Flood Watch covers Susitna Valley and Hatcher Pass through Thursday

A Flood Warning is in effect for the Yentna River above Lake Creek, and a broader Flood Watch covers the Susitna Valley and Hatcher Pass through 4 p.m. Thursday, July 23.

The Yentna River above Lake Creek is forecast to reach Minor Flood stage by Thursday evening and crest around 20.8 feet late Friday morning before falling below flood stage by Saturday morning. Flood stage there is 20.5 feet, the level at which water begins to enter several low-lying cabins. The Flood Watch covers Skwentna, Willow, Talkeetna, Trapper Creek, Petersville, and Chulitna, and extends into Hatcher Pass.

This is not an isolated event. The National Weather Service in Anchorage has issued a series of hydrologic outlooks and flood advisories for the Yentna and Skwentna River basins dating back to mid-July, and a flood advisory for the Western Susitna Valley was in effect through midday Wednesday. Rivers were already running high before this week's storms arrived.

Two storm systems are driving the current concern. The first brought 0.50 to 1 inch of rain from Tuesday afternoon through Wednesday morning. The second arrives Wednesday evening and runs through Thursday afternoon, with an additional 1.0 to 2.5 inches forecast at 70 to 80 percent probability. Combined, the two events could deliver up to 3.5 inches on already-elevated waterways. The highest rainfall totals are expected over the northern and eastern Susitna Valley along the Talkeetna Mountains.

The National Weather Service in Anchorage warns that low-water crossings may be flooded and that fast responding rivers and streams along and east of the Parks Highway are most susceptible to rapid rises.

The Flood Watch is a step below a Flood Warning. The National Weather Service says a Warning upgrade is possible if conditions worsen. The agency advises residents in flood-prone areas to monitor local radio, television, or NOAA Weather Radio. River conditions can be reported to the NWS river forecast center at 907-266-5160.