January 9, 2003

It would take nine more snowfalls like the one January 4-5 to reach the monthly normal total precipitation in the Wisconsin River Valley according to Wisconsin Valley Improvement Company (WVIC), Wausau, the federally licensed water conservation-streamflow regulation company the operates 21 headwater storage reservoirs to regulate a uniform flow in the state's largest river.

Instead of more precipitation, however, the El Nino-influenced winter filled the valley with record warmth. A high temperature of 57 degrees was reported Jan. 8 at Prairie du Chien at the Wisconsin's confluence with the Mississippi. Seasonably cold air was forecast to flow into the valley Jan. 9-15.

January precipitation normally totals an inch. Snow that has fallen so far melted to a tenth of an inch and less. Meteorologists are describing the Midwest as experiencing a snow drought this winter. WVIC noted that what snow has fallen on the Wisconsin basin has been small in amount and melted soon after.

Warm temperatures melted the one to two inches of snow on the basin, but there was insufficient supply to produce runoff. Wisconsin River weekly average regulated flow ranged from above normal in the upper basin to below normal in the lower basin. Cold temperatures will again reduce the supply of liquid water through freezing and river flow will decline through mid-January.

The drawdown of the DuBay, Petenwell and Castle Rock flowages above the respective hydroelectric generating stations on the Wisconsin River has begun. It will continue until spring break up on the river, generally early to mid March. The gradual lowering of the water level will protect the shore from damage by ice movement and create storage capacity to assist with the routing of high flow when melting occurs.

Natural flow in the Wisconsin River at Merrill, flow occurring without reservoir operation, was 1,244 cubic feet per second (cfs) January 5, a decrease of 360 cfs. Natural flow was 92 percent of or 101 cfs below the 1,345 cfs January normal.

Reservoir release above Merrill amounted to 620 million cubic feet of water or 1,024 cfs. Release augmented natural flow by 45 percent to achieve a regulated flow of 2,268 cfs.

WVIC has reduced flow goals because of the decline in natural flow and the lack of headwater basin snowpack. Flow goals currently are 2,300 cfs at Merrill and 3,300 cfs at Wisconsin Rapids.

A combination of factors produced record high temperatures in the Wisconsin River Valley Jan. 8. A deep low pressure system that measured 29.35 inches of mercury at Wausau moved across the upper Great Lakes region. The low supported the continuance of a warm air mass from the Pacific Ocean over Wisconsin. Clouds did not block the sun, and the ground below was not covered with snow.

There were single-digit low temperatures at the beginning of the Jan. 3-9 period at both Willow reservoir in Oneida County and Wausau, but a spike up to nearly 50 degrees Jan. 7 and 8 raised average weekly temperatures 14 and 13 degrees at each location, respectively.

Strong wind accompanied the exit of the low pressure system Jan. 9 and heralded the arrival of a cold front from Canada and decreasing temperatures. Below-zero low temperatures will return the seasonably cold feel of winter and its character-building qualities to the Wisconsin Valley through Jan. 15.

As of Jan. 5, the length of time between sunrise and sunset in the northern hemisphere began to increase at both ends of the day. The earliest sunsets occur at 4:17 p.m. from December 5-15 while the sunrise continues to occur later each morning. The latest sunrises occur at 7:37 a.m. from Dec. 30-Jan. 5 while the sunsets begin to occur later each night. By Jan. 6, sunrise begins to occur earlier and sunset continues to occur later each day, and days lengthen at both beginning and end. The differences in sunrise and sunset changes occur due to the tilt of the earth's axis of rotation from vertical and the elliptical shape of the earth's orbit around the sun.

-End of Report-