Things are setting up for a major surge of moisture into south central Alaska. The 0600 UTC GFS shows the setup with a pronounced upper-level short-wave trough approaching the state from the southwest at 1200 UTC 28 October (4 AM Alaska time Monday morning) and low-level fetch extending from the tropics over the Gulf of Alaska and into the state's interior.
What is most impressive about forecasts of this event is the penetration of moisture into the high latitudes. Over interior Alaska and the Yukon, for example, the forecast precipitable water (a measure of the total water vapor in the atmosphere) reaches 0.5 to 0.75 inches at 4 AM Monday morning (solid contours below). Such values aren't all that unusual over the Gulf of Alaska, but are unusual for this time of year in the Alaskan and Yukon interior. In fact, in some areas they have never been observed over the past 30 years during the 3 week period centered on Monday (color fill below).
"THE FULL EXTENT OF THE IMPACTS ARE UNKNOWN AT THIS TIME BUT SHOULD BECOME MORE CLEAR IN THE COMING DAYS."