2013 Early Spring Basin Conditions
Since the last outlook on February 20 2013, two significant rain/snow events moved through the southern half of the NCRFC region into Michigan, and a strong winter system pushed down from Canada through North Dakota, and Minnesota. These storms provided a slightly higher than normal amount of moisture for this time of year, bringing the snow pack to seasonal or slightly high levels. Temperatures have generally been seasonal, neither advancing the frost depths nor melting the snowpack to any significant extents.
Next Spring Outlook, Optional - Issuance of an outlook in late March will depend on whether or not snow melt runoff has begun.
While the winter precipitation has been normal to above normal across the NCRFC region, the soil moisture conditions remain in drought for all but Michigan, south-eastern Illinois and northern North Dakota. Still, the deep hard frost remains in most areas due to early winter freeze-thaw cycles. This frozen ground could contribute to higher and faster flooding as it impedes infiltration of melt or spring rains. This could also mean a return to low flow conditions across much of the area later in the outlook period.
Much of the NCRFC area has near normal or slightly lower chances of spring flooding from snowmelt and spring rains. The notable exceptions are in the Hudson Bay drainage where snow from recent late winter storms have provided enough snow water to push chances of flooding much above normal.
Additionally, as always, ice jam flooding is possible during the spring melt period.
See the following summaries by major NCRFC drainage area, Hudson Bay, Great Lakes and Upper Mississippi River, for more specific information on current and past basin conditions, and where conditions warrant additional detail.
HUDSON BAY DRAINAGE
Souris River Basin
The early March storm added another inch to inch and a half of snow water equivalent across the basin, bringing the totals to near 3 inches or more. Much of the upper basin snow in Canada is above the flood control reservoirs, and therefore may be able to be controlled. Flooding chances are elevated across the basin, but they are generally higher in the northern extents of the upper and lower basin than they are in the section of river running through Minot to Karlsruhe. Frozen ground will be a factor in spring runoff.
Devils Lake Basin
The early March snow storm has increased the probabilities for higher than normal inflows to Devils Lake.
Red River of the North River Basin
Drought conditions persist over much of the basin...especially across northwestern Minnesota, However, ensemble simulations are putting the chances of spring flooding at much above historical normals. The early March storm added another inch or more of snow water equivalent to much of the Red River basin. Snow water equivalent values are generally above three inches basin-wide, with the far northern valley now pushing 5 inches. The southern valley is holding 4 to 5 inches of water equivalent, with higher amounts observed in isolated areas. Significant frost depths will be a factor in spring runoff. The St.Paul District Corps of Engineers has initiated flood control reservoir drawdowns to increase their capacity to handle the expected snowmelt runoff.
GREAT LAKES DRAINAGE
Recent storms have added a half to one inch of snow water equivalent nearly uniformly across the Great Lake drainage. Overall dry conditions persist in western Upper Michigan in southern lower Michigan.
Locations across western Upper Michigan, especially the Menominee River Basin, continue in drought mode
and therefore indicate below normal chances of flood. Meanwhile, the Lake Superior shore in the Upper Peninsula
has a fairly substantial lake effect snowpack, but flood chances remain near normal. Otherwise conditions in general are indicating very near normal chances of spring flooding across the region.
UPPER MISSISSIPPI RIVER DRAINAGE
The late February and early March storms have brought most of the Wisconsin, Illinois and Missouri to very near historical normal chances for flooding. Southern Wisconsin is one pocket where above normal snow has somewhat elevated the chances of flooding. Also, snow still remains in northeast Missouri and central Illinois from the storms of late February. These locations are expected to see warm temperatures and snow melt early in the outlook period. Ensemble simulations in these areas are indicating very near historical normal flood risk, but the combination of melt and any spring rains could contribute to a heightened risk of flooding in the near future.
Iowa and southern Minnesota both received the lowest amounts of new snow. Chances of flooding are still below normal for these locations. The snow they received may help with the long-term drought, but the frost is still significant and may impede infiltration of melt or rain.
Streamflow in southern Illinois and southern Missouri has returned to nearer to normal conditions after having been at higher levels for the last outlook. Elsewhere, rivers in Iowa and the Mississippi mainstem from Iowa and downstream are at below normal levels. It is not the extreme levels of early January, but the threat remains to return to those levels later in the outlook period.