Tag Archives: NSW

April 2008: fog and black frosts

Posted in Manilla NSW, Monthly weather by

The daily weather log

Weather log April 2008

Usually, the air cools and dries out quickly during April. This time only the daily maximum temperature came steadily down. The average temperature hovered near 16° until the last days.
At first, the air was very dry, with a Dew Point below 5°. Under a clear sky on the 4th the early morning temperature went down to 2.1° in the screen, which would be 0.1° of frost. Because the Dew Point (-3.8°) was much lower than that, there was no ice on the grass, which made it a “black frost”. It is said that frosts seldom occur in Manilla before ANZAC Day (April 25th).
As the month went on the air got moister. By the 24th the clouds in the overcast sky were down on the hills. On the 26th the town was blanketed in fog as the humidity hit 100%. (Temperature and Dew Point were both 8°.)
Evaporation was increased by strong winds on the 27th and 28th.
Dry southerly air made the last three days cool and sunny. Black frosts came back giving screen temperatures of 0.6° and 0.1° (around 2° of frost).
Practically no rain (3.6 mm) fell in more than seven weeks from 29 February to 21 April. After that, there were four rain days, including 12.8 mm on the 24th. In total, 20.2 mm fell in April, on five rain days.

 Comparing April months

Climate April 2008

The mean temperature this month was nearly as low as the coolest  April in ten years (1999). This was the fifth cool month in a row: December (1.0° down)  January (1.9° down) February (3.1° down) March (0.9° down) and April (2.1° down). As a 5-month average the temperature was 1.8° below normal. It is as if Manilla had been moved 400 km south (near Grenfell) or 150 metres higher (like Barraba). (Note added: This was a time of global low temperature.)

The month was as cloudy as usual, but less humid.
At 20 mm, this April’s total rainfall is about 20 mm below average, as in 2001 and 2004. It is much higher than in April 2005, when Manilla was in a rainfall  drought for several months.
The rainfall total for this March and April (22 mm) is in the 4th percentile of two-monthly totals: a severe shortage. However, the three-month total (138 mm) is just below the median, and the totals for 4, 5, 6, 9 and 12 months are all at the median or above it. In particular, the 6-month total (401 mm) is quite high, at the 75th percentile.

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.

 

Dry, Dry March 2008

Posted in Manilla NSW, Monthly weather by

The daily weather log

Weather log March 2008

After 115.6 mm of rain in February, March crashed to just 2.2 mm with only three rain days. In 1971 it was worse: that year February had 173 mm and March 1 mm!
This month the air was very dry, too. Morning Dew Points which had been quite low (10°) all month, plunged to zero or less in the last days.
Although there were six cloudy mornings, eighteen mornings were completely cloud-free. The whole of the summer had only thirteen free of cloud!
Due to the dry, fine weather, three-quarters of the days had a range of temperature higher than the normal value of 15.4°. Three days had a range of 21° or more.
The 7-day average temperature began and ended well below normal, but was above normal in the third week. Nights were cold (8° below normal) in the first and last days.

 Comparing March months

Climate March 2008

The mean daily maximum temperature this March (29.9°) is normal, but the mean daily minimum (12.2°) is the lowest in ten years. It is 2° below the average, and 4° below that of 2007 (and 2000).
The mean morning Dew Point, 8.8°, is 3° lower than normal for March. This shows very dry air, which is wilting many shallow-rooted plants.
The total rainfall of 2.2 mm is much lower than the other Marches on the graph. It is not very low compared with Marches in the long-term record: it is on the 6th percentile. In Manilla, rainfall varies more in March and April than in other months.
There must be a lot of water deep in the soil. Total rainfalls for the last 2, 3… 18 months are all above the median. The four and five-month totals are particularly high, in the 83rd percentile.

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, cloudy wet February 2008

Posted in Manilla NSW, Monthly weather by

The daily weather logWeather log February 2008

Reading the 7-day mean temperatures, the month started near normal, but cooled to unusually low figures by the end of the first week – five degrees down! For a week from the 19th it was only two degrees below normal, then back to four degrees down at the end of the month.
Days were particularly cool, running about 29° instead of 33°.  However, the coolest days were not extreme.
The warmest day, Friday the 22nd, reached only 35.5°. The following morning was the warmest at 26.1°.
Dry air arrived from the south on the 24th, with a Dew Point of only 5.8°.
Rain fell frequently until the 19th, with the 6th being the wettest day (32 mm). The 29th was also very wet. There were nine rain days, totalling 115.6 mm. This is nearly twice the long-term February average of 66 mm.
Very few mornings were “Fine” (with no cloud).

 Comparing February months

Climate February 2008

This was by far the coldest of the last nine Februaries, by day and by night. The mean daily maximum of 28.8°, the mean daily mean of 22.2°, and the mean daily minimum of 15.6° were all well below average, by 3.7°, 3.1°, and 2.5° respectively.
The contrast with the last two years is stark: the days in February 2007 were 4.5° hotter, and those in February 2006, 5.2° hotter than this month. (Note added: This cooling was global.)
With 58% of mornings exceeding 4 octas of cloud, this February, along with December 2007 (58%) and June 2007 (60%) was one of the cloudiest months in nine years. Most months in Manilla have about 30% cloudy mornings.

This month’s rainfall of 116 mm is in the 81st percentile of February totals. (Last February’s 128 mm was the seventeenth wettest February on record.) Taking rainfall totals for more than one month, every total up to 12 months is very high: above the 70th percentile.

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.

 

Very cool January 2008

Posted in Manilla NSW, Monthly weather by

The daily weather logWeather log January 2008

The month began sunny and dry, but two degrees cooler than usual. Three rainy days beginning on the fifth brought high humidity and one daily maximum temperature as low as 24.4°. This is 9.2° below normal! Eight fine days followed, with normal January temperatures.

With a second rainy spell from the 17th to the 21st, days were again remarkably cool: five days were more than 8° below normal. In the dry fine weather that followed, all temperatures – maximum, minimum, and mean – were even lower than when the month began. They slowly rose to normal by the end of the month.
Humidity was normal for January: the morning Dew Point was 10° to 12° in the dry spells and 18° in wet spells, giving an average of 14.2°.
Rain fell on nine days. The wettest day, the 17th, had 17.2 mm, and the total was 65.8 mm.

 Comparing January monthsClimate January 2008

This January had the coolest days in nine years, and the second coolest mean temperature. This month’s mean daily maximum (31.0°) was 2.9° below the nine-year average (33.9°), and an astonishing 4.4° below last year’s figure (35.4°). Because the mean maximum was low and the mean minimum was not, the mean daily temperature range this month (13.7°) was also low.

Using Dew Point to measure humidity, January and February are Manilla’s most humid months. This month’s mean morning Dew Point of 15.3° is normal.

With 39% of mornings having more than 4 octas of cloud, this was a cloudy month, but not as cloudy as December (58%) or November (50%).
The total monthly rainfall of 65.8 mm is 21 mm short of the long-term January average. However, total rainfalls for the last 2, 3, and 4 months are all above the 80th percentile.

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.

 

December 2007 cool, humid, cloudy, rainy

Posted in Manilla NSW, Monthly weather by

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.