971  
FGUS73 KGRR 231621  
ESFGRR  
MIC005-015-025-035-037-045-057-065-067-073-075-077-081-085-  
105-107-117-121-123-127-133-139-159-221800-  
 
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
1217 PM EDT THU JUL 23 2015  
 
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: 07/27/2015 - 10/25/2015  
 
: 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 : 17 11 9 <5 <5 <5  
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 : 7 <5 <5 <5 <5 <5  
:SYCAMORE CREEK  
HOLT 8.0 9.0 10.0 : 16 9 <5 <5 <5 <5  
:GRAND RIVER  
LANSING 11.0 13.0 15.0 : <5 <5 <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 : 9 7 <5 <5 <5 <5  
:MAPLE RIVER  
MAPLE RAPIDS 9.0 11.0 13.0 : 8 7 <5 <5 <5 <5  
:GRAND RIVER  
IONIA 21.0 23.0 25.0 : 6 5 <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 : 6 5 <5 <5 <5 <5  
:THORNAPPLE RIVER  
HASTINGS 7.0 9.0 10.0 : 8 6 <5 <5 <5 <5  
CALEDONIA 10.0 12.0 14.0 : <5 <5 <5 <5 <5 <5  
:GRAND RIVER  
ADA 20.0 22.0 25.0 : 6 5 <5 <5 <5 <5  
:ROGUE RIVER  
ROCKFORD 8.0 10.0 11.0 : 9 5 <5 <5 <5 <5  
:GRAND RIVER  
GRAND RAPIDS 18.0 21.0 23.0 : 6 5 <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 <5 <5 <5 <5 <5  
:MUSKEGON RIVER  
EVART 12.0 13.0 14.0 : <5 <5 <5 <5 <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 : <5 <5 <5 <5 <5 <5  
:KALAMAZOO RIVER  
MARSHALL 8.0 9.0 10.0 : 9 13 8 9 6 8  
: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 : 7 <5 5 <5 <5 <5  
NEW RICHMOND 17.0 19.0 21.0 : <5 <5 <5 <5 <5 <5  
:ST JOSEPH RIVER  
BURLINGTON 6.5 9.0 11.0 : <5 <5 <5 <5 <5 <5  
:PORTAGE RIVER  
VICKSBURG 5.0 7.0 8.0 : 31 10 7 5 6 <5  
:CHIPPEWA RIVER  
MT PLEASANT 8.0 11.0 13.0 : <5 <5 <5 <5 <5 <5  
:PINE RIVER  
ALMA 8.0 10.0 12.0 : <5 <5 <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: 07/27/2015 - 10/25/2015  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:GRAND RIVER  
JACKSON 10.8 11.1 11.6 12.4 13.5 14.7 15.4  
EATON RAPIDS 3.9 3.9 3.9 4.2 4.4 5.0 5.3  
DIMONDALE 5.9 6.0 6.2 7.0 7.6 8.8 9.6  
:RED CEDAR RIVER  
WILLIAMSTON 2.9 3.0 4.3 5.4 6.2 7.4 8.4  
EAST LANSING 3.5 3.5 3.9 4.4 5.2 6.2 7.4  
:SYCAMORE CREEK  
HOLT 3.9 4.0 4.9 6.5 7.6 8.2 8.9  
:GRAND RIVER  
LANSING 3.9 3.9 4.3 4.8 6.5 8.6 9.4  
GRAND LEDGE 5.5 5.5 5.7 6.0 6.9 7.9 8.3  
PORTLAND 6.5 6.6 7.0 7.6 8.7 9.6 10.5  
:LOOKING GLASS RIVER  
EAGLE 3.2 3.2 3.3 4.1 5.8 6.8 7.9  
:MAPLE RIVER  
MAPLE RAPIDS 3.1 3.5 4.4 6.4 8.2 8.8 9.5  
:GRAND RIVER  
IONIA 9.7 9.8 10.6 12.2 15.6 18.1 21.7  
:FLAT RIVER  
SMYRNA 3.6 3.7 4.1 4.5 5.2 5.8 7.4  
:GRAND RIVER  
LOWELL 6.0 6.1 6.4 7.5 9.4 11.6 16.4  
:THORNAPPLE RIVER  
HASTINGS 3.4 3.6 3.9 4.6 5.3 6.4 7.6  
CALEDONIA 3.7 3.8 4.1 5.1 6.0 8.1 9.5  
:GRAND RIVER  
ADA 7.5 7.6 8.5 10.1 13.0 16.4 20.8  
:ROGUE RIVER  
ROCKFORD 4.3 4.5 5.0 5.6 7.0 7.9 8.6  
:GRAND RIVER  
GRAND RAPIDS 3.7 3.8 4.1 5.8 9.1 13.6 19.4  
:PERE MARQUETTE RIVER  
SCOTTVILLE 1.7 1.8 2.1 2.8 3.5 4.5 5.0  
:WHITE RIVER  
WHITEHALL 1.9 2.0 2.1 2.9 4.5 5.7 6.3  
:MUSKEGON RIVER  
EVART 7.1 7.1 7.3 7.6 8.5 9.3 10.4  
:LITTLE MUSKEGON RIVER  
MORLEY 2.4 2.5 2.6 2.9 3.7 4.2 5.0  
:MUSKEGON RIVER  
CROTON 5.2 5.2 5.4 6.0 6.9 7.7 8.3  
:KALAMAZOO RIVER  
MARSHALL 4.7 4.8 5.1 5.2 5.7 7.9 11.8  
:BATTLE CREEK  
BATTLE CREEK 1.2 1.2 1.4 1.7 2.0 2.5 2.8  
:KALAMAZOO RIVER  
BATTLE CREEK 3.5 3.5 3.7 4.1 4.5 5.7 8.1  
COMSTOCK 4.6 4.6 4.9 5.3 6.0 8.1 10.6  
NEW RICHMOND 12.2 12.2 12.5 13.3 14.6 15.5 16.9  
:ST JOSEPH RIVER  
BURLINGTON 4.2 4.2 4.2 4.6 5.2 5.6 6.4  
:PORTAGE RIVER  
VICKSBURG 4.1 4.1 4.3 4.7 5.1 5.3 8.3  
:CHIPPEWA RIVER  
MT PLEASANT 3.1 3.3 3.7 4.3 4.9 5.6 6.6  
:PINE RIVER  
ALMA 1.5 1.7 2.4 3.2 4.3 5.7 7.0  
 
