The National Weather Service has extended a freezing rain advisory Tuesday for the Matanuska Valley, as the Susitna Valley sees heavy snowfall Tuesday -- with more on the way during the afternoon.
The Matanuska Valley advisory -- in effect until 5 a.m. Wednesday for areas to the west of Wasilla -- described a "mixed bag" of weather over the region, as air at varying temperatures blended.
"Cold air remaining in place over the northern Susitna Valley will keep precipitation primarily in the form of snow," forecasters wrote. "Warm air is spreading northward into the Matanuska Valley and southern Susitna Valley, resulting in a mixture of rain, snow and freezing rain. These conditions are expected to continue through early Wednesday morning."
Anchorage dispatchers said police had responded to seven accidents since midnight, with no injuries reported, but had seen 29 vehicles in distress by 1 p.m. Tuesday as temperatures rose into the 40s across Anchorage.
Icy conditions earlier Tuesday were sufficiently severe to close most schools in the Matanuska-Susitna Borough School District. On the district's Facebook page, officials said Superintendent Deena Paramo had ordered the closure of all schools in the district except the Glacier View School in Sutton and the Alaska Middle College School on the Eagle River Campus.
On the Anchorage School District's Facebook page, officials said schools would be open, but parents who kept their children home because of travel concerns could call schools and receive an excused absence for the day. Both the University of Alaska Anchorage and Mat-Su College in Palmer were open and holding regular classes Tuesday.
Police reported vehicles sliding off parts of the Glenn Highway near Birchwood and Eagle River on Tuesday morning. While the initial freezing-rain advisory in effect until 1 p.m. Tuesday focused on the Glenn from Palmer to Chickaloon, Anchorage-based Weather Service meteorologist Joe Wegman said conditions on the highway between the Matanuska Valley and Anchorage might also be treacherous.
"Toward the Matanuska Valley, temperatures are getting just barely above freezing," Wegman said. "Especially because it's been so cold lately, there's concern that there's ice on the roads."
On Tuesday morning, reports from the Susitna Valley were bearing out the Weather Service's forecast of heavy snowfall overnight Monday in the area,
"Near Trapper Creek we've had 11 inches since yesterday," Wegman said. "Willow has has 7 or 8; Chulitna has had 13 in the last 24 hours; Cantwell has had 15 inches."
The Susitna Valley is now under a winter storm warning until 4 p.m. Tuesday. According to the warning, areas north of Talkeetna can expect an additional 10 to 15 inches of snow, with 3 to 6 inches falling south of Talkeetna.
"Pretty much the entire Su Valley is well below freezing at 10, 15 degrees," Wegman said. "We do know, certainly over the past week, they've been getting slammed up there; they've gotten at least 18 inches of snow, probably more."
An earlier version of the freezing rain advisory stated that projections weren't clear as to "how quickly and how far north" snow would become freezing rain Tuesday. Wegman said the shift depends on where warmer air stops mixing with cold layers in the Mat-Su.
"We're thinking somewhere between Willow and Wasilla is where that transition occurs," Wegman said.