####018016207#### FGUS73 KGRR 142031 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 430 PM EDT Thu Mar 14 2024 ...2024 SPRING FLOOD AND WATER RESOURCES OUTLOOK NUMBER 3... This Spring Flood and Water Resources Outlook is for the rivers in Southwest Lower Michigan. ...Flood Outlook Highlights... The overall flood risk this spring is well below average across all of Southwest and West-Central Lower Michigan. This reduced risk is mainly the result of no remaining snowpack and generally unsaturated soils. ...Flood Terminology... The term minor flooding is used to indicate minimal or no property damage. However, some public inconvenience is possible. The term moderate flooding is used to indicate some inundation of structures and roads near streams. Some evacuations of people and/or transfer of property to higher elevations may be needed. The term major flooding is used to indicate extensive inundation of structures and roads. Significant evacuations of people and/or transfer of property to higher elevations will be needed. ...Probabilistic Outlook... The flood risk this spring is below normal in all river basins in Southwest and West-Central Lower Michigan. The chance of flooding is less than 50% at all of the forecast locations on our rivers. ...Past Precipitation... The fall and early winter period was much drier than normal. A few weeks during the middle of January brought wetter than normal conditions, but precipitation has been generally near-normal since then. ...River Conditions... Water levels on the rivers were near-normal for most of the fall and early winter, before climbing to well above-average by late January as heavy rain and complete snowmelt runoff found its way into the river systems. Water levels are now back to near for this time of year, and are trending downard. It's entirely possible that we've seen our spring "high water" episode already. ...Soil Moisture and Frost Depths... Despite a few widespread rain events in the last 10 days, soil moisture remains near to slightly drier than normal for this time fo year. This is largely a result of the fact that there hasn't been any snowmelt happening (because there hasn't been any snow) to keep topsoils saturated. Meanwhile, there remains no frozen ground anywhere in the area. ...Snow Cover and Liquid Water Content... The winter of historically warm temperatures and low snowpack means the snow never got that deep and melted out early. There hasn't been persistent snow on the ground in much of Lower Michigan for the past several weeks. ...River Ice Conditions... The rivers in the Grand and Muskegon River basins briefly formed a stable ice cover during the cold snap in mid January, but by the end of January all of this river ice had melted and broken up. There is no significant river ice to speak of anywhere in the area. ...Weather Outlook. The single biggest factor affecting flood risk is the weather pattern during the sensitive period of melting snow. A slow snow melt with little or no rainfall is ideal to avoid