3-year trends to August 2008

Parametric plots of smoothed climate variables at Manilla
“Years with unusual trends”

Trends to August 2008

These graphs, ending with raw data for August 2008, show fully-smoothed data from September 2005 to February 2008. They include all months of the calendar years 2006 and 2007.
Smoothed daily maximum temperature anomaly (X-axis on all graphs) began 2006 high in the “normal” range, fell to normal by June, and rose again to +0.63°  in November and December. It then fell from high to very low through 2007, reaching the record low value of -1.61°  by February 2008. (Note added: This record low maximum temperature anomaly stood for only 19 months, until September 2010.)
Smoothed rainfall anomaly peaked at +20.6 mm in November 2005, fell rapidly to -11.7 mm in June 2006 and slowly to -14.6 mm in October 2006. It rose again to just above normal by February 2007, and changed little in the following year.
Smoothed percent cloudy mornings followed a similar course to that of rainfall but, as temperature fell through 2007, cloudiness (unlike rainfall) increased, as is normal,  along the blue trend-line.
(Note added in May 2014: Although the minimum value of the cloudiness anomaly in August 2006 (-7.7%) is less negative than the record minimum in August 2002 (-11.3%) (or even than the minimum in February 2005 (-9.1%)) it is more negative than any later value. No smoothed negative values at all were recorded in almost seven years between February 2007 and October 2013.)
Smoothed dew point anomaly also followed a similar course to that of rainfall but, unlike cloudiness, actually declined as temperature fell during 2007. Temperature range anomaly moved like dew point anomaly.
Daily minimum temperature mainly varied in the same sense as daily maximum temperature, but at a higher rate. As an exception, from January to June 2007, it rose slightly as maximum temperature fell. That moved the curve towards a more “maritime” climate for the rest of the time. Subsoil temperature anomaly moved in a similar pattern.

Unusual trends

Through the years 2006 and 2007 shown here, the climate moved as much along the axis from top left to bottom right, as along the usual axis from top right to bottom left. It departed from the typical Quasi-biennial oscillation of “droughts and flooding rains”*. (Note added: The extreme negative maximum temperature anomaly of February 2008 was the only one on this record that was not linked to an extreme positive rainfall anomaly.)
(Note added concerning global temperature: At this time there was a sudden major cooling in mean air temperature, both locally and globally. This linked post  shows that, when 37-month averages of global and local values are plotted, mean temperature fell from a peak in April or May 2006 to a trough in October 2007, breaking the global warming trend. The global (GISS) value fell by 0.074° (and the Manilla value by 0.48°). The connection is enigmatic. The unusual trends shown here do not match the dates of the cooling event, but come mainly before or after it.)

* By arrangement with the Licensor, The Dorothea Mackellar Estate, c/- Curtis Brown (Aust) Pty Ltd.

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.
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.

(Note added in May 2014: A much later post titled “3-year trends to May 2010” is the first of a consecutive series of parametric plots, updated monthly at the time of observation and originally posted elsewhere.
This earlier data was not edited in this form at the time.
To display all existing fully-smoothed data points at least once, I have prepared these back-dated posts in the same format for:
“3-year trends to August 2002” which includes smoothed data September 1999 to February 2002, covering the calendar years 2000 and 2001.
“3-year trends to August 2004” which includes smoothed data September 2001 to February 2004, covering the calendar years 2002 and 2003.
“3-year trends to August 2006” which includes smoothed data September 2003 to February 2006, covering the calendar years 2004 and 2005.
“3-year trends to August 2008” (this post) which includes smoothed data September 2005 to February 2008, covering the calendar years 2006 and 2007.
In these back-dated posts the anomaly values depend on climate normals that are based on the decade ending February 2009, and were thus not available until after that date. I have written the posts as if they were available at the time.
In places I have written some “Notes added in May 2014” (like this) commenting on how values observed at that time relate to more recent events.)



August 2008 very cold and cloudy

The daily weather log

Weather log August 2008

The second week of August was the coldest week of the year. Temperatures by day and night were six degrees below normal. In the whole month few temperatures were above normal. Only six days got above 20°, compared to the usual twelve. The very last night soared to nine degrees above normal.
However, no days or nights were particularly cold. Although the 13th was the coldest morning of the winter at -2.8°, it was only a little lower than -2.7° on the 11th and 20th (and also on the 12th of July).
Most days had very dry air, with morning dew points below zero. Despite that, there was a lot of cloud. The number of mornings free of cloud was only five, the fewest in ten Augusts.
There were nine rain days spaced through the month, totalling 31.6 mm.

 Comparing August months

Climate August 2008

All the mean temperatures (daily maximum, daily mean, and daily minimum) were the lowest for August in a decade. The mean was over two degrees below normal.

It was a frosty month. In ten Augusts, none had as many minima below -2° (6) or below zero (14) as this one, but August 2005 had more total frosts (21 versus 18) counting minima below +2.2° in the screen.
Mean humidity (morning dew point) was extremely low. At -0.4°, it was over two degrees below normal. In the decade, only July 2002 had drier air, with a mean morning dew point of -3.1°.
There were more cloudy mornings (55%) than in any August of the decade. Five of the seven cloudiest months of the decade have come within the last ten months: Nov ’07, Dec ’07, Feb ‘08, Jul ’08, and Aug ’08. All had 50% or more cloudy mornings, almost twice the decade median of 27%.
The rainfall total, 31.6 mm, is on the 46th percentile for August, and below the average (40 mm). Totals for several months together are much the same as a month ago, but the serious shortage has moved back to the six-month total. The total for 2 months (July and August) is in the 28th percentile, 3 months in the 41st, 4 months in the 25th, 5 months in the 17th, and 6 months in the 7th percentile . Rainfall totals for longer periods are normal.

