407
FGUS75 KTFX 292028
ESFTFX
MTC013-015-035-041-045-049-051-059-073-099-101-300600-

Hydrologic Outlook
National Weather Service Great Falls MT
228 PM MDT Fri May 29 2026

What: Heavy heavy rainfall Saturday into Monday.

Where: Greatest impacts will be along and west of the I-15 corridor
of North-Central MT.

Timing: The window for the heaviest rainfall will be between
Saturday afternoon through Sunday morning. Here, rainfall rates of
0.5" to 0.75" every 6 hours are possible. Light to moderate rainfall
lingers through at least Monday.

Details:

Rainfall amounts range from 1 to 3 inches for the area, with a 10%
chance for 4 inches along and west of the I-15 corridor. Additional
snowmelt runoff from the Rocky Mountain Front can enhance creek and
river rises including but not limited to the Sun River, Marias
River, and Saint Mary River. Low lying-areas and poor drainage areas
are also at risk for flooding. Rural dirt roads will be susceptible
to become washed out or impassable.

Due to increasing confidence in flood impacts, a Flood Watch was
issued for areas along and west of the I-15 corridor for
North-Central MT Saturday through Monday. Rivers and creeks are
expected to crest Monday, which can linger impacts for areas prone
to river/creek flooding. Areas farther east of the I-15 corridor are
expected to see lesser flood impacts.

Everyone is reminded that should flooding develop, regardless if the
roadway is paved or not, do not drive through any flood waters, as
you do not know if the road has been washed out under the flood
waters.

Please monitor the National Weather Service or the local media this
weekend for further updates on this spring storm.
$$

Wilson