Extremely Dry October 2013 Recap

It’s time for the October 2013 recap, dry as a skeleton’s bones edition.

Monthly Timelapse:

This October has been extremely dry. Only a handful of Octobers since records began in the Alberni Valley in 1894 have been drier than this one. Our normal amount of rain is around 200 mm. We received a paltry 25.6mm at the official station at the Airport, and similar 24.9mm here at Alberniweather.

Interestingly, the previous driest Octobers all seem to have come before 1936. But the driest ever recorded is actually in 2002… And now we have another top 10 only 11 years later.

Since 1894, the Octobers with the least rain, as recorded in stations across the Valley are listed below. 2002, 1936, 1925 and 1895 all had readings lower than this year.

1. 2002 Airport: 14.2mm
2. 1936 City: 16.5 mm
3. 1925 City: 18.0 mm
4. 1895 Beaver Creek: 18.3 mm
5. 2002 Robertson CreekB: 18.5 mm
6. 2002 Cox Lake: 23.2 mm
7. 2013 Airport: 24.9 mm
8. 1987 Somass :25.5 mm
9. 2013 Airport: 25.6 mm
10. 2013 Maquinna: 26.4 mm
11. 1972 Somass: 26.7 mm
12. 1925 Beaver Creek: 27.7 mm
13. 1972 Lupsi Cupsi: 28.4 mm
14. 1972 Robertson Creek: 29.7 mm
15. 1972 McCoy Lake: 30.2 mm
16. 1987 Cox Lake: 30.6 mm
17. 1936 Beaver Creek: 32.5 mm
18. 1991 Somass: 33.1 mm

What is truly strange: you may remember we got an extreme 215 mm for September which was more than our normal October 203 mm.

As far as temperature, we had higher than normal minimums (+2.7 °C) but maximums and average daily temperatures were close to normal.

The cause?

The cause of the dry weather was an unusually strong ridge of high pressure and stationary, north looping jetstream that persisted for almost three weeks. What would cause this unusual pattern? Research released just on the 28th that studied recent wet summers in the UK have lent more support to the theory that melting Arctic ice and subsequent heating of the Arctic is affecting the jetstream, causing it to take extreme paths. Since the jetstream is like a ribbon stretched around the whole northern hemisphere, if it is being affected in the Atlantic region by the Arctic melt, then that will be felt here as well.

You can watch the scientists from Exeter University explain their work here:

I will update the forecast for tomorrow’s rain and wind storm this afternoon. Expect showers to start this afternoon and some wind tomorrow morning as well followed by a cool down and snow on the mountains.

Stats and Analysis for the Month – (Note we are using 1981-2010 averages)

Average Daily Temperature:
All Station Ave. Difference from 1981-2010 normal: -0.3 °C
Official (Airport) Difference from 1981-2010 normal: -0.3 °C
Alberniweather:10.0 °C
Environment Canada Airport: 9.7 °C
Alberni Elementary:9.7 °C
Maquinna: 9.4 °C
Neptune Canada: 9.9 °C
Overall Average: 9.7 °C
1971-2000 Environment Canada Normal (A – Somass): 9.9 °C
1981-2010 Environment Canada Normal (A – Somass): 10.0 °C

Average Minimum Daily Temperature
All Station Ave. Difference from 1981-2010 normal: +1.8 °C
Official (Airport) Difference from 1981-2010 normal: +2.7 °C
Alberniweather: 6.7 °C
EC: 7.8 °C
AES: 6.4 °C
MAQ:6.5 °C
NEP: 7.0 °C
Overall Average: 6.9 °C
1971-2000 Environment Canada Normal (A – Somass): 5.0 °C
1981-2010 Environment Canada Normal (A – Somass): 5.1 °C

Average Maximum Daily Temperature
All Station Ave. Difference from 1981-2000 normal: +0.15 °C
Official (Airport) Difference from 1981-2000 normal: -0.75 °C
Alberniweather: 16.6 °C
EC: 14.1 °C
AES: 14.9 °C
MAQ: 14.3 °C
NEP: 15.1 °C
Overall Average: 15.0 °C
1971-2000 Environment Canada Normal (A – Somass): 14.8 °C
1981-2010 Environment Canada Normal (A – Somass): 14.85 °C

Average Rainfall
All Station Ave. Difference from 1981-2010 normal: -177.7 mm
Official (Airport) Difference from 1981-2010 normal: -177.7 mm

Alberniweather: 24.9 mm
EC: 25.6 mm
AES: NA (broken)
MAQ: 26.4 mm
NEP: NA (not measured)
Overall Average: 25.6 mm
1971-2000 Environment Canada Normal (A – Somass): 193.6 mm
1981-2010 Environment Canada Normal (A – Somass): 203.3 mm

Comparison to recent years at Alberniweather (only).
Last year. WET. This year. DRY.

2012:
2013 was about the same temperature on average, and we actually had a similar dry (but much warmer) jet stream pattern at the beginning of October right up to Thanksgiving. But after that, the rains came. This year, the rains came in late September and then it just… Dried up.

2011:
2013 was still a little warmer than 2011 on average. However, again, the rain this year has really been exceptional. We got 109mm in 2011 which would be considered somewhat low, half of normal. This year, we got nothing.

2010:
2013 was a little warmer than 2010. Rainfall was normal in 2010.

2009:
2009 was cooler than this year for temperature, but rainfall close to normal.

2008:
2008 was cold and got below average rain. (124mm)

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Alberniweather Blog (Chris)

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