2 thoughts on “NWAC Weather Forecast Timing

  1. Hi Charlie,

    Dennis here from NWAC. If I had known the bins were 1/2 an hour… I would have doubled down to get my forecast out by 8 am; 8:02 am doesn’t look as good in the chart! đŸ™‚

    It’s been a strange season so far, but we hope you’ve found the Mountain Weather Forecast useful at it’s slightly later morning issuance.

    I thought I’d add a couple of pieces of insight to how we create the forecast.

    1.) The morning forecast issuance is based primarily on the 06Z and 00Z forecast runs. The afternoon update usually only maintains minor tweaks based on 12Z guidance. The most common changes in the afternoon will likely deal with precipitation amounts and snow levels, and most likely over the short term period. Our attention turns to the avalanche forecast by late morning, so we only focus on big weather forecast changes in the near future. Future changes to the mountain weather forecast may include an easy guide to see what’s been changed with the afternoon update.

    2.) In the Mountain Weather forecast, we have broken the North Cascades freezing/snow level and 9000 ft winds into two separate forecast zones, the NE Cascades (Washington Pass-Mazama) and NW Cascades (Mt. Baker area). This was done to better serve our partners (NCH/NCMG) and public operating out of the Methow Valley. Also, we removed the 9000 ft wind forecast for the Olympics.

    If you have any questions about how we create and produce the forecast, I’d be happy to answer them.


    • Hi Dennis!

      We’re super happy to have NWAC forecasts whenever they come out, and that you guys get more sleep!

      The binning was determined by the distribution of the morning data; if I’d dug further backward in time, the bin-width would have been narrower. As I recall, they were ~0.4 hr wide, with datum driven by the data, so 8:02 might’ve wound up anywhere :). My intention with generating the plots was curiosity alone as we waited for your forecast; I surely didn’t intend to hurry anything. I’d rather have a slightly-later forecast that’s more accurate than a earlier one that contains a meaningful error.

      Thanks for your forecasts and your comments! I’ve always regarded the afternoon update as a tweak on the morning’s expectations.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s