* WHAT...Long duration cold temperatures in the 40s below zero to around 50 below zero starting tonight, continuing through the weekend. * WHERE...Chatanika River Valley, Eielson AFB and Salcha, Fairbanks Metro Area, Goldstream Valley and Nenana Hills, Nenana, Tanana Flats, Two Rivers, Upper Chena River Valley, Upper Koyukuk Valley, Dalton Highway Summits, White Mountains and High Terrain South of the Yukon River, Delta Junction, Central Interior, Northern Denali Borough, and Eastern Alaska Range North of Trims Camp. * WHEN...Until 3 AM AKST Monday. * IMPACTS...Frostbite and hypothermia will occur if unprotected skin is exposed to these temperatures. Very cold temperatures can lead to hypothermia with prolonged exposure. * ADDITIONAL DETAILS...The coldest temperatures so far this cold snap are likely still to come. The inversion that has kept hills warmer will slowly weaken through the week as colder air aloft filters back over the area. By Friday night, valley temperatures may approach 50 below with the warmest hills near 30 below. These conditions will continue through the weekend. Clouds are not expected to return until early Monday morning at the earliest. Calm or very light winds will allow for areas of ice fog to continue, leading to poor visibility and difficult travel conditions.