Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 060946

Area Forecast Discussion
National Weather Service Missoula MT
346 AM MDT WED MAY 6 2015

.DISCUSSION...The low pressure system centered over Washington
this morning will begin to overtake the Pacific Northwest today.
Model guidance have good agreement that the main low will remain
west and south of the region but the agreement for features over
Idaho and western Montana is poor. Because of this poor agreement
there has been a lot of changeability for chances of precipitation
north of Salmon and Butte. There is now agreement that an area of
precipitation will split off from the low and move through north
central Idaho, and southwest Montana by this evening, and through
west central Montana late this evening and overnight. This means
there are now higher chances for rain through tonight south of

If the progression of the weather system continues its current
trend, the precipitation forecast is going to be quite difficult
through much of this week. The highest confidence for showers and
thunderstorms each day is still through Lemhi County in Idaho,
and through the Butte/Blackfoot/Pintlar regions. Location along
the I-90 corridor are less certain with hit or miss showers
possible, while locations north of I-90 have the lowest chances
for rain this week.

There is still a chance for snow in the high elevations of Lemhi
County and southwest Montana mainly Thursday morning. Lost Trail
Pass has the best chance to see snow, but Homestake and MacDonald
passes also have a chance for low impact snowfall.

Drier and slightly warmer conditions are possible for the weekend
before another system arrives early next week.


Drier weather with calmer winds will remain over the TAF sites
this morning before another round of showers and isolated to
scattered thunderstorms develop near KSMN and KBTM. These showers
and thunderstorms are mainly expected after 06/2100Z, though, KBTM
may not see the effects of rain until after 07/0000Z. Any
thunderstorms that develop will bring erratic gusty winds and
lightning with brief heavy rainfall. Afternoon winds will become
breezy, gusting generally up to 15-25 kts for the TAF sites. Light
SHRA will continue for KSMN, KBTM, and even reach KMSO overnight
tonight, and ceilings will continue to obscure mountains in these



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