flooding. On the other hand, a rapid warmup accompanied by heavy rain is a much worse scenario for spring flooding - especially if the rivers are covered with ice. At this time, the long range weather forecast calls for seasonably normal temperatures for the next week or two, with near or slightly wetter than normal conditions. With no ice in any of the rivers, and no snow on the ground, our future flood risks will be linked entirely to heavy rain events. Currently, there are no major indications of heavy rain storms on the horizon over the next week or two, but as we head through the start of April this will remain an ongoing risk. 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: 03/18/2024 - 06/16/2024 : 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 : 18 31 <5 8 <5 <5 :Buck Creek Grandville 9.0 10.5 12.0 : 11 12 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 : 12 18 <5 <5 <5 <5 :Sycamore Creek Holt 8.0 9.0 10.0 : 39 33 7 7 <5 <5 :Grand River Lansing 11.0 13.0 15.0 : 9 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 : 30 37 7 8 <5 <5 :Maple River Maple Rapids 9.0 11.0 13.0 : 40 56 <5 <5 <5 <5 :Grand River Ionia 21.0 23.0 25.0 : 13 16 <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 15 <5 <5 <5 <5 :Thornapple River Hastings 7.0 9.0 10.0 : 23 35 <5 <5 <5 <5 Caledonia 10.0 12.0 14.0 : 7 14 <5 <5 <5 <5 :Grand River Ada 20.0 22.0 25.0 : 5 9 <5 <5 <5 <5 :Rogue River Rockford 8.0 10.0 11.0 : 12 15 <5 <5 <5 <5 :Grand River Grand Rapids 18.0 21.0 23.0 : 6 13 <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 24 <5 8 <5 6 :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 39 <5 <5 <5 <5 Newaygo 11.0 14.0 15.0 : 24 53 <5 8 <5 <5 Bridgeton 13.0 16.0 17.0 : 24 54 <5 10 <5 <5 :Kalamazoo River Marshall 8.0 9.0 10.0 : <5 10 <5 8 <5 7 :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 : <5 10 <5 <5 <5 <5 New Richmond 17.0 19.0 21.0 : <5 6 <5 <5 <5 <5 :St. Joseph River Burlington 6.5 9.0 11.0 : <5 10 <5 <5 <5 <5 :Portage River Vicksburg 5.5 7.0 8.0 : 5 6 <5 <5 <5 <5 :Chippewa River Mt. Pleasant 8.0 11.0 13.0 : 5 14 <5 <5 <5 <5 :Pine River Alma 8.0 10.0 12.0 : 7 15 <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: 03/18/2024 - 06/16/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Grand River Jackson 11.6 11.7 12.4 12.9 13.4 14.4 14.7 :Buck Creek Grandville 6.3 6.8 7.1 7.7 8.5 9.0 11.7 :Grand River Eaton Rapids 4.0 4.0 4.2 4.4 4.8 5.3 5.5 Dimondale 6.5 6.6 7.1 7.8 8.7 9.7 10.1 :Red Cedar River Williamston 4.3 5.1 6.0 6.6 7.2 8.0 8.3 East Lansing 4.4 4.4 4.9 5.7 6.5 7.5 8.0 :Sycamore Creek Holt 6.0 6.3 6.9 7.5 8.3 8.8 9.1 :Grand River Lansing 5.4 5.4 6.5 7.6 8.6 10.9 11.1 Grand Ledge 6.0 6.1 6.6 7.2 7.8 9.2 9.3 Portland 7.2 7.3 8.0 8.7 9.7 10.8 10.8 :Looking Glass River Eagle 4.6 5.0 5.5 6.5 7.5 8.8 9.4 :Maple River Maple Rapids 7.6 7.7 8.1 8.8 9.4 10.2 10.4 :Grand River Ionia 13.9 14.1 15.6 17.9 19.4 21.6 21.9 :Flat River Smyrna 4.8 4.8 5.1 5.5 6.2 7.3 8.0 :Grand River Lowell 8.4 8.5 9.4 10.9 12.4 15.1 15.7 :Thornapple River Hastings 4.5 4.7 5.1 5.7 