####018012450#### FGUS73 KGRR 012107 ESFGRR MIC005-015-025-035-037-045-057-065-067-073-075-077-081-085- 105-107-117-121-123-127-133-139-159-281600- PROBABILISTIC HYDROLOGIC OUTLOOK NATIONAL WEATHER SERVICE Grand Rapids MI 506 PM EDT Mon Apr 01 2024 In Table 1 below...the current (CS) and historical (HS) or normal probabilities of exceeding minor...moderate...and major flood stages 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 more 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: 04/01/2024 - 06/30/2024 : 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 -------- ----- ----- ----- : --- --- --- --- --- --- :Grand River Jackson 14.0 15.0 16.0 : 16 30 <5 10 <5 <5 :Buck Creek Grandville 9.0 10.5 12.0 : 18 16 6 5 <5 <5 :Grand River Eaton Rapids 6.0 8.0 9.0 : <5 <5 <5 <5 <5 <5 Dimondale 13.0 14.0 16.0 : <5 <5 <5 <5 <5 <5 :Red Cedar River Williamston 9.0 10.0 10.5 : <5 <5 <5 <5 <5 <5 East Lansing 7.0 10.0 13.0 : 15 17 <5 <5 <5 <5 :Sycamore Creek Holt 8.0 9.0 10.0 : 40 37 7 7 <5 <5 :Grand River Lansing 11.0 13.0 15.0 : 8 10 <5 <5 <5 <5 Grand Ledge 11.0 13.0 15.0 : <5 <5 <5 <5 <5 <5 Portland 12.0 14.0 16.0 : <5 <5 <5 <5 <5 <5 :Looking Glass River Eagle 7.0 9.0 11.0 : 35 38 7 10 <5 <5 :Maple River Maple Rapids 9.0 11.0 13.0 : 39 43 <5 <5 <5 <5 :Grand River Ionia 21.0 23.0 25.0 : 12 14 <5 <5 <5 <5 :Flat River Smyrna 8.5 9.5 10.5 : <5 <5 <5 <5 <5 <5 :Grand River Lowell 15.0 18.0 20.0 : 11 12 <5 <5 <5 <5 :Thornapple River Hastings 7.0 9.0 10.0 : 27 28 <5 <5 <5 <5 Caledonia 10.0 12.0 14.0 : 6 12 <5 <5 <5 <5 :Grand River Ada 20.0 22.0 25.0 : 6 7 <5 <5 <5 <5 :Rogue River Rockford 8.0 10.0 11.0 : 14 17 <5 <5 <5 <5 :Grand River Grand Rapids 18.0 21.0 23.0 : 7 10 <5 <5 <5 <5 :Pere Marquette River Scottville 5.5 6.5 7.0 : <5 <5 <5 <5 <5 <5 :White River Whitehall 6.0 7.0 8.0 : 6 8 <5 <5 <5 <5 :Muskegon River Evart 12.0 13.0 14.0 : <5 20 <5 8 <5 <5 :Little Muskegon River Morley 6.0 7.0 8.0 : <5 <5 <5 <5 <5 <5 :Muskegon River Croton 9.0 11.0 12.0 : 12 36 <5 <5 <5 <5 Newaygo 11.0 14.0 15.0 : 22 52 <5 8 <5 5 Bridgeton 13.0 16.0 17.0 : 24 54 <5 9 <5 5 :Kalamazoo River Marshall 8.0 9.0 10.0 : 6 8 <5 7 <5 5 :Battle Creek Battle Creek 4.0 5.0 6.0 : <5 <5 <5 <5 <5 <5 :Kalamazoo River Battle Creek 9.0 10.0 11.0 : <5 <5 <5 <5 <5 <5 Comstock 9.0 10.0 11.0 : 8 12 <5 <5 <5 <5 New Richmond 17.0 19.0 21.0 : 7 8 <5 <5 <5 <5 :St. Joseph River Burlington 6.5 9.0 11.0 : 6 8 <5 <5 <5 <5 :Portage River Vicksburg 5.5 7.0 8.0 : 10 8 <5 6 <5 <5 :Chippewa River Mt. Pleasant 8.0 11.0 13.0 : 8 15 <5 <5 <5 <5 :Pine River Alma 8.0 10.0 12.0 : 6 12 <5 <5 <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: 04/01/2024 - 06/30/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Grand River Jackson 11.5 11.8 12.3 12.9 13.4 14.3 14.7 :Buck Creek Grandville 6.8 7.0 7.2 7.9 8.7 9.3 11.8 :Grand River Eaton Rapids 3.9 3.9 4.0 4.3 4.7 5.2 5.3 Dimondale 6.1 6.3 6.8 7.5 8.3 9.6 10.0 :Red Cedar River Williamston 4.3 5.1 6.0 6.5 7.3 8.2 8.5 East Lansing 4.2 4.4 4.8 5.7 6.6 7.7 8.3 :Sycamore Creek Holt 6.0 6.3 7.0 7.6 8.5 8.8 9.1 :Grand River Lansing 4.6 5.1 6.3 7.2 8.3 10.8 11.2 Grand Ledge 5.8 5.9 6.5 7.1 7.7 9.1 9.3 Portland 7.0 7.1 7.9 8.5 9.6 10.8 11.0 :Looking Glass River Eagle 4.4 4.7 5.2 6.4 7.7 8.9 9.3 :Maple River Maple Rapids 6.5 7.0 7.8 8.7 9.4 10.2 10.4 :Grand