How dry is it?

On the Mallacoota Community Facebook group a few members have been asking questions along the lines of "Why is this year different in terms of fire risk?".  Robin Bryant has answered this by quoting the CFA assessment (emphasis added):

The CFA assessment of 16 December is ... The outlook suggests that above-normal bushfire activity will continue across the coastal and foothill areas of East and West Gippsland, across to the Great Dividing Range, however this now extends west to also includes the Central Goldfields, which takes in parts of the Wimmera and Mallee.

This is due to above average temperatures drying out grasslands and forests over the last three months coupled with three years of significant rainfall deficit in much of East Gippsland and across the Divide. While there has been spring rain in the south, much of inland Victoria received insufficient rainfall and as a result, soil moisture is lower compared to the long-term average.

When grasses and crops are close to fully dry, there is a very high potential for fire behavior to rapidly escalate under elevated fire weather conditions.

I thought it worthwhile illustrating the rainfall deficit.  These data are from the BoM site out near the airport, beginning with the annual totals (I have assumed that we are going to get no more rain in the last three days of December).

Its a pity that there are a few years missing, but such is life.  The decline in the last three years is very evident ending with 2019 being the lowest on record at 595 mm.  (There are only two other years below 700 mm.)

The missing years place difficulties in getting a 3 year series with a lot of observations but it is a good bit smoother than the annual data. This show a high plateau early on, followed by a lower plateau and then the drop-off in the last three years.

Further insights can be gained by looking at the data recorded by BoM for Timbillica, just across the NSW border. This typically has an orographic component to its falls as the air from coast rises as it meets the hills.  This site has very good data with only 1 year missing back to 1910.  (December data for 2019 is not yet available for this site so I have estimated it as 50% more than the December fall for Mallacoota.)  The annual values show a lot of variation and I have cut to the chase with triennial data.

The trend line is essentially flat due to variation over time.  However the three year total ending in 2019 is very low: only the years 1981-82 are lower.  So, again, this period is unusually dry.

I've been quiet recently!

This is mainly because I have shingles and moving around is quite painful.  As is sitting at a computer.  Hopefully I am getting over it so here are a few photos taken in December.

The first one is hopeless as a photo but records that I finally found a Nankeen Night-Heron.  It roosts in a tree beside the bakery and has apparently done so for years!

 The first adult Pacific Gull I have seen here: all the others have been immatures.  Note massive bill and black band on tail.

 This is a juvenile Brown Songlark.  A very unusual species in East Gippsalnd and the first eBird record in the Mallacoota area.  (The little one in the background is a Hosrfield's Bronze-Cuckoo.)

 A flagged Australian Pied Oystercatcher (#85).

 An orchid!!!  Dipodium punctatum.

 A thoroughly confused Xanthorrhea resinosa!

 The bird prowling in the grass is a Swamp Harrier - the first I have seen down here.

 Sunrise through the smoke.

 Cape Conran flies!  I have counted 184 in this image, and reckon I had a similar number.

 A sequence from Lakeside drive.

Weather report November 2019

Overview

I'm afraid there isn't a great deal of detail in this as a few issues have distracted me in early December.  I hope to get  to a series of thematic posts in the next week or so.

Overall a mild month with slightly below median rainfall and strong winds (an evil plot to stop us going out in our kayaks)..

Weather characteristics

Rainfall

We recorded 52.2mm for the month as a whole which at 83.5% of median would not be too bad were it not for:

• only recording 2 months so far this year with above median rainfall; and
• somewhat over half that fall occurring on a single day early in the month (and the only other day with >5mm being the next day).

In terms of history we were, as noted above, below median and very much below last year,

In terms of the possible annual fall, assuming a median fall in December the BoM site was  up (? down might be better) to 656 mm.  This would be either the lowest or second lowest fall recorded since 1975.

Temperature

The best overall measure of temperature is the anomaly calculated as the difference between the mean monthly temperature and the long term average.  BoM data was used entirely for these calculations.  In November that ended the month at -0.1^oC.  The chart shows that the first two days were were hot, but the remainder of the month was quite mild.

The commonest situation (12 of 30 days) was for both minimum and maximum to be below average.  The other three cases (both min and max > average, one above the other below) were even at 6 days each. 

My second overall measure is a presentation of the daily extremes

The highest maximum was 38.8^oC - below the BoM reading which got to 40.7^oC on the 21^st.

Maximum Temperature

The mean maximum temperature was well above the long term average and last year.

Minimum temperature

In contrast to the maximum this was below both the long term value and last year.

Humidity

Both readings for humidity were well below last years's wet November, the  value for 1500 hrs noticeably so

Wind

The month seemed quite windy which is supported by the data.  The longest wind run was 444 km which is the third longest this year, and the strongest gust  64.4 kph (also 3rd highest this yearon the 21st (as the change came through after the hot day).

There is little to compare with but the overall change from previous months looks similar to a long term average.

In terms of wind direction we moved to a Summer pattern with more winds from close to South rather the NW to N.  I shall look at this more closely in the near future.