[Equest-users] New CWEC files and snow/rain flags - update

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Christopher,

This is very interesting information for several reasons:

(1) the snow and rain flags are not part of the raw data stream from the weather stations,
so I've assumed they have to be extracted from the Present Weather reports,

(2) the wy3 is a derived weather file format developed for ASHRAE back in the late 1990s
so old that Env Canada might be the only place still using it; I'm not aware that the wy3
contains the snow/rain flags but they must have been put there by Env. Canada, and I would
be very interested to see how these flags correlate to what I can get from the Present
Weather data in the raw weather files.

In the little bit of time I've spent looking into this issue over the past week, I was
unsure which of the PW codes should be used for the Snow/Rain flags.? Take a look at the
attached table of Present Weather Observation Codes currently used in weather station
reports, i.e., METAR.? Should we use all the 7's as ISNOW, although 74 - 76 refers to "Ice
Pellets", and what about 85 - 87 referring to "Snow showers or intermittent rain"?
Similarly, we can use all the 6's as IRAIN, but what about? 24 (Rain), 25 (Freezing
Drizzle), etc.??? That's why I'm very interested to see what Env. Canada did.

(I'm also adding BLDG-SIM back to this post because the same issue has been in discussions
there, too.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

Joe Huang's picture
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Joined: 2011-09-30
Reputation: 206

Christopher,

This is very interesting information for several reasons:

(1) the snow and rain flags are not part of the raw data stream from the weather stations,
so I've assumed they have to be extracted from the Present Weather reports,

(2) the wy3 is a derived weather file format developed for ASHRAE back in the late 1990s
so old that Env Canada might be the only place still using it; I'm not aware that the wy3
contains the snow/rain flags but they must have been put there by Env. Canada, and I would
be very interested to see how these flags correlate to what I can get from the Present
Weather data in the raw weather files.

In the little bit of time I've spent looking into this issue over the past week, I was
unsure which of the PW codes should be used for the Snow/Rain flags.? Take a look at the
attached table of Present Weather Observation Codes currently used in weather station
reports, i.e., METAR.? Should we use all the 7's as ISNOW, although 74 - 76 refers to "Ice
Pellets", and what about 85 - 87 referring to "Snow showers or intermittent rain"??
Similarly, we can use all the 6's as IRAIN, but what about? 24 (Rain), 25 (Freezing
Drizzle), etc.??? That's why I'm very interested to see what Env. Canada did.

(I'm also adding BLDG-SIM back to this post because the same issue has been in discussions
there, too.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

Joe Huang's picture
Offline
Joined: 2011-09-30
Reputation: 206