Lewistown, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

643
FXUS65 KTFX 292323
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
523 PM MDT Mon Jun 29 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Precipitation diminishes this evening but impacts from recent locally
   excessive rainfall may linger in the Glacier National Park
   area.

 - Drier weather develops with a return to more seasonable temperatures
   for the remainder of the week and upcoming weekend.

 - A few showers and and thunderstorms may develop each afternoon
   through Friday.

&&

.DISCUSSION...
/Issued 240 PM MDT Mon Jun 29 2026/

The closed upper level low centered over central MT continues to
circulate moisture and areas of precipitation across the region this
afternoon with precipitation diminishing this evening as the upper
level low slowly lifts out to the northeast. A few isolated
thunderstorms are possible through early this evening, mainly near
the Canadian border. While lingering precipitation is generally light,
a few heavier showers remain possible in association with weak
thunderstorm activity near the Canadian border, including portions of
Glacier NP.

A drier pattern develops Tuesday through the rest of the week though
some troughing in the larger scale flow lingers across the NW US and
Northern Rockies through Friday. Weak disturbances and residual
moisture will likely combine with daytime instability for isolated
to widely scattered showers and a few thunderstorms each afternoon.
Loosely organized shortwaves moving through the flow Wednesday
and again Friday could facilitate a greater coverage of showers
and thunderstorms those days with the Friday wave potentially
bringing enough shear and CAPE to support a few stronger storms.
Otherwise, temperatures warm back to near seasonal averages through
the rest of the week. Longer range model ensembles generally
support ridging this weekend for overall dry conditions with some
additional warming. Hoenisch

&&

.AVIATION...
30/00Z TAF Period

Rain is expected to continue across Central and North-Central MT
this evening. The rain will be mainly stratiform across Central
MT, and more showery across North-Central MT. Weak instability may
allow for some thunderstorm development this evening, but
probabilities were too low to include in the TAFs. MVFR conditions
will occur across most of the terminals, with ceilings and
visibilities improving back to VFR conditions tomorrow morning.
Mountains will continue to be obscured through most of the TAF
period. -Dzomba

&&

.HYDROLOGY...

A Flood Warning has been issued for the Many Glacier area where
recent excessive rainfall has led to several trail closures and rises
on Swiftcurrent creek are impacting road access with forecasts
indicating additional rises on the creek through early this
evening. A Flood Watch continues for the rest of Glacier Park and
adjacent areas where 2-5 inches of precipitation has fallen over
the last 48hrs and up to 0.50" of precipitation is possible in
additional showers through early this evening. Most creeks
originating from the Glacier NP and the Northern Rocky Mtn front
have shown moderate rises from the runoff and will continue to be
monitored. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  48  73  50  74 /  90  20  10  30
CTB  48  70  48  71 /  90  30   0   0
HLN  48  72  51  72 /  80  40  50  80
BZN  43  70  44  72 /  70  30  40  60
WYS  33  61  33  67 /  70  30  20  20
DLN  40  67  43  71 /  50  50  70  50
HVR  48  75  50  78 /  70  40  10  10
LWT  44  70  45  72 /  90  30  10  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until midnight MDT tonight for East Glacier Park
Region.

&&

$$
http://www.weather.gov/greatfalls