090  
FGUS73 KGRR 132154  
ESFGRR  
MIC005-015-025-035-037-045-057-065-067-073-075-077-081-085-  
105-107-117-121-123-127-133-139-159-271600-  
 
PROBABILISTIC HYDROLOGIC OUTLOOK  
NATIONAL WEATHER SERVICE GRAND RAPIDS MI  
455 PM EST THU FEB 13 2020  
   
..2020 SPRING FLOOD AND WATER RESOURCES OUTLOOK NUMBER 1
 
 
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 HIGHER THAN NORMAL ACROSS  
SOUTHWEST AND WEST-CENTRAL MICHIGAN. THE MUSKEGON RIVER BASIN, GRAND  
RIVER BASIN, AND THE CHIPPEWA RIVER BASIN ARE THE MOST AT-RISK, WITH  
A SLIGHTLY LOWER RISK ACROSS THE KALAMAZOO RIVER BASIN.  
 
THE MOST SIGNIFICANT FACTOR AFFECTING THE FLOOD RISK THIS SPRING IS  
THE ONGOING SATURATED SOIL MOISTURE CONDITIONS. THE WETTEST FALL ON  
RECORD IN MANY LOCATIONS CONTINUED THROUGH JANUARY WITH MULTIPLE  
ROUNDS OF HEAVY RAIN CONTINUING. THIS MEANS THAT THE GROUND WILL NOT  
BE ABLE TO ABSORB MUCH WATER THIS SPRING, AND INSTEAD A HIGHER AMOUNT  
OF WATER WILL MOVE INTO THE RIVERS. EVEN TYPICAL SPRINGTIME  
CONDITIONS COULD RESULT IN FLOODING IN SOME SPOTS ALONG THE RIVERS  
THIS SPRING.  
 
MEANWHILE, RECORD-HIGH SPRING WATER LEVELS ON LAKE MICHIGAN WILL  
CREATE A SIGNIFICANTLY HIGHER RISK OF SPRING FLOODING ALONG THE  
MOUTHS OF ALL RIVERS THAT DRAIN INTO LAKE MICHIGAN.  
   
..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 INUNDATIONS 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 OVERALL FLOOD RISK THIS SPRING OVER SOUTHWEST MICHIGAN IS HIGHER  
THAN AVERAGE. THE MUSKEGON, GRAND, AND CHIPPEWA RIVER BASINS ARE THE  
MOST AT-RISK, WHILE THE RIVERS GENERALLY SOUTH OF THE I-96 CORRIDOR,  
INCLUDING THE KALAMAZOO RIVER, ARE NEAR-NORMAL.  
   
..PAST PRECIPITATION
 
 
THE FALL AND WINTER PERIOD OVER VIRTUALLY ALL OF LOWER MICHIGAN WAS  
MUCH WARMER AND WETTER THAN NORMAL. IN MANY CASES, THIS MULTI-MONTH  
PERIOD WAS THE WETTEST ON RECORD. THIS HAS HELPED REINFORCE  
INCREDIBLY SATURATED SOILS, MUCH HIGHER THAN NORMAL WINTERTIME  
STREAMFLOWS, AND HIGHER WATER LEVELS ON LAKE MICHIGAN.  
   
..RIVER CONDITIONS
 
 
OVERALL, THE AMOUNT OF WATER CURRENTLY MOVING THROUGH OUR RIVERS  
CONTINUES TO BE WELL ABOVE THE LONG-TERM AVERAGE. IN FACT, ACROSS  
PARTS OF THE GRAND AND MUSKEGON RIVER BASINS, THE AMOUNT OF WATER  
THAT HAS FLOWED THROUGH THE SYSTEM IN THE LAST 4 MONTHS HAS SURPASSED  
THE VOLUME OF WATER THAT TYPICALLY PASSES DURING AN ENTIRE YEAR. AS  
OF FEBRUARY 13, STREAMFLOWS ACROSS VIRTUALLY THE ENTIRE STATE OF  
MICHIGAN ARE STILL ABOVE THE 75TH PERCENTILE FOR THIS DATE. EVEN AS  
COLDER TEMPERATURES AND A GROWING SNOWPACK HAVE DEVELOPED OVER THE  
LAST WEEK OR TWO, THE WET SOIL CONDITIONS CONTINUE TO MAINTAIN THESE  
SIGNIFICANTLY ELEVATED STREAMFLOWS.  
   
