Wildfire — Copper River Basin, Alaska

2023-07-24 to 2023-07-25 · Copper River Basin, Alaska

Event narrative

The Global Lightning Detection Network and daily lightning summary from the Alaska Inter-agency Coordination Center and Bureau of Land Management showed numerous lightning strikes across much of the Copper River Basin during the afternoon and evening of 7/24. This lightning occurred for several hours in intense thunderstorms observed on satellite and radar, with one thunderstorm cell moving into the area of greater concern for drier fire fuels over Glennallen and Gulkana late at night on 7/24, or right around 12 am AKST 7/25. In spite of this, no new fire starts were reported.

Wider weather episode

A strong ridge of high pressure developed over Canada and spread into Southcentral near the end of July 2023. Recent wet, cool and cloudy conditions over the region quickly snapped to sunny and warm weather as the high pressure moved into place, resulting in a large release of water vapor from evaporation from wet soils and transpiration from plants/trees. A cap of warm, dry air coupled with high temperatures and moisture near the surface allowed large amounts of instability to build up through the afternoon of 7/24, with thunderstorms with frequent lightning developing as the cap broke. Most of the lightning activity occurred where fuels were wetter on the north side of the Copper Basin, but a late night thunderstorm with fairly frequent lightning eventually was able to move off of the Wrangell Mountains into Glennallen and Gulkana where fuels were much drier near 12 AM AKST 7/25. Fortunately, no new fire starts were recorded despite the ample lightning activity observed for most of the afternoon and evening.

Source: NOAA Storm Events Database, event_id 1105291. Narrative written by the NWS forecast office that issued the report.