The Howard Pass Wind Chil and Meteorlogical Records

The discussion here on Deep Cold and elsewhere concerning the wind chill values reported from the Howard Pass RAWS platform over the weekend have been useful in helping to clarify the way the meteor/climatological community thinks about "records" and what constitutes a record.

From an operational viewpoint, "on the fly" data quality evaluation is a routine, every day, indeed every hour part of the job. Doing it correctly though requires a detailed understanding of not only the general meteorological situation but details through the meso and mircoscales, the dominant physical processes, the impact of orography on the variables in question and the details of instrumentation measuring and reporting the physical parameters of interest.

Alaska, with it's complex terrain and high latitude location is an exceptionally difficult arena for meteorological quality control. In Interior Alaska, it's boringly common in mid-winter for temperatures in two locations five miles apart to be 30ºF different, and for such differences to persist for days. How would that fly in Minnesota? Now in this case we happen to have a good physical understanding of how that happens. But temperatures are simple compared to winds.

Details of terrain and instrumentation are even more important for winds than temperatures. Consider the variability of winds but relative uniformity of temperatures in the heavily instrumented areas along the Delta River south of Fort Greely or in the Healy/Denali Park Entrance area. No one who has ever driven through Glitter Gulch in winter in  during a Chinook doubts the 70 mph winds reported at Antler Creek from the RWIS and at the same time the 15 mph or less winds at the AWOS at the Denali Park train station.

So how does all this play into the Howard Pass report? We know that outlets of constricted terrain can be remarkably windy in the appropriate meteorological conditions. We know the details of the instrumentation and know it is research grade equipment. We know it was installed and is maintained by experts in high latitude meteorological instrumentation (thanks Ken and Pam!). We know that the highest resolution numerical models routinely run over Alaska do capture something of the extreme winds and temperatures observed (thanks to Richard for this useful post illustrating this). I made an educated but incomplete scour of observations some years ago for this kind of information and Brian has now systematically checked hourly observations for most of the North Slope sites that might have ever have wind chills in the 90s below.

So, as I see it, to the best of our ability to determine, Howard Pass RAWS did observe the lowest wind chill reported in real-time in Alaska, and I think we can say so with confidence. That does not mean it is certain. And certainly we can argue whether the wind speeds should be adjusted due to the low height. But this is detail: the base observation has verisimilitude, and with no other observations anywhere close (KTZA2 is 67 miles away, and IMYA2, in a completely different physiographic setting, is 42 miles away), the best hope we have for verification would be higher, say 1km, horizontal resolution modeling. Even this will simply make the case more or less solid. There can be no proof.

In the past ten years we've seen a dramatic increase in the amount of quality surface data available in Alaska. but in winter. I expect we'll see more of these kind of "oddball records".