..SOIL MOISTURE AND FROST DEPTHS
 
 
SOIL MOISTURE LEVELS ARE VERY HIGH, AND HAVE BEEN THAT WAY FOR MORE  
THAN 15 CONSECUTIVE MONTHS. THIS MEANS THE SOIL, EVEN IF THAWED, WILL  
NOT BE ABLE TO ABSORB MUCH WATER AT ALL THIS SPRING. MEANWHILE, THE  
WARM WINTER SO FAR HAS LEFT US WITH LESS FROST IN THE GROUND THAN  
NORMAL. MOST LOCATIONS ALONG AND SOUTH OF I-96 CURRENTLY HAVING  
THAWED GROUND, AND EVEN LOCATIONS IN THE MUSKEGON BASIN ARE ONLY  
SHOWING 2 TO 4 INCHES OF FROST DEPTH. THAWED GROUND WOULD TEND TO  
LOWER FLOOD RISKS A BIT AS SOME OF THE WATER WOULD BE ABLE TO SOAK  
IN, BUT WITH THE SOILS SO SATURATED THIS YEAR, THE OVERALL EFFECT OF  
THIS WILL BE MINIMAL. THUS, WE ARE EXPECTING MORE RUNOFF THIS SPRING  
THAN NORMAL, WHICH WILL INCREASE THE OVERALL RISK OF FLOODING.  
   
..SNOW COVER AND LIQUID WATER CONTENT
 
 
AS OF MID-FEBRUARY, THE AMOUNT OF WATER CONTAINED WITHIN THE SNOWPACK  
WAS LESS THAN NORMAL ACROSS THE GRAND AND KALAMAZOO RIVER BASINS, AND  
NEAR-NORMAL ACROSS THE MUSKEGON, CHIPPEWA, PERE MARQUETTE, AND WHITE  
RIVER BASINS. IN TERMS OF FLOOD RISK, THIS WOULD FAVOR HIGHER FLOOD  
CHANCES ON THE RIVER SYSTEMS GENERALLY NORTH OF I-96, INCLUDING THE  
MAJOR TRIBUTARIES OF THE GRAND RIVER INCLUDING THE MAPLE RIVER AND  
LOOKING GLASS RIVER. HOWEVER, IF ADDITIONAL SNOWPACK WERE TO DEVELOP  
IN LOWER MICHIGAN, THIS WOULD CONTINUE TO SIGNIFICANTLY RAISE THE  
SPRING FLOOD RISKS IN ALL AREAS.  
   
..RIVER ICE CONDITIONS
 
 
THE WARM WINTER HAS LIMITED ICE FORMATION ON MOST OF THE RIVERS IN  
LOWER MICHIGAN. THIS OBVIOUSLY SIGNIFICANTLY LOWERS THE RISK OF ICE  
JAMS THIS SPRING, ALTHOUGH IT IS STILL POSSIBLE RIVERS COULD FREEZE  
UP IN THE NEXT 4 WEEKS.  
   
..WEATHER OUTLOOK
 
 
THE SINGLE BIGGEST FACTOR AFFECTING SPRING FLOOD RISKS ARE THE  
WEATHER CONDITIONS DURING THE SENSITIVE PERIOD OF MELTING SNOW. A  
SLOW SNOW MELT WITH LITTLE OR NO RAINFALL WOULD LOWER FLOOD RISK  
CONSIDERABLY. ON THE OTHER HAND, A RAPID WARMUP ACCOMPANIED BY HEAVY  
RAIN WOULD REPRESENT A MUCH WORSE SCENARIO FOR SPRING FLOODING. AT  
THIS TIME, THE LONG-RANGE WEATHER FORECAST IS FOR NEAR OR SLIGHTLY  
COOLER TEMPERATURES THAN NORMAL THIS SPRING, BUT A CONTINUATION OF  
THE WETTER THAN NORMAL CONDITIONS. THUS, ALL INTERESTED PARTIES NEED  
TO PAY VERY CAREFUL ATTENTION OVER THE NEXT 5-8 WEEKS AS SPRING  
CONDITIONS MOVE INTO LOWER MICHIGAN.  
 
