Flood Potential Outlook
Issued by NWS Gaylord, MI

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FGUS73 KAPX 011830
ESFAPX
MIC001-007-009-011-019-029-031-033-039-047-051-055-069-079-089-097-
101-113-119-129-135-137-141-143-165-150000-

Probabilistic Hydrologic Outlook
National Weather Service Gaylord MI
130 PM EST Thu Mar 1 2018

...SPRING FLOOD OUTLOOK FOR NORTHERN MICHIGAN...

THE SPRING 2018 FLOOD OUTLOOK FOR NORTHERN MICHIGAN INDICATES AN
AVERAGE PROBABILITY OF FLOODING 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 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:  03/11/2018 - 06/02/2018

                                       :    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 :  30   18   <5   <5   <5   <5
:BOARDMAN RIVER
MAYFIELD--BROWN B    7.0   99.0   99.0 :  <5   <5   <5   <5   <5   <5
:AU SABLE RIVER
RED OAK              7.0   99.0   99.0 :  <5   10   <5   <5   <5   <5
:RIFLE RIVER
STERLING             6.0   11.0   13.0 :  56   63   <5   <5   <5   <5
:PINE RIVER
RUDYARD             17.0   19.0   99.0 :  <5   <5   <5   <5   <5   <5
:TOBACCO RIVER
BEAVERTON           12.0   14.0   99.0 :  <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 56 PERCENT CHANCE OF REACHING OR
EXCEEDING FLOOD STAGE...WHICH IS 7 PERCENTAGE POINTS BELOW NORMAL.
DURING THE 90 DAY PERIOD LISTED...THE NORMAL PROBABILITY OF THE RIFLE
RIVER NEAR STERLING REACHING FLOOD STAGE IS 63 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: 03/11/2018 - 06/02/2018
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:MANISTEE RIVER
SHERMAN              13.5   13.6   13.9   14.6   15.1   15.6   15.9
:BOARDMAN RIVER
MAYFIELD--BROWN B     4.6    4.7    4.8    5.1    5.4    5.7    6.1
:AU SABLE RIVER
RED OAK               4.4    4.6    5.0    5.4    5.8    6.4    6.6
:RIFLE RIVER
STERLING              4.0    4.7    5.3    6.1    7.6    9.1   10.1
:PINE RIVER
RUDYARD               6.5    7.4    8.7    9.5   11.8   12.4   12.6
:TOBACCO RIVER
BEAVERTON             4.6    5.4    6.1    7.0    7.4    8.8   10.0

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--NONEXCEEDANCE PROBABILITIES...

                            CHANCE OF FALLING BELOW STAGES
                                 AT SPECIFIC LOCATIONS
                          VALID PERIOD: 03/11/2018 - 06/02/2018
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:MANISTEE RIVER
SHERMAN              12.7   12.6   12.3   12.1   11.9   11.8   11.6
:BOARDMAN RIVER
MAYFIELD--BROWN B     4.2    4.1    4.0    3.9    3.9    3.8    3.8
:AU SABLE RIVER
RED OAK               3.9    3.8    3.7    3.5    3.3    3.2    3.1
:RIFLE RIVER
STERLING              2.3    2.2    2.1    1.9    1.9    1.8    1.7
:PINE RIVER
RUDYARD               1.5    1.5    1.4    1.3    1.3    1.2    1.2
:TOBACCO RIVER
BEAVERTON             2.7    2.7    2.6    2.6    2.6    2.5    2.5

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...OR IF ICE JAMS DEVELOP.

...CURRENT CONDITIONS...

FALL MONTHS (SEPTEMBER THROUGH NOVEMBER): THE AUTUMN WAS WET ACROSS
NORTHERN MICHIGAN...WITH PRECIPITATION TOTALS RUNNING 100-150 PERCENT
OF NORMAL.  THIS WAS LARGELY THE RESULT OF A VERY WET OCTOBER...WITH A
RECORD WETTEST OCTOBER RECORDED AT TRAVERSE CITY (9.29 INCHES) AND
GAYLORD (8.21 INCHES).  PRECIPITATION REMAINED ABOVE NORMAL INTO
NOVEMBER AS WELL.

