865
FXUS65 KGGW 272003
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
203 PM MDT Sat Apr 27 2024

.DISCUSSION...

KEY MESSAGES:

1) Southeast winds will increase into tonight, but remain
borderline for a Lake Wind Advisory for Fort Peck Lake.

2) Forecast higher rainfall totals have shifted north, though wet
conditions continue to be favored Monday afternoon through
Tuesday. A further shift north may raise fire weather concerns for
the southern zones.

3) West winds on Tuesday will increase to between 30 and 40 mph
with gusts as high as 50 mph.

WEATHER PATTERN OVERVIEW:

Upper ridging is beginning to shift to the east and will lead to
increasing clouds tonight for NE Montana while most showers remain
to the west. Gusty southeast winds will tend to increase on the
back side of the ridge. Right now, conditions appear borderline
for Lake Wind conditions for Fort Peck Lake, but the evening shift
will have one more chance to assess the potential more closely.

The next weather system will arrive from the west on Monday
afternoon with ensembles showing rain lifting from southwest to
northeast into Tuesday. There may be enough instability in the
southern zones for some of this to be convective with isolated
thunderstorms initially before it becomes more steady rain showers
across the north. NBM is a bit to the north with highest QPF from
the previous cycle. While wetting rains are still favored area
wide, the greatest probabilities of seeing 0.25 to 0.50 inches of
QPF and beyond exist closer to the Canadian border at the moment.
To the south, dry slotting is possible on Tuesday. There is a low
probability that southern zones may miss out on enough rain and
break out into dry and windy conditions on Tuesday, raising fire
weather concerns. Cool and cloudy conditions may still limit the
risk, and there is uncertainty with preceding showers, but this
remains an open potential worth following.

Ensembles continue to favor an active pattern through the second
half of the week with a series of shortwaves tracking through the
region in a progressive fashion, thus, chances for precipitation
remain throughout most of the forecast period even if timing and
precise details remain uncertain.

CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:

Confidence is growing that increasing southeast winds tonight will
reach borderline Lake Wind Advisory criteria for Fort Peck lake,
but not yet high enough to issue any headlines.

Medium confidence exists on the wet weather for Monday into
Tuesday with potential for initial thunderstorms. The 48 hour
probability of at least a tenth of an inch of rainfall ending
Wednesday morning remains above 70 percent area wide, though an
area of 30 percent probabilities for a half inch of rainfall is
shifting toward the Canadian border.

Medium to high chances exist for wind gustS area wide on Tuesday
to exceed 40 mph, especially from Malta to Glendive and points to
the southeast where the probability exceeds 70 percent. Isolated
high wind gusts of 58 mph or greater cannot be ruled out.

There is a low probability that precipitation shifts far enough
north that the southern zones end up in dry and windy conditions,
raising fire weather concerns. Cool and cloudy conditions and any
preceding rainfall may limit the risk, but this will be worth
following in the days to come.

&&

.AVIATION...
LAST UPDATED: 2000Z

FLIGHT CAT RANGE: VFR.

DISCUSSION: An upper ridge across the area will maintain dry
weather and seasonable temperatures through tonight. Look for
winds out of the southeast at 5 to 15 kts.


&&

.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/glasgow