Warm Wet May 2017

Photo of blossoms on a gum tree

Mugga Ironbark Blossoms

The weather was normal for the first half of the month, bringing a mild first frost on the 11th, close to the normal date for it. Then the weather became warmer and wetter. Rain totalling 32.8 mm was recorded on the 20th, while the minimum temperature of 14.0° that morning was 8.6° above normal. The weekly average temperature rose to 3.8° above normal, before falling below normal as the rain eased towards the end of the month. The last two mornings were frosty.
In all, there were five rain days (over 0.2 mm) when there are usually three.

Weather log for May 2017

Comparing May months

Like May last year, this month was about one degree warmer than normal, unlike May of 2007, which was half a degree warmer again. The dew point (4.7°) was a little low, the daily temperature range (15.3°) normal, the cloudiness (32%) and the rainfall rather high.
The total rainfall of 55.6 mm was at the 70th percentile, well above the May average of 41 mm. There are no shortages of rainfall for groups of months to this date.

Climate for May 2017


Data. A Bureau of Meteorology automatic rain gauge operates in the museum yard. From 17 March 2017, 9 am daily readings are published as Manilla Museum, Station 55312.  These reports use that rainfall data when it is available. All other data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to May 2017

Parametric plots of smoothed climate variables at Manilla
“Record cold subsoil November 2016”3-year climate trends to May 2017

May raw anomaly data (orange)

While not far from normal, May 2017 was warm and humid (“Interglacial”), in contrast to April, which had been cool and arid (“Glacial”).The daily temperature range remained normal as both maximum and minimum temperature anomalies rose. Subsoil temperature rose above normal.

 Fully smoothed data (red)

The most recent fully-smoothed data point, for November 2016, completes data for the spring season. Following a winter that had been cool and moist, spring showed rapid warming and drying. The November dew point seems to have reached a minimum: one not nearly as low (arid) as in the previous two years.
The smoothed anomaly of daily minimum temperature, which had hit a record high value in May 2016, approached a minimum value that was near normal in October, and began to rise again.
Smoothed subsoil temperature anomaly reached a new record low value of -1.16° in November. It beat a record that was set in March 2008, a few months after the global temperature minimum of October 2007.


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.

May 2016: cooling down

Photo of caterpillars in procession.

White Cedar caterpillars.

Until the last week of May, the warm weather of March and April continued. Three nights (early mornings) were more than eight degrees warmer than normal. At 16.5°, the early morning of the 1st was the second warmest for May in this century after 16.9° on 3/5/2000. The first frost (a black frost) came on the 25th, not as late as in 2014, when the first frost came on the 8th of June! (More frost information is here.)

I recorded rain on 7 days (normally 3 in May) but 4 of them had less than 2 mm. The highest reading was 13.8 mm on the 2nd. The afternoon humidity was very high (seldom below 40%) which may explain the bothersome mosquitoes.

 Weather log for May 2016

Comparing May months

The month was warm, especially at night, but not as warm as May in 2007 or 1999.
Skies were more cloudy than usual, at 45% cloudy mornings (more than 4/8 cloud). May is usually sunny, with only 24%, but both 2014 and 2015 had a record 52%
The total rainfall of 34.5 mm was near the average of 41 mm, in the 54th percentile. (Since 1998, every May rainfall except 2011 has been below average.) For the seventh month in a row, there are no serious rainfall shortages for totals for any number of months. Again, the greatest shortage is the 48-month total (2211 mm) which is now in the 14th percentile. Ponds persist in Greenhatch Creek, but a neighbour’s dam is dry.

Climate for May 2016


Data. All data, including subsoil at 750 mm, are from 3 Monash Street, Manilla. Rainfall data up to 26/3/15 is from Manilla Post Office, Station 055031.

Very cloudy days in May 2015

Photo of a case moth

A case moth

While there were four frosts (usually 6) that came early in the month, a record number of eleven nights were warmer than 10°. Some were very warm. At 15.1°, the night of the 3rd was the 4th warmest May night. Although the night of the 31st was only 13.0°, since it came so late, that was 9.0° above normal for that date. By contrast, most days were cooler than normal.
The frostier times were sunny, but skies later became cloudy. Finally, days were chilly and overcast. Cloud blanketed the hills, but steady rain (16.5 mm) held off until the very end.