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: 02/17/2020 - 05/17/2020  
 
: 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 : 42 30 21 17 11 12  
:BUCK CREEK  
GRANDVILLE 9.0 10.5 12.0 : 13 8 6 <5 <5 <5  
:GRAND RIVER  
EATON RAPIDS 6.0 8.0 9.0 : 8 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 : 24 25 <5 <5 <5 <5  
:SYCAMORE CREEK  
HOLT 8.0 9.0 10.0 : 66 40 16 9 <5 <5  
:GRAND RIVER  
LANSING 11.0 13.0 15.0 : 15 11 <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 : 59 46 9 12 <5 <5  
:MAPLE RIVER  
MAPLE RAPIDS 9.0 11.0 13.0 : 79 74 <5 <5 <5 <5  
:GRAND RIVER  
IONIA 21.0 23.0 25.0 : 12 17 <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 : 17 21 <5 <5 <5 <5  
:THORNAPPLE RIVER  
HASTINGS 7.0 9.0 10.0 : 32 34 <5 7 <5 <5  
CALEDONIA 10.0 12.0 14.0 : 11 18 <5 <5 <5 <5  
:GRAND RIVER  
ADA 20.0 22.0 25.0 : 12 12 <5 <5 <5 <5  
:ROGUE RIVER  
ROCKFORD 8.0 10.0 11.0 : 24 10 <5 <5 <5 <5  
:GRAND RIVER  
GRAND RAPIDS 18.0 21.0 23.0 : 12 13 <5 <5 <5 <5  
:PERE MARQUETTE RIVER  
SCOTTVILLE 5.5 6.5 7.0 : 12 <5 <5 <5 <5 <5  
:WHITE RIVER  
WHITEHALL 6.0 7.0 8.0 : 26 13 <5 <5 <5 <5  
:MUSKEGON RIVER  
EVART 12.0 13.0 14.0 : 44 25 23 8 9 <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 : 62 34 10 <5 <5 <5  
NEWAYGO 11.0 14.0 15.0 : 81 49 23 6 11 <5  
BRIDGETON 13.0 16.0 17.0 : 83 49 24 7 11 <5  
:KALAMAZOO RIVER  
MARSHALL 8.0 9.0 10.0 : 7 10 <5 9 <5 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 : 11 7 <5 <5 <5 <5  
NEW RICHMOND 17.0 19.0 21.0 : 9 8 <5 <5 <5 <5  
:ST JOSEPH RIVER  
BURLINGTON 6.5 9.0 11.0 : 11 13 <5 <5 <5 <5  
:PORTAGE RIVER  
VICKSBURG 5.5 7.0 8.0 : 9 6 <5 <5 <5 <5  
:CHIPPEWA RIVER  
MT PLEASANT 8.0 11.0 13.0 : 37 15 <5 <5 <5 <5  
:PINE RIVER  
ALMA 8.0 10.0 12.0 : 14 11 <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: 02/17/2020 - 05/17/2020  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:GRAND RIVER  
JACKSON 12.6 12.7 13.1 13.8 14.8 16.3 17.3  
