Happy Fall Equinox! – Friday’s Rainfall marks first September deluge in the records. Weekend Rain.

Happy First (half) Day of Fall!

The Equinox officially happened at 12:20PM Pacific Time today. Make sure you wave to the sun as we head around to the other side!

Friday’s record rainfall:

The rain on Friday was not something the Alberni Valley has experienced on a September day since record keeping began in 1894.

Here are the stats from each Alberni Valley station for Friday September 17, 2021 in order of amount:

Maquinna Elementary (IW): 137.2mm
Nick’s Weather (near Maquinna): 105mm
Alberni Elementary (IW): 104.1mm
Alberniweather.ca : 102.9mm
Alberni Harbour (BWD): 79.0mm
Alberni Airport (EC): 76.2mm
Robertson Creek (EC/CCN): TBD

You can see from the graph above that the rain ‘storm’ lasted into Saturday as well. Taken together, Maquinna measured 164.6mm of rain from Friday through Sunday. This is compared to measuring 179.5mm in all of April, May, June, July, August, and the preceding days of September. Most of that came in April and May.

September historical records:

Day Record – Easily Broken

The old record measured by any station in the Alberni Valley on a September 17th since 1894 was 47.2mm September 17, 2006 at Robertson Creek Fish Hatchery. In terms of official records kept by Environment Canada. The new value of 76.2mm at the Alberni Airport will be the highest ever recorded for September 17th, nearly double.

The 137mm at Maquinna represents a total that is beyond extreme for that particular day.

Month Record – All Station Record Broken

The rainfall measured at stations around the Valley, at Maquinna, Nicks, Alberni Elementary, and Alberniweather beat any measurements ever taken in September before. The highest rainfall ever recorded before Friday was 81.3mm. This was smashed by those three stations.

The official Airport station set its own September record since 1994 but was just shy of other historical Environment Canada records from Robertson Creek and and Beaver Creek.

Here are the highest 24hr rainfall totals in September for each historic Environment Canada station in order of total:

Beaver Creek (1894-1958): 81.3mm on Sept 21, 1924
Robertson Creek (1963-2020): 79.5mm on Sept 29, 2007
Alberni Airport (1994-2021): 76.2mm on Sept 17, 2021
Lupsi Cupsi (1949-1974): 62.2mm on Sept 20, 1972
China Creek (1960-1980): 61.5mm on Sept 20, 1972
Alberni “A” Somass Airport (1970-1994)): 58.4mm on Sept 20, 1972
Port Alberni (1917-1958): 57.7mm on Sept 27, 1927
McCoy Lake (1958-1972): 56.1mm on Sept 20, 1972
Cox Lake (1987-2013): 52.5mm on Sept 28, 2013
Shuhum Creek: 44.4mm on Sept 29, 1997
Redford School (1959-1971): 41.9mm on Sept 16, 1969

I was interested to see some of the differences between locations on dates of these extreme events. For example, the earliest extreme rainfall, Beaver Creek on Sept 21, 1924, was 81.3mm, but only 51.6mm was measured on the same day at the Port Alberni station. Very different from last week’s pattern of the same or more falling at the City station as out at the Valley Airport.

Another common date that pops out is September 20, 1972. We had 5 stations reporting to Environment Canada at that time. All but one have their highest September rain date happening on September 20th 1972 measuring between 56mm at McCoy Lake and 62mm at Lupsi Cupsi (Catalyst Paper Mill). The outlier is Robertson Creek, which has a much longer period of measurement and got 79.5mm on Sept 29 2007, relegating the Sept 20, 1972 to 2nd in its September records.

Very near the All Time Record for rainfall in Port Alberni

Most impressive of all, is the 137.2mm measured at Maquinna Elementary this past Friday will now be among the highest daily totals *ever measured* in the Alberni Valley.

Here are the top rainfall measurements ever recorded in the Alberni Valley (all EC and non-EC stations available):

McCoy Lake: 141.2mm on Nov 30, 1958
Port Alberni: 139.7mm on Nov 30, 1958
China Creek: 138.7mm on Jan 17, 1968
Maquinna Elementary: 137.2mm on Sept 17, 2021
Cox Lake: 135.8mm on Jan 3, 2012
Shuhum Creek: 134.4mm on Mar 16, 1997
Cox Lake: 134.0mm on Feb 1, 1991
McCoy Lake: 133.4 on Dec 12, 1960
Cox Lake: 130.8mm on March 12, 2003
McCoy Lake: 128.5mm on Oct 20, 1963

It is a shame that the Beaver Creek station ended its record keeping earlier in 1958 or we would have probably had 3 stations on this list with the same November 30, 1958 value. Without a doubt though, that day, along with January 17 1968 (which is in the top 5 of other stations) and now September 17, 2021 are the strongest storms Port Alberni has seen since records began in 1894.

Given all of this, it is no surprise there was flooding on 3rd and 4th Avenue and road closures. At one point, around 3:45PM on Friday, my station measured an instantaneous rainfall rate of 97.5mm/hr! It was enough to temporarily plug one of our drains, and temporarily flood our basement. Thankfully it was noticed quickly and no permanent damage was done. Hopefully others fared ok.

September — An Expanded Rain Season?

One more thing. In all of the top-5 lists for all of the stations, never has a date in September featured. There is often rain in September of course, but as noted at the beginning, 40mm is more the maximum we are used to see, not 140mm.

October, November, December, January, February and March all feature in the top 5 lists of the historic EC stations. September is new.

It is strange to consider this given that we have just completed 4 months of extreme drought. But perhaps extremes are what we should be expecting in future with climate change. And part of that is seeing our Fall storm season start a little earlier than we might be used to.