946
FXUS65 KGGW 110601
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1201 AM MDT Mon May 11 2026

.KEY MESSAGES...

- Warm conditions are expected the next few days, peaking on
  Wednesday. There is an opportunity for thunderstorms today, with
  a few strong to severe storms possible.

- A Red Flag Warning has been issued for today for gusty northwest
  winds and low relative humidity. A Lake Wind Advisory is also
  in effect for today.

- The forecast becomes potentially wetter Wednesday night into the
  weekend with more scattered showers and isolated thunderstorms
  possible. High winds are possible Wednesday into Thursday, and a
  Lake Wind Advisory will likely be needed.




&&

.DISCUSSION...

WEATHER PATTERN OVERVIEW:
An oncoming warm front is expected to bring a few isolated showers
and thunderstorms through about 10 AM today, then a bit of
clearing and warming ahead of a surface cold front that will move
through in the afternoon. There are scattered showers and isolated
thunderstorms forecast to occur between noon and 9 PM. Some of the
CAM models suggest severe gusts around 60 mph are expected in the
strongest storms. It would not take very much to get to this
threshold since strong northwest winds are already forecast to
move through with the cold front. Strong boundary layer mixing
aloft and pre- frontal warming will aid in bringing afternoon
humidity readings below 20 percent. This combined with strong
winds and a low greenness index will bring critical fire weather
conditions. Upper ridge builds into the area on Tuesday with
lighter winds and dry weather. A few random locations may reach
criteria for red flag conditions on Tuesday in the east, but there
is marginal evidence for this set up thus far.

On Wednesday the upper ridge axis moves through eastern Montana
with the warmest day of 2026 so far expected. Some locations will
likely have highs in the 90s with increased southerly flow, adding
to ongoing fire weather concerns. These fire concerns are expected
on Thursday too. As the trough Wednesday into Thursday moves
through, the weather prediction centers is suggesting a few
locations reaching high wind criteria. This situation will be
monitored closely.

A more zonal flow pattern develops thereafter to moderate
temperatures some and bring smaller synoptic ridge/trough
couplets embedded in it. This will bring chances for showers and
thunderstorms at times across the region through the weekend with
possible wetting rains or even a marginal severe potential
depending on whether it matches up with peak heating. Individual
ensemble members continue to disagree on what day/time any given
ridge/trough couplet moves through though.

FORECAST CONFIDENCE & DEVIATIONS:
The main deviations were to increase winds in the afternoon, to
increase PoPs, and increase thunder on Day 1. Also decreased
relative humidity to line up with the Red Flag Warning for later
today.

There is high confidence on isolated to scattered showers and
thunderstorms occurring through 8 PM today, and high confidence in
the Red Flag Warning timing and location. There is moderate (50
percent) confidence of these storms producing a severe wind gust.

There is moderate confidence on a fire weather product being
needed on Tuesday. There is high confidence of a lake wind
advisory being needed for Wednesday and Thursday, and in
temperatures reaching the 90s for many locations. There is
moderate confidence on a high wind product being needed Wednesday
into Thursday as well.

Confidence is low on Wednesday afternoon for thunderstorms being
strong to severe as the trough moves through.


&&

.AVIATION...

LAST UPDATED: 0600Z

FLIGHT CAT RANGE: VFR, MVFR in thunderstorms and areas blowing
dust.

DISCUSSION: An oncoming shortwave trough is bringing enough
forcing to get a few showers and isolated thunderstorms going
through the early morning. Then mid to high clouds clear out
ahead of a surface cold front that will have enough forcing to get
a few isolated thunderstorms going from 19Z to around 02Z Tuesday.
There is moderate confidence (50 percent) of MVFR conditions
occurring with these storms. There is also moderate to high
confidence (50-70 percent) of blowing dust occurring for KSDY and
KGDV in the afternoon as the front passes through.

WIND: Mainly south southeast at 6 to 16 knots, becoming northwest
at 15 to 27 knots with gusts to 39 knots after 18Z, decreasing to
10 to 15 knots after 03Z Tuesday.

LLWS: South southeast at 30 to 40 knots for most TAF sites through
12Z, then northwest through 15Z before ending.

EQUIPMENT: No obs from KSDY. TAF will be AMD NOT SKED until obs
return.


&&

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

Red Flag Warning from 11 AM to 8 PM MDT Monday for
Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck
Reservation and Daniels/Roosevelt/Sheridan Counties-Northern
Valley and Northern Phillips Counties-Southern Petroleum and
Southern Garfield Counties-The Little Rockies-The Lower Missouri
River Breaks including the Charles M Russell National Wildlife
Refuge.

&&

$$

weather.gov/glasgow