Tag Archives: Manilla

January 2015: cool rainy days

Posted in Manilla NSW, Monthly weather by
Crepe myrtle shrubs

Crepe Myrtles in Arthur Street

Only five days were warmer than average. The final five days and four nights were very cool, taking the weekly average (normally the hottest of the year) down to five degrees below normal. (This would be normal for the end of March, not January!) There were fifteen rain days, equalling the 125-year record number for January, set in 1941. Rain was spread evenly through the month, with the highest reading 29.2 mm on the 2nd.

Weather log January 2015

Comparing January months

The mean daily maximum temperature (31.4°) was well below the average of 33.8°. Since nights, at 17.6°, were near normal, the daily temperature range was the record narrow value for January of 13.8°.
The dew point (humidity) returned to a normal value of 12.9°, after last January’s arid 6.9°. Subsoil temperature (25.3°) fell to normal after two January months above normal.
The total rainfall of 117.4 mm was in the 75th percentile, well above the average of 87 mm. This clears all shortages in rainfall totals for groups of months. The lowest percentile value remaining (15th) is for the 18 month total of 746 mm.

Climate for January 2015

Data. Rainfall data is from Manilla Post Office, courtesy of Phil Pinch. Temperatures, including subsoil at 750 mm, and other data are from 3 Monash  Street, Manilla.

January Climate Anomalies Log

Posted in 21st-century climate, Calendar month anomalies, Climate Change, Manilla NSW by

Heat indicators log for January

This post is the eleventh in a set for the 12 calendar months that began with March. Graphs are sixteen-year logs of the monthly mean anomaly values of nine climate variables for Manilla, NSW, with fitted trend lines. I have explained the method in notes at the foot of the page.

Raw anomaly values for January

Extreme values of January anomalies were as follows:

Daily Maximum Temperature Anomalies (1) -3.7 deg: January 2012;
Rainfall Anomalies (5) -70 mm: January 2002; -75 mm: January 2003; +80 mm: January 2004; +94 mm: January 2006; -85 mm: January 2014;
Dew Point Anomalies (2) +3.1 deg: January 2006; -7.4 deg: January 2014.

Trend lines for January

Heat Indicators

All heat indicator quartic trends began low and ended slightly high, and had a low peak in 2003, -05, or -06, and a shallow trough about 2012.

Moisture indicators log for January

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3-year trends to January 2015

Posted in 3-year climate trends, Manilla NSW by

Parametric plots of smoothed climate variables at Manilla
“January 2015: rainy cool days”

Trends to January 2015

 

January raw anomaly data (orange)

Anomalies for all variables except subsoil temperature moved across the graphs, from “droughts” in November to “flooding rains” in January. Subsoil temperature had been normal from February to December (11 months!), then became cooler than normal in January.
Most raw anomaly values for January were close to the fully-smoothed anomaly values of the La Niña-affected cool summer of 2012. This month’s daily temperature range was even narrower, and the subsoil temperature lower, but the daily minimum temperature was not so low.

Fully smoothed data (red)

The latest fully-smoothed data anomalies (July 2014) were near normal. (Dew point, like most recent values of that variable, was 3° lower than normal.)

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.

Rainfall Deficiencies IV: 120-months Duration

Posted in Australian Climate, Climate Change, Manilla NSW, Rainfall from 1883 by

Log of severe and extreme rainfall deficiency of 120-month duration at Manilla This is the fourth of four graphs that show Manilla’s history of rainfall deficiencies (rainfall droughts), for periods of duration 3 months, 12 months, 36 months, and 120 months.

This fourth graph includes those periods of severe or extreme rainfall deficiency that last one-hundred-and-twenty months. They are rainfall droughts that affect about ten successive years.

(As I note below, in this series, a time of severe rainfall deficiency is one that is drier than the 5th percentile of cases, and a time of extreme rainfall deficiency is one that is drier than the 1st percentile of cases.)

In Manilla’s climate, a time of severe 120-month rainfall deficiency has a rainfall total less than 5860 mm, when it normally would be 6390 mm: that is, through the 10-year period, there is as an average a rainfall deficit of 53 mm each year. A time of extreme 120-month rainfall deficiency has a rainfall total less than 5670 mm: that is, through the 10-year period, there is as an average a rainfall deficit of 72 mm each year.

Even more than three-year droughts, these ten-year droughts have quite different effects to those that are shorter. The importance of severe and extreme rainfall deficiencies of 120-month duration is that even very large surface and sub-surface reservoirs may not be adequate to supply demand through to the end of the drought.

The graph shows that such ten-year droughts hardly occurred earlier than 1915 or later than 1955, but were confined to that 40-year interval. While deficiencies of this duration were twice as common as normal (5%) in the decades around 1920 and 1925, it was the decades around 1945 and 1950 that were extraordinary: 26% of all months had a severe rainfall deficiency of this duration.

Again, extreme 120-month droughts generally comprised about one-fifth of the total, as one might expect (unlike the case for one-year droughts).

Areas shown on the graph

Rainfall deficiencies are called “severe” when they are lower than are recorded for five percent of the months. I have called deficiencies “extreme” when they are lower than are recorded for one percent of the months. In this graph, I have coloured extreme deficiencies in blue. The maroon colour is deficiencies that are severe, but not extreme. The top edge of the maroon area marks the proportion of severe deficiencies including extreme deficiencies. As an average, this line is at five percent.

Data analysis

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Rainfall Deficiencies III: 36-months Duration

Posted in Australian Climate, Climate Change, Manilla NSW, Rainfall from 1883 by

Log of severe and extreme rainfall deficiency of 36-month duration at Manilla

This is the third of four graphs that show Manilla’s history of rainfall deficiencies (rainfall droughts), for periods of duration 3 months, 12 months, 36 months, and 120 months.

This third graph includes those periods of severe or extreme rainfall deficiency that last thirty-six months. They are rainfall droughts that affect about three successive years.
In Manilla’s climate, a time of severe 36-month rainfall deficiency has a rainfall total less than 1505 mm, when it normally would be 1940 mm. A time of extreme 36-month rainfall deficiency has a rainfall total less than 1380 mm.
Droughts of this duration have quite different effects to those that are much shorter.
While the 3-month drought that just qualifies as “severe” (by having rainfall in the fifth percentile) would have a rainfall total of 50 mm, in the similarly defined 36-month drought, each 3-month period within it would have, on average, a rainfall total of 125 mm (i.e. 1505*3/36). This 3-month rainfall total is only 25 mm less than the normal 150 mm total. It would scarcely be noticed if it did not persist for 36 months.
The importance of severe and extreme rainfall deficiencies of 36-month duration is that they use up the reserves that are held in surface and sub-surface water storage.

In the Manilla rainfall record, such three-year droughts were concentrated in just a few decades. They were very common around 1910-1915 and 1945 (in more than 12% of months) and in 1965 (in 9% of months). They were very rare or absent (less than 2% of months) before 1900, from 1925 to 1935, and in the entire forty years since 1975.
Extreme 36-month droughts generally comprised about one-fifth of the total, as one might expect (unlike the case for one-year droughts).

Areas shown on the graph

Rainfall deficiencies are called “severe” when they are lower than are recorded for five percent of the months. I have called deficiencies “extreme” when they are lower than are recorded for one percent of the months.
In this graph, I have coloured extreme deficiencies in blue. The maroon colour is deficiencies that are severe, but not extreme. The top edge of the maroon area marks the proportion of severe deficiencies including extreme deficiencies. As an average, this line is at five percent.

Data analysis

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