The continuation of a split jet stream Feb. 21-27 had the south branch of the high altitude river of wind carry precipitation-producing storms across the country downstream of the Wisconsin River Valley and the north branch pour Arctic cold into the valley from above to sustain the dry biting character winter has displayed since mid-January according to Wisconsin Valley Improvement Company (WVIC), Wausau.

WVIC has been looking for storms to increase the supply of water in the snowpack on the Wisconsin basin that will become available to its 21 headwater storage reservoirs and the state's largest river after the last three weeks of winter. WVIC's reservoir operation is regulated by the Federal Energy Regulatory Commission because flow regulation contributes to increased hydroelectric generation at 25 power dams on the Tomahawk and Wisconsin rivers.

The short wave troughs that have rippled just under the northern jet have produced only light snowfall with little water content. When added, however, to the significant snow that fell Feb. 3-4, monthly precipitation totals at central and upper basin locations were near or at normal Feb 27.

As predicted, temperatures turned frigid Feb. 25 and 26, particularly over the northern portion of the basin. Dueling for lack of heat honors among all valley reporting stations were Harrison and Tomahawk in Lincoln County. Both reported minus 25 degrees Feb. 25. Harrison, however, dipped to minus 29 degrees Feb. 26 while Tomahawk reached minus 26 degrees.

The depth and persistence of the below-zero cold seems to numb the memory to the 44 degree and 48 degree high temperatures at Willow reservoir in Oneida County and at Wausau Feb. 21, respectively. As has been the trend, the cold lowered the results and weekly average temperatures were below normal.

Natural flow in the Wisconsin River, the flow that occurs without reservoir operation, averaged 1,117 cubic feet per second (cfs) during February, 92 percent of or 98 cfs less than the 1,215 cfs normal. After an autumn of above normal precipitation, WVIC had forecast above normal winter base flow. A cold, snowless winter has proven to be the critical variable in the forecast. Although they are opposite in degrees, cold this winter intercepted the supply of water to the river similar to the way high evaporation rates can in summer.

Waiting for warmth to release it from this winter's strong icy grip, the 430-mile long gravity induced hydraulic flowed Feb. 21-27 at below normal weekly average flow rates.

Temperatures warm enough to ripen the snow and produce runoff from melting were not in the forecast for the first 10 days of March. Reservoir operation will continue in the flow augmentation mode, albeit a gradually reducing one, until natural flow rises and surpasses the current federal license regulated target flows.

Total reservoir storage Feb. 23 of 4,889 million cubic feet of water was 28 percent of the 21 reservoirs' total capacity.

The National Weather Service Climate Prediction Center forecast cold air from Canada would bring frigid weather to the central United States March 5-6. Then, it said, forecast models differ too much to provide a confident forecast on the timing and location of significant low pressure areas during the period, but that a model run on Feb. 26 showed a broad storm system affecting the country by March 7.

-End of Report-