WINTER MONTHS (DECEMBER THROUGH FEBRUARY): LAKE EFFECT AREAS OF EASTERN
UPPER AND NORTHWEST LOWER MICHIGAN BORE THE BRUNT OF THE PRECIPITATION
DURING DECEMBER...WITH DRIER THAN NORMAL CONDITIONS OVER NORTHEAST
LOWER.  PRECIPITATION WAS NEAR NORMAL DURING JANUARY WITH A RETURN TO
WET WEATHER IN FEBRUARY WITH PORTIONS OF THE AU SABLE...RIFLE...AND
TOBACCO RIVER BASINS IN NORTHEAST LOWER MICHIGAN RECEIVING MORE THAN
200 PERCENT OF NORMAL RAINFALL.  THE HEAVIEST OF THIS RAINFALL OCCURRED
DURING THE PERIOD OF FEBRUARY 19-21...WHICH RESULTED IN SIGNIFICANT
FLOODING EXACERBATED BY DAMMING FROM ICE JAMS ALONG THE RIFLE AND AU
GRES RIVERS IN ARENAC COUNTY.  PRECIPITATION FOR WINTER AS A WHOLE WAS
NEAR TO A LITTLE ABOVE NORMAL ACROSS NORTHERN MICHIGAN (100-125 PERCENT
NORMAL) ALTHOUGH SNOWFALL THIS SEASON HAS BEEN BELOW NORMAL ESPECIALLY
OVER NORTHEAST LOWER MICHIGAN (50-75 PERCENT OF NORMAL).  SOIL MOISTURE
IS RUNNING WELL ABOVE NORMAL ACROSS NORTHERN MICHIGAN THANKS TO THE WET
AUTUMN SEASON...MOISTURE IN THE TOP 1 METER OF SOIL WAS IN THE 90TH
PERCENTILE ACROSS JUST ABOUT ALL OF NORTHERN MICHIGAN.  SNOW DEPTH
ACROSS THE REGION RANGED FROM 12 TO 18 INCHES OVER NORTHERN CHIPPEWA
COUNTY...AND FROM 3 TO 12 INCHES OVER THE REMAINDER OF THE EASTERN U.P.
SNOW DEPTH ACROSS NORTHERN LOWER MICHIGAN WAS CONFINED TO A SMALL AREA
BETWEEN GRAND TRAVERSE AND LITTLE TRAVERSE BAYS OF 3 TO 8 INCHES.  SNOW
COVER OVER THE REST OF NORTHERN LOWER MICHIGAN WAS MINIMAL.  SNOW WATER
EQUIVALENT IN THE SNOW PACK IS GENERALLY 4 TO 6 INCHES OVER NORTHERN
CHIPPEWA COUNTY...DOWN TO LESS THAN AN INCH OVER FAR EASTERN MACKINAC
COUNTY AND EXTENDING EAST TO DRUMMOND ISLAND.

RIVERS ACROSS NORTHERN MICHIGAN ARE RUNNING WELL ABOVE NORMAL TO NEAR
RECORD STREAMFLOWS WITH LITTLE ICE COVER.

...WEATHER OUTLOOK...

THE LATEST 30 DAY OUTLOOK FOR THE MONTH OF MARCH FROM THE CLIMATE
PREDICTION CENTER SHOWS A HIGHER PROBABILITY OF ABOVE NORMAL
TEMPERATURES...AND NEAR TO BELOW NORMAL PRECIPITATION.  THE 90 DAY
OUTLOOK FOR THE SPRING MONTHS (MARCH THROUGH MAY) SHOWS NO DISCERNIBLE
SIGNAL FOR TEMPERATURE TRENDS (AN EQUAL LIKELIHOOD OF NORMAL/ABOVE
NORMAL/BELOW NORMAL TEMPERATURES)...AND A HIGHER PROBABILITY OF ABOVE
NORMAL PRECIPITATION.

...ADDITIONAL INFORMATION...

THIS IS THE LAST SPRING FLOOD OUTLOOK FOR 2018.  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



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