Flood Potential Outlook
Issued by NWS Gaylord, MI

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FGUS73 KAPX 152049
ESFAPX
MIC001-007-009-011-019-029-031-033-039-047-051-055-069-079-089-097-
101-113-119-129-135-137-141-143-165-172049-

Probabilistic Hydrologic Outlook
National Weather Service Gaylord MI
349 PM EST Thu Feb 15 2018

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

THE SPRING 2018 FLOOD OUTLOOK FOR NORTHERN MICHIGAN INDICATES
AN 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 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/MAJOR FLOODING
                    VALID PERIOD:  02/18/2018 - 05/19/2018

                                       :    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 :  28   16    6   <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 :  10   10   <5   <5   <5   <5
:RIFLE RIVER
STERLING             6.0   11.0   13.0 :  66   64   <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 66 PERCENT CHANCE OF REACHING OR
EXCEEDING FLOOD STAGE...WHICH IS 2 PERCENTAGE POINTS ABOVE NORMAL.
DURING THE 90 DAY PERIOD LISTED...THE NORMAL PROBABILITY OF THE RIFLE
RIVER NEAR STERLING REACHING FLOOD STAGE IS 64 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--EXCEEDENCE PROBABILITIES

                               CHANCE OF EXCEEDING STAGES
                                  AT SPECIFIC LOCATIONS
                          VALID PERIOD: 02/18/2018 - 05/19/2018
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:MANISTEE RIVER
SHERMAN              13.5   13.7   14.1   14.6   15.1   15.7   16.1
:BOARDMAN RIVER
MAYFIELD--BROWN B     4.7    4.8    4.9    5.2    5.5    5.9    6.2
:AU SABLE RIVER
RED OAK               4.5    4.7    5.2    5.6    6.2    7.0    7.5
:RIFLE RIVER
STERLING              4.6    4.9    5.6    6.5    7.9    9.3   10.1
:PINE RIVER
RUDYARD               6.2    6.5    7.9    9.4   11.6   12.2   13.0
:TOBACCO RIVER
BEAVERTON             5.8    6.1    6.6    7.2    8.1    9.2    9.9

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: 02/18/2018 - 05/19/2018
LOCATION              95%    90%    75%    50%    25%    10%     5%
--------            ------ ------ ------ ------ ------ ------ ------
:MANISTEE RIVER
SHERMAN              12.2   12.2   12.1   12.1   12.0   11.9   11.8
:BOARDMAN RIVER
MAYFIELD--BROWN B     4.0    3.9    3.9    3.9    3.9    3.9    3.8
:AU SABLE RIVER
RED OAK               3.2    3.2    3.2    3.1    3.1    3.0    3.0
:RIFLE RIVER
STERLING              1.8    1.8    1.8    1.8    1.7    1.7    1.7
:PINE RIVER
RUDYARD               1.2    1.2    1.2    1.1    1.1    1.1    1.1
:TOBACCO RIVER
BEAVERTON             2.6    2.6    2.6    2.6    2.5    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...
THE FALL MONTHS (SEPTEMBER THROUGH NOVEMBER) WERE WET ACROSS
NORTHERN MICHIGAN...WITH PRECIPITAITON 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.  FOR THE WINTER MONTHS SO FAR...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.
SNOWFALL SO FAR THIS SEASON HAS RANGED FROM AROUND 75 TO NEAR 100
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 95TH PERCENTILE ACROSS EASTERN UPPER
AND PORTIONS OF NORTHERN LOWER MICHIGAN NORTH OF THE M-72 CORRIDOR.
SNOW DEPTH ACROSS THE REGION RANGED FROM 12 TO 18 INCHES IN SMALL
POCKETS OF FAR EASTERN UPPER MICHIGAN AND BETWEEN GRAND TRAVERSE AND
LITTLE TRAVERSE BAY OVER NORTHWEST LOWER MICHIGAN...DOWN TO 1 TO 4
INCHES OVER FAR NORTHEAST LOWER MICHGIAN.  SNOW WATER EQUIVALENT
IN THE SNOW PACK IS GENERALL 4 TO 6 INCHES OVER NORTHWEST
CHIPPEWA COUNTY...DOWN TO LESS THAN AN INCH OVER FAR EASTERN
MACKINAC COUNTY AND EXTENDING EAST TO DRUMMOND ISLAND.  MOST
OF NORTHERN LOWER MICHIGAN HAS LESS THAN AN INCH OF WATER
EQUIVALENT IN THE SNOW PACK...WITH SOME POCKETS OF 2 TO 4
INCHES OVER NORTHWEST LOWER MICHIGAN.  RIVER ACROSS NORTHERN
MICHIGAN ARE MOSTLY ICE COVERED DUE TO THE RECENT COLD SPELL
DURING THE FIRST HALF OF FEBRUARY...SO ICE JAM FLOODING REMAINS
A DISTINCT POSSIBILITY GOING FORWARD.

...WEATHER OUTLOOK...
THE LATEST 30 DAY OUTLOOK FOR THE MONTH OF MARCH FROM THE
CLIMATE PREDICTION CENTER SHOWS NO DICERNABLE SIGNAL FOR
TEMPERATURES OR PRECIPITATION (EQUAL CHANCES FOR BELOW NORMAL/
NORMAL/ABOVE NORMAL TEMPERATURES AND PRECIPITATION).  THE 90 DAY
OUTLOOK FOR THE SPRING MONTHS (MARCH THROUGH MAY) DOES INDICATE
THE POSSIBILITY OF ABOVE NORMAL PRECIPITATION.

...ADDITIONAL INFORMATION...
AN UPDATED SPRING FLOOD OUTLOOK WILL BE ISSUED ON THURSDAY
MARCH 1. 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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