textproduct: Anchorage

SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)

Key Messages:

- Some of the coldest temperatures and wind chills of the season are expected across Southcentral to continue through this weekend. An Extreme Cold Warning is in effect for the Copper River Valley, including Glennallen and Chitina through Sunday. Cold Weather Advisories are in effect through Sunday for most of the Copper River Basin, Thompson Pass, Anchorage, Whittier, and Western Kenai Peninsula. Apparent temperatures well below zero are expected. Frostbite and hypothermia are likely if exposed to these temperatures.

- Frostbite on exposed skin can occur in as little as 5 minutes. Prepare for the weather by wearing appropriate clothing, hat, and gloves. Protect your pipes and trickle faucets. While traveling, use caution. Carry extra supplies and wear your winter gear while traveling. Check on yourself and others who may be vulnerable to these temperatures.

- Most of southern Alaska should plan ahead and prepare for a significant switch towards a snowier weather pattern expected late this weekend and next week. Monitor for updates to forecast as details evolve through this weekend.

Other than the cloud cover lingering near McCarthy and Cordova, frigid cold and clear conditions remain this morning as northwesterly flow continues across Southcentral. Gusty winds flowing through coastal terrain gaps are a little stronger than expected this morning and those winds are expected to persist until Sunday morning when the pattern shifts. Calm winds and clear skies across the rest of Southcentral will continue to allow for bitterly cold temperatures to stick around through the weekend. Ambient high temperatures will continue to be in the single digits above and below zero across the Cook Inlet region (Anchorage, western Kenai, Mat-Su) and in the teens for much of the immediate coastline along the northern Gulf and Prince William Sound (including Seward, Whittier, Valdez, and Cordova). Low temperatures across Cook Inlet communities and into the Mat-Su could see low temperatures in the minus single digits to nearly 30 below. Meanwhile, the Copper Basin will likely be in the range of 20 to 30 below zero for the highs and lows of 30 to 60 below zero. Although winds are expected to generally remain calm, any bit of wind would drop the apparent temperatures lower.

Temperatures are set to trend relatively warmer and become more dynamic heading into early next week. Confidence is increasing for a return to snowfall for many locations across southern Alaska, including Southcentral. Current thinking is for precipitation to begin Sunday afternoon/evening for Kodiak Island and lift north and east through the Kenai Peninsula and Prince William Sound by midnight. Anchorage could see snow by midnight, give or take a couple hours. The Susitna Valley, the rest of the northern Gulf coast (Cordova), and Copper River Basin are likely to see snowfall through the overnight hours Sunday and into Monday morning. Cold surface temperatures will likely not scour out very quickly and any gusty winds could cause dry, fluffy snow to blow and drift easily. Reduced visibility and blowing snow will be a potential problem, especially of locations prone to gustier winds such as Thompson Pass. Once stronger easterly flow moves across the Kenai and Chugach mountains later Monday morning, there could be some downslope drying, cutting off snowfall briefly for those on the leeside. However, another wave of snow will quickly follow later on Monday, with precipitation enhancement for the Cook Inlet communities. Higher snowfall rates and accumulating snowfall amounts is possible with the snow liquid ratios on the higher side. Details on this shift towards a more progressive and snowy pattern are expected to evolve over the next few days. Monitor for updates to forecast.

Rux/JH

LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)

Multiple waves of low pressure moving over southern Alaska will keep the region wet through Tuesday night with rain along the Aleutian Chain and widespread snowfall for Southwest and Southcentral Alaska. Expect strong northwesterly winds out of Alaska Peninsula bays and passes as low pressure pulls east of Prince William Sound Tuesday and Wednesday.

Guidance is hinting at another strong North Pacific low pressure system lifting up into the Eastern Aleutians and Alaska Peninsula on Thursday. There is significant disagreement regarding exact timing and placement, but it looks likely this system will bring a round of heavy precipitation to the southern coast of Alaska. High winds will also be a threat with this system as it possibly deepens to around 950mb by Friday morning. A lot may change with this system as it is still a week away but we will keep a close eye on it going forward.

AVIATION

PANC... VFR conditions with light and variable winds will persist through the TAF period.