WASHINGTON, June 18, 2014 -- The
final water supply forecast for this year shows the West divided into a
wet north and dry south while snowpack has already melted in much of
the region, according to data from the USDA National Water and Climate
Washington, most of
Idaho, Montana, Wyoming and the northern parts of Colorado and Utah are
expected to have near normal or above normal water supplies through the
rest of summer, according to the forecasts. Far below normal streamflows
are expected for the southern parts of Oregon and Utah, southwestern
Idaho, California, Arizona, New Mexico and western Nevada.
Many of these areas
are in the nearly 500 counties across the country experiencing drought,
57 of them in California alone, according to USDA disaster designations.
This year saw
near-record low snowfall in parts of Nevada, California, Arizona, New
Mexico and the southern parts of Utah and Oregon. Even with some May
precipitation, those areas remain dry. The biggest change this season
was in the Washington Cascades. At the beginning of February the
snowpack was about half of normal, but it recovered and most of
Washington will have a near normal water supply from snowmelt, according
to the Center.
Spring snowmelt is
well underway, according to NWCC hydrologist Cara McCarthy. “A lot of
our SNOTEL sites have already melted out, especially those in the
southern half of the West,” McCarthy said.
Colorado had mixed
weather during May. “They had winter and summer all in one month:
snowmelt, snowfall, snowmelt,” said McCarthy. Heavy precipitation
combined with snowmelt, causing flooding in parts of the state.
conditions all year, but June is the final forecast of the season.
“These are snow-based water supply forecasts,” McCarthy said. “Typically
by July there won't be enough snow left on the ground (to measure).”
In Western states
where snowmelt accounts for the majority of seasonal water supply,
information about snowpack serves as an indicator of future water
availability. Streamflow in the West consists largely of accumulated
mountain snow that melts and flows into streams as temperatures warm
into spring and summer. USDA scientists analyze the snowpack, air temperature, soil moisture and other measurements taken from remote sites to develop the water supply forecasts.
The NWCC water supply
forecast is part of several USDA efforts to improve public awareness and
mitigate the impacts of climate change, including drought and other
extreme weather events. Through the creation of the National Drought
Resilience Partnership, launched as part of the President’s Climate Action Plan, federal agencies are working closely with states, tribes and local government to develop a coordinated response to drought.
Since 1939, USDA has conducted snow surveys and issued regular water supply forecasts. View information by state.
In dry years most Therophytes like Asteriscus aquaticus are able to flower as very small plants and produce seeds that are able to survive evon more unfavourable seasons.