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperature and other data are from 3 Monash Street, Manilla.


July 2008: more cloud, less frost

The daily weather log

Weather log July 2008

With 52% cloudy mornings, this was the cloudiest July (and the fifth cloudiest month) in a decade.
There were no long warm or cold spells, so the seven-day mean temperature scarcely changed until the cooler final days. Yet each day’s temperatures were quite different from the day before. Wednesday the 9th was the 4th coldest day of the decade. It reached only 9.8°, and Monday the 28th, at 11.3°, was not much warmer.
Five nights were warmer than 8°. They were separated by cold nights, but there were only fourteen frosts, the coldest, on the 12th, being 2.7°. Widespread fog on the 15th did not lift until 11 am, and there was thick fog in the valley on the 26th.
Eight rain days were scattered through the month. The wettest day had 9.4 mm, and the total was 33 mm.

 Comparing July months

Climate July 2008

The mean daily maximum and daily mean temperatures for the month were normal but, on the average, nights were warm. As a result, the mean daily temperature range, 13.6°, was the narrowest in ten July months. Sunny, frosty, droughty July 2002 had a range of 18.5°: more than 30% wider! (The month with the narrowest mean temperature range for the decade was June 2007, with 10.9°. That was also the cloudiest month.)

July usually has about 17 frosts. This month’s total of 14 made it the least frosty July this century. July 1999 had only 13 frosts, with none below -2°.
Humidity (early morning dew point) was normal for the time of year.
The rainfall total is not far below the average: 33 mm is in the 46th percentile for July. The total for this June and July together (98 mm) is better than usual: in the 52nd percentile of two-monthly totals. Not so good are the three-monthly total (112 mm) in the 30th percentile and the four-monthly total (132 mm) in the 20th percentile. Worse, the five-month total (134 mm) is only in the 8th percentile, due to the 2 mm rainfall of March. The six-month total is much better (in the 29th percentile). Rainfall totals for longer periods are normal.

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperature and other data are from 3 Monash Street, Manilla.


June 2008 warm, with rain

The daily weather log

Weather log June 2008

Most of June was very warm. The 7-day average temperature stayed three degrees above normal for the first three weeks. All five rain days came during that time. The first, with 38.2 mm, was the wettest June day in a decade. By the 4th of the month the average rainfall for June (44 mm) had already been beaten. Sadly, the total rose only to 65.2 mm, the same as last year. Around the rainy days the nights were about 7° warmer than usual, and humidity was high (morning Dew Points near 10°). There were frequent fogs, including one on Saturday the 7th that was widespread and thick, and lasted a long time.

The fourth week saw a return to normal June temperatures, with sunny cloudless days. Frosts came back, but there were only eight altogether instead of the usual thirteen.

 Comparing June months

Climate June 2008

This June was warm and humid. However, due to the cool, dry change in the fourth week, it was no warmer or more humid than June of 2005. The graph shows that June 2005 had very high rainfall. It was the sixth wettest June on record.

While this month had more cloud than usual, June last year was much cloudier, and had bitterly cold days – nearly five degrees colder! By contrast, sunny June 2006 had very cold nights, including 21 frosts.
The rainfall total of 65 mm is high. It is in the 78th percentile for June, and nearly twice the median value (36 mm).
The rainfall total for this May and June together (79 mm) is in the 38th percentile of two-monthly totals, while the three-monthly total (99 mm) is in the 23rd percentile. Being above the tenth percentile, these do not count as “serious” shortages of rainfall. The four-month total (101 mm) is a serious shortage: it is only in the 9th percentile. The five-month total is much better (in the 35th percentile). Rainfall totals for longer periods are all normal, that is, near the median.

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperature and other data are from 3 Monash Street, Manilla.


Perfect May weather in 2008

The daily weather log

Weather log May 2008

The mean daily temperature rose to a normal value by the middle of the month and then tracked down along the usual curve. Daily maxima were near normal except for one cool Sunday. Daily minima were also normal, except for a warm night (12°) on the 16th and six mild frosts.
The second week had very dry air, but the third week was humid, with four days of rain showers totalling 14 mm. A  number of cloudy days produced no rain.

 Comparing May months

Climate May 2008

The weather for May was normal in all respects: maximum, mean, and minimum temperatures, humidity, cloudiness, and rain. Some of us would call it perfect weather!
Normal temperatures break a five-month spell of unusually cool weather. On the other hand, as the graph shows, this month is much cooler than May last year. Six frosts is the normal number for May, and compares with 3 last year and 14 the year before.
Humidity, indicated by early morning Dew Point, is similar to that in 2004 and 2005. It had been higher early in the decade, due to moisture from “La Niña”.
At 14 mm, this May’s rainfall is not very low. Being well below the May average (40 mm) does not mean much. In Manilla, rainfalls in the months of March, April and May are highly “skewed” so that the very lowest rainfalls are the most common. Rainfalls of 5 mm or less occur often – more often than one May month in eight (There are two on the graph!). Fourteen millimetres is in the 25th percentile of May rainfalls.
The rainfall total for this April and May together (34 mm) is in the 9th percentile of two-monthly totals (a serious shortage) and the three-monthly total (36 mm) is in the 2nd percentile (a severe (almost extreme) shortage). The four-month total is better (in the 28th percentile) and the five-month total better still (in the 35th percentile). The six-month total (summer plus autumn) is high: in the 61st percentile. Beyond that, the totals for 9, 12 and more months are all normal, that is, near the median.

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Dew point values before August 2005 are from Tamworth Airport 6 am data supplied by the Bureau of Meteorology. Temperature and other data are from 3 Monash Street, Manilla.