by Lorien Nettleton ~ April 25th, 2013
The National Weather Service River Forecast Center is keeping an eye on chaining temperature conditions that will play a role in how rivers around the state break-up for spring.
Hydrologist Scott Lindsey says the colder-than-average April has delayed the point at which maximum ice thickness is reached. This means the ice on the rivers hasn’t had as much chance to deteriorate. That, combined with ample low-elevation snow-pack, could mean trouble if there is a sharp warm-up with temperatures in the 60s for several days.
While Lindsey says that in South Central it is not typical for rapid melting of snow melt to cause flooding problems, it is more likely that cold or saturated ground can cause issues with drainage, where water is trapped on the surface.
The longer weather conditions follow a freeze-thaw pattern, with temperatures in the 40s during the day to below freezing at night, the more time there is for the river ice to become brittle and break-up into smaller chunks that can be swept out. Lyndsey says the forecast looks as though it will stay cooler for the time being, which diminishes chances of dramatic ice activity.
The River Forecast Center does not have records of spring flooding due to break-up on the Talkeetna river. For the hydrologists, a bigger concern is on the Susitna river, where the main river channel shifted eastward in 2012, bringing the river to bear more directly toward Talkeetna. Lyndsey says he sees potential for the re-directed river channel to bring large amounts of ice towards town.