, but to go to Cocora Beach and try the walk to Quarantine Bay.  At the beach the pontoon was well endowed with a range of species of Cormorants.

The holey rock was looking photogenic.

As the walk emerged on to Quarantine Bay Road we came across a boat trailer graveyard.

There were several people cleaning fish and throwing scraps - in some cases quite large items to the team of cormorants, pelicans and stingrays below the tables.  This guy was hand-feeding a very large stingray - I suspect an Eagle Ray.  However, experts on iNaturalist have identified them as Bathytoshia brevicaudata Smooth Stingray (also known as Short-tailed Stingray).

There were 2 rays present.

4 Sooty Oystercatchers watched on!

In a few centuries people will be mining this breakwater for Pelican and Cormorant guano!

At times the competition for food got a little vigorous.

Sometime the eyes hold more than the gullet!

So you have to retreat to shred your meal in peace.

The walk back was a bit of a slog going up 47m to a ridge line!

Updated weather report for February 2024

 We have been in Canberra since 26 February, and will be until 8 March, so I don't have weather station (WS)  data for the last 4 days of the month.  However it looks as though the BoM data will be quite adequate to plug the gap, at least in broad terms. That being said, this report will be a draft until we get back to Mallacoota and can incorporate the final WS material.  We are now back in Mallacoota and I will make updating comments (or 'no change') in red, as necessary.

In the past a climatologist has commented that for weather East Gippsland sometimes marches to its own drum.  That has been the case for the last year.  In mid 2023 our area experienced very dry conditions, typical of El Nino, but the BoM refused to call an El Nino event as that is defined by atmospheric and oceanographic indicators.  They did declare an El Nino in about October last year and we duly recorded abnormally high rainfall in November, December and January.  An emerging La Nina (wet) was suggested in February which has resulted - of course - in a return to a dry month!  Of course there are many other climatic indicators (vide http://www.bom.gov.au/climate/enso/ ) so treat 'fashionable' nicknames and acronyms, especially in lay media, with caution.

In summary a warm dry month.

Rainfall

No change needed

We totalled 22.6 mm for the month which is just below 50% of the median February fall.

We only recorded more than 5mm of rain on one day in February.  This has occurred in 6 previous Februarys, with the median number of days >5mm at 3.  So dry, but not off the scale.

Not surprisingly my pro rata estimate of the annual fall has continued the downward outcome evident in late January and is now below 1000mm.

Temperatures

The anomaly this month was +0.79C so above average no change.  There was a very warm spell early in the month followed by a cooler period and then a gradual warming.

Looking at the time series of anomaly values, the 12 month moving average (red line) continues the climb seen since December 2022.

The daily extreme temperatures through the month as usual resemble a cross section of a mountain range.  

The average maximum is a greater amount above the long term mean than is the average minimum.  It seems this is due to a few very high maxima (notably the 36.7C on the 13th) biasing the overall outcome.  This will be discussed in more detail below.  There are very small differences due to finalising the records, making no difference to the overall view.

Minimum temperatures

The average minimum temperature was 16.33C which was 0.58C above the long term mean and well above the value for 2023.  It was also 0.53C above the median minimum for February 2024 suggesting a slight bias by very high values. 

7 days had a minimum >1 SD above the long term mean minimum and only 3 days had a minimum >1 SD below the long term mean minimum.  None of these constituted long runs of extremes.

Maximum temperatures

The average maximum temperature was 26.02C which was 1.13C above the long term mean and a little above the value for 2023.  The median temperature was slightly higher as a result of the adjustments but was still 0.92C below the average minimum for February 2024 suggesting a stronger bias by very high values. 

The next chart shows monthly average maxima for financial years since 2019.  All these data are from my WS to avoid the issues of sea breezes affecting the maxima for earlier years.

Clearly 2023-24 is one of the warmer recent years.

7 days had a value>1 SD above the long term mean maximum but only 2 days had a maximum >1 SD below the long term mean maximum.  None of these constituted long runs of extremes and in 5 days the high maxima coincided with high minima.

Humidity

I suspect there is considerable differences between humidity at the BoM site and my WS, so for the sake of consistency this chart is all BoM data.  A fairly dry first half of the month and a moist second half.

Watch this space for more detail when I return to Mallacoota.

The average morning humidity was 3.1% points higher (79.9 vs 76.8) at my WS while the average afternoon reading was 4.6% points lower (66.4 vs 71.0).  There were some major differences to the daily readings most notably in the afternoon with differences of -23% on the 12th and -19% on the 22nd.  The overall pattern however was not too different.  Note that I have included the afternoon BoM data in this chart.

Wind

I know the wind readings are very different at the BoM site and my WS.  Also BoM doesn't publish - at no cost - wind run data.  So the next chart shows maximum daily gust at the BoM site.  (The BoM had no readings for 13th and 14th - probably due to lack of power - so those dates are estimated based on reports from Gabo Island.

I have now extracted the run data for my WS and show that below together with the BoM Gust data: note that they us (very) different scales.

Overall the pattern is quite similar apart from the days where either measure is an extreme.  The longest run (350km on 28 February) reflects a very windy day with the hourly runs between 12km and 19km for most of the day.  That was the 16th longest run of 1845 observations since my WS records began.