The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through May precipitation was near 65 percent of average in the Upper Colorado mainstem basin. May was the third month in a row with much below average precipitation coming in at just 35 percent of average.

Snow:
As of June 1st there was essentially no snow left at any of the SNOTEL sites within the Upper Colorado mainstem basin. Many of these sites melted out at the earliest time in their 30 year history this year.
--- Upper Colorado basin snow water equivalent plot

Streamflow:
May streamflow was much below average in the basin as a whole. Monthly volumes at individual sites ranged from 20 to 70 percent of average.

Soil Moisture:
Modeled soil moisture states were above average heading into the winter.

Climate Forecasts:
La Nina climate conditions existed throughout the winter but these do not show a strong correlation with winter precipitation in the Upper Colorado mainstem basin, and therefore were not influential in the development of streamflow volume forecasts.

Forecast Summary:
A wet October was followed by much below average precipitation in November and December. Near average precipitation occurred in January and February. March, April and May were warm and dry causing the early meltout of a near record low snowpack. As a result, the seasonal runoff forecasts have been continually reduced the last few months. Most of the June through July forecasts are for volumes that would be the 2nd lowest on record if they occurred, while most of the April through July forecasts would be in the bottom 3 of their historical records. Current June through July streamflow volume forecasts range between 12 and 35 percent of average with a median value of 30 percent. Current April through July streamflow volume forecasts range between 30 and 50 percent of average with a median value of 40 percent.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through May precipitation ranged from 50 to 80 percent of average in most of the Gunnison River Basin.

For the third consecutive month very dry conditions were experienced in the Gunnison Basin. May precipitation ranged from 10 to 50 percent of average at most locations. The Basin average precipitation was 30 percent of average.

Snow:
The snow had melted out of nearly all measuring sites by June 1st. The snow melt was very early this season due to the warm dry spring. Many sites were void of snow a full 4 to 6 weeks earlier than average.

Gunnison Basin snow water equivalent plot

Streamflow:
Streamflow volumes for May were much below average due to the lack of snow. Runoff volumes for the month of May ranged from 25 to 70 percent of average at most locations. Volumes below 20 percent of average occurred at lower elevation streams where snow had melted out during April.

Soil Moisture:
Modeled soil moisture states were above average entering the winter season.

Climate Forecasts:
La Nina climate conditions existed throughout the winter but these do not show a strong correlation with winter precipitation or Apri-July runoff volumes in the Gunnison Basin. Therefore they were not influential in the development of streamflow volume forecasts.

Forecast Summary:
The 2012 season was defined by extremely dry and warm conditions during the spring, with record or near record low snow amounts due the dry conditions and early snow melt. Seasonal runoff forecasts were progressively reduced throughout the season as the dry conditions persisted. Forecast runoff volumes were reduced slightly from those issued in early May. Several April-July forecasts are the 2nd or 3rd lowest on record. For June-July many some volume forecasts are the lowest on record.Record Seasonal April-July streamflow runoff volumes are expected to range from near 10 to 50 percent of the 1981-2010 average. June-July streamflow runoff volumes are expected to range from near 5 to 30 percent of average.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October through May precipitation ranged between 60 and 85 percent of average at most locations in the Dolores Basin.

May was the third consecutive month with very dry conditions in the Dolores Basin. May precipitation ranged from 0 to 15 percent of average at most locations. The Basin average precipitation was near 5 percent of average.

Snow:
The snow had melted out of nearly all measuring sites by June 1st. The snow melt was very early this season due to the warm dry spring. Many sites were void of snow a full 4 to 6 weeks earlier than average.

Dolores Basin snow water equivalent plot

Streamflow:
Streamflow volumes for May ranged from 35 to 65 percent of average in the Dolores Basin.

Soil Moisture:
Modeled soil moisture states were near average entering the winter season.

Climate Forecasts:
La Nina climate conditions existed throughout the winter but these do not show a strong correlation with winter precipitation or April-July runoff volumes in the Dolores Basin. Therefore, it was not influential in the development of streamflow volume forecasts.

Forecast Summary:
The 2012 season was defined by extremely dry and warm conditions during the spring, with record or near record low snow amounts due the dry conditions and early snow melt. Seasonal runoff forecasts were progressively reduced throughout the season as the dry conditions persisted. Forecast runoff volumes were reduced slightly from those issued in early May. Some forecasts are among the bottom 5 on record. Forecast April-July streamflow runoff volumes are expected to range from 30 to 45 percent of the 1981-2010 average. June-July streamflow runoff volumes are expected to range between 15 and 30 percent of average.

Differences between the full period forecasts and the residual forecasts may not exactly equal the actual observed volumes due to rounding conventions (see Definitions section).