December 2007 cool, humid, cloudy, rainy

The daily weather logWeather log December 2007

Only four days, early in the month, had daily maximum temperatures warmer than normal. Decembers average five days over 35°, but there were none this month. The 22nd was nine degrees cooler than normal, at 24.2°. Daily minimum temperatures varied around the normal values (16°). The 7-day daily average temperature stayed below normal most of the time.

The graphs include the humidity of the air, using the Dew Point idea. All air contains moisture. If it cools to its Dew Point temperature, it gets so moist that cloud or fog forms, and dew appears. On humid days when the Dew Point is above 17°, most people find the weather unpleasantly sultry or sweaty. They find air with a low Dew Point, such as 5° or 10°, very pleasant and refreshing. The Dew Points shown on this graph are the early morning minimum values. Morning Dew Points this December were often between 15° and 18°: too humid for comfort. They never came below 10°.
Many mornings this month were overcast, and there were never two fine mornings together until the 29th.
There were fourteen rain days, with a total rainfall of 129.4 mm. The wettest day was the 4th, with 25.2 mm. There were only two runs of four days without rain, beginning on the 18th and 28th.

 Comparing December monthsClimate December 2007

The average daily maximum temperature this month, 29.4°, was far below the average for the last nine Decembers (31.7°). Only December 1999 had a slightly lower value (29.2°). The daily mean temperature (23.0°) was below average (24.0°), and the daily minimum temperature (16.6°) was near average (16.4°). As a result, the daily temperature range this month was only 12.8°.

The mean morning Dew Point for December 2007 is 14.2°. This high value, (meaning high humidity) seems to be about 2° above normal, but my record is short.
This was one of the three cloudiest months in nine years. The other two were also in 2007: November (50%) and June (60%).
The rainfall total of 129 mm makes this a very wet month. Only 14 Decembers since 1884 were wetter.
The year 2007 was wet: the total rainfall amounted to 741 mm. This is on the 68th percentile, meaning that higher rainfall has occurred roughly one year in three. The rainfall was 90 mm above the average (651 mm). It was the highest total since the strange wet year of 1998 (919 mm). That year nearly 400 mm more rain than usual fell in the six months that are normally the driest: from April to September.


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.

 

Spring 2007 climate much as usual

Weather log spring 2007

The daily weather log

As sometimes happens, temperatures did not rise in September until late in the month. They then rose to several degrees above normal and stayed there until the end of October. Early November was very cool, and mid-November warm. The daily temperature range increased in dry periods and decreased in rainy periods.
There were two late frosts below 2.2° in September.

Only 2.2 mm of rain fell in September. Much more fell later, in short wet spells around October 12th and 26th, and November 7th and 24th. The two best daily falls were 17 mm each. Total spring rainfall was 122 mm, falling on 23 rain days.

Very cloudy or overcast skies became common in November.

Comparing spring seasons

Although each month this spring had unusual temperatures, the three months taken together did not. Daily maximum, minimum and mean temperatures for the spring, as well as the daily temperature range (16.0°), were all normal. In the extreme drought of spring 2002, the values had been two degrees higher, and the daily temperature range 17.1°. The spring of 2001 had the lowest temperatures in this record.

Two frosts this spring compare with three on the average. Spring 2004 had 10 frosts, including one in mid-October, and one on 3rd November!

Spring rainfall in 2007 (122 mm) fell 44 mm short of the long-term average (166 mm), due to September being 39 mm down. October was only 6 mm down, and November 2 mm up. Spring rainfall averaged over the last nine years is above the long-term average, because the droughty spring of 2002 is more than balanced by the very wet springs of 1999, 2000, and 2005. These were in the ninth decile for spring rainfall.

Climate spring 2007

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. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

Very cloudy November 2007

The daily weather logWeather log November 2007

Warm humid weather, including one night 8° above normal, continued into early November. This developed into a cool rainy week. The coldest day (the 7th), registering 18.6° (9.8° below normal!), followed the wettest day, which had 17.2 mm of rain.