6.9 7.8 8.5 Caledonia 5.2 5.3 5.8 6.4 8.4 9.8 10.2 :Grand River Ada 11.7 11.8 13.3 14.8 16.9 19.4 20.0 :Rogue River Rockford 5.0 5.2 5.7 6.3 7.0 8.3 8.6 :Grand River Grand Rapids 8.5 8.7 10.3 11.7 14.6 17.4 18.3 :Pere Marquette River Scottville 3.0 3.0 3.2 3.8 4.3 4.7 4.9 :White River Whitehall 3.2 3.3 3.7 4.3 5.3 5.7 6.1 :Muskegon River Evart 8.8 8.9 9.1 9.4 10.2 11.3 12.1 :Little Muskegon River Morley 2.9 3.0 3.2 3.7 4.3 5.0 5.2 :Muskegon River Croton 6.8 6.9 7.1 7.6 8.3 9.5 10.1 Newaygo 9.2 9.2 9.5 10.0 10.9 12.4 13.2 Bridgeton 10.6 10.6 11.0 11.7 12.9 14.4 15.5 :Kalamazoo River Marshall 5.0 5.0 5.1 5.7 6.5 6.9 7.9 :Battle Creek Battle Creek 1.4 1.5 1.6 2.0 2.3 2.7 2.8 :Kalamazoo River Battle Creek 3.9 3.9 4.1 4.7 5.5 6.1 6.6 Comstock 5.0 5.1 5.3 6.2 7.0 8.4 8.8 New Richmond 13.5 13.6 14.0 14.6 15.3 16.4 16.8 :St. Joseph River Burlington 4.6 4.8 5.1 5.3 5.8 6.0 6.5 :Portage River Vicksburg 4.4 4.5 4.7 4.9 5.2 5.4 5.5 :Chippewa River Mt. Pleasant 4.4 4.5 5.1 5.7 6.8 7.5 8.3 :Pine River Alma 4.3 4.4 4.8 5.5 6.5 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: 03/18/2024 - 06/16/2024 Location 95% 90% 75% 50% 25% 10% 5% -------- ------ ------ ------ ------ ------ ------ ------ :Grand River Jackson 10.1 10.0 9.7 9.5 9.3 9.1 8.9 :Buck Creek Grandville 4.8 4.7 4.7 4.6 4.5 4.5 4.5 :Grand River Eaton Rapids 3.8 3.8 3.7 3.7 3.6 3.6 3.6 Dimondale 5.9 5.6 5.4 5.1 4.9 4.7 4.6 :Red Cedar River Williamston 2.8 2.8 2.6 2.5 2.4 2.3 2.3 East Lansing 3.6 3.5 3.5 3.3 3.3 3.2 3.2 :Sycamore Creek Holt 3.2 3.2 3.1 3.1 3.0 3.0 3.0 :Grand River Lansing 4.0 3.8 3.6 3.2 3.0 2.8 2.7 Grand Ledge 5.5 5.5 5.3 5.2 5.1 5.0 4.9 Portland 6.2 6.0 5.9 5.6 5.5 5.4 5.3 :Looking Glass River Eagle 3.6 3.5 3.4 3.2 3.1 3.0 3.0 :Maple River Maple Rapids 4.8 4.6 4.3 4.0 3.8 3.7 3.6 :Grand River Ionia 10.8 10.7 10.2 9.8 9.6 9.3 9.1 :Flat River Smyrna 4.0 4.0 3.8 3.7 3.6 3.5 3.4 :Grand River Lowell 6.5 6.4 6.2 5.9 5.6 5.4 5.2 :Thornapple River Hastings 3.5 3.4 3.3 3.2 3.1 3.0 3.0 Caledonia 3.9 3.9 3.7 3.5 3.4 3.3 3.2 :Grand River Ada 8.6 8.4 7.9 7.4 7.0 6.5 6.2 :Rogue River Rockford 4.4 4.3 4.2 4.1 4.0 3.9 3.8 :Grand River Grand Rapids 4.1 4.0 3.4 2.9 2.4 2.1 1.7 :Pere Marquette River Scottville 1.8 1.6 1.4 1.3 1.1 1.1 1.0 :White River Whitehall 2.2 2.0 1.8 1.7 1.6 1.5 1.4 :Muskegon River Evart 7.6 7.5 7.4 7.2 7.0 6.8 6.8 :Little Muskegon River Morley 2.4 2.4 2.3 2.3 2.3 2.2 2.2 :Muskegon River Croton 5.5 5.5 5.3 5.1 4.9 4.7 4.7 Newaygo 7.9 7.9 7.7 7.5 7.4 7.2 7.2 Bridgeton 8.5 8.5 8.2 7.9 7.7 7.5 7.4 :Kalamazoo River Marshall 4.2 4.1 3.2 3.2 3.2 3.2 3.2 :Battle Creek Battle Creek 1.1 1.1 1.0 1.0 0.9 0.9 0.9 :Kalamazoo River Battle Creek 3.5 3.4 3.3 3.2 3.1 3.0 2.9 Comstock 4.6 4.5 4.4 4.3 4.1 4.1 4.0 New Richmond 12.0 11.7 11.5 11.3 10.8 10.5 10.3 :St. Joseph River Burlington 4.1 4.0 3.9 3.8 3.6 3.4 3.4 :Portage River Vicksburg 4.1 4.1 4.0 3.9 3.8 3.8 3.7 :Chippewa River Mt. Pleasant 3.7 3.6 3.5 3.4 3.3 3.2 3.2 :Pine River Alma 2.1 2.1 1.9 1.7 1.5 1.4 1.3 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 March. $$ AMD