Thu. Sep 20th, 2018

Gauging the rain to come

  • Vancouver Island Inland Sections Forecast - SPECIAL WEATHER STATEMENT IN EFFECT
    Issued: 05:42 AM PDT Thursday 20 September 2018

    Forecast Issued 05:00 AM PDT Thursday 20 September 2018 - Thursday: Cloudy. Rain beginning this morning. Amount 10 to 15 mm. High 14. UV index 1 or low. Thursday night: Rain. Amount 20 to 30 mm. Temperature steady near 12. Friday: Showers at times heavy. Risk of a thunderstorm late in the morning and early afternoon. Amount 25 mm. High 16. UV index 2 or low. Friday night: Showers. Low 11. Saturday: Rain. High 16. Saturday night: Showers. Low 11. Sunday: A mix of sun and cloud. High 20. Sunday night: Clear. Low 8. Monday: Sunny. High 21. Monday night: Clear. Low 7. Tuesday: Sunny. High 20. Tuesday night: Clear. Low 8. Wednesday: Sunny. High 20.

  • Current Conditions
    Temperature
    13.2° C
    0.5 ° C/hr
    Barometer
    101.93 kPa
    0.0
    Wind
    SSE 0.0 km/h
    gusting 1.6 km/h
    Humidity
    89 %
    Rain Rate
    0.0 mm/hr
    Wind Chill
    13.2° C
    Heat Index
    13.2° C
    Dewpoint
    11.4° C
    UV
    0.9
    Solar
    119 W/m2
    Last Updated: 10:55:00 PDT
    Click to Refresh or See All Conditions
  • Day Almanac
    Day's Rain
    0.0 mm
    Day ET
    0.0 mm mm
    Rain Storm
    NotAvailable mm
    Civil Rise
    06:30
    Moon Phase
    Waxing gibbous (83% full)
    Civil Set
    19:53
    Day Length
    13:12:31
    Day High
    13.2° C @ 10:27 Tdy.
    Day Low
    11.7° C @ 07:28 Tdy.
    Day High Rain Rate
    0.0mm/hr00:00
    Day High Barometer
    101.98 kPa @ 08:43 Tdy.
    Day Low Barometer
    101.87 kPa @ 01:28 Tdy.
    Day Low Windchill
    11.7° C @ 07:28 Tdy.
    Day High Heat Index
    13.2° C @ 10:27 Tdy.
    Day High Wind Gust
    S 1.6km/h @ 05:10 Tdy.
    Day High Solar Radiation
    178W/m2 @ 10:44 Tdy.
    Day High UV Index
    1.2 @ 10:42 Tdy.

There is no doubt it will rain starting Thursday or Friday. In fact, as I type this there is a light mist falling in Qualicum.

First, it’s worth remembering how much rain we need, which is a lot even for us on the West Coast.

Not since 1896 (in Beaver Creek) and 1929 (at City Hall) has there been a summer and fall this dry in Port Alberni. However, already this October has been more extreme than 1896. If you look at the daily data, rain fell on and off throughout October 1896. In 2012 we have yet to register rain in October. (October 1929 was a more typical month with over 180mm falling throughout)

The totals are most compelling though so again, July-October, 1896 got 159mm, 1929 got 214.9mm, and 2012 has 36.2mm so far. So we need over 122.8mm to dodge the 1896 record. (Apologies I’ve said 140mm in the past, bad in-head math on my part)

So will we get it and avoid the record? It is still hard to say. Initially this weekend’s rain looked intense. But it has flipped and flopped. Here is the latest GFS prediction.

20121010-073338.jpg
It shows a very merger start with a strong punch on Saturday and Sunday night totalling over 144mm!

That would take care of the record.

However, the GFS often overestimates. So what does the Canadian model say? Here are the accumulations from Friday through Monday with graphics available here.
20121010-073726.jpg
10mm on Friday.

20121010-073714.jpg
30mm on Saturday

20121010-073721.jpg
35mm on Sunday

20121010-073732.jpg
50mm on Monday

Total: 125mm

That would also put us over the 1896 amount and avoid setting a new record.

So now we wait and see if the forecast holds. There is rain in the long range forecast too… But we will address that maybe on the weekend. Rain amounts are often the most difficult to predict, but whatever we get, it will be a blessing for local rivers and the people and animals that depend on them.