We
resume after the 1-week break. Nome, AK is going to be quite the
challenge to forecast for. Just to start off, temperatures this morning
fluctuated between -4F and 12F with clear skies and a light
northeasterly wind. Since there is snow cover to efficiently radiate
heat into outer space and almost no solar radiation to mix the boundary
layer at this time of year, when skies are clear, there is a permanent
nocturnal inversion with high spatial variability which is more
pronounced when winds are light. With mostly clear skies through
tomorrow morning with just a few thin cirrus clouds, surface
temperatures will be dictated by “random” slightly stronger gusts of
wind that mix warmer air down to the surface or horizontally from
elsewhere (sometimes 10F or more warmer). This kind of chaotic surface
layer temperatures with little vertical mixing are extremely hard for
models to grasp. Nonetheless, the low should occur tonight before modest
warm advection begins aloft as the cold high pressure moves off to the
east. Light northeasterly winds might increase somewhat and shift to
easterly towards the end of the day (towards Wednesday 06z-09z), but
that depends on how strong the nocturnal inversion is. Increasing and
thickening low and mid-level clouds and warm advection will lead to a
significant warmup, even without solar radiation, with the high
occurring near the end (Wednesday 06z). Note that the high resolution
models we’re used to and could really use at a coastal location with
strong land-to-sea temperature contrasts are not available in Alaska.
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