Seasons were strange in 2016

In the year 2016, the seasonal climate cycles at Manilla, NSW were abnormal. Heat and cold, moisture and dryness did not come at the usual times.

Temperature and rainfall graphs

Mean monthly temperature

 

Graphs of monthly temperatures, normal and 2016The first graph shows the mean temperatures for each calendar month, both in a normal year (red) and in the year 2016 (blue). In 2016. earlier months, such as April, were warmer, and later months, such as October, were cooler. The difference (anomaly) is plotted below. Anomaly values in this year rise and fall rather steadily in a single cycle that lags months behind the normal summer-winter cycle. The amplitude of this anomaly cycle in 2016 is 5.3 degrees, which is nearly one third of the normal summer to winter amplitude of 16.4 degrees.

 

Monthly total rainfall

Graphs of monthly rainfall totals, normal and 2016In the same format, the second graph shows the rainfall totals for each calendar month, both in a normal year (red) and in the year 2016 (blue). The mid-year months of June, August, and September, usually dry, were very wet in 2016. The anomaly graph adds to this that rainfall was very low in February, March and April, and again in November and December. Rainfall anomaly does not show such a clear cycle as temperature does, but the effect is bigger. The difference in anomaly between September (+80 mm) and November (-40 mm) is 120 mm, while normally the difference between the wettest month (January) and the driest month (April) is only 48 mm.

Climate anomaly graphs and trends for 2016

The other two graphs add more climate anomaly variables and show the trends through the year 2016.
[See Notes below for an explanation.]

Monthly heat anomalies for 2016

Heat anomalies and trends

Continue reading

December 2016 was hot

A bearded dragon camouflaged on a bush

Hidden Dragon

Hot weather in this month came in the first and last weeks which, on average, were 4.8° and 3.6° warmer than normal. On the 5th, both day and night were nine degrees above normal. There was just one 40° day, on the 30th. In December months from 1999, there have now been five with one 40° day, but none with more than one. The two hottest, at 40.6°, came in 2005 and 2012.
Rain fell frequently (on 12 days), but it was light (max: 17.8 mm). Plants dried out.
Throughout the month, tiny “flies” swarmed in millions. They are native Rutherglen Bugs (Nysius vinitor), a sap-sucking pest of crops such as sunflower.

 Weather log December 2016

Comparing December months

This was the hottest December of the new century. December 2009 had been the hottest, but this month had a higher mean daily maximum (33.8° vs. 33.1°) and a slightly higher average (26.0° vs. 25.9°). December 2009 still had the warmest nights: the daily minimum was 18.6° then versus 18.2° now. As this month’s days and nights were both so warm, the daily temperature range was quite normal (15.6°).
Contradicting the high air temperatures, the subsoil temperature was well below the normal value of 24.3°. At 22.7°, it was the coolest December value since 1999, when it had been 22.5°.
The month was rather cloudy, which does not match well with the rather low dew point and rainfall. The monthly rainfall total of 48.8 mm is in the 34th percentile, well below the average of 74 mm.

Climate fro December 2016

The Year 2016

As in 2015, the average temperatures for the year 2016 were close to normal by day, and half a degree above normal by night. The subsoil temperature, which had been normal in 2015, fell to half a degree low. Air temperatures had been warmer in 2014 and 2009, and cooler in 2008.
Rainfall, at 775 mm, was in the 76th percentile, well above the 125-year average of 652 mm. The mid-year months of June, August, and September were very wet, while November as well as February, March and April were dry. High rainfall is rare in mid-year months, but 1998 had a similar pattern.
Temperatures also were far from normal in some months. They were about 2° higher than normal through the autumn and 2° lower than normal through the spring.


Data. Rainfall figures are usually from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. However, the gauge ceased recording on the 8th of October, and later readings are from my non-standard gauge. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to December 2016

Parametric plots of smoothed climate variables at Manilla
“December 2016 hot with cold subsoil”

3-year trends to December 2016

December raw anomaly data (orange)

In December 2016 both days and nights became hot, but the subsoil remained cold. Other variables were near normal. During the last six months all partially-smoothed anomaly values moved around the edges of the graphs.

 Fully smoothed data (red)

At the time of the latest fully-smoothed anomalies, in June 2016, most variables were moving rapidly towards cool and moist.
Daily minimum temperature and subsoil temperature, however, fell slightly from a peak in May. The subsoil temperature was normal, but the daily minimum temperature anomaly had reached a new record high for a smoothed value in May 2016: +1.34 degrees.

Subsoil temperature

The observed changes in subsoil temperature are a mystery. Generally, they are like those of daily maximum temperature, but with leads or lags as shown by curved arrows on the bottom right graph. They relate well to daily minimum temperature, as shown by the similar patterns on the bottom two graphs. This month, however, the raw anomaly of subsoil temperature is very low, while those of maximum and minimum air temperature are very high.


Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

 * Normal values for rainfall are based on averages for the 125 years beginning 1883.

Cool spring 2016

Photo of a wildflower

Nodding Chocolate Lilies

Through September, days were very cool, making for a narrow daily temperature range. Then, through October, both days and nights were very cool. In November, days and nights were nearer to normal but, in contrast to September, the daily temperature range was wide. The dew point failed to rise during the season, making the air very dry in November.
Rain fell frequently up to the middle of November, then ceased. There were 24 rain days, when there are normally 19 in spring. The highest reading was 28.8 mm on the 14th of September. The season total of 216.4 mm was rather high, in the 77th percentile.

