####018010370#### FGUS73 KGRB 151740 ESFGRB WIC125-085-041-037-075-069-067-083-073-115-125-078-029-141-097- 135-087-061-009-137-139-015-071-1918000- PROBABILISTIC HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 1140 AM CST THU FEB 15 2024 ...NEAR TO BELOW AVERAGE RISK OF FLOODING THIS SPRING... This outlook references information from the following partners including: the United States Geological Survey (USGS), the U.S. Army Corps of Engineers, Regional Climate Centers, U.S. Drought Monitor, the Climate Prediction Center and NOAA Office of Water Prediction. This is the first in a series of three spring flood outlooks. The next outlook will be provided on February 29, 2024. Flood outlook factors... Soil moisture values across most of northeast Wisconsin is now considered normal to below normal. Northern Wisconsin was considered below normal mainly due to the dry conditions that carried over from 2023. Once the ground thaws, this would allow more moisture to be absorbed into the soils and result in a normal runoff. Streamflows range from below normal over north-central Wisconsin, to above normal over parts of east-central Wisconsin. This scenario would likely lead to normal river levels and an average risk of flooding across northern and central Wisconsin. However, the high streamflows over east-central Wisconsin may lead to above normal river levels and an average to above average risk of flooding across east-central Wisconsin. Snow water equivalent indicated that much of northeast Wisconsin was well-below normal, primarily due to warmer than normal temperatures and below normal snowfall. The exception was east-central Wisconsin where snowfall was considered slightly below normal due to the major snowstorm in January. Frost depth this season is considered shallow, even more shallow than last year. This was due again to the above normal temperatures seen so far this winter. Frost depths ranged from zero to around 20 inches, which is similar to the same time in 2023. The more shallow frost depth may lead to decreased runoff as the less frozen ground will allow water to readily pass through the surface. Lake Michigan water levels continue to run slightly above normal which has been the case the past two years. This level will allow for decreased flooding impacts this season. For a comparison of impacts, there were very few impacts in 2022 and 2023, and Lake Michigan levels are slightly lower this year. The warm conditions for most of January 2024 and well-above normal temperatures through early February has led to thinner ice on area rivers this season. There is a low risk of break up ice jamming on area rivers this season. The potential for ice jams generally increases with heavy rainfall events before the ice is out of the river system. ...Weather/climate outlook... Temperatures are expected to trend above normal through the last half of February. This would lend support to a quicker snowmelt and a faster release of the water in the snowpack. Precipitation during this same time frame has a normal to slightly better chance to trend above normal. There is a signal for these conditions to become normal to slightly better chance to trend below normal February through April time frame. ...Probabilistic Forecast Information for River Forecast Points... In Table 1 below, the current (CS) and historical (HS) or normal probabilities of exceeding Minor...Moderate...And Major flood stage are listed for the valid time period. CS values indicate the probability of reaching a flood category based on current conditions. HS values indicate the probability of reaching a flood category based on historical or normal conditions. When the value of CS is greater than HS...the probability of exceeding that level is higher than normal. When the value of CS is less than HS...the probability of exceeding that level is lower than normal. ...TABLE 1--PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING... VALID