River Ionia 12.8 13.3 14.7 17.8 19.6 21.3 22.0 :Flat River Smyrna 4.5 4.7 5.1 5.4 6.2 7.2 8.0 :Grand River Lowell 7.7 8.0 9.1 10.8 12.5 15.3 15.8 :Thornapple River Hastings 4.3 4.7 5.1 5.7 7.0 8.0 8.2 Caledonia 4.7 5.2 5.9 6.4 8.2 9.5 10.1 :Grand River Ada 10.6 11.2 12.9 15.0 16.5 19.3 20.1 :Rogue River Rockford 4.9 5.3 5.8 6.4 7.1 8.4 9.0 :Grand River Grand Rapids 6.8 7.4 9.8 11.9 14.1 17.6 18.4 :Pere Marquette River Scottville 2.3 2.4 3.1 3.8 4.3 4.8 4.9 :White River Whitehall 2.8 3.2 3.7 4.4 5.4 5.7 6.2 :Muskegon River Evart 8.2 8.3 8.8 9.5 10.2 11.0 11.7 :Little Muskegon River Morley 2.9 3.0 3.3 3.7 4.5 5.1 5.4 :Muskegon River Croton 6.2 6.5 7.0 7.6 8.3 9.3 9.9 Newaygo 8.6 8.8 9.4 10.0 10.9 12.2 13.2 Bridgeton 9.6 10.0 10.8 11.8 12.9 14.6 15.5 :Kalamazoo River Marshall 4.9 5.0 5.1 5.7 6.5 6.9 8.3 :Battle Creek Battle Creek 1.4 1.5 1.7 1.9 2.5 2.8 3.5 :Kalamazoo River Battle Creek 3.8 3.9 4.2 4.6 5.5 6.6 7.1 Comstock 4.9 5.0 5.5 6.1 7.2 8.8 9.9 New Richmond 12.9 13.4 14.0 14.6 15.5 16.5 18.2 :St. Joseph River Burlington 4.1 4.5 4.9 5.2 5.7 6.1 6.7 :Portage River Vicksburg 4.3 4.5 4.7 5.0 5.2 5.5 6.6 :Chippewa River Mt. Pleasant 4.5 4.6 5.3 5.9 6.9 7.8 8.7 :Pine River Alma 3.7 4.2 5.0 5.5 6.7 7.8 8.1 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: 04/01/2024 - 06/30/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Grand River Jackson 9.9 9.8 9.5 9.3 9.1 9.0 8.8 :Buck Creek Grandville 4.7 4.7 4.6 4.6 4.5 4.5 4.5 :Grand River Eaton Rapids 3.7 3.7 3.7 3.6 3.6 3.6 3.5 Dimondale 5.5 5.4 5.2 4.9 4.7 4.5 4.4 :Red Cedar River Williamston 2.7 2.7 2.5 2.4 2.4 2.3 2.3 East Lansing 3.5 3.5 3.4 3.3 3.2 3.2 3.2 :Sycamore Creek Holt 3.2 3.1 3.1 3.0 3.0 3.0 2.9 :Grand River Lansing 3.7 3.6 3.2 2.9 2.8 2.6 2.6 Grand Ledge 5.4 5.3 5.2 5.0 5.0 4.8 4.8 Portland 5.9 5.9 5.7 5.4 5.4 5.2 5.1 :Looking Glass River Eagle 3.6 3.4 3.2 3.1 3.0 2.9 2.9 :Maple River Maple Rapids 4.7 4.5 4.2 3.8 3.6 3.5 3.5 :Grand River Ionia 10.6 10.3 9.9 9.6 9.3 9.1 9.0 :Flat River Smyrna 4.0 3.9 3.8 3.6 3.5 3.4 3.4 :Grand River Lowell 6.5 6.3 6.0 5.6 5.4 5.2 5.1 :Thornapple River Hastings 3.5 3.3 3.2 3.1 3.0 3.0 2.9 Caledonia 3.9 3.8 3.6 3.4 3.3 3.2 3.2 :Grand River Ada 8.5 8.2 7.5 6.9 6.5 6.2 6.1 :Rogue River Rockford 4.4 4.3 4.2 4.0 3.9 3.8 3.8 :Grand River Grand Rapids 4.1 3.6 3.0 2.4 2.0 1.8 1.6 :Pere Marquette River Scottville 1.7 1.6 1.4 1.2 1.1 1.0 0.9 :White River Whitehall 2.1 2.0 1.8 1.6 1.6 1.5 1.4 :Muskegon River Evart 7.5 7.4 7.3 7.1 6.9 6.7 6.7 :Little Muskegon River Morley 2.4 2.3 2.3 2.3 2.2 2.2 2.2 :Muskegon River Croton 5.5 5.4 5.2 4.9 4.8 4.6 4.6 Newaygo 7.8 7.7 7.6 7.4 7.2 7.1 7.1 Bridgeton 8.5 8.3 8.0 7.7 7.5 7.3 7.2 :Kalamazoo River Marshall 4.3 4.2 3.9 3.2 3.2 3.2 3.2 :Battle Creek Battle Creek 1.0 1.0 1.0 0.9 0.9 0.9 0.8 :Kalamazoo River Battle Creek 3.4 3.3 3.2 3.1 3.0 3.0 2.9 Comstock 4.5 4.5 4.3 4.2 4.1 4.0 4.0 New Richmond 11.9 11.8 11.5 11.3 11.1 10.9 10.8 :St. Joseph River Burlington 4.0 4.0 3.8 3.6 3.4 3.2 3.1 :Portage River Vicksburg 4.1 4.0 4.0 3.9 3.8 3.7 3.6 :Chippewa River Mt. Pleasant 3.6 3.6 3.5 3.4 3.3 3.2 3.2 :Pine River Alma 2.1 2.0 1.8 1.6 1.4 1.3 1.2 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 weather.gov/grr for more weather and water information. The next outlook will be issued near the end of April. $$ AMD