918
FXUS65 KGGW 290912
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
312 AM MDT Mon Apr 29 2024

.DISCUSSION...

KEY MESSAGES:

- High probability (70-90%) for a wetting rain for most of
 northeast Montana with a moderate probability (40-70%) for 0.5
 inches of rainfall for the northwest zones.

- Strong west winds develop Tuesday morning with gusts to 50 mph
 possible, elevating fire weather concerns through Tuesday evening
 mainly in the southeast.

- Cooler and slightly unsettled weather continues into next
 weekend.

WEATHER PATTERN OVERVIEW:
Low pressure system moves across northern Montana over the next
few days, resulting in cooler, wetter and windier weather for
tonight into Tuesday. The low will be slow to move east, lingering
over southern Saskatchewan on Wednesday before slowly wobbling
east into the weekend. This will keep cooler and unsettled weather
over northeast Montana.
CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:

There is high confidence for at least a wetting rain for the
northwest zones from late this afternoon through Tuesday morning.
Models have a tendency to overestimate rainfall, so uncertainty
increases for higher QPF and away from the developing 700mb low.

Blended in NBM90 winds with the NBM due to tendency for
underestimation of speeds by the NBM for tonight and Tuesday. This
still does not put winds at a high probability for a High Wind
Warning, but a Lake Wind Advisory is likely. Will leave for next
shift to determine timing, but early morning through late evening
Tuesday is most likely.

The strong winds will also increase fire concerns in areas that
don`t get much precipitation. For now this will mainly be the
southern portion of FWZ122. Even without much QPF, cloudy skies
and cold air convective potential could keep RH from dropping much
below 20%. Will continue with Fire Weather Watch for now.

Following the initial frontal passage, the upper low lingers over
the northern plains. Cooler and unsettle weather is likely but
with highly variable positioning of the low in the ensembles,
confidence for precipitation chances is low into the weekend.

&&

.AVIATION...
VFR dropping to MVFR or lower late tonight with rain moving across
the region behind a cold front. West winds will also increase
behind the frontal passage, with gusts up to 40kts possible
Tuesday afternoon.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Tuesday morning through Tuesday evening
for Dawson/McCone/Prairie/Richland/Wibaux Counties.

&&

$$

weather.gov/glasgow