Flood — Matanuska Valley, Alaska

2022-08-08 to 2022-08-10 · near Wasilla, Matanuska Valley, Alaska

Event narrative

Flooding was verified by Alaska State Troopers in Wasilla. The Regional Operations Center and the State Emergency Operations Center reported on August 8th, 2022 at approximately 22:09 hours, Alaska State Troopers (AST) began receiving multiple 911 calls reporting flooding in the area of Schrock Road and Sitze Road in Wasilla. AST responded to the area discovering the road has been washed out and is impassible just past the Little Susitna River Bridge due to a culvert failing. Matsu Borough along with DOT is on scene working to repair the culvert and roadway. It's also been advised there is a bridge farther down Sitze Road that may be compromised and is being assessed. At this time, residence past this washout are un accessible. Additional patrols of the area also discovered North Sushana Drive is impassible due to the Little Susitna River flooding the road. These neighborhoods are also un accessible at this time. There were pictured posted on social media from the Alaska State Department of Transportation. SEOC also forwarded maps & pics of flooding in Houston. A news article with pictures can be seen here: https://www.adn.com/alaska-news/mat-su/2022/08/09/mat-su-flooding-closes-roads-threatens-homes-after-deluge-soaks-talkeetna-mountains/.

Wider weather episode

The set up was a broad longwave trough in place over much of the Bering Sea through southern Alaska. Embedded in this broad longwave trough was an upper level low meandering over the Yukon-Kuskokwim Delta. Multiple upper level shortwaves rotated around this upper level low along with a jet stream aimed right up Cook Inlet into Southcentral. The southwesterly flow at 700 millibars was also very moist with all this moisture being advected northeastward into the Cook Inlet region and Mat-SU Valleys. As a result, heavy rain occurred throughout the region resulting in flooding for some areas.

View location on OpenStreetMap → (61.6711, -149.5246)

Source: NOAA Storm Events Database, event_id 1050699. Narrative written by the NWS forecast office that issued the report.