888
FGUS73 KLOT 302131
ESFLOT
ILC007-031-037-043-053-063-075-089-091-093-097-099-103-105-111-141-
197-201-INC007-073-089-111-127-310300-

Hydrologic Outlook
National Weather Service Chicago IL
331 PM CST Thu Jan 30 2025

...Locally Heavy Rainfall and Flooding Possible Friday Morning...

...River rises and localized ice jam flooding possible Friday into
the weekend...

Rain, heavy at times, is expected Friday morning. Rainfall amounts
of 0.25 to 0.50 inches will be widespread, with an band of locally
heavier rainfall near and exceeding 1 inch likely somewhere in the
area. Although this amount of rainfall typically is not associated
with flooding, a combination of frozen soils and river ice cover
will increase the risk of localized flooding.

The measured soil frost depth Thursday morning was 12 inches with no
near surface thaw. Soil temperature sensors from the Illinois State
Water Survey WARM network indicate widespread frost depths of at
least 8 inches are present across northern Illinois. Although river
ice has been slowly melting in recent days, some areas of heavy
river ice cover likely remain on most area rivers. River rises, even
those within the banks, may be large enough to break up and shift
existing river ice cover and cause ice jams.

Currently forecasted rainfall on completely frozen or nearly
completely frozen ground will result in significant runoff and
possible flooding in at least isolated areas. Flooding will be most
likely in low-lying and flood prone areas, including roadways,
underpasses, ditches, and fields. There is still uncertainty in
where the heaviest rain will fall, which also means there is
uncertainty with regard to the river basins that have the highest
risk of river rises and ice jam flooding.

This outlook means that locally elevated water levels are possible,
but not yet certain. Persons living along area streams and rivers,
especially those prone to experience ice jam flooding, should
closely monitor the latest forecasts including the possibility of
flood watches and warnings.

$$

WSL