August 2019 Forecasts and Discussions

[Forrest Gump]

Not good for the YXX airshow.

In a heavy British accent:You can't have your cake and eat it too

[SouthSardiswx]

Holy Sh*t! The master is back!

Welcome back dude, I missed you.

You were always on our minds frozen one you were always on our minds. Welcome back! sherriff Goosed was lost without you we missed your stats during some of our weather events the past several months.

[Bonovox]

In a heavy British accent:You can't have your cake and eat it too

Haha. True enough.

[John]

0z still wet weekend

Trough after trough.

[Glacier]

Crazy how Trail/Warfield can be 38C and not be under a heat warning. Meanwhile, Bella Coola can't even hit 27 and is under one!

https://questioningthedata.wordpress.co ... heat-wave/

[Canada Goose]

Crazy how Trail/Warfield can be 38C and not be under a heat warning. Meanwhile, Bella Coola can't even hit 27 and is under one!

https://questioningthedata.wordpress.co ... heat-wave/

Ya, this is ridiculous, even if we all know the two places have different climates.

Wow, so impressive!

Terrace.jpg

[Monty]

Models are liking the continuation of large blocking ridges building into the NE pacific and Alaska. Too soon to say what the downstream effects will be here, with cold troughs dropping somewhere into western Canada. But safe to say the blob isn’t going anywhere with big ridges centered offshore.

[Typeing3]

We need this type of pattern to repeat in December and January!

[Typeing3]

Models are liking the continuation of large blocking ridges building into the NE pacific and Alaska. Too soon to say what the downstream effects will be here, with cold troughs dropping somewhere into western Canada. But safe to say the blob isn’t going anywhere with big ridges centered offshore.

Nudge the ridge a touch west and add a bit of tilt and we've got an excellent Arctic blast in the Nov thru March timeframe. Too bad it's occuring now.

The placement of the blob currently is reminding me of 2016...warmest anomalies placed in the GOA rather than hugging the direct coastline.

[Abby_wx]

Crazy how Trail/Warfield can be 38C and not be under a heat warning. Meanwhile, Bella Coola can't even hit 27 and is under one!

https://questioningthedata.wordpress.co ... heat-wave/

Yup, this is a good example of why I think the criteria for heat warnings needs to be rethought. There's nothing wrong with having a relativistic threshold for warnings, but they need to get the numbers right. It makes zero sense to suggest that heatwaves are more common on the north coast than in the southern interior.

One problem with the current criteria is that two thresholds must be met: high and low temperature. If either one is just a degree too low, no heat warning will be issued.

Abbotsford could hit 40C during the afternoon, but there would be no heat warning as long as the temperature dropped below 18C at night.

I would discard the current thresholds and use deviation from the normal daily mean as the basis. If the daily mean for a location is 20C, then a certain amount above that would trigger a heat warning... say 25C.

[Glacier]

Yup, this is a good example of why I think the criteria for heat warnings needs to be rethought. There's nothing wrong with having a relativistic threshold for warnings, but they need to get the numbers right. It makes zero sense to suggest that heatwaves are more common on the north coast than in the southern interior.

One problem with the current criteria is that two thresholds must be met: high and low temperature. If either one is just a degree too low, no heat warning will be issued.

Abbotsford could hit 40C during the afternoon, but there would be no heat warning as long as the temperature dropped below 18C at night.

I would discard the current thresholds and use deviation from the normal daily mean as the basis. If the daily mean for a location is 20C, then a certain amount above that would trigger a heat warning... say 25C.

Between last year and this year Environment Canada has changed to the criteria for Abbotsford (actually, Hope to the Surrey). It now only needs to be 17 as the low and 33 as the high (instead of 18 and 35). Still, in the past 4 years only Hope has managed to meet that one. Nothing for YXX, Agassiz, Pitt Meadows, or Cultus Lake.

See update at the bottom of this page: https://questioningthedata.wordpress.co ... time-ever/

[Monty]

Nudge the ridge a touch west and add a bit of tilt and we've got an excellent Arctic blast in the Nov thru March timeframe. Too bad it's occuring now.

The placement of the blob currently is reminding me of 2016...warmest anomalies placed in the GOA rather than hugging the direct coastline.

2008 saw a persistent pattern similar to this in late August, so it’s not a bad sign.

3807777A-5213-477D-8EB1-E0BCC8347A15.gif

6E5C99C0-8F34-4484-AB76-3689CCD2A6D3.gif

[Typeing3]

2008 saw a persistent pattern similar to this in late August, so it’s not a bad sign.

3807777A-5213-477D-8EB1-E0BCC8347A15.gif6E5C99C0-8F34-4484-AB76-3689CCD2A6D3.gif

That was probably our last legitimately cool mid to late August period. Throwback to the 1990s

[Abby_wx]

Between last year and this year Environment Canada has changed to the criteria for Abbotsford (actually, Hope to the Surrey). It now only needs to be 17 as the low and 33 as the high (instead of 18 and 35). Still, in the past 4 years only Hope has managed to meet that one. Nothing for YXX, Agassiz, Pitt Meadows, or Cultus Lake.

See update at the bottom of this page: https://questioningthedata.wordpress.co ... time-ever/

Good catch. That's a lot better than before, actually. I think it still need a bit of tweaking, though.

What's odd to me is that Vancouver is generally warmer at night on average, yet their overnight threshold is a degree lower than the Fraser Valley.

I looked at the overnight lows for the last four mornings at Vancouver and Abbotsford. I'll spare you the math but Vancouver averaged just under 13.8C, compared to 12.7C for Abbotsford. It's going to be a lot easier for Vancouver to reach their 16C threshold than for Abbotsford to reach their 17C threshold.

Edit: Average overnight lows in July.

Vancouver 13.7
White Rock 13.0
Abbotsford 12.2
Chilliwack 12.5
Hope Slide 9.1

[Glacier]

Good catch. That's a lot better than before, actually. I think it still need a bit of tweaking, though.

What's odd to me is that Vancouver is generally warmer at night on average, yet their overnight threshold is a degree lower than the Fraser Valley.

I looked at the overnight lows for the last four mornings at Vancouver and Abbotsford. I'll spare you the math but Vancouver averaged just under 13.8C, compared to 12.7C for Abbotsford. It's going to be a lot easier for Vancouver to reach their 16C threshold than for Abbotsford to reach their 17C threshold.

Edit: Average overnight lows in July.

Vancouver 13.7
White Rock 13.0
Abbotsford 12.2
Chilliwack 12.5
Hope Slide 9.1

A heat warning should be issued whenever the forecast mean is more than two standard deviations above the hottest day of the year for two or more days in a row.

Or alternatively, when the mean is forecast to be 25C for two days in a row, irrespective of where you are in the country.