COLCHESTER, Vt. - It's early April, and the snow in the mountains of Vermont holds the equivalent of 15 inches of rain.
Emergency planners in Vermont - and in New Hampshire Maine, where the mountains hold similar snowpacks - know that in the next few weeks the snow is going to melt, filling rivers and streams to the tops of their banks. If heavy rains start soaking the snow, the region could experience significant spring flooding, specialists warn.
There is a flood watch in effect through this afternoon for much of Vermont, but the ice is out on most rivers and streams, and ideal melting conditions are forecast for the next several days: daytime temperatures just above freezing and nighttime temperatures below freezing.
Officials from the National Weather Service and Vermont Emergency Management are urging people to be vigilant.
"If we get the wrong conditions we're going to have a serious problem," said Mark Bosma, Emergency Management spokesman. "We don't want to cause alarm, but the conditions are not good."
Even if ideal snow-melt conditions persist and areas along rivers escape flooding, it is likely that Lake Champlain will reach its flood stage of 100 feet. Yesterday the lake level was about 98 feet.
In New Hampshire, officials have been warning residents for weeks to prepare for the flooding after a winter that dumped more snow in some areas than has been seen in a century. The New Hampshire Transportation Department is reviewing detour routes, stockpiling equipment, clearing culverts and drainage areas, and asking communities to do the same.
The Maine Emergency Management Agency said the state's most flood-prone months are April, January, and March. The agency advises homeowners to have personal evacuation plans and to check on flood insurance coverage.
The Weather Service predicts fair weather through tomorrow night before showers return Friday.
The last time Vermont had this much snow this late in the year was 2001. That spring's perfect melting weather with no significant rains drained the state without serious flooding.
For the next week, the forecast calls for cold nighttime temperatures with daytime temperatures just above freezing. There is no significant rain in the forecast. But the ideal conditions seven years ago presaged an extended dry spell.
"I'd hate to wish us into a drought," said Greg Hanson, a hydrologist with the Weather Service office in South Burlington.
One evolving tool in the Vermont's emergency management kit is the National Guard's Joint Operations Center at Camp Johnson in Colchester. There, soldiers monitor the conditions on the ground so the Guard can be ready to respond as needed, be it with earth-moving equipment, high-wheeled vehicles that can drive through flood water, or generators.
"Our job in here is to stay that one step ahead, so the adjutant general will be expecting the call from the governor," said Major Scott Tousignant, in charge of the Joint Operations Center.
The National Guard supports other state agencies only after being ordered to do so by the governor, said Lieutenant Colonel Sonny Schumacher, the guard's director of military support.
The new system, developed after the 2001 attacks on the United States and Hurricane Katrina highlighted failures in the national response, is designed to bring the resources of the entire National Guard to bear within hours.
"You can't be caught flat-footed," Schumacher said.