PROBABILISTIC OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
105 PM EST THU FEB 11 2021
...2021 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: 02/15/2021 - 05/16/2021
: 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 26 25 23 21 7 8
Shiawassee River
Owosso 7.0 9.0 10.0 25 23 <5 <5 <5 <5
Kearsley Creek
Davison 10.0 11.0 12.0 22 25 <5 <5 <5 <5
Flint River
Flint 13.0 15.0 17.0 5 6 <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 5 <5 <5 <5 <5
Frankenmuth 17.0 20.0 25.0 19 32 <5 9 <5 <5
Saginaw River
Saginaw 17.0 19.0 24.0 27 28 8 16 <5 <5
LEGEND
CS = CONDITIONAL SIMULATION (CURRENT OUTLOOK)
HS = HISTORICAL SIMULATION
FT = FEET
...TABLE 1--PROBABILITIES FOR MINOR...MODERATE AND MAJOR FLOODING...
VALID PERIOD: 02/15/2021 - 05/16/2021
: 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 13 17 8 9 <5 <5
North Branch Clinton River
Mt Clemens 15.0 16.0 18.0 <5 7 <5 <5 <5 <5
Clinton River
Mt Clemens 16.0 17.0 18.0 <5 <5 <5 <5 <5 <5
River Rouge
Detroit 15.0 18.0 20.0 28 31 6 <5 <5 <5
Middle River Rouge
Dearborn Heights 10.0 11.0 12.0 6 11 <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 8 14 5 8 <5 <5
Huron River
Hamburg 6.5 7.0 7.5 30 50 16 32 8 15
Ann Arbor 16.0 17.0 18.0 9 13 <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 14 21 <5 7 <5 <5
Dundee 650.0 652.0 653.0 14 18 <5 8 <5 7
Monroe 9.0 10.0 11.0 15 21 <5 6 <5 <5
LEGEND
CS = CONDITIONAL SIMULATION (CURRENT OUTLOOK)
HS = HISTORICAL SIMULATION
FT = FEET
...PAST PRECIPITATION...
Precipitation across southeast Michigan so far Fall through Winter
has been below average. Around 70% of normal.
...RIVER CONDITIONS...
River base flow is below average on all rivers. River ice was little
to none due to the warm temperatures and lack of any extended Arctic
outbreaks until the past week where river ice has increased but still
below average in coverage.
...SOIL CONDITIONS AND FROST DEPTH...
Abnormally dry soil conditions exist, especially across the southern
three tiers of counties. Frost depths were also shallow, mostly under
a foot but have increased rapidly the past week.
...SNOW COVER AND LIQUID WATER CONTENT...
Snow cover is below average for this time of year, under 10 inches.
Water equivalents are also below average, less then an inch.
...WEATHER OUTLOOK...
The outlook for the next 8-14 days calls for below average temperatures
and precipitation. The outlook for the Spring is for better then normal
chance for above normal temperatures and much better chance for above
normal precipitation.
...FLOOD SUMMARY OUTLOOK...
With below normal snowpack, water equivalent, soil moisture and base flow
in the rivers, the probability for minor flooding is slightly below normal
while well below normal for moderate or major flooding. Localized flooding
from an ice jams is always a threat.
The next spring flood probabilistic outlook will be February 25.
Additional supportive data and explanations are available on the
internet at WWW.CRH.NOAA.GOV/DTX
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