Surface Climate and SnowWeather Relationships of the Kuparuk Basin
25
come from the SE to E. The strongest wind of record occurred in October at the
coastal plain sites, with the October record at FRA of 26.4 m s1 (59 mph) being
the highest wind speed recorded on the network during this five-year period. In
summary, EC in the uplands results in low wind conditions, while the coast and
coastal plains are windier.
Deep Cold
Mean wind regimes seem to be best established during DC, with the coastal
plains sites BET and FRA the windiest, the uplands between the coastal plains
and the Brooks Range foothills having seasonally the weakest winds found in the
record, and foothills IMN falling between these two regions. The same regimes
generally exist for peak winds, except IMN, which has sufficient windy episodes
to bring the smoothed results similar to those found along the coast.
The coastal locations show a gradual increase in mean winds from a mini-
mum in early December and a strongly preferred wind direction from the NE to
E. This preference becomes even more pronounced when considering the strong-
est winds, which are almost exclusively northeasterlies. It is curious that PRU
shows a decided preference for strong westerlies. (It should be noted that the
PRU record for these years shows much less likelihood for winds ≥10.0 m s1
than the other coastal stations. We were unable to determine a reason for this dis-
crepancy.)
Considering the direction for winds of all speeds, IMN has a fairly uniform
distribution throughout the octants. As wind speed increases, however, the slight
preference for southerlies becomes more and more pronounced, almost com-
pletely dominating the record for the strongest winds. DC is also the most likely
season for winds at IMN to exceed the 10-m s1 threshold. IMN's location on the
northern edge of the deep Atigun Valley makes it ideally situated to experience
strong southerly channeled flow during periods when interior Alaska is experi-
encing high surface pressure. Such gap flows (Reed 1931, Scorer 1952) are
commonly observed in other regions of Alaska where mountains separate dispa-
rate air masses (e.g., Macklin et al. 1990, Bond and Macklin 1993). Since DC is
also the most likely time of year for the existence of the stability criteria that
support mountain waves and the development of supercritical flow (e.g., Durran
1986, Klemp and Lilly 1975) associated with downslope windstorms as well as
those favoring gap flows, it seems likely that these southerly wind events are
inherently mesoscale in nature and likely confined to a region near and to the lee
of the higher terrain of the Brooks Range. At lower wind speeds the intermediate
sites of SAG and WKU both show the preference for NE winds seen on the
coastal plain. However, for the strongest winds the probability of winds from the
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