000
FXUS65 KMSO 172043
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
243 PM MDT Mon Jun 17 2013

...THREAT FOR STRONG THUNDERSTORMS TUESDAY & TUESDAY NIGHT...

.DISCUSSION...A few isolated thunderstorms are possible this
afternoon, mainly across southwest Montana and along the
Continental Divide, but should remain fairly benign.

Tuesday...Temperatures will rise into the 80s while the upper
levels of the atmosphere will become increasingly favorable for
strong to severe thunderstorms.

* Timing: The storms will develop by the mid-afternoon across the
  higher terrain of north-central Idaho near the Montana border
  and across west- central Montana. By Tuesday evening these
  storms will have moved into northwest Montana.

* Impacts: Large hail to 1 inch may damage vehicles and
  vegetation. Wind gusts > 50 mph could cause tree damage, spotty
  power outages and dislodge unsecured outdoor property. Localized
  heavy rain could impact flood-prone areas such as the West
  Riverside burn scar, Hot Springs and the Going-to-the-Sun road.
  Frequent lightning could impact outdoor events and those hiking
  in the back country.

Tuesday night...Southwest Montana will see a continued chance for
strong thunderstorms with the main threats being gusty winds,
heavy rain and small hail.


.Wednesday and Thursday...A very wet period will occur as the upper low
pressure system slowly enters and moves through the region. The
entire Northern Rockies will receive significant precipitation
with the greatest amounts north of the I-90 corridor in Northwest
Montana. Some strong and gusty winds are possible in southwest
Montana as the front moves through the region Wednesday. Wednesday
night into Thursday morning, snow levels may drop low enough to
bring snow to the higher terrain along the Continental Divide,
potentially impacting areas such as Marias Pass and Glacier
National Park.

Expected rain amounts from Tuesday night through Thursday:

Mountains including Lookout Pass and Glacier National
Park: 1.0"-1.5"

Valley locations including Kalispell, Libby, Polson, Eureka,
Seeley Lake: .50"-.75"

Valleys south of the I-90 Corridor including:
Missoula, Hamilton, Butte, Salmon, Grangeville: .20"-.50"

Conditions will remain cool and showery through Saturday. Forecast
models do indicate a warm up for Sunday and early next week, with
the potential for thunderstorms increasing by Monday.


&&

.AVIATION...Mid level cumulus clouds will continue to increase
across western Montana and north central Idaho this afternoon. Isolated
to scattered thunderstorms will develop this afternoon and last
into the evening, mainly across western Montana. KBTM has the greatest
threat at seeing a thunderstorm, mainly between 17/22z and 18/03z.
The main threat with thunderstorms will be for gusty winds.
Convection should be on the decrease after 18/0300z. Another round
of potentially strong thunderstorms is possible by tomorrow afternoon.

&&

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

$$

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