PERIOD: 02/19/2024 - 05/19/2024 : CURRENT AND HISTORICAL : CHANCES OF EXCEEDING : FLOOD CATEGORIES : AS A PERCENTAGE (%) CATEGORICAL : FLOOD STAGES (FT) : MINOR MODERATE MAJOR LOCATION MINOR MOD MAJOR : CS HS CS HS CS HS -------- ----- ----- ----- : --- --- --- --- --- --- :WISCONSIN RIVER MERRILL 11.0 13.5 15.0 : <5 24 <5 <5 <5 <5 ROTHSCHILD 25.0 27.0 28.0 : <5 21 <5 8 <5 6 :YELLOW RIVER BABCOCK 12.0 15.9 16.6 : 51 78 10 18 <5 11 :WISCONSIN RIVER WISCONSIN RAPIDS 12.0 13.5 14.5 : <5 11 <5 <5 <5 <5 :OCONTO RIVER OCONTO 9.0 12.0 14.0 : 11 24 <5 <5 <5 <5 :UPPER WOLF RIVER LANGLADE 11.5 12.5 14.0 : <5 <5 <5 <5 <5 <5 :WOLF RIVER SHIOCTON 11.0 13.5 15.0 : 28 44 <5 5 <5 <5 NEW LONDON 9.0 10.5 11.1 : 33 50 <5 6 <5 <5 :LITTLE WOLF RIVER ROYALTON 5.0 8.0 10.0 : 24 40 <5 <5 <5 <5 :WAUPACA RIVER WAUPACA 6.0 7.5 9.0 : <5 8 <5 <5 <5 <5 :FOX RIVER APPLETON 8.4 9.0 10.5 : <5 <5 <5 <5 <5 <5 :MENOMINEE RIVER FLORENCE 9.0 11.0 13.0 : 6 37 <5 14 <5 <5 NIAGARA 13.0 15.0 16.0 : <5 32 <5 14 <5 <5 VULCAN 15.0 17.0 19.0 : <5 25 <5 6 <5 <5 MCALLISTER 15.0 18.0 19.0 : 12 52 <5 14 <5 <5 LEGEND CS = CONDITIONAL SIMULATION (CURRENT OUTLOOK) HS = HISTORICAL SIMULATION FT = FEET IN TABLE 2 BELOW...THE 95 THROUGH 5 PERCENT COLUMNS INDICATE THE PROBABILITY OF EXCEEDING THE LISTED STAGE LEVELS (FT) FOR THE VALID TIME PERIOD. ...TABLE 2--EXCEEDANCE PROBABILITIES... CHANCE OF EXCEEDING STAGES AT SPECIFIC LOCATIONS VALID PERIOD: 02/19/2024 - 05/19/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :WISCONSIN RIVER MERRILL 5.8 6.1 6.6 7.6 8.3 9.2 11.0 ROTHSCHILD 16.3 16.9 18.5 19.5 21.2 23.2 24.4 :YELLOW RIVER BABCOCK 5.9 7.3 8.3 12.1 14.1 15.9 16.2 :WISCONSIN RIVER WISCONSIN RAPIDS 4.1 4.8 5.6 6.5 8.2 9.5 10.5 :OCONTO RIVER OCONTO 6.2 6.3 6.7 7.3 8.1 9.1 10.0 :UPPER WOLF RIVER LANGLADE 8.2 8.4 8.6 8.8 9.1 9.3 9.6 :WOLF RIVER SHIOCTON 7.4 8.4 9.1 10.2 11.1 11.9 12.5 NEW LONDON 6.3 7.5 7.8 8.6 9.2 9.7 9.9 :LITTLE WOLF RIVER ROYALTON 2.9 3.1 3.6 4.2 5.0 5.9 6.1 :WAUPACA RIVER WAUPACA 2.4 2.5 2.9 3.6 4.7 5.0 5.2 :FOX RIVER APPLETON 6.2 6.3 6.5 7.0 7.5 7.9 7.9 :MENOMINEE RIVER FLORENCE 4.6 4.9 5.4 6.1 7.0 8.5 9.1 NIAGARA 7.0 7.2 7.9 8.8 10.0 11.8 12.5 VULCAN 7.1 7.5 8.4 9.4 10.8 12.8 13.7 MCALLISTER 10.8 11.3 11.9 12.7 13.8 15.2 16.1 IN TABLE 3 BELOW...THE 95 THROUGH 5 PERCENT COLUMNS INDICATE THE PROBABILITY OF FALLING BELOW THE LISTED STAGE LEVELS (FT) FOR THE VALID TIME PERIOD. ...TABLE 3--NONEXCEEDANCE PROBABILITIES... CHANCE OF FALLING BELOW STAGES AT SPECIFIC LOCATIONS VALID PERIOD: 02/19/2024 - 05/19/2024 LOCATION 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :WISCONSIN RIVER MERRILL 4.6 4.5 4.4 4.3 4.2 4.1 4.0 ROTHSCHILD 13.2 13.1 13.1 12.9 12.6 12.5 12.3 :YELLOW RIVER BABCOCK 2.1 2.1 2.0 2.0 1.9 1.9 1.9 :WISCONSIN RIVER WISCONSIN RAPIDS 1.5 1.5 1.4 1.3 1.3 1.3 1.3 :OCONTO RIVER OCONTO 4.5 4.4 4.4 4.4 4.4 4.3 4.3 :UPPER WOLF RIVER LANGLADE 7.7 7.7 7.7 7.6 7.6 7.6 7.6 :WOLF RIVER SHIOCTON 3.9 3.8 3.7 3.5 3.3 3.1 3.0 NEW LONDON 2.7 2.6 2.5 2.3 2.2 2.1 2.0 :LITTLE WOLF RIVER ROYALTON 1.4 1.3 1.3 1.2 1.2 1.2 1.2 :WAUPACA RIVER WAUPACA 1.5 1.5 1.5 1.5 1.5 1.5 1.5 :FOX RIVER APPLETON 5.6 5.5 5.3 5.1 4.9 4.9 4.9 :MENOMINEE RIVER FLORENCE 3.2 3.2 3.1 3.1 3.1 3.1 3.1 NIAGARA 4.9 4.9 4.9 4.9 4.8 4.8 4.8 VULCAN 5.1 5.0 5.0 5.0 5.0 5.0 4.9 MCALLISTER 8.8 8.8 8.8 8.7 8.7 8.7 8.7 These long-range probabilistic outlooks contain forecast values that are calculated using multiple season scenarios from 30 or more years of climatological data...including current conditions of the River...Soil Moisture...Snow Cover and 30 to 90 day long-range outlooks of temperature and precipitation. By providing a range of probabilities...The level of risk associated with long-range planning decisions can be determined. These probabilistic forecasts are part of the National Weather Service's advanced hydrologic prediction service. Visit our web site at weather.gov/grb for more weather and water information The next outlook will be issued February 29, 2024. $$