Jet stream giveth and taketh away

  • Vancouver Island Inland Sections Forecast - No watches or warnings in effect.

    Forecast Issued 4:00 PM PDT Tuesday 20 March 2018 - Tuesday night: Cloudy. Periods of rain beginning before morning. Low plus 4. Wednesday: Periods of rain. High 9. Wednesday night: Periods of rain. Low plus 5. Thursday: Rain. High 7. Thursday night: Rain showers or flurries. Low plus 1. Friday: Snow or rain. High 6. Friday night: Showers. Low zero. Saturday: Rain. High 7. Saturday night: Cloudy periods. Low plus 2. Sunday: Cloudy with 60 percent chance of showers. High 9. Sunday night: Cloudy with 60 percent chance of showers. Low plus 2. Monday: A mix of sun and cloud. High 11.

  • Current Conditions
    9.6° C
    -0.6 ° C/hr
    101.41 kPa
    SSW 9.3 km/h
    gusting 19.3 km/h
    72 %
    Rain Rate
    0.0 mm/hr
    Wind Chill
    8.2° C
    Heat Index
    9.6° C
    4.8° C
    96 W/m2
    Last Updated: 18:10:00 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
    Moon Phase
    Waxing crescent (14% full)
    Civil Set
    Day Length
    Day High
    11.6° C @ 16:28 Tdy.
    Day Low
    3.2° C @ 02:34 Tdy.
    Day High Rain Rate
    Day High Barometer
    102.15 kPa @ 00:00 Tdy.
    Day Low Barometer
    101.41 kPa @ 17:59 Tdy.
    Day Low Windchill
    3.2° C @ 02:34 Tdy.
    Day High Heat Index
    11.6° C @ 16:28 Tdy.
    Day High Wind Gust
    S 12.9km/h @ 17:10 Tdy.
    Day High Solar Radiation
    925W/m2 @ 14:17 Tdy.
    Day High UV Index
    3.2 @ 14:22 Tdy.

It’s the height of the cold snap back East. I saw wind chills of -60F reported in the Midwest. New York City has set a new record low of -5F (-20C) for this day. It’s cold and here’s why.

The news has clung on to the words “Polar Vortex”. I think it’s kind of a silly term, not really based on anything other than it sounds great… Invoking memories of what of my favourite weather disaster movies, The Day After Tomorrow.


But thankfully it’s not quite to the freeze-the-Statue-of-Liberty-solid level of seriousness.
The polar vortex isn’t some evil weather system hell bent on freezing Toronto solid… It’s more accurately, I think, really the jetstream itself as it is the jetstream that forms the boundary between warm southern air and cold northern air.

Right now, as it has been many times over the past few months, the jet is seriously kinked, and particularly over North America. It rises to the West of us, forming a big ridge that has kept us dry and reaching into Alaska, pulling Arctic air all the way from Siberia, over the Pole, and down deep into North America. Before it rises north again, sending storms to the UK and Europe and record warmth to the newly crowned World Junior Champions Finland.


This will only last a little longer though. As is in evidence with our rain today, the jet is starting to shift East, pulling warmer and wetter air off the Pacific and finally breaking our drought.

You can see the warm patch of ocean off our coast here:


That warm patch is both a cause and a symptom of our dry spell and now our warmth as the unusually warm area has been created by the strong ridge of high pressure that has dominated over the pacific in the past few weeks. And now it helps to reinforce and return to those conditions.

For now though, it is delivering relief. That relief will peak on the weekend when the jet nearly straightens completely and we get a big bout of rain and possibly wind.


Those winds will travel across the continent and break the cold snap in the East.

But the relief may be short lived. It’s a very long way out, but the models are predicting a return to a big ridge here at home and a big trough in the East. Dry for us and cold for them again.


It looks strong. One thing is for sure. We are a slave to the jetstream. And it is making its power over us felt this winter.