Day 3 of Nome, AK (PAOM)

 Well, Nome is constantly throwing curveballs at us, but it’s Alaska, right? It seems like the outlier GFS is at least partially right for never bringing the warm sector into Nome (still 25F), with easterly surface winds just having flipped to northerly and not as strong as expected, not much stronger than yesterday. The low-level cold air that’s entrenched is preventing strong winds from mixing down from aloft effectively. Snow fell heavily for longer than expected and despite potential precipitation undercatch with snow and wind, the station still recorded 0.61” of precip. The warm, moist Pacific air ramming into an extremely cold Alaskan air mass, in addition to slight upslope enhancement (southeast winds just aloft ramming into mountains just to the north) really does wonders in producing ascent and precipitation. The snow and associated sublimational cooling at the start led to a morning low of 17F, but it remains to be seen if it will get lower than that by 06z tonight. The wind direction change could still cause more vertical mixing and a brief temperature spike, albeit less than earlier thought with the low-level cold air mostly winning out. Partly cloudy skies with light winds should lead to decent radiational cooling tonight, especially with the fresh snow cover. With the radiational cooling but low-level moisture leftover from the snowstorm and no strong advection of dry air at the low-levels, freezing fog and low-level clouds will form, and combined with easterly winds and warm advection returning later in the day, it will warm up, leading to the high at Friday 06z.

 

Source: TropicalTidbits

 

Source: PivotalWeather

 

Source: Meteogram Generator

 

Day 2 of Nome, AK (PAOM)

 Tough low forecast last night with it dropping to -2F before 06z but then wind increased to just above the threshold for good radiational cooling by 06z, so the low will be 4F. Really could have gone either way and it would have been -5F had it been a bit calmer. Easterly winds are strengthening and already reached 14 kt, stronger than expected so far, and will continue to increase tonight into tomorrow and shift to southeasterly. The winds are advecting warmer air (16F already), so it will continue to warm up tonight and spike tomorrow morning, accompanied by thickening clouds and snow as the storm in the Bering Sea approaches. There will be a steady snow for 4-6 hours as the warm front passes through. Temperatures will briefly spike in the afternoon for a couple of hours as Nome barely enters the warm sector with westerly wind, before winds turn to northerly with cold advection in the evening. Models usually underdo these spikes, so I am leaning to the warm side for the high. Winds will weaken with skies clearing somewhat, leading to some radiational cooling, but it’s not clear if it can get any lower than the early low at Wednesday 06z.

 

Source: NWS

Source: TropicalTidbits

Source: PivotalWeather

Source: Meteogram Generator

Day 1 of Nome, AK (PAOM)

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.

 

Source: NWS

Source: PivotalWeather

Source: Meteogram Generator