:BUCK CREEK  
GRANDVILLE 6.7 7.1 7.4 7.9 8.5 9.2 11.1  
:GRAND RIVER  
EATON RAPIDS 4.5 4.5 4.7 4.9 5.4 5.8 6.5  
DIMONDALE 7.8 7.9 8.3 9.0 9.9 10.8 11.9  
:RED CEDAR RIVER  
WILLIAMSTON 5.7 6.0 6.4 7.0 7.5 8.2 8.4  
EAST LANSING 5.3 5.4 5.8 6.4 6.9 7.9 8.3  
:SYCAMORE CREEK  
HOLT 7.0 7.2 7.7 8.2 8.9 9.4 9.7  
:GRAND RIVER  
LANSING 6.9 7.4 7.9 9.1 10.2 11.8 12.3  
GRAND LEDGE 6.9 7.0 7.3 8.0 8.7 9.5 9.8  
PORTLAND 8.2 8.6 8.9 9.7 10.3 11.2 11.7  
:LOOKING GLASS RIVER  
EAGLE 5.2 5.8 6.5 7.2 8.3 8.9 9.7  
:MAPLE RIVER  
MAPLE RAPIDS 8.6 8.6 9.0 9.3 9.6 10.0 10.2  
:GRAND RIVER  
IONIA 15.6 16.6 17.8 18.5 20.0 21.3 22.0  
:FLAT RIVER  
SMYRNA 5.4 5.5 5.8 6.2 6.9 7.8 8.1  
:GRAND RIVER  
LOWELL 9.5 10.6 11.4 12.3 14.4 16.0 16.5  
:THORNAPPLE RIVER  
HASTINGS 4.8 5.2 5.7 6.2 7.3 7.8 8.2  
CALEDONIA 6.1 6.5 7.0 7.8 9.2 10.1 10.7  
:GRAND RIVER  
ADA 13.3 14.6 15.6 16.7 18.6 20.1 20.4  
:ROGUE RIVER  
ROCKFORD 5.8 6.1 6.5 7.0 8.0 8.6 8.9  
:GRAND RIVER  
GRAND RAPIDS 10.1 11.3 12.9 14.2 16.9 18.2 18.7  
:PERE MARQUETTE RIVER  
SCOTTVILLE 3.5 3.9 4.3 4.7 5.1 5.5 5.7  
:WHITE RIVER  
WHITEHALL 4.1 4.8 5.2 5.6 6.0 6.4 6.6  
:MUSKEGON RIVER  
EVART 10.2 10.4 10.9 11.9 13.0 13.8 14.4  
:LITTLE MUSKEGON RIVER  
MORLEY 3.3 3.6 4.0 4.5 4.9 5.5 5.7  
:MUSKEGON RIVER  
CROTON 7.9 8.2 8.6 9.2 10.1 10.9 11.8  
NEWAYGO 10.3 10.7 11.2 12.0 13.6 15.4 17.3  
BRIDGETON 12.0 12.6 13.4 14.4 15.9 17.3 18.8  
:KALAMAZOO RIVER  
MARSHALL 5.3 5.4 5.7 6.2 6.6 7.3 8.7  
:BATTLE CREEK  
BATTLE CREEK 1.7 1.9 2.0 2.3 2.5 2.9 3.2  
:KALAMAZOO RIVER  
BATTLE CREEK 4.3 4.4 4.7 5.2 5.9 6.7 7.0  
COMSTOCK 5.6 5.8 6.4 7.0 7.8 9.1 9.7  
NEW RICHMOND 14.6 14.7 15.0 15.4 16.1 16.9 17.3  
:ST JOSEPH RIVER  
BURLINGTON 5.3 5.4 5.6 5.9 6.2 6.5 6.8  
:PORTAGE RIVER  
VICKSBURG 4.7 4.7 4.8 5.0 5.3 5.5 6.3  
:CHIPPEWA RIVER  
MT PLEASANT 6.4 6.7 7.1 7.6 8.6 9.7 10.4  
:PINE RIVER  
ALMA 4.7 5.2 5.7 6.3 7.1 8.1 8.3  
 
