####018009193#### FGUS73 KAPX 151728 ESFAPX MIC001-007-009-011-019-029-031-033-039-047-051-055-069-079-089-097- 101-113-119-129-135-137-141-143-165-161728- Probabilistic Hydrologic Outlook National Weather Service Gaylord MI 1228 PM EST Thu Feb 15 2024 ...SPRING FLOOD OUTLOOK FOR NORTHERN MICHIGAN... THE SPRING 2024 FLOOD OUTLOOK FOR NORTHERN MICHIGAN INDICATES A BELOW AVERAGE PROBABILITY OF FLOODING DUE TO SNOW MELT WITHIN MAJOR EASTERN UPPER AND NORTHERN LOWER MICHIGAN RIVER BASINS. THIS OUTLOOK COVERS CHIPPEWA AND MACKINAC COUNTIES IN EASTERN UPPER MICHIGAN WHICH INCLUDES THE PINE RIVER BASIN...AND THE NORTHERN HALF OF LOWER MICHIGAN ENCOMPASSING THE AU SABLE...BOARDMAN...MANISTEE... RIFLE...AND TOBACCO RIVER BASINS. THE FIRST TABLE BELOW LISTS THE PROBABILITIES OF REACHING FLOOD STAGE (MINOR FLOODING)...AS WELL AS MODERATE AND MAJOR FLOOD LEVELS FOR THE SIX FORECAST POINTS WITHIN THE GAYLORD NATIONAL WEATHER SERVICE OFFICE HYDROLOGIC SERVICE AREA. THE CURRENT (CS) AND HISTORICAL (HS) 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 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/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 -------- ----- ----- ----- : --- --- --- --- --- --- :Manistee River Sherman 15.0 16.0 17.0 : 6 12 <5 <5 <5 <5 :Boardman River Mayfield--Brown B 7.0 8.0 9.0 : <5 <5 <5 <5 <5 <5 :Au Sable River Red Oak 7.0 8.0 9.0 : <5 12 <5 <5 <5 <5 :Rifle River Sterling 6.0 11.0 13.0 : 44 62 <5 <5 <5 <5 :Pine River Rudyard 17.0 19.0 20.0 : <5 <5 <5 <5 <5 <5 :Tobacco River Beaverton 12.0 14.0 17.0 : <5 <5 <5 <5 <5 <5 Legend CS = Conditional Simulation (Current Outlook) HS = Historical Simulation FT = Feet DEPARTURE FROM NORMAL OF REACHING FLOOD STAGE IS THE DIFFERENCE BETWEEN THE CURRENT PROJECTED CHANCE FOR REACHING FLOOD STAGE (CS) AND THE CLIMATIC NORMAL (HS). FOR EXAMPLE...THE RIFLE RIVER NEAR STERLING...WITH A FLOOD STAGE OF 6 FEET...HAS A 44 PERCENT CHANCE OF REACHING OR EXCEEDING FLOOD STAGE...WHICH IS 18 PERCENTAGE POINTS BELOW NORMAL. DURING THE 90 DAY PERIOD LISTED...THE TYPICAL PROBABILITY OF THE RIFLE RIVER NEAR STERLING REACHING FLOOD STAGE IS 62 PERCENT. THE NEXT TABLE SHOWS THE CHANCE THAT A PARTICULAR RIVER LOCATION COULD RISE ABOVE THE LISTED STAGES IN THE SPECIFIED 90 DAY PERIOD (HIGH FLOW FORECAST): ...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% -------- ------ ------ ------ ------ ------ ------ ------ :Manistee River Sherman 12.7 12.9 13.2 13.8 14.2 14.6 15.1 :Boardman River Mayfield--Brown B 3.9 4.0 4.1 4.4 4.7 4.9 5.1 :Au Sable River Red Oak 3.7 3.9 4.3 4.7 5.3 5.8 6.1 :Rifle River Sterling 3.9 4.2 4.5 5.6 6.8 8.1 8.6 :Pine River Rudyard 4.2 4.9 6.4 7.7 9.5 10.4 10.9 :Tobacco River Beaverton 5.0 5.4 5.8 6.3 7.1 8.7 9.2 CURRENT FORECASTS SUGGEST PROBABILITIES OF EXCEEDING FLOOD STAGE AT ANY GIVE LOCATION ARE LESS THAN 5 PERCENT. THE LAST TABLE INDICATES THE CHANCE THAT A PARTICULAR RIVER LOCATION COULD FALL BELOW THE LISTED STAGES IN THE SPECIFIED 90 DAY PERIOD (LOW FLOW FORECAST): ...TABLE 3--NON-EXCEEDANCE 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% -------- ------ ------ ------ ------ ------ ------ ------ :Manistee River Sherman 11.7 11.7 11.6 11.5 11.4 11.3 11.2 :Boardman River Mayfield--Brown B 3.5 3.5 3.5 3.5 3.4 3.4 3.3 :Au Sable River Red Oak 3.1 3.1 3.0 3.0 2.9 2.9 2.9 :Rifle River Sterling 1.8 1.7 1.7 1.6 1.6 1.6 1.5 :Pine River Rudyard 1.1 1.1 1.1 1.1 1.0 1.0 1.0 :Tobacco River