Weather log for May 2015

 Comparing May months

The most remarkable mean value for the month is the daily temperature range: at 12.9°, it is 2.4° below normal. The May months with the narrowest ranges to date, in 2001 and 2014, had ranges of 14.7°, only 0.6° below normal. The narrow temperature range is due to cloudy skies which, at 52%, equal the record for May.
Linked with these figures are a very cool mean daily maximum temperature of 20.2°, and a very warm mean daily minimum temperature of 7.3°. The mean early morning dew point (5.0°) is not high, but higher than in any May month since 2007.
The total rainfall of 30.8 mm is in the 51st percentile. (While the long-term May average is 40 mm, May rainfall in the 21st century has averaged only 21 mm.) Among rainfall totals for more than one month, there are no serious shortages. The lowest percentile value (14th) is for the 24-month total of 1019 mm.

Climate for May 2015


Data. All data, including subsoil at 750 mm, are from 3 Monash Street, Manilla.

3-year trends to May 2015

Parametric plots of smoothed climate variables at Manilla
“May 2015: less moist”

Trends to May 2015

May raw anomaly data (orange)

May anomalies moved back towards normal from the cool moist conditions of April for the variables daily maximum temperature, rainfall, and daily temperature range. Cloudiness, however, became extreme, as it had been in the (smoothed data) a year earlier. Daily minimum temperature became very high, keeping the climate in the “Maritime” area. This, again, prevailed just one year ago.

Fully smoothed data (red)

The latest fully-smoothed data anomalies (November 2014) complete the season for spring 2014 (SON). As is most clearly seen in the graph at the bottom right, the daily maximum temperature anomaly (smoothed) reached a minor maximum just above normal in October. Other variables moved little. All were “normal” except the Dew Point anomaly, which had the low value of minus three that has now become normal.

Springtime temperature peaks

Each of the spring seasons of 2012, 2013 and 2014 marked a peak in daily maximum temperature anomalies. Spring 2013 was the hottest, breaking the record for this data set. Spring 2013 also had extreme peaks of lowest rainfall, least cloud, lowest dew point, and highest daily temperature range. This is just what is expected at an extreme El Niño, but there was no El Niño at that time.


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.

May Climate Anomalies Log

Heat Indicators log for May months

This post is the third in a set for the 12 calendar months. 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 May

Extreme values of May anomalies in this period were:
Daily Minimum Temperature anomaly -3.6 deg: May 2006;
Morning Dew Point Anomaly +3.6 deg: May 1999;
Morning Dew Point Anomaly -3.9 deg: May 2006;
Morning Dew Point Anomaly -3.2 deg: May 2011;
Morning Dew Point Anomaly -4.4 deg: May 2012;
Temperature range anomaly (minus) -3.2 deg: May 2006.

Trend lines for May

Heat Indicators

The trends of all three air temperature anomalies were almost the same, except that anomalies of daily minimum temperature were more negative. All began high in 1999, reached a minimum in 2002, a maximum in 2007, and a minimum in 2011-12. The trend of subsoil temperature was contrary, and generally increasing.

Moisture Indicators log for May months Continue reading

3-year trends to May 2014

Parametric plots of smoothed climate variables at Manilla
“Drought status not clear”

Trends to May 2014

May data (orange)

Raw data for May 2014 give mixed signals on whether the drought is fading. Daily maximum temperature is now on the high limit of the normal range and rainfall again well into the “drought” range. However, other variables do not agree: skies were very cloudy, and dew point and daily temperature range were back to normal.

Fully smoothed data (red)

The spring months (SON) of 2013 are now fully smoothed, with some variables showing a drought peak in that season.
Smoothed daily maximum temperature anomaly peaked in October, reaching a record high of +1.39°, beating +1.34° in November 2009 and +1.30° in September-October 2002. Through spring the smoothed rainfall anomaly decreased; it may have reached a minimum in January. Dew point also decreased, the smoothed anomaly reaching a new record low of -4.85° in November, and likely to reach a minimum in December.
Cloudiness reached a minimum in October, and daily minimum temperature and subsoil temperature anomalies had reached maximum values earlier, in July.

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.