Sidney, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

319
FXUS65 KGGW 260608
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1208 AM MDT Tue May 26 2026

.KEY MESSAGES...

- Hot temperatures continue though at least Friday with highs in
  the mid 80s to low 100s. A Heat Advisory is in effect for today
  and Wednesday for most parts of the area as a result.

- Gusty southeast winds starting today will lead to critical fire
  weather in areas of dry fuels in the east and a hazard to small
  craft on Fort Peck Lake.

- Isolated thunderstorms are expected by Tuesday evening, with
  additional chances through the week. Some of the storms could be
  strong, with isolated severe gusts for today.





&&

.DISCUSSION...

WEATHER PATTERN OVERVIEW:
Temperatures are expected to climb into the 90s and low 100s as an
upper ridge sets up from now through Friday. The lowest
temperatures will be in the locations with the highest elevations,
or in a river if you feel like swimming. There will be sufficient
heating and enough moisture at the surface to help generate
isolated thunderstorms this afternoon, mainly between 3 PM and 10
PM. The most likely threat is strong winds up to 60 mph since a
wide dewpoint depression (around 45 degrees) is expected. There
will be low wind shear (less than 30 knots from 0 to 3 km) in the
environment, so any storm that occurs will likely just spread out
in all directions as it hits the ground and will not move in any
particular direction. There is a chance of thunderstorms like
these in the southwest part of the area as well. Wednesday and
Thursday are expected to be similar to today, with most convection
confined to the western part of the area though. There is
critical fire weather, strong winds over Fort Peck Lake, and
intense heat over the area the next few days, so various weather
products have been issued for all these hazards.

For Saturday, high PWAT values (1 to 1.3 inches) are expected in
the atmosphere over the area, so thunderstorms that occur this day
will be prone to heavy downpours. So far, the deterministic GFS
has these values dropping back down below one inch by Sunday
afternoon. Overall, there are at least isolated thunderstorms
possible each day through June 3rd, and temperatures will drop
into the 70s and 80s for highs thankfully.

FORECAST CONFIDENCE & DEVIATIONS:
Only deviation was to increase PoPs to reflect CAMs through late
Tuesday evening.

There is high confidence in temperatures hitting the 100 mark
through Friday for at least a few locations. Low temperatures will
struggle to drop below the mid 60s as well, so adequate water
intake will be important.

There is moderate confidence in thunderstorms bringing strong
wind gusts to a few locations today, and low confidence for these
type of gusts on Wednesday. There is moderate to high confidence
in isolated to scattered thunderstorms occurring somewhere in the
area from Thursday through early June.

There is high confidence in the Red Flag Warnings, the Heat
Advisories, and the Lake Wind Advisory products.

&&

.AVIATION...
LAST UPDATED: 0630Z.

FLIGHT CAT RANGE: VFR, MVFR possible in the afternoon.

DISCUSSION: Some high clouds will move through the area during
this TAF cycle. Northeast Montana will be on the edge of an upper
trough starting tomorrow, so there is low to moderate confidence
of isolated thunderstorms bringing erratic winds and brief MVFR
conditions from 21Z today through 01Z Wednesday.

DENSITY ALTITUDE: Will be high due to near 100 degrees temps creating
thinner air in the afternoons through Thursday. Temperatures of
around 104 are expected to occur near KOLF.

WIND: Southeast at 6 to 15 knots, increasing to 15 to 25 knots
with gusts to 35 knots after 18Z.

LLWS: South to southeast at 40 knots through 14Z with wind
heights around 1900-2000 feet.

EQUIPMENT: KSDY obs are unavailable and will be AMD NOT SKED.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory from 9 AM this morning to 6 AM MDT Thursday
for Central and Southeast Phillips-Central and Southern Valley-
Garfield-McCone-Petroleum.

Heat Advisory from noon today to 9 PM MDT this evening for
Central and Southeast Phillips-Central and Southern Valley-
Daniels-Dawson-Eastern Roosevelt-Garfield-McCone-Northern
Phillips-Northern Valley-Petroleum-Prairie-Richland-Sheridan-
Western Roosevelt-Wibaux.

Heat Advisory from noon to 9 PM MDT Wednesday for Central and
Southeast Phillips-Central and Southern Valley-Daniels-Dawson-
Eastern Roosevelt-Garfield-McCone-Northern Phillips-Northern
Valley-Prairie-Richland-Sheridan-Western Roosevelt-Wibaux.

Red Flag Warning from noon today to 9 PM MDT this evening for
Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck
Reservation and Daniels/Roosevelt/Sheridan Counties.

Red Flag Warning from noon to 10 PM MDT Wednesday for
Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck
Reservation and Daniels/Roosevelt/Sheridan Counties.

&&

$$

weather.gov/glasgow