National Weather Service United States Department of Commerce
PROBABILISTIC OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1030 AM EST THU FEB 13 2020


...2020 SPRING FLOOD AND WATER RESOURCES OUTLOOK NUMBER 1...

Advanced Hydrologic Prediction Service probabilistic outlook
 for the major rivers in the Saginaw River basin and the Clinton
 ...Rouge...Huron and Raisin River basins...

The Detroit/Pontiac office of the National Weather Service has
implemented Advance Hydrologic Prediction Service (AHPS) for all
the model locations in the above mentioned basins. AHPS enables
the National Weather Service to provide long range probabilistic
river outlooks. This service is also available on the internet
at WWW.CRH.NOAA.GOV/DTX.

In the table 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 then HS...the probability of
exceeding that level is higher then normal. When the value of CS is
less then 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
--------          ----- ----- ----- : ---- ---- ---- ---- ---- ----
 Clinton River
Clinton Township 16.0   17.0   19.0    17   20    8    9   <5   <5
Mt Clemens       16.0   17.0   18.0    <5   <5   <5   <5   <5   <5
 North Branch Clinton River
Mt Clemens       15.0   16.0   18.0    <5    6   <5   <5   <5   <5
 River Rouge
Detroit          15.0   18.0   20.0    26   31   <5   <5   <5   <5
 Middle River Rouge
Dearborn Heights 10.0   11.0   12.0     9    7   <5   <5   <5   <5
 Lower Rouge River
Dearborn         11.0   12.0   13.0    <5   <5   <5   <5   <5   <5
 Mill Creek
Dexter           12.0   13.0   14.0     6   14   <5    5   <5   <5
 Huron River
Hamburg           6.5    7.0    7.5    93   49   61   33   30   18
Ann Arbor        16.0   17.0   18.0    14   10   <5   <5   <5   <5
 River Raisin
Tecumseh         13.0   14.0   15.0    <5   <5   <5   <5   <5   <5
Adrian           18.0   19.0   20.0    <5   <5   <5   <5   <5   <5
Blissfield      683.0  685.0  687.0    13   17    6    8   <5   <5
Dundee          650.0  652.0  653.0    12   15    5    7   <5    6
Monore            9.0   10.0   11.0    12   19   <5   <5   <5   <5

LEGEND
CS  = CONDITIONAL SIMULATION (CURRENT OUTLOOK)
HS  = HISTORICAL SIMULATION
FT  = FEET

:...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
--------          ----- ----- ----- : ---- ---- ---- ---- ---- ----
 Pine River
Midland          12.0   14.0   16.0    <5   <5   <5   <5   <5   <5
 Tittabawassee River
Midland          24.0   25.0   28.0    27   17   17   15   <5   <5
 Shiawassee River
Owosso            7.0    9.0   10.0    25   19   <5   <5   <5   <5
 Kearsley Creek
Davison          10.0   11.0   12.0    35   33   <5   <5   <5   <5
 Flint River
Flint            13.0   15.0   17.0     7    7   <5   <5   <5   <5
 Cass River
Cass City        14.0   18.0   20.0    <5    5   <5   <5   <5   <5
Vassar           14.0   15.0   18.0    <5    7   <5   <5   <5   <5
Frankenmuth      17.0   20.0   25.0    16   25   <5    8   <5   <5
 Saginaw River
Saginaw          17.0   19.0   24.0    28   23    7   12   <5   <5

LEGEND
CS  = CONDITIONAL SIMULATION (CURRENT OUTLOOK)
HS  = HISTORICAL SIMULATION
FT  = FEET



...PAST PRECIPITATION...
Precipitation across the area for the fall through winter so far
has been above average.  Around 150% of normal.

...RIVER CONDITIONS...
River flow is above average on all rivers due to the wet fall
and winter. River ice is little to none due to the warm temperatures
and lack of any extended arctic outbreaks.

...SOIL CONDITIONS AND FROST DEPTH...
Ground temperatures are below freezing down to about 2 feet across
southeast Michigan with frost depths ranging from zero to 2 inches.
This is very shallow for this time of winter.

...SNOW COVER AND LIQUID WATER CONTENT...
Snow cover is well below average for this time of year.  Generally
less then five inches with higher pockets up to 8 inches across
Midland county and the Thumb where water equivalent is around an inch.
Elsewhere basically a half inch or less of water equivalent.

...WEATHER OUTLOOK...
The outlook for the next 8-14 days calls for above average temperatures
and near normal precipitation.  The outlook for the spring is for above
normal temperatures and near normal precipitation.

...FLOOD SUMMARY OUTLOOK...
With the lack of a snow pack and water equivalent, the risk for moderate
to major flooding this spring is very low.  However, with soil moisture
and rivers running high, the probability for minor flooding is higher
then normal and would be driven by local heavy rain events.

The exception is the Huron river at Hamburg, where the probability for
moderate to major flooding is higher then normal for this spring.

The other exception is the Saginaw River as the high level of Lake Huron
has raised the base level to just below minor flood stage. Heavy rain
events and/or high northeasterly winds could easily pushed the river to
moderate flood stage.


The next spring flood probabilistic outlook will be March 12.

Additional supportive data and explanations are available on the
internet at WWW.CRH.NOAA.GOV/DTX