Eight sunny days followed, (Good luck for the NSW Gliding Championships at Lake Keepit!) ending with a storm on the 19th. Four more cool wet days brought the rain total to 67.8 mm. The last days of the month were overcast with very little rain (0.4 mm).
This was an average November for rainfall and mean temperature. Generally, days were cooler than normal, and nights were warmer, making the daily temperature range (12.8°) the lowest by far in nine Novembers. It was also the cloudiest of those months, with 50% cloudy mornings. Typically, November has about two days hotter than 35°, but there were none this time.

 Comparing November monthsClimate November 2007

November 2007 was not a drought month. The total rainfall was near average, not only for the month itself, but also for the last 2, 3, 4…months up to 60 months. Beyond that, total rainfalls for the last 6 to 9 years were rather low, because they included the extreme drought of 2002.

Since 2002 there has been only one extreme drought event: May 2006 had no rain. A less extreme, but still severe event was the two to five month drought peaking in May 2005.


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.

 

October 2007 warm, with rain

The daily weather logWeather log October 2007

October was very warm. All but four days had daily maximum temperatures above normal. Night time minima varied at first, and then settled on the warm side. As a result, the seven-day mean temperature was a couple of degrees above normal nearly all the time.

The month began in a dry spell that reached 50-days before good rain fell on the 12th. After that, there was another 12-day dry spell. The dry spells had clear skies, very low humidity, and high daily temperature ranges of around 20°.
By the end of the month, however, a lot of rain had fallen, totalling 52 mm. It fell mainly in four days, with 17 mm on the 26th. The final wet spell was uncomfortably humid.

 Comparing October monthsClimate October 2007

This October was the warmest in nine years. Daily minima were 1.2° above average, daily means were 1.7° above average, and daily maxima were 2.3° above average. The high daily maximum value of 29.4° is usually seen in November, not October.

The rainfall of 52 mm was near the long-term average of 58 mm for October. Similar amounts fell in October 2005 and 2006. October 2000 had been wet (110 mm) and October 2002 dry (15 mm).
The total rainfall for the two months ending in October 2007 was rather low compared to the same two months in other years. At 54 mm, it was on the 19th percentile: that is, there has been less than 54 mm rainfall in September-October about one year in five. By contrast, the three months ending in October had rainfall above normal, and the last nine month period had rainfall well above normal. Most other periods, up to 48 months, have been slightly drier than normal. Just 2 mm extra per month would have made these last four years wetter than 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.

 

September 2007 fine and dry

The daily weather logWeather log September 2007

Very light rain fell on three days in September, for a total of only 2.4 mm. By the end of the month, it had been 40 days since good rain. Such dry Septembers occurred only in 1914 and 1919, and drier ones in 1925 (1 mm) and 1980 (0 mm).

Although this month’s rainfall was in the 3rd percentile of monthly values, rainfall in recent months has not been far below normal. The two-month rainfall ending this month was in the 41st percentile and the nine-month rainfall was actually above the median, in the 53rd percentile. Low rainfalls near the 20th percentile are seen for groups of 3, 5, 6, and 18 months. Other groups of months, (4, 12, 15, 24, 30, 36, 42, and 48 months) are not so bad. They had rainfalls from the 30th to the 45th percentile.
September days and nights were a little cooler than normal. As in some other years, the 7-day mean temperature did not rise until late in the month. The 5th was a very cold day, with daily maximum 7° below normal; the 27th was a very warm night, with daily minimum 7° above normal. Two mornings (7th and 23rd) were as cold as 1.9°, qualifying as “frosts”.
There were only 5 cloudy mornings. All the others were fine, with 1/8 cloud or less.Climate September 2007


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.

