Winter Weather in Nern P.w. Snd, Alaska

Alaska 511 (Department of Transportation) reported freezing rain and ice buildup on the Richardson Highway for the 5 AM AKST report on October 16th from MP 18 to 30 of the Richardson Highway near Thompson Pass. A DOT provided surface observing site in Thompson Pass recorded 'unknown precipitation' for several hours through the afternoon of October 15th, with temperatures then remaining above freezing for the duration of remaining precipitation. Ice and slush covered roads were also clearly visible on webcams along portions of the Richardson Highway through the early morning of October 16th.

Following quickly on the heels of a heavy snowfall event a few days prior, another low pressure system and front moving into the Gulf of Alaska brought a second round of impactful winter weather that affected a large portion of Southcentral between mainly October 14th and 15th. Once again, cold temperatures in place away from the immediate coast were able to remain stubbornly entrenched over valleys from the surface to around 1000 ft above ground level as warm, moist air advected overtop of the colder air mass in place in association with the low and front approaching the northern Gulf coast.

This system was able to push a much more pronounced warm nose of air above freezing overtop of the colder air in place as precipitation moved across Prince William Sound and into the Copper River Basin on October 14th, then shifting and expanding into the Susitna Valley and Anchorage area on October 15th, with heavier precipitation finally letting up across the entire region by the morning of October 16th. The temperature profile for much of the event was favorable for a mixture of snow, sleet and freezing rain due to the warmer air intruding aloft over a shallow layer that persistently remained below freezing for the duration of the event. The heaviest freezing rain accumulations were reported over the Copper River Basin, where up to 0.25 inches of accumulating ice was observed.