Wed. Aug 22nd, 2018

Difficult Thursday Forecast – Possible Freezing Rain or Snow and Rain

  • Vancouver Island Inland Sections Forecast - SPECIAL AIR QUALITY STATEMENT IN EFFECT
    Issued: 9:31 PM PDT Tuesday 21 August 2018

    Forecast Issued 4:00 PM PDT Tuesday 21 August 2018 - Tuesday night: Partly cloudy. Widespread smoke. Low 12. Wednesday: A mix of sun and cloud. Widespread smoke becoming local smoke near noon. High 31. Humidex 34. UV index 7 or high. Wednesday night: Partly cloudy. Local smoke. Low 12. Thursday: Cloudy with 30 percent chance of showers. High 23. Thursday night: Cloudy periods with 30 percent chance of showers. Low 12. Friday: A mix of sun and cloud. High 22. Friday night: Cloudy with 60 percent chance of showers. Low 12. Saturday: Cloudy with 60 percent chance of showers. High 20. Saturday night: Cloudy with 30 percent chance of showers. Low 13. Sunday: Cloudy with 30 percent chance of showers. High 18. Sunday night: Cloudy with 30 percent chance of showers. Low 11. Monday: A mix of sun and cloud. High 20.

  • Current Conditions
    Temperature
    18.4° C
    -1.4 ° C/hr
    Barometer
    101.45 kPa
    0.0
    Wind
    N/A 0.0 km/h
    gusting 0.0 km/h
    Humidity
    62 %
    Rain Rate
    0.0 mm/hr
    Wind Chill
    18.4° C
    Heat Index
    18.4° C
    Dewpoint
    11.0° C
    UV
    0.0
    Solar
    0 W/m2
    Last Updated: 0:10:00 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
    05:45
    Moon Phase
    Waxing gibbous (85% full)
    Civil Set
    20:56
    Day Length
    13:22:01
    Day High
    18.8° C @ 00:00 Tdy.
    Day Low
    18.4° C @ 00:09 Tdy.
    Day High Rain Rate
    0.0mm/hr00:00
    Day High Barometer
    101.45 kPa @ 00:00 Tdy.
    Day Low Barometer
    101.45 kPa @ 00:00 Tdy.
    Day Low Windchill
    18.4° C @ 00:09 Tdy.
    Day High Heat Index
    18.8° C @ 00:00 Tdy.
    Day High Wind Gust
    S 0.0km/h @ 00:05 Tdy.
    Day High Solar Radiation
    0W/m2 @ 00:00 Tdy.
    Day High UV Index
    0.0 @ 00:00 Tdy.

I’m glad I waited through the morning a bit for the morning models to finish.  The forecast for tomorrow is not uncommon, but still a difficult one.


California Calling

While not nearly as torrential, the rainy weather that has been soaking parts of California is moving north and pushing our cold air out of the way at the same time.

 

Today you can see the rains still affecting parts of northern California and Southern Oregon
Today the rains are still affecting northern California and southern Oregon…
by Thursday evening the system shifted north to us.
… by Thursday evening the system has shifted north to us.

 

 

 

 

 


 

Calling for Cold Air Confusion – Be Cautious

(sorry for the gratuitous alliteration 😉 )

Here are the line up of forecasts for Thursday around 10AM, click for larger versions.  All models roughly agree on timing.  The precipitation should occur from around mid-morning to mid afternoon on Thursday.  Where the critical disagreement lies is, what the temperature will be the night before and the in the morning.

High Resolution Local Canadian model - GEM LAM  HRDPR
High Res Local Canadian model – (GEM LAM HRDPS) – Rain
GEM Regional - Very cold overnight - Freezing Rain.
GEM Regional (RDPS) – Very cold overnight – Freezing Rain.
GEM Global - Very cold overnight - Freezing Rain.
GEM Global (GDPS) – Very cold overnight – Freezing Rain.
US NAM - Just above 0ºC but windchill below zero and snow.
US NAM – Just above 0ºC but windchill below zero and snow.
US GFS - Over 2ºC overnight, rain.
US GFS – Over 2ºC overnight, rain.
UWash 24hr snow to 4PM Thursday. Nothing.
UWash 24hr snow to 4PM Thursday. Nothing.

If it is like it is right now as I type in Port Alberni.  Foggy, easily below freezing, and stagnant… then you can expect snow to fall.

If the fog lifts but there is no pulse of warm air andthen we could have snow, or freezing rain, or sleet… who knows.

If it warms up today and lasts through the night, then we could have nothing but rain showers.

 

 


 

The Verdict?

At this point, I’m going to go with the UWash and GFS models as they are generally the most accurate… though UWash was notably completely wrong on last Fridays’ snow I think this system is a tad more predictable for the models to get a handle on.

However, they do not always predict the very local effects of our Valley and the cold air that it can harbour jealously for many more hours than other places might.

So… I’m going with ain… with a chance of sleet or freezing rain but this is a very low confidence forecast.

If we wake up tomorrow and it is at or below freezing… get ready.   If it’s 3º and overcast… there should be less to worry about.


 

Timing

The first very light showers/flurries/sleet/freezing rain should begin around 8 or 9AM Thursday morning and be on and off all morning.

wa_pcp1.28.0000
We are talking very very light…

It will get a little more serious from around Noon to 2PM.

Pockets of moisture start to expand... this will be the critical moment of either some very sketchy weather, especially on the mountain passes, or the beginning of simple rain showers.
Pockets of moisture start to expand… this will be the critical moment of either some very sketchy weather, especially on the mountain passes, or the beginning of simple rain showers.

By nightime 8PM we should have full rain.  There is always the outside chance the cold air has hung around all day and this falls as a nasty mix of sleet and rain and snow.  Lets hope mother nature keeps it simple.  If the temperature is still within the 3º C range though, any heavy precipitation could drag down the temperature back into the 1-2ºC range and produce heavy snow or sleet.

Main force of front comes through in the evening 8PM.
Main force of front comes through in the evening 8PM.

 

It will remain showery all Friday and pick up steam again on Saturday.

Happy Thursday!