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: 07/27/2015 - 10/25/2015  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:GRAND RIVER  
JACKSON 8.8 8.8 8.9 9.0 9.2 9.3 9.3  
EATON RAPIDS 3.6 3.6 3.6 3.6 3.6 3.7 3.7  
DIMONDALE 4.5 4.5 4.6 4.7 4.9 5.0 5.1  
:RED CEDAR RIVER  
WILLIAMSTON 2.4 2.4 2.4 2.4 2.5 2.5 2.6  
EAST LANSING 3.1 3.1 3.1 3.2 3.2 3.2 3.3  
:SYCAMORE CREEK  
HOLT 3.1 3.1 3.1 3.1 3.1 3.2 3.2  
:GRAND RIVER  
LANSING 2.6 2.6 2.7 2.7 2.9 3.0 3.2  
GRAND LEDGE 4.7 4.8 4.8 4.9 5.0 5.1 5.2  
PORTLAND 5.3 5.3 5.4 5.5 5.6 5.7 5.8  
:LOOKING GLASS RIVER  
EAGLE 2.5 2.5 2.5 2.5 2.6 2.6 2.7  
:MAPLE RIVER  
MAPLE RAPIDS 2.6 2.6 2.6 2.7 2.8 2.8 2.9  
:GRAND RIVER  
IONIA 7.8 7.9 7.9 8.2 8.4 8.7 8.8  
:FLAT RIVER  
SMYRNA 3.2 3.3 3.3 3.3 3.4 3.5 3.5  
:GRAND RIVER  
LOWELL 4.8 4.8 4.8 4.9 5.1 5.3 5.5  
:THORNAPPLE RIVER  
HASTINGS 2.9 2.9 2.9 2.9 3.0 3.1 3.1  
CALEDONIA 2.9 2.9 3.0 3.0 3.2 3.2 3.3  
:GRAND RIVER  
ADA 5.0 5.0 5.2 5.5 5.9 6.2 6.6  
:ROGUE RIVER  
ROCKFORD 3.7 3.7 3.8 3.8 3.9 4.0 4.1  
:GRAND RIVER  
GRAND RAPIDS 3.0 3.0 3.0 3.1 3.2 3.3 3.3  
:PERE MARQUETTE RIVER  
SCOTTVILLE 1.2 1.2 1.3 1.4 1.4 1.5 1.5  
:WHITE RIVER  
WHITEHALL 1.3 1.3 1.4 1.4 1.5 1.6 1.7  
:MUSKEGON RIVER  
EVART 6.7 6.7 6.7 6.7 6.8 6.9 6.9  
:LITTLE MUSKEGON RIVER  
MORLEY 2.2 2.2 2.2 2.2 2.2 2.2 2.2  
:MUSKEGON RIVER  
CROTON 4.5 4.5 4.5 4.6 4.7 4.7 4.8  
:KALAMAZOO RIVER  
MARSHALL 3.4 3.4 3.4 3.4 4.1 4.1 4.1  
:BATTLE CREEK  
BATTLE CREEK 0.8 0.8 0.9 0.9 0.9 1.0 1.0  
:KALAMAZOO RIVER  
BATTLE CREEK 2.8 2.9 3.0 3.0 3.1 3.1 3.2  
COMSTOCK 3.9 3.9 4.0 4.0 4.1 4.2 4.2  
NEW RICHMOND 8.9 9.4 10.0 10.3 10.6 10.9 11.0  
:ST JOSEPH RIVER  
BURLINGTON 2.9 3.0 3.1 3.3 3.6 3.7 3.8  
:PORTAGE RIVER  
VICKSBURG 3.6 3.6 3.7 3.8 3.8 3.9 4.0  
:CHIPPEWA RIVER  
MT PLEASANT 2.8 2.8 2.8 2.8 2.9 2.9 2.9  
:PINE RIVER  
ALMA 1.0 1.0 1.1 1.1 1.2 1.3 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 AT THE END OF AUGUST.  
 

 
 
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