Graphical log for spring 2016
All temperature measures were below normal by 1.5° to 2.0°. Only spring of 2001 had low values like that but in 2010 the mean daily maximum (only) was 2.5° below normal.
Measures of moisture were near normal, with cloud, rainfall, and daily temperature range on the moist side, and dew point on the dry side.

Climate for spring 2016


Data. Rainfall figures for this season began from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. That gauge ceased reporting on the 8th of October, and later readings are from my non-standard gauge. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

November 2016 was arid

While there was some rain, measures of moisture this month were at or near their lowest November values for this century.

Photo of a yellow dragon lizard

Eastern Bearded Dragon

There were five rain days early in the month, the highest reading being 15.0 mm on the 10th. Some early days were overcast, but skies were sunny after the 15th.
Temperatures rose and fell, but few days or nights were especially hot or cold. The early morning of the 6th went as low as 5.4° , which is 7.8° below normal. Curiously, the month had a record number of cool nights: 12 nights were cooler than 10°, when there are usually only about 5.
Weekly average temperatures, which had been very low in October, were nearer to normal through this month.

Weather log November 2016

Comparing November months

Both the mean maximum temperature (30.2°) and the mean average temperature (20.9°) were near normal, but the mean minimum temperature (11.7°) was very low. On this record, only 1999 had colder November nights (at 11.6°!). This extreme value brought a very wide mean daily temperature range of 18.5°, also a record.
The subsoil was at its coolest recorded November value: 19.5°.
A very wide daily temperature range is one of the measures of moisture showing this month to be arid. The early morning dew point of 5.6° was the lowest November value on this record, and the cloudiness (30%) was low. The monthly rainfall total of 21.9 mm, while not really low (22nd percentile), was the lowest November total in the 26 years since 1990, which had only 15 mm.

Climate for November 2016


Data. Rainfall figures are usually from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. However, the gauge ceased recording on the 8th of October, and later readings are from my non-standard gauge. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to November 2016

Parametric plots of smoothed climate variables at Manilla
“November 2016 cold nights warm days”

3-year trends to November 2016

 

November raw anomaly data (orange)

In November 2016 the daily maximum temperature anomaly rose sharply to a high value. Moisture variables also moved high on the graphs: Temperature range became very high, rainfall low, dew point low, and cloud below normal. Daily minimum air temperature and subsoil temperature (bottom graphs) remained extremely low.

 Fully smoothed data (red)

The autumn months (MAM) of 2016 are now fully smoothed. Daily maximum temperature moved down into the normal range. All moisture values increased, but only the rainfall and daily temperature range were in the normal range of values: skies were more cloudy than normal, but the dew point was below normal.
Daily minimum temperature and subsoil temperature rose slightly during the autumn season. However, while the subsoil temperature was normal, the daily minimum temperature anomaly reached a new record high for a smoothed value in May 2016: +1.34°, beating the value of +1.32° reached in December 2009. This variable may peak in June 2016.


Note:

Fully smoothed data – Gaussian smoothing with half-width 6 months – are plotted in red, partly smoothed data uncoloured, and raw data for the last data point in orange. January data points are marked by squares.
Blue diamonds and the dashed blue rectangle show the extreme values in the fully smoothed data record since September 1999.

Normal values are based on averages for the decade from March 1999.* They appear on these graphs as a turquoise (turquoise) circle at the origin (0,0). A range of anomalies called “normal” is shown by a dashed rectangle in aqua (aqua). For values in degrees, the assigned normal range is +/-0.7°; for cloudiness, +/-7%; for monthly rainfall, +/-14 mm.

 * Normal values for rainfall are based on averages for the 125 years beginning 1883.

October 2016 was cold

Photo of the bark of a Eucalyptus tree

White Box at Sunset

In this month, each of five sunny spells of normal temperature was followed by a cold, cloudy, humid break, generally with rain. Only a few days were warmer than normal, including the 27th. That was the first 30° day of the season, five weeks late.
The average weekly temperature was persistently three or four degrees cooler than normal. One cold week about the 15th was more than five degrees below normal, and the warmest week, about the 29th, was still half a degree low.
Most nights were very cool. I recorded no frosts, but others may have done. My most recent frost was early in September.
There were six rain days, not counting two readings of 0.2 mm. The highest reading was 20.0 mm on the 23rd.

Weather log for October 2016

Comparing October months

This was the coldest October on this record from 1999. That includes not only the maximum, mean, and minimum air temperatures read in the Gill Screen, but also the subsoil temperature at 750 mm. Noting that October 2015 had the highest October temperatures, the sudden collapse is astonishing. Last October was three degrees warmer than normal; this month was almost three degrees colder than normal. Put another way, the seasonal warming is a month late this year and was a month early last year.
Unlike September, there was not an unusual amount of moisture in October. Humidity, cloudiness and daily temperature range were near normal.
The monthly rainfall total of 72.1 mm was above the average of 58 mm, in the 70th percentile.
I have discussed the current drought status (that is, drought-free) in another post.

Climate for October 2016


Data. Rainfall figures are usually from the automatic rain gauge at Manilla, published on the internet by the Bureau of Meteorology as Station 55031. However, the gauge ceased recording on the 8th of October, and later readings are from my non-standard gauge. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.