Beaverton 2.4 2.4 2.3 2.3 2.3 2.3 2.3 SPRING FLOOD OUTLOOKS ARE ROUTINELY ISSUED IN FEBRUARY AND MARCH IN ORDER TO GIVE ADVANCE NOTICE OF POSSIBLE FLOODING. THE LONG RANGE PROBABILISTIC OUTLOOKS GIVEN IN THE ABOVE TABLES CONTAIN FORECAST VALUES THAT ARE CALCULATED USING MULTIPLE SEASON SCENARIOS FROM 30 OR MORE YEARS OF CLIMATOLOGICAL DATA...AND INCORPORATE CURRENT RIVER LEVELS...SOIL MOISTURE CONDITIONS...SNOW DEPTH AND SNOW WATER EQUIVALENT VALUES...AND BOTH 30 AND 90 DAY OUTLOOKS FOR TEMPERATURE AND PRECIPITATION PROVIDED BY THE NOAA/NWS CLIMATE PREDICTION CENTER. ACTUAL RIVER CRESTS WILL DIFFER FROM THIS OUTLOOK IF FUTURE CONDITIONS DIFFER SIGNIFICANTLY FROM FORECAST CONDITIONS (SUCH AS SIGNIFICANT LATE WINTER/EARLY SPRING SNOWFALL) OR IF ICE JAMS DEVELOP. ...CURRENT CONDITIONS... PRECIPITATION DURING THE FALL MONTHS OF 2023 (SEPTEMBER THROUGH NOVEMBER) WAS NEAR NORMAL ACROSS EASTERN UPPER AND NORTHWEST LOWER MICHIGAN...TRENDING BELOW NORMAL (50 TO 75 PERCENT OF NORMAL) CLOSER TO SAGINAW BAY. BUT THE OBVIOUS FACTOR IN THE BELOW NORMAL PROBABILITIES FOR SPRING FLOODING ACROSS NORTHERN MICHIGAN HAS BEEN THE OVERALL LACK OF SNOW COVER THROUGH LATE WINTER. SNOWFALL THUS FAR SINCE JULY 1 IS RUNNING ABOUT 50 TO 75 PERCENT OF NORMAL...THOUGH A LOT OF THAT OCCURRED DURING THE PERIOD OF JANUARY 9-23 WHERE SOME LOCATIONS RECEIVED MORE THAN 50 PERCENT OF THEIR SEASONAL TOTAL THUS FAR IN JUST THAT TWO WEEK PERIOD. THIS COMBINED WITH A TOP TEN WARMEST JANUARY ON RECORD...AND WHAT SO FAR IS SETTING UP TO BE A RECORD WARMEST FEBRUARY (TEMPERATURE DEPARTURES OF 11 TO 14 DEGREES ABOVE NORMAL THROUGH FEBRUARY 14)...HAS RESULTED IN A MINIMAL AMOUNT OF SNOW COVER ESPECIALLY ACROSS NORTHERN LOWER MICHIGAN. AS OF FEBRUARY 12 (PRIOR TO THE AREA WIDE SNOWFALL OCCURRING ON 15 FEBRUARY)... SNOW WATER EQUIVALENT OF THE SNOWPACK THAT DOES EXIST (PRIMARILY ACROSS EASTERN UPPER MICHIGAN) IS LESS THAN 10 PERCENT OF NORMAL. SOIL MOISTURE IS RUNNING BELOW NORMAL ACROSS EASTERN UPPER AND FAR NORTHWEST LOWER MICHIGAN...ONLY ABOUT 10 TO 20 PERCENT OF NORMAL. SOIL MOISTURE IS NEAR NORMAL FOR MUCH OF NORTHEAST LOWER MICHIGAN. CURRENT DROUGHT CONDITIONS BASED ON THE U.S. DROUGHT MONITOR FOR FEBRUARY 15 INDICATES MODERATE DROUGHT CONDITIONS ACROSS EASTERN UPPER MICHIGAN AS WELL AS ACROSS MANISTEE COUNTY IN NORTHWEST LOWER MICHIGAN...AND ABNORMALLY DRY CONDITIONS FOR THE REMAINDER OF NORTHERN LOWER MICHIGAN ALONG AND SOUTH OF THE M-32 CORRIDOR. MOST GAGING STATIONS ON AREA RIVERS ARE RUNNING AT NORMAL STREAMFLOWS WITH A MINIMAL AMOUNT OF ICE ACTIVITY DUE TO THE WARM WEATHER. ...WEATHER OUTLOOK... THE CURRENT CLIMATOLOGICAL OUTLOOK THROUGH THE REMAINDER OF FEBRUARY INDICATES 40 TO 60 PERCENT PROBABILITY OF ABOVE NORMAL TEMPERATURES... AND AN OVERALL TREND OF ABOVE NORMAL PRECIPITATION. THE OUTLOOK FOR THE MONTH OF MARCH IS CALLING FOR A HIGHER PROBABILITIES FOR ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION. ...ADDITIONAL INFORMATION... AN UPDATED SPRING FLOOD OUTLOOK WILL BE ISSUED ON THURSDAY FEBRUARY 29. LONG RANGE PROBABILISTIC OUTLOOKS SUCH AS THOSE GIVEN IN THE ABOVE TABLES ARE ISSUED DURING THE LAST WEEK OF EACH MONTH THROUGHOUT THE YEAR. VISIT WATER.WEATHER.GOV/AHPS2/INDEX.PHP?WFO=APX (ALL LOWER CASE) FOR MORE RIVER INFORMATION...INCLUDING GRAPHS OF THE PROBABILISTIC INFORMATION GIVEN IN THE ABOVE TABLES...AS WELL AS THE LATEST OBSERVED CONDITIONS ON NORTHERN MICHIGAN STREAMS. $$ JPB