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: 02/17/2020 - 05/17/2020  
LOCATION 95% 90% 75% 50% 25% 10% 5%  
-------- ------ ------ ------ ------ ------ ------ ------  
:GRAND RIVER  
JACKSON 10.3 10.2 10.0 9.7 9.6 9.5 9.3  
:BUCK CREEK  
GRANDVILLE 4.8 4.8 4.7 4.6 4.5 4.4 4.4  
:GRAND RIVER  
EATON RAPIDS 4.0 4.0 3.9 3.8 3.8 3.7 3.7  
DIMONDALE 6.4 6.4 6.2 5.8 5.7 5.4 5.3  
:RED CEDAR RIVER  
WILLIAMSTON 3.4 3.3 3.1 2.9 2.7 2.6 2.5  
EAST LANSING 4.0 3.9 3.8 3.6 3.6 3.5 3.4  
:SYCAMORE CREEK  
HOLT 3.9 3.8 3.8 3.7 3.7 3.6 3.6  
:GRAND RIVER  
LANSING 4.7 4.7 4.3 4.0 3.8 3.5 3.4  
GRAND LEDGE 5.8 5.8 5.7 5.5 5.5 5.3 5.2  
PORTLAND 6.8 6.8 6.5 6.3 6.1 5.9 5.8  
:LOOKING GLASS RIVER  
EAGLE 4.0 3.9 3.7 3.5 3.2 3.1 3.0  
:MAPLE RIVER  
MAPLE RAPIDS 6.1 5.8 5.3 4.6 4.2 4.0 3.9  
:GRAND RIVER  
IONIA 12.2 11.9 11.3 10.7 10.3 9.8 9.5  
:FLAT RIVER  
SMYRNA 4.2 4.2 4.1 4.0 3.9 3.8 3.7  
:GRAND RIVER  
LOWELL 7.4 7.2 6.9 6.6 6.4 6.1 5.8  
:THORNAPPLE RIVER  
HASTINGS 3.7 3.7 3.6 3.5 3.4 3.2 3.2  
CALEDONIA 4.4 4.4 4.3 4.1 3.9 3.7 3.6  
:GRAND RIVER  
ADA 9.9 9.7 9.3 8.8 8.3 7.6 7.2  
:ROGUE RIVER  
ROCKFORD 4.7 4.7 4.6 4.4 4.3 4.2 4.1  
:GRAND RIVER  
GRAND RAPIDS 5.7 5.4 4.8 4.3 3.8 3.0 2.6  
:PERE MARQUETTE RIVER  
SCOTTVILLE 2.5 2.4 2.4 2.2 2.0 1.9 1.9  
:WHITE RIVER  
WHITEHALL 2.5 2.4 2.4 2.3 2.1 2.0 1.9  
:MUSKEGON RIVER  
EVART 7.8 7.8 7.8 7.7 7.6 7.6 7.5  
:LITTLE MUSKEGON RIVER  
MORLEY 2.4 2.4 2.4 2.4 2.4 2.4 2.4  
:MUSKEGON RIVER  
CROTON 5.8 5.8 5.8 5.8 5.6 5.5 5.4  
NEWAYGO 8.1 8.1 8.1 8.0 7.9 7.8 7.7  
BRIDGETON 9.0 8.9 8.9 8.8 8.6 8.4 8.2  
:KALAMAZOO RIVER  
MARSHALL 4.5 4.3 3.7 3.3 3.3 3.3 3.3  
:BATTLE CREEK  
BATTLE CREEK 1.2 1.2 1.2 1.1 1.1 1.0 1.0  
:KALAMAZOO RIVER  
BATTLE CREEK 3.8 3.7 3.6 3.5 3.4 3.2 3.2  
COMSTOCK 4.9 4.8 4.7 4.5 4.4 4.3 4.2  
NEW RICHMOND 13.6 13.5 13.3 12.9 11.0 10.3 9.9  
:ST JOSEPH RIVER  
BURLINGTON 4.6 4.5 4.3 4.2 4.1 4.0 3.9  
:PORTAGE RIVER  
VICKSBURG 4.3 4.2 4.2 4.1 4.0 3.9 3.9  
:CHIPPEWA RIVER  
MT PLEASANT 3.6 3.6 3.6 3.5 3.4 3.3 3.3  
:PINE RIVER  
ALMA 2.6 2.6 2.5 2.2 2.0 1.8 1.7  
 
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 WEATHER.GOV/GRR FOR MORE WEATHER AND WATER  
INFORMATION.  
 
AN UPDATED SPRING FLOOD OUTLOOK WILL BE ISSUED ON THURSDAY, FEBRUARY  
27TH.  
 

 
 
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