FXUS65 KMSO 240946
Area Forecast Discussion
National Weather Service Missoula MT
346 AM MDT TUE MAY 24 2016
.DISCUSSION...Early this morning, the elongated trough extending
from the low pressure center in southern Saskatchewan has moved
south, leading to the band of steady precipitation shifting south
over west central Montana and parts of central Idaho. This
precipitation is forecast to continue through the morning hours
and slowly migrate further south. By the afternoon, most locations
across the western half of Montana and northern half of Idaho will
see scattered showers develop. Isolated lightning is also possible from
some showers given modest instability. Temperatures will be 5 to
10 degrees warmer than in previous days as some clearing should
allow a slight warm-up.
Although light rain showers will likely continue today for the
ranges of northwest Montana, decreasing rainfall rates will spell
some relief for the rain-soaked areas of northwest Montana,
including Flathead county cities such as Columbia Falls, Coram,
Whitefish, and West Glacier. Flood advisories and warnings continue
to highlight regions most affected, as local streams will likely
still flow high and fast today despite the decreasing rain rates:
the stream response is delayed due to the time it takes for the
terrain to transport water away. At any rate, the flood situation
should slowly improve moving into mid-week.
Wednesday and Thursday the atmosphere will continue to be
unsettled as a trough of low pressure remains over the region.
This will translate into afternoon and evening showers and perhaps
a thunderstorm or two.
Friday through the Memorial Day weekend another organized weather
disturbance will enter the pacific northwest. This closed upper
low will meander or circulate over the pacific northwest into the
Northern Rockies. CONFIDENCE IS INCREASING FOR A WET MEMORIAL DAY
WEEKEND. Specifics such as who will receive the most precip is
pretty uncertain given the erratic movements of these closed upper
low pressure systems.
.AVIATION...Steady rain for KMSO and KBTM will likely continue
though the morning under a trough of low pressure. Expect low
ceilings and mountain obscurations through noon. KBTM could even
see a few hours of a rain-snow mix, which would limit visibility.
Patchy fog is also possible at terminals before sunrise due to
nearly saturated air at the surface, but thick clouds will limit
any cooling, so ground-based fog will have a hard time forming.
Scattered showers this afternoon could produce very isolated
lightning. Precipitation intensity and coverage decreases area-
wide by sunset.