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000
FXUS65 KMSO 252036
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
236 PM MDT Sat May 25 2013

...Potential for Heavy Rain for mid to late next week...

.DISCUSSION...

Today...A shortwave of energy will continue to rotate northeast
through Idaho and western Montana today, which will help initiate
a few showers and thunderstorms later this afternoon. Most of the
action is expected to stay confined to areas of Missoula south
into southwestern Montana. Any thunderstorms that do develop are
expected to be fairly weak, with just brief gusty winds and short
burst of heavy rain. However, occasional lightning can occur, so
if spending time outdoors this Memorial Day weekend, take cover if
any storms drift overhead. A low pressure system spinning in
Alberta may kick off a few showers across northwestern Montana
today, though the atmosphere is a little more stable further
north, which should keep any showers from developing into
thunderstorms.

Sunday...A low pressure currently off the coast of Washington
State will swing through the region in the early afternoon that
will bring more widespread showers and thunderstorms to the area.
The atmosphere will be more unstable and energetic with this
system, so a few isolated strong thunderstorms could occur in the
late afternoon. At this time the stronger storms look to mainly be
in central Idaho and southwest Montana. These storms could bring
strong gusty winds and small hail, though are anticipated to be
sub-severe.

On Monday and Tuesday a couple of weak disturbance will be moving
through the Northern Rockies causing afternoon and evening showers
and thunderstorms. Temperatures for the first part of the week
will be near normal readings.

The models are indicating another round of widespread heavy rain,
especially across northwest Montana, for the later part of next
week. A mid-level circulation will move over Wyoming causing
moisture from the Gulf of Mexico to stream into the region. Areas
along the Continental Divide could potentially see several inches
of moisture. Confidence is growing that the region will see the
heavy rain, but the timing and path of the circulation is still
uncertain.

&&

.AVIATION...Clouds and showers are increasing this afternoon as the
lower atmosphere destabilizes. A weak disturbance passing through
southern Idaho and into southwest Montana will add a little bit
better lift for a thunderstorm or two across southwest Montana,
mainly impacting KBTM until 26/03z. Mountains will be obscured at
times in clouds and precipitation during this period.

Conditions are expected to improve once again overnight tonight as
showers dissipate and clouds slowly erode. Yet another spoke of
moisture/energy will be sweeping across central Idaho and western
Montana on Sunday. Clouds and showers will be increasing by early
afternoon. Stability parameters would suggest a better chance of
thunderstorms with a few potential strong storms with 35mph gusts
and small hail. All airfields will be impacted by clouds and
showers after 26/20Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$

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