Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 071119
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
519 AM MDT TUE JUL 7 2015

...Several rounds of thunderstorms today, fire starts possible...

.DISCUSSION...

A weather disturbance currently sliding out of BC Canada into
northwest Montana has initiated some showers and a few
thunderstorms early this morning from around Thompson Falls to
West Glacier. These cells are expected to strengthen later this
morning, perhaps organizing into a convective line as it drifts
southeastward. By this afternoon, high-resolution forecast models
indicate that showers and thunderstorms will be possible across
much of western Montana and portions of central Idaho, lasting
into the evening. The main threats would be lightning and brief
heavy rain. Although some storms will be capable of wetting rains,
given the extremely dry fuels across northwest Montana, any
lightning strikes outside of the main rain cores will present
concerns for fire starts. At this point, the greatest lightning
coverage is expected across far Northwest Montana where a Red Flag
Warning is in effect. However, additional areas of Northwest
Montana may need to be added if the threat is expected to expand.

As the trough axis moves into the area this evening, it will push
a backdoor cool front across western Montana and as far west as
the Clearwater Mountains of central Idaho. Northeast to east winds
will develop for many locations as a result, with the gustiest
winds expected in areas where the terrain channels such winds. In
particular, Badrock Canyon to Kalispell, parts of Flathead Lake,
and Hellgate Canyon will see another round of windy conditions,
though not as strong as what was experienced Sunday. Winds should
weaken by Wednesday morning.

Drier air moves in Wednesday as the trough exits the region,
along with warmer temperatures. Shower and thunderstorm chances
will be greatly diminished and generally confined to areas well
south of I-90, such as Lemhi County Idaho and the Anaconda-
Pintler vicinity of Montana.

Starting Thursday, a trough will being to develop off the West
Coast and will bring an increasing threat of thunderstorms
through the weekend and into early next week. Precipitable water
values will be above normal during this time, thus the thunderstorms
will be capable of producing heavy rain. At this time, Friday and
Saturday look to be the most active day of showers and
thunderstorms. But overall, an active weather pattern will be
setting up by the later half of this week so stay tuned for more
details.

&&

.AVIATION...An increasingly unstable atmosphere and an
approaching cold front will create modestly turbulent conditions
today, with thunderstorms possible at all area terminals by this
afternoon. Expect intermittent reductions in vsby in areas of
heaviest thundershowers. KGPI will be the first to see a chance
by mid morning, spreading thereafter to KMSO/KBTM/KSMN by the
early afternoon. KGPI may also see some breezy northeast winds as
the first line of storms moves through. Also, KGPI/KMSO and
possibly KBTM may experience gusty east winds later this
afternoon, lasting into the evening.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING until 9 PM MDT this evening Kootenai.

ID...None.
&&

$$



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