 

Cold days in 2007 winter

Weather log winter 2007

The daily weather log

The temperature trends this winter look like a roller-coaster.
June had daily maximum temperatures about four degrees below normal. Two miserable days had maxima eight degrees below. Meanwhile, minimum temperatures were normal.
Maxima returned to normal in early July but, by that time, nightly minimum temperatures were well above normal. All temperatures then plummeted, losing 8°: by mid-July both maxima and minima were about 5° below normal.
By the end of July and early August maxima and minima had shot up again to well above normal. Next, maxima went up while minima went down, making the daily temperature range very large. This temperature range then collapsed to become very small. The winter ended with temperatures near normal.
The high ground in Manilla had 38 frosts* in June, July, and August. The nine-year average is 45. Seventeen nights went below zero and two nights below -4°.
There was quite a lot of rain, but not much fell in July. The amounts were 65 mm in June, 9 in July, and 81 in August. June was above average, July in the second decile, and August in the ninth decile.
There were ten rain days in June, seven in July, and five in August. One event was remarkable: rain fell continuously for more than 36 hours from the morning of 19th August, to a total of 55 mm.
Skies were overcast (8/8) around the periods of rain. In contrast, there were long sunny spells (0/8 or 1/8) in mid-July and the first half of August.

Comparing winter seasons

The average daily maximum temperature was the coldest in the last nine winters. At 16.6°, it was 1.6° below average.
Although the nights of 2005 were warmer, this winter also had warm nights. At 3.4°, they raised the daily mean temperature up to 10.0°, close to normal.
The daily temperature range in winter in Manilla is usually 15.4°. This winter’s cool days and warm nights made its daily range the lowest in these years. It was only 13.2°, typical of places nearer to the coast, such as Singleton.
The winter that stands out is 2002. With the warmest daily maxima (19.2°) and the coldest daily minima (1.7°) it had the remarkably high daily range of 17.5°. Such a range is found mainly in desert areas – which Manilla was at the time!.

Winter is the driest season in Manilla. The average winter rainfall, 125 mm, is just over half the average summer rainfall (227 mm).
This year’s winter rainfall (155 mm) was above average, and near that of 2005 (157 mm). None of the winters on the graph is far from the average except 2002.
The very dry winter of 2002, at 44 mm, was the ninth driest on the 124-year record. It was the driest since 1982 and 1972 (both 32 mm).
The graph just misses the very wet winter of 1998, nine years ago. Split Rock Dam suddenly filled up for the first time. At 304 mm, that was the second wettest winter on record. Only the winter of 1920 was wetter, with 318 mm.
The graph shows the peracentage of mornings with more than four octas of cloud. The winter average is 31%.
This winter, and winter 2000 were the cloudiest. The insulating blanket of cloud stopped the days from getting warm, and the nights from getting cold.
The winter of 2002 had the fewest cloudy days, another sign of how like a desert it was then.

Climate winter 2007

*Frost: A frost occurs when the temperature on the grass is below zero, causing water to freeze in the leaves. Not many stations measure grass temperature. My rule-of-thumb is to declare a frost if the temperature in the thermometer screen (at 1.5 metres) is below +2.2°.

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. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash Street, Manilla.

In 2007: Rainy warm August nights

The daily weather logWeather log August 2007

Nearly all of the welcome rain this month fell on only four days. Most of it (55 mm) was steady soaking rain through the 20th and 21st. At Tamworth airport there was rain in every hour for 37 hours.

Daily average temperatures were close to normal for August, rising slowly from 11 to 15 degrees. There were wild swings in daily maxima and minima, though. In the first half of the month, with clear skies nearly every morning, days were very warm, mainly above 20 degrees, and nights were cold, hovering around zero. There was seldom frost on the grass because the air was extremely dry. Two days had extreme temperature ranges: over 22 degrees.
That desert-like weather suddenly stopped. The overcast, rainy days from the 16th to the 21st had day-time and night-time temperatures that were almost the same. One night was 10° warmer than normal, and one day was 8.5° cooler than normal.
After the rain, the days slowly warmed up, the nights cooled down, and the skies cleared, until the 30th was desert-like again.

 Comparing August monthsClimate August 2007

Compared with Augusts since 2000, this August had the warmest nights by far: 5.2° compared to an average of 3.2°. This raised the daily mean temperature as well, so that it was also the warmest. However, daily maximum temperatures were not as high as they were in 2002. The August of 2001 was colder than the others; its daily maxima were especially cold.

This month was cloudy (35% mornings >4 octas) and humid (mean morning dew point 3.9°) as well as rainy.  Manilla’s total rainfall of 81 mm this month is in the 90th percentile: the fourteenth wettest August on record. Rainfall totals for more than one month are near 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.