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Hi Chris,

The climate divisions are effectively unrelated to the PHA. They are geographic regions selected to identify regions within Alaska that share similar climate regimes, to the extent that is possible. They show up on maps like this: https://www.ncdc.noaa.gov/monitoring-content/sotc/national/divisionalta… ... The methods used to define those (Bienek et al.) were independent of PHA.

PHA is useful to get the best long-term values on a station-by-station basis. Then its job ends. The resulting values are then used in subsequent analysis, like the interpolation we do to come up with the gridded data set that is then used to compute these divisional values.

There are 982 Alaskan stations on the GHCN-Daily roster. Some of those are defunct/retired. A fraction of those remaining report in a timely enough manner to be used in the latest month's climate analysis. I'd say "a few hundred" which includes a handful in bordering parts of Canada that help inform near-border analysis. I'll have to get back with you with exactly how many went into, say, the January 2018 analysis.

The USHCN has not been used operationally as a network since 2014. The stations that were part of USHCN are incorporated into GHCN. USHCN is no longer relevant to discussions of US temperature.

Deke